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New Materials of 

Masiakasaurus knopfleri

Sampson, Carrano, and Forster, 

2001, and Implications for the 

Morphology of the Noasauridae 

(Theropoda: Ceratosauria)

Matthew T. Carrano, Mark A. Loewen, 

and Joseph J. W. Sertich
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smithsonian contributions to paleobiology • number 95

New Materials of 

Masiakasaurus knopfleri

Sampson, Carrano, and Forster, 

2001, and Implications for the 

Morphology of the Noasauridae 

(Theropoda: Ceratosauria)

Matthew T. Carrano, Mark A. Loewen, 

and Joseph J. W. Sertich

washington d.c.

2011
ABSTRACT

Carrano, Matthew T., Mark A. Loewen, and Joseph J. W. Sertich. New Materials of Masiakasaurus 

knopfleri Sampson, Carrano, and Forster, 2001, and Implications for the Morphology of the Noasauridae (Theropoda: Ceratosauria). Smithsonian Contributions to Paleobiology, number 95, viii + 53 

pages, 26 figures, 3 tables, 2011. — Osteology of the noasaurid theropod Masiakasaurus knopfleri

Sampson et al., 2001, is now two-thirds complete. We describe Masiakasaurus knopfleri in detail on 

the basis of examination of new specimens and emphasis on previously unknown elements. The skull 

is anteroposteriorly long but low in height, unlike the foreshortened abelisaurid condition. Premaxillary teeth are procumbent, like those of the dentary. Frontal bones are flat and unornamented, but the 

lacrimal and postorbital exhibit surface texturing. The braincase resembles that of abelisaurids but is 

more highly pneumatized. The neck is curved anteriorly but horizontal posteriorly, and it transitions 

to the trunk without significant proportional changes. Centrum pneumaticity appears confined to the 

neck and anterior trunk. The sacrum includes six vertebrae, and the expanded transverse processes of 

caudal vertebrae may articulate with caudal ribs. The scapulocoracoid is large and broad. The ilium is 

both anteroposteriorly long and dorsoventrally deep, and it bears pegs for articulation with sockets on 

the pubis and ischium, as in other ceratosaurs. The nearly complete pes shows no particular locomotor 

specializations and allows reinterpretation of the “raptorial” pedal ungual of Noasaurus as a manual 

element. These new specimens also illuminate the morphology of other noasaurids, especially those 

from the Lameta Formation.

In addition to Madagascar, noasaurids are known from Europe, India, South America, and Africa, 

spanning at least Aptian–Albian through Maastrichtian time. The new materials of Masiakasaurus

increase character resolution within Abelisauroidea, identifying many formerly equivocal features as 

synapomorphies of the nodes Noasauridae, Abelisauridae, or Abelisauroidea. Unfortunately, the fragmentary nature of nearly all other noasaurids obviates any meaningful ingroup resolution, and as a 

result no particular evolutionary or biogeographic scenarios for the clade can presently be supported 

(or rejected) with confidence.

Cover images: Skeletal reconstruction of skull (left) and life restoration of head (right) of the theropod 

Masiakasaurus knopfleri. Skull image by Mark Loewen; head restoration by Lukas Panzarin.

Published by SMITHSONIAN INSTITUTION SCHOLARLY PRESS

P.O. Box 37012, MRC 957

Washington, D.C. 20013-7012

www.scholarlypress.si.edu

Text and images in this publication may be protected by copyright and other restrictions or owned by individuals and entities other than, and in addition to, the Smithsonian Institution. Fair use of copyrighted material includes the use of protected materials for personal, educational, or noncommercial purposes. Users must 

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any other use.

Library of Congress Cataloging-in-Publication Data

Carrano, Matthew T.

New materials of Masiakasaurus knopfleri Sampson, Carrano, and Forster, 2001, and implications 

for the morphology of the Noasauridae (Theropoda: Ceratosauria) / Matthew T. Carrano, Mark A. 

Loewen, and Joseph J. W. Sertich.

 p. cm. — (Smithsonian contributions to paleobiology, ISSN 0081-0266 ; no. 95)

Includes bibliographical references.

1. Masiakasaurus. 2. Noasauridae—Morphology. 3. Paleontology—Cretaceous. I. Loewen, 

Mark A. II. Sertich, Joseph J. W. III. Title.

QE862.S3C276 2011

567.912—dc22 2010042359

ISSN: 0081-0266 (print) / 1943-6688 (online)

The paper used in this publication meets the minimum requirements of the American National Standard 

for Permanence of Paper for Printed Library Materials Z39.48–1992.
Contents

LIST OF FIGURES v

LIST OF tables vii

INTRODUCTION 1

Institutional Abbreviations 2

Acknowledgments 2

Systematic Paleontology 3

DISCUSSION 34

Noasaurid Morphology 34

Comparative Anatomy 35

Relationships within Noasauridae 37

Evolutionary Implications for Ceratosauria 38

 Noasaurids 38

 Character Distributions 38

CONCLUSIONS 39

APPENDIX 41

REFERENCES 51

Figures

1. Composite skeletal reconstruction of Masiakasaurus knopfleri 2

2. Left premaxilla of M. knopfleri 4

3. Lacrimal and postorbital of M. knopfleri 5

4. Left frontal of M. knopfleri 6

5. Right quadrate of M. knopfleri 7

6. Braincase of M. knopfleri 8

7. Braincase of M. knopfleri 9

8. Left dentary of M. knopfleri 10

9. Left angular of M. knopfleri 10

10. Right prearticular and articular of M. knopfleri 11

11. Reconstructed skull of M. knopfleri 12

12. Cervical and anterior dorsal vertebrae of M. knopfleri 14

13. Morphological changes in the cervical and anterior dorsal 

vertebrae of M. knopfleri 17

14. Sixth dorsal vertebra of M. knopfleri 19

15. Sacrum of M. knopfleri 20

16. Middle caudal vertebra of M. knopfleri 21

17. Right sixth cervical rib of M. knopfleri 22

18. Right scapulocoracoid of M. knopfleri 24

19. Left humerus of M. knopfleri 25

20. Manual phalanges of M. knopfleri 28

21. Left ilium of M. knopfleri 29

22. Ventral pelvic elements of M. knopfleri 30

23. Right fibula of M. knopfleri 32

24. Right astragalus of M. knopfleri 33

25. Metatarsals of M. knopfleri 33

26. Associated individuals of M. knopfleri 34

Tables

1. Measurements of associated individuals of Masiakasaurus 

knopfleri from locality MAD05-42 26

2. Isolated noasaurid specimens from the Lameta Formation 36

A.1. Complete list of Masiakasaurus knopfleri specimens from 

the Upper Cretaceous Maevarano Formation of Madagascar 

collected through 2007 42

New Materials of Masiakasaurus knopfleri

Sampson, Carrano, and Forster, 2001, and 

Implications for the Morphology of the 

Noasauridae (Theropoda: Ceratosauria)

Introduction

Masiakasaurus knopfleri was first described from disassociated elements 

discovered in the Upper Cretaceous Maevarano Formation of northwestern 

Madagascar (Sampson et al., 2001). Representing nearly 40% of the skeleton, 

these remains were identified as pertaining to a small-bodied abelisauroid, 

which implied a greater morphological diversity within Ceratosauria than had 

been depicted by the better-known Ceratosaurus, Elaphrosaurus, and Abelisauridae. Masiakasaurus bore specific resemblances to otherwise poorly understood 

forms such as Noasaurus and Laevisuchus, but little more could be said about 

its relationships at that time.

A more detailed study of Masiakasaurus by Carrano et al. (2002) elaborated 

on these similarities and proposed that the three latter taxa—Masiakasaurus,

Noasaurus, and Laevisuchus—might pertain to a single clade, Noasauridae, albeit with equivocal phylogenetic support. A secondary result was an increase in 

the evidence supporting the dissolution of Ceratosauria sensu Gauthier (1986), 

in favor of a more basal placement for Coelophysoidea within Theropoda. This 

hypothesis has since received further support (Rauhut, 2002; Wilson et al., 

2003; Sereno et al., 2004), although it is not universally accepted (e.g., Tykoski 

and Rowe, 2004; Allain et al., 2007).

A recent phylogeny of Ceratosauria (Carrano and Sampson, 2008) provided 

further evidence for a monophyletic Noasauridae, which also included Velocis‐

aurus and Genusaurus but not Deltadromeus or Elaphrosaurus, as has been 

suggested (Sereno et al., 2004; Canale et al., 2009). Noasaurids have now been 

recognized in South America, Africa, Madagascar, India, and Europe, and in 

deposits as ancient as Aptian, implying a history reaching back at least into 

the earliest Cretaceous (Carrano and Sampson, 2008). Jurassic ceratosaurs 

appear to be more primitive, for example Ceratosaurus, Elaphrosaurus, and 

Matthew T. Carrano, Curator of Dinosauria, 

Department of Paleobiology, National Museum 

of Natural History, Smithsonian Institution, 

P.O. Box 37012, MRC 121, Washington, D.C. 

20013‐7012, USA; Mark A. Loewen, Depart‐

ment of Geology and Geophysics, University 

of Utah, 1390 East Presidents Circle, Salt Lake 

City, Utah 84112‐0050, USA; and Joseph J. W. 

Sertich, Department of Anatomical Sciences, 

Stony Brook University, Stony Brook, New 

York 11794‐8081, USA. Correspondence: M. T. 

Carrano, carranom@si.edu. 

Manuscript received 2 February 2009; accepted 

9 June 2010.
2 • smithsonian contributions to paleobiology

Limusaurus (Xu et al., 2009), but also include indeterminate abelisauroids (Rauhut, 2005).

Unfortunately, most noasaurid species are represented by extremely fragmentary remains (e.g., Novas et 

al., 2004), and as a result several important aspects of the 

noasaurid skeleton remain poorly known, particularly the 

skull and forearm. This makes it difficult to resolve many 

important character states within Ceratosauria. In particular, it remains equivocal whether numerous distinctive 

“ceratosaur” features are primitive for Ceratosauria or 

Abelisauroidea, or instead characterize only more highly 

nested clades.

Here we describe abundant new materials of Ma‐

siakasaurus that help resolve several of these problems (a 

complete list is given in the Appendix). Most of the skull 

is now known, along with nearly the entire vertebral series 

and hind limb, and additional bones from the forelimb. 

Overall, approximately 65% of the skeletal elements of 

Masiakasaurus have been found (Figure 1). These new 

specimens, some of which derive from associated individuals, permit a much more accurate reconstruction of Ma‐

siakasaurus and allow greater insight into the anatomical 

specializations of noasaurids more generally.

Institutional Abbreviations

The following institution names are abbreviated for 

subsequent mention in the text.

FMNH Field Museum of Natural History, 

Chicago 

GSI Geological Survey of India, Kolkata 

UA Université d’Antananarivo, Madagascar

Acknowledgments

We are very thankful for the efforts of participants in 

the 2001, 2003, 2005, and 2007 Mahajanga Basin Project 

expeditions (funded by the National Science Foundation 

and the National Geographic Society), which yielded these 

new discoveries of Masiakasaurus, as well as participants 

in previous expeditions for the original finds. D. Krause 

(Stony Brook University) and S. Sampson (University of 

Utah) have been particularly supportive of our research 

and encouraged us to continue as new materials were unearthed, and C. Forster (George Washington University) 

was especially helpful with access to specimens. We thank 

J. Groenke and V. Heisey (Stony Brook University) for 

their expert preparation of the fossils, often on short notice, and W. Simpson (Field Museum) for curatorial work. 

The manuscript was significantly improved thanks to thorough reviews by M. Lamanna and C. Forster. Figure 6 was 

skillfully rendered by M. Parrish (Department of Paleobiology, National Museum of Natural History). Translations 

of Accarie et al. (1995), Bonaparte and Novas (1985), and 

Janensch (1925) are available from the Polyglot Paleontologist web site (http://www.paleoglot.org).

FIGURE 1. Composite skeletal reconstruction of Masiakasaurus knopfleri in left lateral view, showing recovered (white) and missing (gray) 

elements. Scale bar = 1 m.

one meter 
n u m b e r 9 5 • 3

Systematic Paleontology

Dinosauria Owen, 1842

Saurischia Seeley, 1888

Theropoda Marsh, 1881

Ceratosauria Marsh, 1884

Abelisauroidea (Bonaparte and Novas, 1985) 

Bonaparte, 1991

Noasauridae Bonaparte and Powell, 1980

Type Taxon. Noasaurus leali Bonaparte and 

Powell, 1980.

Included Taxa. Compsosuchus solus Huene 

and Matley, 1933; Genusaurus sisteronis Accarie et al., 

1995; Jubbulpuria tenuis Huene and Matley, 1933; Lae‐

visuchus indicus Huene and Matley, 1933; Masiakasaurus 

knopfleri Sampson et al., 2001; Ornithomimoides? bara‐

simlensis Huene and Matley, 1933; Velocisaurus unicus

Bonaparte, 1991. Note that not all of these are valid, although they do represent noasaurids, and that the clade 

Noasauridae also includes unnamed taxa from Niger 

(Sereno et al., 2004; Sereno and Brusatte, 2008) and Argentina (Brissón Egli and Apesteguía, 2008).

Geographic Range. Europe (France), South 

America (Argentina), India, Madagascar, and Africa 

(Niger).

Temporal Range. Cretaceous, Aptian–

Albian through Maastrichtian (minimum).

Masiakasaurus knopfleri Sampson, Carrano, 

and Forster, 2001

Figures 1–20

Holotype. UA 8680, a right dentary with several teeth (Sampson et al., 2001).

Referred Specimens. See Appendix for 

complete list.

Localities. Thirty distinct localities near the 

village of Berivotra, along Route National 4 in Mahajanga 

Province (Boeny Region), northwestern Madagascar (see 

Appendix for complete list).

Age. Maastrichtian, Late Cretaceous (Rogers 

and Hartman, 1998; Rogers et al., 2000, 2007).

Strata. Anembalemba and Masorobe members, Maevarano Formation.

Description.

Skull and Lower Jaw

Important new materials from the skull of Masiakasau‐

rus provide a far better understanding of the general morphology of the skull. Only the nasal, squamosal, parietal, 

jugal, quadratojugal, and palate remain unknown, and 

whereas only three elements from the lower jaw were previously known, only the surangular is now lacking.

Premaxilla: A partial left premaxilla (FMNH PR 

2453, Figure 2) reveals that this element mirrors some of 

the unusual morphologies of the dentary (Sampson et al., 

2001; Carrano et al., 2002). This fragment preserves two 

anterior alveoli along with the adjacent body of the bone; 

the narial margin and maxillary contact are absent. However, if the ventral margin of the preserved premaxilla is 

held horizontally, these two alveoli are anteroventrally 

oriented (Figure 2A). Thus, the first and second premaxillary teeth (missing in this specimen) complemented the anterodorsal orientation of the anterior dentary teeth. This 

had been suggested previously on the basis of the anteroventral orientation of the first maxillary alveolus (FMNH 

PR 2183; Carrano et al., 2002) and is confirmed here, but 

the premaxillary teeth appear to be more strongly angled 

than the first maxillary tooth.

In ventral view, the alveoli are large, oval, and separated by a thin interdental plate (Figure 2B). The medial 

surface is flat and largely featureless, and presumably 

articulated against the contralateral element. The lateral 

surface is broadly convex and exhibits a number of small 

foramina that open into neurovascular channels directed 

toward the ventral margin of the bone (Figure 2A).

Lacrimal: One nearly complete lacrimal is known 

(FMNH PR 2473; Figure 3A–D), preserving most of the 

ventral ramus. The lateral surface shows a high degree of 

texturing and numerous vessel traces, as in abelisaurids 

(Figure 3B), but is otherwise flat, with sinuous anterior 

and posterior margins. The presence of an orbital flange 

cannot be definitively ascertained, but the preserved orbital curvature is consistent with an eye that filled most of 

the orbital fenestra, as is typical for small theropods. As in 

most theropods, the dorsal and ventral moieties of the lacrimal antorbital fossa are separated on the external bone 

surface; however, unlike nearly all other theropods except 

Torvosaurus, this separation is incomplete.

Anteriorly, the ventral portion of the antorbital fossa 

is well developed but shallow, whereas the dorsal portion 

houses a large opening into the nasolacrimal canal, as in 
4 • smithsonian contributions to paleobiology

Ceratosaurus and abelisaurids (Figure 3A; e.g., Sampson 

et al., 1998; Sampson and Witmer, 2007). Only the ventral margin of this foramen can be seen; it connected to 

a large internal chamber, the lacrimal pneumatic recess, 

which is visible through the broken dorsal surface of the 

bone. Also in anterior view, a vertical ridge separates the 

lateral components of the antorbital fossa from the shallow medial vacuity.

Posteriorly, a large, teardrop-shaped medial nasal 

pneumatic fossa (Sampson and Witmer, 2007) is visible at 

the level of the mediolateral widening of the lacrimal (Figure 3C). It sits nearly centered within the concave anterior 

orbital wall and leads to a foramen that enters the body 

of the bone. The medial surface of the lacrimal is marked 

by a thin ridge that connects dorsally with a triangular 

concave area (Figure 3D). It is not clear whether this represents the contact surface for the ventral process of the 

prefrontal or the medial surface of a fused prefrontal.

Postorbital: Like the lacrimal, the postorbital 

(Figure 3E–G) exhibits some of the characteristic texturing seen in abelisaurids. The lateral surface of the ventral 

ramus bears numerous vessel traces and small tubercles, 

which continue onto the anterior ramus (Figure 3E). A 

thickened and roughened brow ridge, also bearing vessel traces, emerges where these two rami join. The ventral 

ramus curves slightly anteriorly as it descends to its distal 

point, but lacks a flange that enters the orbital fenestra, as 

in many abelisaurids. The posterior, or squamosal, ramus 

is a shorter, flat, blunt triangle of bone that would have 

lodged within a slotted facet on the squamosal.

The medial surface of the ventral ramus (Figure 3F) 

is marked by a distinct curving ridge that separates the 

orbital and lateral temporal fossae, as in many theropods 

including abelisaurids such as Carnotaurus and Majun‐

gasaurus (Sampson and Witmer, 2007). Dorsally, this 

ridge terminates at an elongate fossa for the laterosphenoid head. The dorsal margin of this fossa is adjacent to a 

very dorsoventrally thin, medially facing articular surface, 

probably for the parietal. The more expansive frontal articulation would have been present along the thin anterolateral and anterior margins, and is only partly preserved 

in the present specimens. Finally, the posterodorsal corner 

of the orbital fenestra houses a shallow, elliptical fossa 

containing a small foramen. In Majungasaurus, a similar foramen is present but without a corresponding fossa 

(Sampson and Witmer, 2007).

The dorsal surface of the postorbital is triangular, 

broad anteriorly along the frontal but tapering to a point 

posteriorly where it articulates with the squamosal (Figure 

3G). This surface is most markedly textured along the lateral edge. The medial margin is smooth along much of its 

length, where it forms the anterolateral corner and lateral 

margin of the upper temporal fenestra. The parietal contact is straight and may have been a lappet joint. 

Figure 2. Left premaxilla (FMNH PR 2453) of Masiakasaurus knopfleri in lateral (A) and ventral (B) views. Abbreviations: idp = interdental plate; nvc = neurovascular channel; 1, 2 = alveoli. Scale bar = 1 cm. (Anterior is down in B.)
n u m b e r 9 5 • 5

Frontal: The frontal (Figure 4) is a very dorsoventrally thin, gently curved bone that entirely lacks the 

texturing or thickening seen in many abelisaurids (e.g., 

Majungasaurus; Sampson and Witmer, 2007). Instead, it 

more closely resembles the frontals of other small-bodied, 

primitive theropods such as Coelophysis in its proportions 

(quadrangular in dorsal view) and in the large orbital component along its lateral edge. It is also quite long relative to 

its width; it exhibits none of the anterior shortening seen in 

many larger or more derived theropods.

The anterior fifth of the lateral edge is occupied by a 

triangular articulation that leads into a conical socket for 

Figure 3. Lacrimal (A–D) and postorbital (E–G) of Masiakasaurus knopfleri. Partial right lacrimal (FMNH PR 2473) in anterior (A), lateral 

(B), posterior (C), and medial (D) views. Right postorbital (FMNH PR 2456) in lateral (E), medial (F), and dorsal (G) views. Abbreviations: 

aofe = antorbital fenestra; aofo = antorbital fossa; ar = anterior ramus; lsc = laterosphenoid contact; ltf = lateral temporal fenestra; ltfo = lateral 

temporal fossa; mr = medial ridge; mv = medial vacuity; nlc = opening into nasolacrimal canal; npf = nasal pneumatic fossa; of = orbital fenestra; 

ofo = orbital fossa; pac = parietal contact; sqr = squamosal ramus; utf = upper temporal fenestra; vr = ventral ramus. Scale bar = 1 cm. (Anterior 

is up in G.)
6 • smithsonian contributions to paleobiology

the prefrontal (Figure 4C). The depth of this socket suggests that it may have allowed for limited invasion of the 

frontal by pneumatic structures from the lacrimal, as in 

Majungasaurus (Sampson and Witmer, 2007). The posterior fifth bears a small, flat, triangular facet for the anterior 

ramus of the postorbital. Between these two articulations, 

the lateral edge of the frontal is sharp, subtends an arc of 

approximately 70°, and forms the dorsal rim of the orbit.

The anterior edge is also sharp, forming the underside 

of a broad lappet joint for the nasal that covers approximately 10% of the dorsal surface (Figure 4A). This edge 

is relatively straight and meets the midline at an angle of 

about 20°. The medial surface is a nearly flat and weakly 

striated facet for the opposing frontal (Figure 4D). It exhibits almost no curvature, and tapers in thickness both anteriorly and posteriorly from its thickest point, dorsal to the 

posterior half of the orbit. Although broken in both specimens, the posterior frontal appears to have been thicker 

and more rounded than the anterior. It arcs ventrally to 

form the anteromedial wall of the upper temporal fossa, 

the border of which is marked by a distinct rim. This fossa 

occupies about one-fifth of the surface of the frontal.

Ventrally, the lateral portion of the frontal is markedly concave and forms the roof of the orbital fossa (Figure 

4B). It is demarcated from the medial portion by a strongly 

curving ridge that thins mediolaterally from anterior to 

posterior. This medial moiety is flat and narrows between 

its expanded anterior and posterior portions. The anterior 

expansion contains a small, elliptical fossa for the olfactory lobe of the brain. Posteriorly, the expansion marks the 

location of the cerebral hemisphere, which is followed by 

a deeper concavity. A groove runs along the medial edge of 

the curved ridge anteriorly from the cerebral fossa.

Quadrate: A partial right quadrate (Figure 5; 

FMNH PR 2496) is one of few elements that can be directly compared with material in other noasaurids (i.e., 

Noasaurus). It has a fairly straight shaft, as in most abelisaurids, but unlike the strongly posteriorly concave condition seen in Noasaurus.

There is no evidence of a foramen on the posterior 

surface, either in the body of the bone or along the quadratojugal contact (Figure 5B). However, the body is sufficiently damaged that the presence of a small foramen or 

fossa (as in Majungasaurus; Sampson and Witmer, 2007) 

cannot be ruled out. The quadratojugal contact is very 

thin, and wraps around onto the posterior surface along 

the ventralmost portion of the bone (Figure 5A), as in Car‐

notaurus, Abelisaurus, and other abelisaurids.

The quadrate condyles are similar in width but markedly asymmetrical in anteroposterior length, with the medial condyle length nearly twice that of the lateral. The 

two condyles are oriented at an acute angle to one another 

Figure 4. Left frontal (FMNH PR 2475) of Masiakasaurus knopfleri in dorsal (A), ventral (B), lateral (C), and medial (D) views. Abbreviations: chf = cerebral hemisphere fossa; mfrc = midline frontal contact; nac = nasal contact; of = orbital fenestra; ofo = orbital fossa; olf = olfactory 

lobe fossa; poc = postorbital contact; prfc = prefrontal contact; utfo = upper temporal fossa. Scale bar = 1 cm.
n u m b e r 9 5 • 7

(Figure 5D). This is comparable to the condition in No‐

asaurus, Ilokelesia, and Majungasaurus. The intercondylar 

sulcus is only about two-thirds of the width of either condyle, and is oriented approximately 45° anteromedially.

On the medial side of the quadrate, the pterygoid 

articular flange is only partly preserved (Figure 5C). Its 

ventral extent reaches nearly to the base of the quadrate, 

unlike the condition in some theropods (e.g., Afrovenator,

Baryonyx) where up to one-third of the quadrate shaft extends ventral to the flange. There does not appear to be a 

ventral shelf on the pterygoid ramus, as seen in Majungas‐

aurus (Sampson and Witmer, 2007).

Braincase: FMNH PR 2457 (Figures 6, 7) is a 

partial braincase that comprises the basioccipital, basisphenoid, and left exoccipital-opisthotic. It is evidently 

from a subadult individual because the right exoccipital–

opisthotic has separated from the remaining braincase elements part way along their natural sutural planes. The 

braincase is broken just anterior to the prootic pendant, 

transecting the hypophyseal fossa. This affords an anterior 

view of the fossa along with the foramina for the entrance 

of cranial nerve VI.

As seen in posterior view, the foramen magnum is 

large (Figure 6A). A wide, shallow furrow in the dorsal 

surface of the occipital condyle indicates the path of the 

spinal cord. The condyle itself is semilunate; its dorsolateral edges are formed by the exoccipitals but the remainder is composed of the basioccipital. The exoccipital gives 

rise to a narrow ridge along the edge of the foramen magnum, ventrolateral to which are found the exits for cranial 

nerves XI and XII. A median vertical ridge descends from 

the base of the condyle and is flanked laterally by gently 

concave areas that probably represent a ventral extension 

of the paracondylar recesses. The basioccipital–basisphenoid contact is incomplete, but appears to have been horizontal (transverse) as in abelisaurids, rather than oblique 

as in most other theropods.

When observed in lateral view (Figures 6B, 7A), the 

braincase is extensively pneumatized by numerous fossae, 

many of which are also present in the braincases of the 

basal tetanurans Eustreptospondylus and Piatnitzkysaurus

(Rauhut, 2004; Sadleir et al., 2008), as well as the abelisaurid Majungasaurus (Sampson and Witmer, 2007). These include a large triangular fossa that comprises the columellar 

recess and the foramen ovale. The anterior tympanic recess 

is oval and located posteroventral to the prootic pendant. 

Smaller fossae are present both dorsal and posterodorsal to 

this recess, separated from it by an oblique ridge.

The prootic pendant has a short, ventrally directed 

ala. Its anteroventral edges are much less distinct than 

its posterior ones, similar to Majungasaurus (Sampson 

and Witmer, 2007) and Carnotaurus, but unlike Sinrap‐

tor (Currie and Zhao, 1993 [1994]) in which the ala is 

strongly demarcated around its entire margin. The ala itself floored a fossa, bounded by a dorsally situated ridge. 

Ventral to the ala, the canal for the cerebral carotid artery 

Figure 5. Right quadrate (FMNH PR 2496) of Masiakasaurus 

knopfleri in posterolateral (A), posterior (B), medial (C), and ventral 

(D) views. Abbreviations: ics = intercondylar sulcus; lc = lateral condyle; mc = medial condyle; ptf = pterygoid flange; qjc = quadratojugal contact. Scale bar = 1 cm.
8 • smithsonian contributions to paleobiology

passes horizontally into the anterior tympanic recess and 

toward the exit for the internal carotid artery. The large, 

oval trigeminal foramen lies dorsal to the prootic pendant, along the broken anterior margin of the braincase. 

Although the margins of the foramen are incomplete as 

a result of breakage, the dorsal edge appears to be complete and the ventral edge exhibits a partial partition; thus 

we interpret that the exit for cranial nerve V was incompletely segregated into distinct openings for the ophthalmic (V1

) and maxillary (V2) plus mandibular (V3) nerves, 

as in abelisaurids (Sampson and Witmer, 2007; Carrano 

and Sampson, 2008). The groove for the middle cerebral 

vein is visible along the dorsal margin of the trigeminal 

foramen. The exit for cranial nerve VII is posteroventral to 

this, separated from it by a low ridge. Further posterodorsally, the otosphenoidal crest (crista prootica) bounds the 

stapedial groove and forms the anterodorsal margin of the 

columellar recess/foramen ovale. This large fossa would 

have housed the exits for cranial nerves IX and X; the 

margins of these exits are broken, but are more intact on 

the endocranial surface.

Much of the ventral surface has been damaged, but a 

deep basisphenoidal recess is present, including the remnant of a laminar median partition. The recess appears to 

have been teardrop-shaped, as in abelisaurids, rather than 

oval, as is typical of other theropods. Anterior to it lies the 

base of the cultriform recess, which is transversely narrow 

and would have invaginated into the (now lost) ventral 

portion of the basisphenoid.

Some of the internal structures of the braincase can be 

seen, including foramina for the passage of cranial nerves 

and cerebral vasculature, as well as portions of the inner 

Figure 6. Braincase (FMNH PR 2457) of Masiakasaurus knopfleri in posterior (A) and left lateral (B) views. Abbreviations: atr = anterior 

tympanic recess; bocc = basioccipital; bsp = basisphenoid; ccac = cerebral carotid artery canal; cr/fo = columellar recess/foramen ovale; ex/op = 

exoccipital/opisthotic; df = dorsal furrow; fm = foramen magnum; mcvg = middle cerebral vein groove; oc = occipital condyle; otsc = otosphenoidal crest; pcr = paracondylar recess; prp = prootic pendant; sg = stapedial groove; V2-3, VII, XI, XII = exits for respective cranial nerves. Scale 

bar = 1 cm.
n u m b e r 9 5 • 9

ear and semicircular canals (Figure 7B). Details on these 

will be reported elsewhere (e.g., Sipla, 2007).

Dentary: A complete left dentary (Figure 8A; 

FMNH PR 2471) shows—for the first time—the true proportions of this bone, which are somewhat more elongate 

than had been reconstructed originally (Sampson et al., 

2001; Carrano et al., 2002). Specifically, the ventral process of the dentary is not shortened as in abelisaurids, but 

extends posteriorly far past the surangular contacts.

The articulations with the postdentary bones are also 

better preserved than in previously described specimens 

and reveal more detail about the unusual morphology of 

the intramandibular articulations. The posterior region of 

the dentary is very similar to that of both Carnotaurus and 

Majungasaurus in exhibiting four distinct processes, three 

of which form a dorsally placed “socket” for reception of a 

prong from the surangular (Figure 8B). These three dorsal 

processes are arrayed in close proximity to one another: 

the short dorsal and ventral surangular processes mark the 

lateral margins of this socket; the moderate-sized intermediate surangular process forms the medial wall (Sampson 

and Witmer, 2007). The proportions of these three processes are more heterogeneous in Masiakasaurus than in 

Majungasaurus, and the fossa is narrower and deeper.

In medial view, the intermediate surangular process 

lies at the terminus of a longitudinal buttress that is ventral to the paradental plates and forms the dorsal limit of 

the splenial articulation (Figure 8C). This articulation is 

particularly pronounced toward its anterior end, at about 

midlength along the dentary. Along the ventral dentary, 

Figure 7. Braincase (FMNH PR 2457) of Masiakasaurus knopfleri in left lateral (A) and left medial (B) views. Abbreviations: atr = anterior 

tympanic recess; cr/fo = columellar recess/foramen ovale; ic = foramen for internal carotid artery; mcvg = middle cerebral vein groove; oc = occipital condyle; prp = prootic pendant; scc = region housing semicircular canals; sg = stapedial groove; V2-3, VII, IX, X, XI, XII = foramina for 

respective cranial nerves. Scale bar = 1 cm.
1 0 • smithsonian contributions to paleobiology

the splenial ridge is more elongate and farther from the 

ventral margin of the bone than in Majungasaurus (Sampson and Witmer, 2007). As in Majungasaurus, a single 

neurovascular foramen is visible at the base of the first alveolus on the medial side, although this is correspondingly 

more posteriorly placed in Masiakasaurus.

The neurovascular foramina on the lateral surface of 

the dentary are relatively large and arrayed serially within 

the longitudinal sulcus (Figure 8A). They become more elliptical posteriorly. Unusually, these foramina also extend 

down along the dorsoventral depth of the first alveolus.

Angular: Two nearly complete left angulars 

(FMNH PR 2455, UA 9147) throw suspicion on the identification of FMNH PR 2166, previously described as 

a right angular (Carrano et al., 2002). The identities of 

FMNH PR 2166 and its parent taxon remain unclear.

The angular of Masiakasaurus is triangular in mediolateral view and broadly curved along its dorsal and 

ventral edges (Figure 9). In this view, the dorsal curve 

suggests an anteroposteriorly elongate external mandibular fenestra, the posterior terminus of which is indicated 

by a subtle change in curvature (Figure 9A). The posterior edge of the element is blunt but incomplete at the 

Figure 8. Left dentary (FMNH PR 2471) of Masiakasaurus knopfleri in lateral view (A). Enlargement of intramandibular joint in posterolateral (B) and medial (C) views. Abbreviations: dsap = dorsal surangular process; emf = external mandibular fenestra; isap = internal surangular 

process; lb = longitudinal buttress; ls = longitudinal sulcus; sfo = surangular fossa [“socket”]; vp = ventral process of dentary; vsap = ventral 

surangular process; 1–11 = tooth positions/alveoli. Scale bar in A = 1 cm.

Figure 9. Left angular (UA 9147) of Masiakasaurus knopfleri in 

lateral (A) and medial (B) views. Abbreviations: addi = insertion for 

adductor musculature; dc = dentary contact; emf = external mandibular fenestra; sac = surangular contact; splc = splenial contact; 

arrow marks posterior extent of emf. Scale bar = 1 cm.
n u m b e r 9 5 • 1 1

posteroventral corner, where it presumably had a long, 

thin extension along the ventral mandible as in other theropods. The anterior end tapers to a slender point. A long, 

convexo-concave facet along the anteroventral edge represents the splenial articulation, above which the angular 

is slightly textured and thickened. This facet is longer and 

more laterally exposed than in Majungasaurus (FMNH 

PR 2100). A shallow fossa is also present near the posterodorsal corner, presumably for the anterior portion of 

the M. pterygoideus ventralis (Holliday, 2009).

Medially, the posterior part of the angular bears a 

long, dorsally facing, oval fossa that marks the insertion 

site of the adductor musculature (Figure 9B). This fossa 

lies adjacent to a faint contact surface along the vertical 

face of the posterior angular for the surangular. A flat, 

dorsally facing facet sits on the dorsomedial surface of 

the anterior prong, marking the dentary contact. This is 

unlike the condition in Majungasaurus, where these two 

bones were not in direct articulation (Sampson and Witmer, 2007). The prearticular would have articulated along 

the convex ventral margin of the bone.

Prearticular: The prearticular resembles that 

of most basal theropods in overall shape (Figure 10). In 

mediolateral view, it is much longer than tall, gently curved 

along its ventral edge, and more strongly curved dorsally, 

where it forms the ventral border of the internal mandibular fenestra (Figure 10A,B). This curvature is shallow, contrasting the stronger arc seen in the foreshortened jaws of 

the abelisaurids Majungasaurus and Carnotaurus.

Anteriorly and posteriorly, the prearticular expands 

to approximately equal dorsoventral depths. The anterior 

flange is incompletely known, but a short portion of convex curvature along its ventral edge suggests that it may 

have had a shape similar to Majungasaurus (Sampson and 

Witmer, 2007). The posterior flange articulates against 

and is partly ventral to the lateral portion of the articular. 

This flange is complete in UA 9149, where it tapers posteroventrally to a long, finger-like projection with a concave dorsal surface for the articular.

The prearticular curves ventrolaterally to create a 

concavity (Figure 10A). Below this, the ventral edge forms 

a flat, posteromedially twisted facet for the angular. The 

lateral surface is marked by thickenings along the ventral and dorsal edges, which bound a narrow furrow that 

runs from the articular contact to the anterior flange. A 

roughened patch at the posterodorsal edge of the internal 

Figure 10. Right prearticular and articular (UA 9166) of Masiakasaurus knopfleri

in lateral (A) and medial (B) views. Dorsal 

view (C) of mandibular glenoid. Abbreviations: ac = angular contact; art = articular; 

igr = inerglenoid ridge; imf = internal mandibular fenestra; mg = medial glenoid fossa; 

rf = retroarticular fossa; sac = surangular 

contact. Scale bars = 1 cm.
1 2 • smithsonian contributions to paleobiology

mandibular fenestra represents the contact surface for the 

surangular.

Articular: The single right articular (UA 9166) 

is articulated with the corresponding prearticular but is 

somewhat damaged, obscuring several of its surfaces. 

However, most of the medial glenoid fossa is intact, and 

presents a deeply concave trough for the medial quadrate 

condyle that is oriented approximately 30° anteromedial 

to the midline axis (Figure 10C). The medial edge of the 

fossa is tall, and the lateral edge is marked by a low interglenoid ridge. The surangular would have contacted the 

angular lateral to this point, forming most of the lateral 

glenoid fossa for articulation with the lateral quadrate 

condyle. A concave fragment lying posterior to the medial glenoid fossa represents the anteriormost portion of 

the dorsally facing retroarticular fossa, the lateral side of 

which would have been formed by the surangular.

In medial view, a small, convex portion of the articular is exposed dorsal to the prearticular, but the remainder 

is covered (Figure 10B). The lateral side is damaged and 

much is missing, including the lateral glenoid fossa and the 

area of the chorda tympani foramen.

Hyoid: A long, slender, curved element associated 

with FMNH PR 2481 is identified as a ceratobranchial. 

The articulation with the basihyal has two facets that meet 

at a 120° angle. The shaft tapers adjacent to the articulation, but remains uniformly narrow throughout most of 

the rest of its length. The distal end is not preserved. The 

lateral surface is convex, but a thin concavity runs along 

the medial side. Overall it is similar to the same element in 

Carnotaurus (Bonaparte et al., 1990) and Majungasaurus.

General skull morphology: With these new elements we have attempted to reconstruct the entire skull 

and lower jaw (Figure 11). We have restored the skull to 

be relatively long and low based on the primitively proportioned maxilla and frontal. Nonetheless, an accurate 

length:height ratio cannot yet be provided. In profile the 

skull of Masiakasaurus superficially resembles those of 

other small theropods, including Coelophysis, Compsog‐

nathus, and Ornitholestes; these similarities are a result of 

the relatively large orbit and long snout rather than any 

particular phylogenetic affinity. The most unusual features 

of the skull are confined to the anterior portions of the 

jaws. In dorsal view, the skull likely had a similarly plesiomorphic shape, tapering to a narrow snout from its widest 

point near the anterior edge of the frontal; posteriorly, the 

sides of the skull were approximately parallel. The lower 

jaw is closer to the abelisaurid condition than to that of 

other theropods, particularly in the morphology of the intramandibular joint.

Axial Column

Numerous vertebrae from all parts of the column 

greatly extend our knowledge of axial column morphology 

Figure 11. Reconstructed skull of Masiakasaurus knopfleri in left lateral view. Known elements 

(or parts thereof) are stippled; unknown elements are outlined.
n u m b e r 9 5 • 1 3

in Masiakasaurus and clarify comparisons with Noasau‐

rus and Laevisuchus (Huene and Matley, 1933; Bonaparte 

and Powell, 1980; Carrano et al., 2002). Most of the 

cervical series is represented; only the atlas is missing. 

Among the dorsals, only portions of the midtrunk remain 

unknown or unidentified. All sacrals and portions of all of 

the major caudal regions are also represented.

Although individual variations make precise identification of position uncertain for some specimens, the 

relatively complete cervical and dorsal series of Carnotau‐

rus (Bonaparte, 1991), Elaphrosaurus (Janensch, 1925), 

Majungasaurus (O’Connor, 2007), and Spinostropheus

(Sereno et al., 2004) provide instructive comparative materials. We can also clarify the positions of some previously 

identified cervicals (Carrano et al., 2002). The pre-caudal 

vertebral formula of Masiakasaurus matches well with 

that of Carnotaurus, which possesses 10 cervicals, 12 free 

dorsals, and 6 sacrals (including 2 dorsosacrals and 2 caudosacrals). The terminology of Wilson (1999) regarding 

most laminae and fossae is followed here.

Cervical vertebrae: The axis (Figure 12A–D) is 

known from two specimens (FMNH PR 2462, 2466), and 

in both cases the axial centrum and atlantal intercentrum 

are coossified. Two isolated atlantal intercentra (FMNH 

PR 2477, 2630) show a morphology consistent with these 

fused examples.

In lateral view, the axis bears a small but distinct oval 

parapophysis; the long axis is oriented slightly posteroventrally (Figure 12A). A large, horizontally oval pneumatic 

foramen lies posterior to the parapophysis and leads into 

a sizable internal chamber. A second, smaller foramen is 

present more posteriorly in FMNH PR 2462. Unlike in 

Majungasaurus, this foramen is not located exclusively 

posterior to the diapophysis but also partly ventromedial 

to it (O’Connor, 2007). The outer edges of the foramen 

are smooth, showing no evidence of a surrounding pneumatic fossa. The chamber is separated from its opposite 

by a median septum; it is further subdivided in FMNH PR 

2466. The neurocentral suture can still be seen although 

it is clearly tightly closed in both specimens. The intercentrum projects horizontally anterior to the parapophysis; 

it is not upturned as in Sinraptor (Currie and Zhao, 1993 

[1994]). The odontoid projects farther anteriorly than the 

intercentrum and bears a shallow lateral fossa.

On the neural arch, a distinct oval facet marks the 

articular surface of the prezygapophysis. The pendant diapophysis is located directly posteroventrally and is angled slightly posteriorly. On its posteroventral surface, a 

small infradiapophyseal fossa is demarcated by anterior 

and posterior laminae. The diapophysis is connected to 

the epipophysis and postzygapophysis by a pronounced 

postzygodiapophyseal lamina. This lamina forms the 

anterodorsal edge of the infrapostzygapophyseal fossa, 

which houses either a distinct foramen or a deep fossa. 

The postzygapophysis is quadrangular, and is considerably surpassed by the dorsoventrally flat epipophysis. In 

lateral view, the neural spine is broadly arched, closer in 

shape to that of Carnotaurus than Majungasaurus, and 

hangs slightly posteriorly over the centrum.

Ventrally, the axis is nearly flat, with a very faint 

midline ridge but no keel. A similar transverse ridge 

connects the parapophyses. The centrum is somewhat 

spool-shaped, and its width is subequal to that of the atlantal intercentrum.

Anteriorly, the intercentrum presents a wide, reniform, 

concave articular facet for the atlantal centrum (Figure 

12B). It sits ventral to the prominent, D-shaped odontoid, 

which has a nearly flat dorsal surface, flanked laterally by 

slight ridges that would have floored the neural canal. The 

odontoid is rounded anteriorly. In this view the diapophyses curve ventrolaterally, whereas the prezygapophyses 

face dorsolaterally. In posterior view the epipophyses are 

nearly as wide as the postzygapophyses (Figure 12C), although they do not project laterally as in Majungasaurus

(O’Connor, 2007).

The third cervical vertebra (C3) is characterized by 

anterior and posterior centrum faces that are dorsoventrally offset and not parallel in lateral view. A small, round 

pneumatic foramen pierces the centrum posterodorsal to 

the parapophysis, which is broken in the only known 

specimen (UA 9121). On the arch, a strong posterior 

centrodiapophyseal lamina runs from the diapophysis to 

the posterior end of the neurocentral suture, separating 

the elongate infradiapophyseal fossa ventrally from the 

expansive infrapostzygapophyseal fossa dorsally. A longer postzygodiapophyseal lamina is discriminated from 

the diapophysis by a kink in its trajectory. The infraprezygapophyseal fossa is shallow and faces anteriorly. The 

prezygapophyseal–epipophyseal lamina is pronounced, 

and exhibits a small rise and thickening at its midlength. 

The short diapophysis hangs nearly vertically.

Anteriorly, the centrum face is flat and approximately 

rectangular. More dorsally, the neural canal is circular and 

approximately 80% as large as the centrum face. The small, 

triangular infraprezygapophyseal fossa is separated from 

the more medially placed anterior peduncular fossa by an 

additional lamina. The prezygapophyses are widely separated from the midline, where they flank a deep prespinal 

fossa. The posterior centrum face is concave and D-shaped. 

The postzygapophyses are angled laterally approximately 
1 4 • smithsonian contributions to paleobiology
n u m b e r 9 5 • 1 5

30°. The deep postspinal fossa houses a pair of large subsidiary foramina, and is separated from the triangular peduncular fossae ventral to it by thin laminae.

In dorsal view, the arch is rectangular, with two 

V-shaped incisions marking the prespinal and postspinal 

fossae between their respective zygapophyses. A distinct 

dorsal fossa is visible adjacent to the prezygapophyseal–

epipophyseal lamina, near the base of the prezygapophysis. The neural spine is very thin transversely, located 

above the midlength of the centrum, and extends only a 

few millimeters above the flat dorsal surface. The ventral 

surface of the centrum is nearly flat.

The fourth cervical vertebra (C4; Figure 12E–H) more 

strongly resembles the only known cervical of Noasaurus

than any of those previously described, especially in its 

elongate proportions (Carrano et al., 2002). It is generally similar to C3, although the centrum faces are more 

strongly offset, and a second pneumatic foramen is present on the centrum (Figure 12E). This smaller foramen is 

located posterior to the diapophysis, and on one specimen 

(UA 9106) has a scalloped posteroventral margin marking the path of associated soft-tissues. In this specimen, a 

portion of the cervical rib is still articulated, but not fused, 

with the left diapophysis.

The proportions of the laminae and fossae are similar 

to those of C3. Here, the infrapostzygapophyseal fossa is 

partitioned into a large dorsal chamber, which communicates with the interior of the arch, and a smaller, blind 

posteroventral fossa. The infradiapophyseal fossa has an 

uneven surface, and may connect to the infrapostzygapophyseal fossa on the right side. The neural spine 

is thicker and more rectangular than in C3. In C4 the 

prezygapophyseal–epipophyseal lamina undulates such 

that the zygapophyses are more dorsally positioned than 

is the midpoint of this lamina. The epipophysis is long and 

acuminate, extending posteriorly well past the postzygapophysis and the posterior centrum face. The neural 

spine is half as long anteroposteriorly as the centrum, and 

bears a sloping anterior edge but a more vertical posterior 

one (Figure 12E, H).

Anteriorly, the centrum face is reniform, and the peduncular fossae are more conical and larger than in C3 

(Figure 12F). The prezygapophyses extend laterally only 

as far as the diapophysis, which has a shallower infraprezygapophyseal fossa. The prespinal fossa is narrower and 

deeper than in the preceding vertebra. The posterior centrum face is rounder than the anterior face. In dorsal view, 

the prezygapophyses are oblate, and the postzygapophyses 

are visible laterally, ventral to the acuminate epipophyses 

(Figure 12H). The prezygapophyseal–epipophyseal lamina 

is straight. Ventrally, the centrum is more elongate than in 

C3; the anterior and posterior edges are twice as wide as 

the midcentrum.

The fifth cervical vertebra (C5) is generally similar 

to the preceding elements, but the prezygapophyseal–epipophyseal lamina is less distinct at its midlength, represented by an undulating curve rather than a marked ridge. 

This change is related to the emergent elevation of the 

prezygapophysis relative to the dorsal arch surface. The 

neural spine is shorter anteroposteriorly and more posteriorly positioned over the neural arch; the epipophysis is 

more downturned.

The anterior centrum face is more rounded than in 

C3 and C4, and the prezygapophyses are more horizontally oriented and spaced farther apart laterally. The infraprezygapophyseal fossa is very small and shallow, and is 

contiguous with a fossa on the medial portion of the cervical rib in FMNH PR 2465. The shallow prespinal fossa is 

wide and more open dorsally. Posteriorly, the peduncular 

fossae are very shallow.

In the only known sixth cervical vertebra (C6; Figure 

12I–L; FMNH PR 2628), the centrum faces remain offset from one another and are vertically inclined (Figure 

12I). A single pneumatic foramen is present, adjacent to 

the left parapophysis, but faint traces of a pair of pneumatic fossae are evident on both sides of the centrum. 

The prezygapophysis is now elevated to the same height 

as the neural spine, and the infrapostzygapophyseal fossa 

is large but less pronounced than in preceding vertebrae. 

The prezygapophyseal–epipophyseal lamina dips ventrally 

Figure 12. Cervical (A–O) and anterior dorsal (M–P) vertebrae of Masiakasaurus knopfleri in left lateral (A, E, I, M), anterior (B, F, J, N), 

posterior (C, G, K, O), and dorsal (D, H, L, P) views. A–D, axis (FMNH PR 2466); E–H, fourth cervical vertebra (UA 9106); I–L, sixth cervical 

vertebra (FMNH PR 2481); M–P, first dorsal vertebra (FMNH PR 2837). Abbreviations: ai = atlantal intercentrum; dp = diapophysis; epi = 

epipophysis; hs = hyposphene; idf = infradiapophyseal fossa; ipof = infrapostzygapophyseal fossa; iprf = infraprezygapophyseal fossa; ncs = neurocentral suture; ns = neural spine; od = odontoid; pcdl = posterior centrodiapophyseal lamina; pdf = peduncular fossa; pf = pneumatic foramen 

or fossa; podl = postzygodiapophyseal lamina; poz = postzygapophysis; pp = parapophysis; prepl = prezygapophyseal-epipophyseal lamina; prz 

= prezygapophysis. Scale bars = 1 cm. (Anterior is up in D, H, L, and P.)
1 6 • smithsonian contributions to paleobiology

before rising to meet the very small epipophysis, and lacks 

any thickening at midlength. The neural spine is shorter 

anteroposteriorly than in C3–C5.

Anteriorly, the infraprezygapophyseal fossa is deeper 

and extends along the length of the extended diapophysis, 

whereas the peduncular fossa is very shallow (Figure 12J). 

The prezygapophyses are angled at 45°. As seen in posterior view, the postspinal fossa is very deep but narrow, and 

the peduncular fossa is small but also deep (Figure 12K). 

The posterior centrum face is more transversely oval than 

in preceding vertebrae.

The prezygapophyseal–epipophyseal lamina is more 

distinct in dorsal view than in more anterior cervicals, 

and is slightly concave along its course (Figure 12L). A 

U-shaped margin leads to the prespinal fossa; the postspinal fossa sits at the base of a V-shaped embayment. A 

pair of large foramina is evident on the dorsal surface, 

just posteromedial to the prezygapophyses. In ventral 

view, the parapophyses are connected by a thin transverse 

ridge, and the infradiapophyseal fossa appears deep and 

multi-chambered.

The previously illustrated Laevisuchus vertebra (GSI 

K27/696; Carrano et al., 2002: fig. 7B) is very similar to 

this specimen in proportions, and we intepret it as C6 

based on the offset of the centrum faces and the relative 

positions of the neural spine and neural arch processes.

The seventh and eighth cervical vertebrae (C7, C8) 

lack any offset between the centrum faces but are otherwise similar to C6. In these elements the epipophysis is 

slender and does not extend posteriorly past the postzygapophysis; the neural spine is small and blocky. Note that 

three specimens (FMNH PR 2140, 2139, and 2141) were 

originally assigned to three successive positions within the 

neck (Carrano et al., 2002). Based on comparison with 

newly discovered material, we now identify FMNH PR 

2139 as C7, FMNH PR 2141 as C8, and FMNH PR 2140 

as C10 (see Appendix). C7 and C8 have, therefore, been 

previously described in detail (Carrano et al., 2002).

In lateral view, the ninth cervical vertebra (C9) differs from the two preceding elements in that it exhibits a 

slightly backswept neural arch. The distance between the 

prezygapophysis and postzygapophysis is reduced such 

that the prezygapophyseal–epipophyseal lamina is folded. 

The epipophysis is very small. The postzygodiapophyseal 

lamina exhibits a distinct kink along its trajectory.

Relative to more anterior elements, in C9 the diapophysis extends more directly laterally and bears a 

well-defined infraprezygapophyseal fossa that is very deep 

medially. Anteriorly, the peduncular fossa is absent, and 

the neural canal is smaller relative to the centrum face. 

The prespinal fossa is very shallow and fully opened anteriorly. Posteriorly, the peduncular fossa is much smaller 

than the postspinal fossa, and the infrapostzygapophyseal 

fossa exhibits deep foramina.

The tenth cervical vertebra (C10) lies at or near the 

cervicodorsal transition, although this can be difficult to 

define in theropods. Its unusually long proportions indicate that Masiakasaurus was characterized by anteroposteriorly lengthened centra throughout the presacral 

vertebral column. This is unlike the condition in most theropods, where the cervicodorsal transition is marked by 

one or two anteroposteriorly short vertebrae.

Vertebra C10 retains a small, anteriorly placed pneumatic foramen, but lacks any evidence of a more posterior 

foramen or fossa. The parapophysis is elevated just dorsal 

to the ventral margin of the centrum. Unlike all other cervicals (and dorsals), the prezygapophysis is oriented nearly 

vertically, such that its posterior margin is approximately 

even with the anterior edge of the neural spine. In addition, the postzygodiapophyseal lamina is not concave but 

bears an outward kink close to its dorsal terminus.

In anterior view, the diapophysis is more elevated 

than in C9, with a more expansive anterior face and associated infraprezygapophyseal fossa. As seen in posterior 

view, the postzygapophysis is elevated to the level of the 

neural spine. As in C8 and C9, the dorsal surface of the 

arch bears a pneumatic foramen that faces the area of 

the prezygapophysis. The arch is visibly set back from the 

anterior border of the centrum in dorsal view.

Trends within the cervical series: The entire cervical series of Masiakasaurus is highly pneumatized. This 

pneumaticity includes: (1) two fossae on the centrum, the 

anterior of which consistently forms a foramen; (2) communications between the centrum and arch pneumaticity 

via the neurocentral suture; (3) three deeply invaginated 

fossae ventral to the transverse process on the neural 

arch, each with one or more foramina; and (4) peduncular fossae and foramina. Within the series, pneumaticity 

increases posteriorly; examples include the appearance of 

peduncular fossae subsequent to C4 and the presence of 

foramina on the dorsal surface of the arch starting on C6. 

It is likely that the pneumaticity of the anterior centrum 

fossae is directly related to cervical rib pneumaticity (see 

below). Similarly, the dorsal arch fossae of C6–C10 might 

bear some relation to the presence of a fossa alongside the 

prezygapophyseal–epipophyseal lamina in C3 and C4.

The anterior half of the cervical series articulates 

along a gentle curve in its neutral position, but the last 

half is nearly straight because of the lack of offset between 

the anterior and posterior centrum faces. The epipophyses 
n u m b e r 9 5 • 1 7

are more pronounced anteriorly as well, and the neural 

spine is longer, although still small. Pronounced left-right 

asymmetry is common with respect to both the presence 

and degree of development of pneumatic structures.

Although the absence of significant centrum length 

changes obscures some aspects of the cervicodorsal transition in Masiakasaurus, this transition is nonetheless evident 

in other morphological features. For example, the transverse distance between both the pre- and postzygapophyses declines rapidly from C9–D2, and both articulations 

become more horizontally oriented (Figure 13). A the same 

time, the prezygapophysis and its peduncle become vertically oriented in lateral view, and then abruptly lower again.

Dorsal vertebrae: Compared with the most posterior cervicals, the only known first dorsal vertebra (D1; 

Figure 12M–P; FMNH PR 2837) has a more equilateral 

profile overall. The centrum remains proportionally long 

(length:height = 2.0), although the ventral margin is more 

strongly arched (and this arch has a more posteriorly positioned apex) than in the posterior cervicals. The parapophysis is D-shaped and situated just ventral to the neurocentral 

suture, which remains visible but not patent (Figure 12M). 

A large, elliptical pneumatic foramen lies directly posterior to the parapophysis and opens into a chamber within 

the centrum. Marked, longitudinally oriented striations are 

present along the rims of the centrum faces.

The arch laminae are well developed (Figure 12M). 

An extensive pneumatic fossa occupies most of the large 

infraprezygapophyseal fossa on the left side, whereas 

the right is perforated by a large foramen; on both sides 

a smaller, round foramen is present in the posterodorsal 

corner of the fossa. The infradiapophyseal fossa is small 

Figure 13. Morphological changes in the cervical and anterior dorsal vertebrae of Masiakasaurus knopfleri. Dashed 

lines represent interpolations across missing data; gray area indicates the region of the cervicodorsal transition. Abbreviations: pedA (diamonds) = angle between floor of neural canal and axis of prezygapophyseal peduncle in lateral view; 

pospA (solid squares) = angle between left and right edges of postspinal fossa in dorsal view; pozA (solid circles) = angle 

of vertical inclination of postzygapophysis in posterior view; prspA (open squares) = angle between left and right edges 

of prespinal fossa in dorsal view; przA (open circles) = angle of vertical inclination of prezygapophysis in anterior view.
1 8 • smithsonian contributions to paleobiology

and leads to the arch interior via a rounded foramen. Likewise, another foramen is present at the anterior corner of 

the intermediate-sized infrapostzygapophyseal fossa. The 

transverse processes are broken on both sides, although 

the left is more complete. The neural spine is moderately 

tall (about the height of the centrum), anteroposteriorly 

short, and located on the posterior half of the arch.

In anterior view, the centrum appears weakly concave 

and slightly wider than tall, whereas the neural canal is 

nearly circular and much smaller (Figure 12N). The pedicles are imperforate, and the base of the transverse process 

suggests that it was slightly elevated. The prezygapophyses 

are angled at 45° and connected medially to the more ventrally positioned hypantrum. Between them, a small fossa 

is visible at the base of the neural arch, positioned ventral 

to a flat but extensively roughened contact surface for the 

interspinous ligaments. The centrum is more strongly concave posteriorly. A narrow kink demarcates the postzygapophyses from the adjacent (and slightly dorsolaterally 

facing) hyposphene (Figure 12O). The posterior face of 

the neural spine also bears a surface for the interspinous 

ligaments, but is somewhat concave and terminates ventrally at a more acuminate fossa.

Dorsally, the prezygapophyses are trapezoidal with 

rounded edges, and are separated from one another along 

the midline by a space approximately equal to the transverse width of the neural spine (Figure 12P). The neural 

spine has a complex dorsal outline that has a “waisted” appearance. In ventral view, the centrum is hourglass-shaped, 

and bears neither a keel nor a groove.

The second dorsal vertebra (D2) is represented only by 

the neural arch. This is proportionally taller than the arch 

of D1, and it has a larger, shallower infradiapophyseal 

fossa and a more expansive infraprezygapophyseal fossa. 

The infrapostzygapophyseal fossa is smaller and faces 

more posteriorly. Here and in successive vertebrae, the 

hypantrum and hyposphene are more vertically oriented.

Dorsal vertebra three (D3) is identified based on the 

position of the parapophysis, the dorsalmost portion of 

which overlaps the neurocentral suture. The parapophysis is dorsoventrally elongate, and lies anterior to a large, 

elliptical pneumatic foramen. The neurocentral suture is 

marked and rugose. Proportionally, the infraprezygapophyseal fossa is the largest arch fossa, and is subdivided into 

at least two chambers. The neural spine is taller than in 

D2, and the prezygapophyses extend nearly horizontally, 

with a vertically deep hypantrum visible in lateral view. 

Dorsally, the neural spine apex is Y-shaped, and located 

over the posterior half of the centrum. The prezygapophyses are rectangular and separated by a narrow incisure.

In the fourth dorsal vertebra (D4), the parapophysis 

sits directly on the neurocentral suture. Its dorsal migration 

intersects the anterior centrodiapophyseal lamina, thereby 

forming the paradiapophyseal lamina. This lamina is more 

anteriorly placed, enlarging the infradiapophyseal fossa at 

the expense of the infraprezygapophyseal fossa. The infrapostzygapophyseal fossa is very small and forms a narrow 

triangle. The centrum is weakly concave on its lateral surface but bears neither fossae nor foramina. The neural spine 

is slightly more anteroposteriorly expanded at its tip than in 

D2, and bears projecting rugosities for the attachment of interspinous ligaments. The centrum faces are more D-shaped 

than in the preceding dorsals, and the parapophysis projects 

significantly laterally in anterior view. Posteriorly, the posterior centrodiapophyseal lamina is visible along the entire 

edge of the transverse process. This process is rectangular 

but deflected posteriorly about 30° in dorsal view.

It is difficult to determine whether the immediately 

subsequent vertebrae are represented in our sample, or one 

or more positions are missing instead. We interpret two 

dorsal vertebrae associated with a partial skeleton (FMNH 

PR 2481) to represent the fifth (D5) and sixth (D6) dorsal 

vertebrae (Figure 14); they are certainly more posteriorly 

positioned than D4. Both are distinguished from preceding vertebrae in the position of the parapophysis, which is 

located entirely on the neural arch (Figure 14D). It is hung 

beneath the transverse process at two-thirds of its length 

from the centrum, and connected to it via distinct anterior 

and posterior centroparapophyseal laminae. The transverse process is projected far laterally, and terminates with 

a stout diapophyseal facet at its posterolateral corner (Figure 14B,C). It is much broader anteroposteriorly than in 

D4. The neural spine is considerably longer anteroposteriorly than in D4. In anterior view, the prezygodiapophyseal 

lamina forms a strong ledge along the anterodorsal margin 

of the diapophysis. The centrum face is slightly taller than 

wide and much larger than the neural canal. The neural 

spine shows a slight trasverse widening at its apex.

A third dorsal vertebra associated with partial skeleton FMNH PR 2481 is identified as the seventh dorsal 

vertebra (D7) based on the preceding interpretation, but 

could also be placed more posteriorly (although anterior 

to the vertebrae described below). Here the parapophysis 

is located farther laterally along the transverse process, 

closer to the position of the diapophysis. The neural spine 

is anteroposteriorly longer than in D5. In posterior view, 

a triangular, deeply inset infrapostzygapophyseal fossa is 

visible on the transverse process between a marked postzygodiapophyseal lamina and a rounded posterior centrodiapophyseal lamina.
n u m b e r 9 5 • 1 9

Several posterior dorsal vertebrae are preserved nearly 

articulated in this associated specimen (FMNH PR 2481). 

These dorsals, probably equivalent to D11–D14, show no 

reduction in centrum length or significant proportional 

changes from the anterior dorsals. The centra remain apneumatic, but the arches are highly pneumatized. Vertebrae D12 and D13 preserve the parapophysis, which is 

located on a pedestal that is slung below the anterior edge 

of the transverse process. The transverse processes are 

tilted dorsally about 30°. The neural spines are embedded 

in matrix and cannot be observed.

A similar morphology is also evident in isolated posterior dorsals (UA 9103, 9176), in which the neural spine 

is located over the posterior two-thirds of the centrum, 

although the transverse processes are angled upward at 

about 25°. The anterior centrum face is concave, whereas 

the posterior face is flattened. The neural canal is nearly 

round, although the centrum face has a horizontal edge at 

the entry and exit of the canal. The three lateral arch fossae 

are subequal in size, although the infrapostzygapophyseal 

fossa is the deepest and largest. On UA 9176, the infraprezygapophyseal and infradiapophyseal fossae each have 

a foramen on the right side only; a foramen is present in 

the infrapostzygapophyseal fossa on both sides. The preand postzygapophyses are close together near the midline 

and approximately horizontal (the prezygapophyses face 

slightly laterally). The adjacent hyposphene–hypantrum is 

longer dorsoventrally than the respective zygapophysis is 

wide transversely. The small prespinal fossa is deep, and 

it gives way dorsally to a concave interspinous ligament 

attachment. The incomplete postspinal fossa appears to 

contain additional foramina. The neural spine is vertical 

and placed over the posterior half of the centrum.

Trends within the dorsal series: Unlike many 

other theropods, the dorsal centra of Masiakasaurus show 

little change in proportion from anterior to posterior. The 

posterior dorsals are unusually long, like the posterior 

cervicals, and there is no pronounced shortening through 

the cervicodorsal transition. Neural arch pneumaticity is 

pronounced throughout, continuing into the sacral series. 

As in other abelisauroids, the parapophysis migrates onto 

the neural arch in the first few dorsals and eventually out 

along the transverse process by the midtrunk. Laminae 

remain distinct throughout, although they become less 

pronounced close to the sacrum. Finally, the hyposphenehypantrum articulation is present in all dorsals.

Figure 14. Sixth dorsal vertebra (FMNH PR 2481) of Masiakasaurus knopfleri in right lateral (A), dorsal (B), ventral (C), anterior (D), and 

posterior views. Abbreviations: dp = diapophysis; hs = hyposphene; idf = infradiapophyseal fossa; ipof = infrapostzygapophyseal fossa; iprf = 

infraprezygapophyseal fossa; nc = neural canal; ns = neural spine; poz = postzygapophysis; pp = parapophysis; prdl = prezygodiapophyseal 

lamina; prz = prezygapophysis. Scale bar = 1 cm.
2 0 • smithsonian contributions to paleobiology

Sacral vertebrae: Several new specimens nearly 

complete our knowledge of the sacrum in Masiakasaurus, 

previously known only from three articulated elements 

(FMNH PR 2142; Carrano et al., 2002). Specimen UA 

9098 includes a large sacral 6 that retains an attachment 

to the partial preceding vertebra. The centrum has a flattened ventral surface but lacks a distinct groove or keel, 

and its flat, finished posterior face marks it as the last 

sacral. The posteroventral edge is lower than the anteroventral edge, indicating that the ventral margin of the sacrum was arched. The lateral centrum surface is devoid of 

fossae or foramina.

The neural arch bears a distinct hyposphene that borders a more anteriorly placed fossa. This fossa is separated 

from the true infraprezygapophyseal fossa by a vertical 

ridge (also present on sacral UA 9115). The transverse 

process and sacral rib are fused, forming a large, curved, 

dorsally concave structure that sweeps anteroventrally 

from the centrum. Its attachment spans the upper half 

of the centrum. A deep, distinct, and subdivided (pneumatic?) fossa is present on the anterior part of the dorsal surface of the transverse process, while another fossa 

excavates more posteriorly into the postzygodiapophyseal 

lamina. These fossae are connected internally within the 

transverse process and sacral rib, as shown by the chambers exposed on the damaged left side.

Another sacrum (FMNH PR 2460) is composed 

of four fused centra, overlapping the three preserved in 

FMNH PR 2142 (Carrano et al., 2002) and including one 

additional vertebra posteriorly (the last sacral). This latter 

vertebra resembles UA 9098 and shows even more clearly 

that the sacrum is ventrally arched in Masiakasaurus as in 

abelisaurids, although it lacks the strong mediolateral constriction seen in some other abelisauroids. The first sacral 

in this series bears a sutural anterior centrum face, indicating the presence of at least one additional sacral.

The ventral surface of the neural canal is exposed in 

the last two sacrals of this specimen, and is transversely 

wide and relatively flat. The transverse process and sacral 

rib are missing at the junction of these two vertebrae; this, 

along with the sutural face of sacral 3, suggests that this 

was an immature individual. The ventral surfaces of all 

preserved sacrals are flat, and none of the centra show evidence of pneumatic foramina.

Finally, an associated specimen (FMNH PR 2481; 

Figure 15) includes the full complement of six sacrals in 

near-articulation with the ilia. Although only the dorsal 

surfaces of the neural arches and sacral ribs are visible in 

Figure 15. Sacrum (FMNH PR 2485) of Masiakasaurus knopfleri in dorsal view. Abbreviations: li = left iliac blade; ri = right iliac blade; s1–s6 

= sacral vertebrae 1 through 6. Scale bar = 1 cm. (Anterior is to the right.)
n u m b e r 9 5 • 2 1

this specimen (which is in a block of matrix), it is clear 

that all six vertebrae contacted the iliac blades. Most of 

the sacral ribs appear to contact one another at or near 

their articulation with the ilium. The morphology of the 

sacral ribs and transverse processes suggests that the full 

sacrum consisted of two primordial sacrals plus two dorsosacrals and two caudosacrals. In all of the specimens 

that can be observed in anteroposterior view, the centra 

are D-shaped as in abelisaurids such as Majungasaurus

(O’Connor, 2007).

Caudal vertebrae: Additional specimens of anterior caudal vertebrae reveal that, like the presacrals, all the 

caudals in Masiakasaurus are proportionally long, with 

the centrum length at least twice the height. Unlike the 

anterior presacrals, the caudal vertebral centra are taller 

than wide, as in Carnotaurus and Majungasaurus. These 

anterior caudals do not show any evidence of centrum 

pneumaticity, but the neural arch retains three distinct 

laminae connected to the diapophysis, which delimit three 

corresponding arch fossae. These are pronounced when 

compared to those in most other theropods, although 

weaker than those of sauropods (e.g., Wilson, 1999). The 

centrum is amphicoelous and often bears a weak ventral 

groove, as well as chevron facets at the anteroventral and 

posteroventral corners of the centrum.

The neural arch in these anterior caudals retains a 

hyposphene and hypantrum, both of which are smaller 

than their respective zygapophyses, which are large and 

oriented at about 75° above the horizontal. In most of 

these vertebrae the neurocentral suture is faint, but the 

arch and centrum have separated along this suture in one 

large specimen (UA 9173), indicating immaturity of that 

individual. The lobate transverse process is swept posteriorly about 45°, and is tilted dorsally approximately 

10°. On UA 9112, a shallow longitudinal fossa can be 

seen alongside the base of the neural spine on the dorsal 

surface of the transverse process. The prespinal fossa is 

reduced to a small foramen at the base of a narrow interspinous ligament groove. Here the zygapophyses are 

angled at only 45°, again contiguous with a smaller, vertical hyposphene–hypantrum.

Vertebrae from toward the middle of the tail show the 

reduction in centrum height and size of the neural spine 

that often characterizes theropods (Figure 16). However, a 

significant transverse process is retained until well into the 

posterior part of the tail, along with short prezygapophyses. For example, a low, elongate middle caudal associated with FMNH PR 2481 includes a small, acuminate 

neural spine but also exhibits a large, posteriorly deflected 

transverse process and a prezygapophysis that extends less 

than one millimeter beyond the anterior edge of the centrum. The slightly more anteriorly placed FMNH PR 2482 

shows the neural spine to be anteroposteriorly short but 

still tall and rectangular.

The transverse process is reduced to a thin spur in 

more posteriorly positioned caudals of FMNH PR 2481, 

which have a more extended prezygapophysis, a lower 

relative centrum height, and a low, rounded neural spine. 

In the posterior half of the tail, the prezygapophysis overlaps at least one-third of the preceding centrum, although 

a rudimentary neural spine and transverse ridge may still 

be evident (e.g., FMNH PR 2638). The neural spine is absent only in the most posterior caudals, which nonetheless 

retain both the transverse ridge and a ventral groove.

Trends within the caudal series: The anterior caudals of Masiakasaurus are strikingly similar to the posterior dorsals, particularly in their proportions but also 

in the retention of arch laminae. The transverse processes 

remain lengthy and pronounced well into the middle caudals, where they become increasingly upturned (although 

even the transverse processes of the anterior caudals are 

slightly upturned). As in abelisaurids, anteroposterior expansion of the lateral end of the transverse processes occurs well into the middle caudals (but see “Caudal Ribs?” 

below). The neural spine becomes increasingly posteriorly 

Figure 16. Middle caudal vertebra (FMNH PR 2485) of Ma‐

siakasaurus knopfleri in left lateral view, showing the potential 

contact surface for a caudal rib at the lateral end of the transverse 

process. Abbreviations: crc = caudal rib contact; ncs = neurocentral 

suture; ns = neural spine; prz = prezygapophysis. Scale bar = 1 cm.
2 2 • smithsonian contributions to paleobiology

positioned on the arch, then shrinks to a low ridge. The 

zygapophyses lengthen to overlap the adjacent vertebra in 

the posterior caudals, subsequent to the disappearance of 

the transverse process. There does not appear to be any 

“transition point” in the tail, but rather all features shift 

gradually and independently along the series.

Cervical and dorsal ribs: Several partial cervical and dorsal ribs have been found. The cervical ribs are 

highly pneumatized, as in Carnotaurus, Majungasaurus, 

Noasaurus, and Spinostropheus, and bear a web that connects the triangular capitulum to the more rounded tuberculum. On both sides of this capitulotubercular web, 

pneumatic fossae are variably developed along the cervical series. Although pneumaticity persists into the anterior 

dorsal ribs, it is much less extensive and does not continue 

throughout the trunk. Ribs from the most posterior section of the trunk are unknown.

In the fourth cervical rib, the tuberculum and capitulum are closely placed, connected by a thin capitulotubercular web. Both are circular, but the capitulum is concave, 

whereas the tuberculum is convex. Two foramina pierce 

the rib between these and the anterior flange. Distal to the 

capitulotubercular web, a single large fossa, subdivided 

into two foramina, enters the bone. The shaft flares distally, showing evidence of bifurcation (a small notch) on 

the broken surface. This morphology is consistent with 

one of the cervical ribs of Noasaurus, which may also pertain to C4 (Bonaparte and Powell, 1980: fig. 8I–J).

The sixth cervical rib (Figure 17) is also bifurcate distally, with a long slender main shaft flanked by a shorter, 

finger-like accessory process. There is just a shallow concavity between the capitulotubercular web and the short 

anterior flange, but a true fossa was apparently present 

on the flange itself (Figure 17D). The circular tuberculum 

has only a short neck, as does the capitulum. Pneumaticity is variable. In a cervical rib associated with FMNH 

PR 2485, there is a large pneumatic fossa, which contains 

three subsidiary foramina, at the shaft base (Figure 17D). 

Two smaller fossae flank this large one proximally, at the 

bases of the tuberculum and capitulum, respectively. In 

contrast, UA 9169 has one foramen both proximal and 

distal to the capitulotubercular web.

On the seventh cervical rib, the anterior flange is bifurcate, the tubercular neck is quite short, and the fossa 

between these two and the capitulum is teardrop-shaped 

and placed closer to the flange. The posterior rib fossae 

distal to the capitulotubercular web are damaged, but may 

have interconnected through the interior of the bone. 

The ninth cervical rib houses two pneumatic foramina 

along with a faint, anteriorly directed capitulotubercular 

web. Four additional pneumatic foramina populate an 

equally deep fossa distal to this web. The lateral surface of 

the rib is smooth and convex. The capitulum is not visible 

in this view, obscured by the prominent, bifurcate anterior 

flange. In this view the rib can be seen to widen significantly at the base of the shaft, as in abelisaurids (e.g., Car‐

notaurus and Majungasaurus).

Figure 17. Right sixth cervical rib (FMNH PR 2485) of Ma‐

siakasaurus knopfleri in dorsal (A), medial (B), and lateral (C) views, 

with a close-up medial view of pneumaticity surrounding the capitulotubercular web (D). Abbreviations: ca = capitulum; ctw = capitulotubercular web; dlp = dorsolateral process; pf = pneumatic fossae 

and foramina; stp = styliform process; tu = tuberculum. Scale bar = 

1 cm for A–C.
n u m b e r 9 5 • 2 3

The tenth cervical rib bears a long, thick anterior 

flange, and remains wide distal to the capitulum, where it 

bears both the main shaft and a second, thinner styliform 

process that terminates in a small knob. Between the capitulum and tuberculum medially, a large fossa bears three 

distinct foramina, two of which are as large as the tuberculum. The tuberculum sits on a short neck, whereas the 

capitulum exists as an articular pad that is barely elevated 

above the connecting web. A single, small, circular foramen penetrates into the rib at the junction of the capitulum, tuberculum, and anterior flange. Another specimen 

(FMNH PR 2672) may be the tenth cervical or the first 

dorsal rib. The preserved capitulum sits on a short neck, 

and is circular. Only a single pneumatic fossa is present, 

situated anteriorly adjacent to the capitulotubercular web. 

The second known cervical rib of Noasaurus (originally 

described as a squamosal; Bonaparte and Powell, 1980: 

fig. 7D–E) corresponds to one of these two positions.

Two fragmentary ribs (FMNH PR 2458, UA 9160) 

appear to have articulated with approximately the fourth 

dorsal vertebra. In these, the capitulum is small and 

square, terminating a long, slender neck. In contrast, the 

tuberculum is mediolaterally elongate, and sits atop a 

short but distinct pedicle. The connecting capitulotubercular web is thin. The anterior surface is generally concave, 

whereas the posterior surface is convex. The proximal 

part of the shaft exhibits some broadening, created via 

distinct flanges that extend both anteriorly and posteriorly from the main shaft. The cross-section is T-shaped 

proximally but becomes oval distally. The shaft bears a 

posterior neurovascular groove. A small, elliptical fossa 

is present in the proximal shaft of a dorsal rib associated 

with FMNH PR 2485 and indicates that, unlike Majun‐

gasaurus (O’Connor, 2007), at least some of the dorsal 

ribs of Masiakasaurus were pneumatized.

Several ribs are from unknown positions within the 

trunk but nonetheless are anatomically informative. Specimen FMNH PR 2481 includes the proximal third of a right 

dorsal rib, preserving only the elongate tuberculum and part 

of the shaft. The tubercular neck is very short. The lateral 

part of the shaft is expanded into a T-shaped cross-section 

just distal to the rib heads. Both the anterior and posterior edges of this expansion are bounded by grooves, the 

posterior bearing a bisected, oval pneumatic fossa near the 

proximal end. The rib curves strongly in its proximal part, 

then acquires a nearly straight shaft for much of its length, 

suggesting a relatively narrow body shape. 

Gastralia: Specimen FMNH PR 2481 includes a 

fused set of anterior gastralia. This is a partially complete, 

V-shaped element composed of two very slender rami that 

meet at a broad angle (approximately 120°). On the anterior surface, a low bump is present along the ventral midline marking the zone of fusion. The distal ends of the 

rami are lacking.

Chevrons: Several chevrons have been identified, 

one of which is complete and probably from the middle 

part of the tail (UA 9152). It is curved posteriorly along 

its length and terminates in a broad point. The anterior 

and posterior curvatures are not parallel, however, creating a slight expansion near the distal end. The distal end 

is neither rounded as in Allosaurus and many other basal 

tetanurans, nor “boat-shaped” as in many coelurosaurs. 

The saddle-shaped proximal articulation encloses the haemal canal, as is typical of theropod chevrons. In lateral 

view this articulation bulges dorsally. The anterior and 

posterior processes are small but distinct; the anterior is 

moderately sized, blunt, and tall, whereas the posterior is 

upturned and acuminate. The anterior processes approach 

one another toward the midline but do not contact.

Caudal ribs? Two caudals of Masiakasaurus

(FMNH PR 2469, 2481) show an apparent suture directed 

longitudinally across the lateral part of the transverse process. This suture discriminates the expanded lateral portion 

of the process from the more conventionally shaped medial 

part. We interpret this suture as evidence that the expanded 

lateral end of the transverse process is actually a caudal 

rib, likely present throughout at least the anterior half of 

the tail. Two additional caudal vertebrae preserve a roughened, suture-like surface at the ends of both transverse processes (FMNH PR 2126, 2458; Figure 16:crc). In this light, 

we also reinterpret the similar morphology previously observed in other abelisauroids (Carnotaurus, Aucasaurus) as 

evidence of caudal ribs, and suggest that the absence of 

these structures in Majungasaurus (O’Connor, 2007) is due 

to the subadult nature of many individuals of this taxon.

Appendicular Skeleton

The pectoral girdle and forelimb of Masiakasaurus

were the most poorly known parts of the animal after the 

skull, and unfortunately we can shed only some new light 

on these regions. The radius and ulna remain unknown, 

but portions of the manus and pectoral girdle can now be 

described. Fortunately, both the pelvis and hind limb are 

now almost completely represented.

Pectoral girdle: The scapula and coracoid show 

an unusual morphology that finds some complement 

among other members of Ceratosauria. When articulated 

(Figure 18A), the scapulocoracoid is mediolaterally curved 

and presents an enormous area for muscle attachment anterior and ventral to the glenoid.
2 4 • smithsonian contributions to paleobiology

The scapula has a curved blade that reflects the shape 

of the underlying rib cage, and is broad relative to its 

length as in coelophysoids as well as other ceratosaurs. It 

appears to taper uniformly dorsally, but the dorsal-most 

end is not known and so we cannot determine whether 

it was reexpanded as in coelophysoids. As preserved, the 

blade is almost twice as long as the distance between the 

glenoid and acromion.

The glenoid has a pronounced anterodorsal rim, as in 

Ceratosaurus and Majungasaurus. In posterior view the 

scapular portion of the glenoid is D-shaped, and substantially taller dorsoventrally than wide mediolaterally (Figure 18B). Its ventral margin along the coracoid suture is 

oriented obliquely rather than horizontally. This ventral 

portion is mediolaterally thicker than the blade, especially 

as it approaches the coracoid suture. In posterior view, 

nearly the entire scapula is extremely thin, tapering to a 

sharp edge.

The coracoid is expansive and oval, with the long 

axis oriented anteroposteriorly (Figure 18A). It is much 

broader than the same element in basal theropods such as 

Dilophosaurus and Coelophysis, more closely resembling 

the condition in Elaphrosaurus, Limusaurus, and abelisaurids (although it is more anteroposteriorly elongate than 

in the latter). The posteroventral process is blunt, projecting only slightly beyond the posteriormost part of the glenoid. It is extremely thin mediolaterally, more so than in 

almost any other theropod, and lacks the characteristic 

medial concavity. The coracoid foramen is placed close 

to the scapular contact, such that most of the coracoid 

is anterior and ventral to the foramen. The passage between the lateral and medial openings of the foramen runs 

obliquely ventrolaterally-dorsomedially, as in other theropods. The glenoid region shows that more than two-thirds 

of the articular surface is formed by the scapula, although 

a weak rim also bounds the coracoid portion of the glenoid ventrally.

One specimen (UA 9160; Figure 18A) shows a series 

of openings arranged in a line directed posteroventrally 

from the coracoid foramen. These could be unhealed 

puncture marks, created during predation or scavenging. 

Alternatively, they may have a pathological origin; one of 

the openings bears a raised rim that may indicate the presence of a suppurating infection.

Humerus: Two complete left humeri associated 

with partial skeletons (FMNH PR 2481, 2485) provide 

nearly the entire morphology of this bone. They resemble 

previously described specimens (e.g., FMNH PR 2143; 

Carrano et al., 2002) but include the distal end and therefore the correct proportions of the element (Figure 19; 

Table 1). Overall it is concave curved medially but nearly 

straight in the anteroposterior plane. The deltopectoral 

crest is proportionally short, extending down only about 

one-third of the total shaft length. The distal condyles, although slightly damaged, are clearly flattened proximodistally as in abelisaurids, Ceratosaurus, and Elaphrosaurus. 

Both the entepicondyle and ectepicondyle are located 

along the narrow margins close to the distal end, but 

are indistinctly developed in this specimen. The FMNH 

Figure 18. Right scapulocoracoid (UA 9160) of Masiakasaurus 

knopfleri in lateral view (A), with a close-up of the glenoid in posterior/articular view (B). Abbreviations: ap = acromial process; cf = 

coracoid foramen; cgl = coracoid portion of glenoid; gl = glenoid; sgl 

= scapular portion of glenoid. Scale bar = 1 cm for A.
n u m b e r 9 5 • 2 5

Figure 19. Left humerus (FMNH PR 2485) of Masiakasaurus knopfleri in lateral (A), posterior (B), medial (C), anterior (D), proximal (E), 

and distal (F) views. Abbreviations: dpc = deltopectoral crest; gt = greater trochanter; hh = humeral head; rc = radial condyle; uc = ulnar condyle; 

scale bars = 1 cm.
2 6 • smithsonian contributions to paleobiology

TABLE 1. Measurements (in mm) of associated individual Masiakasaurus knopfleri from locality MAD05-42. At least four differentsized individuals were present at the site. Some specimens are assigned to two of the individuals below; additional elements are preserved 

but cannot yet be assigned to any individual. Abbreviations: L = anteroposterior length (unless otherwise indicated); AP = anteroposterior diameter; ML = mediolateral diameter; H = dorsoventral height; prz = prezygapophysis; poz = postzygapophysis; s = sacrum; asc 

proc = ascending process; D = diameter; W = width. An ‘x’ indicates an inapplicable measurement; a tilde (~) indicates an estimated 

position; a question mark (?) indicates missing data; an asterisk (*) indicates estimated length; and a dagger (†) indicates an incomplete 

measurement.)

Measurement (mm)

Element Field number L AP ML H Other

Larger Individual (FMNH PR 2481)

Atlantal intercentrum MAD 07508 5.0 x 15.3 9.4 46.9 (prz–poz)

Cervical vertebra ~5 MAD 07494 ? x ? ? 43.5 (prz–poz)

Cervical vertebra 6 MAD 07436 32.7 x 16.2 11.7 36.4 (prz–poz)

Cervical vertebra 7 MAD 07219 29.4 x 17.1 12.2 33.3 (prz–poz)

Cervical vertebra 9 MAD 07212 26.5 x 17.7 12.0 34.5 (prz–poz)

Dorsal vertebra 5 MAD 07215 26.9 x 15.3 14.2 36.4 (prz–poz)

Dorsal vertebra 6 MAD 07445 28.0 x 15.3 14.4 37.7 (prz–poz)

Dorsal vertebra 7 MAD 07213 28.7 x 17.5 15.3 ?

Dorsal vertebra 9 (s-4) MAD 07494-5 29.0 x ? 20.1 ?

Dorsal vertebra 10 (s-3) MAD 07494-4 29.6 x ? 18.6 ?

Dorsal vertebra 11 (s-2) MAD 07494-3 29.3 x ? 19.8 ?

Dorsal vertebra 12 (s-1) MAD 07494-2 28.9 x ? 21.7 ?

Sacrum, complete MAD 07218-3 148.8 x 35.6 ? x

Anterior caudal vertebra MAD 07494-1 29.3 x ? ? ?

MAD 07779 29.1 x 13.6 15.7 ?

MAD 07779 29.0 x 14.8 16.8 ?

Mid-caudal vertebra MAD 07690 28.9 x 13.0 15.0 ?

MAD 07507 29.8 x 12.1 11.1 ?

Posterior caudal vertebra MAD 07503 30.0 x 12.0 10.3 ?

MAD 07211 31.2 x 12.7 10.2 ?

MAD 07213 31.1 x 12.9 10.2 ?

MAD 07208-1 ? x 12.5 10.3 ?

MAD 07838 31.0 x 11.0 8.5 ?

MAD 07443 29.2 x 8.9 7.10 ?

Right scapula MAD 07442 128.4 20.6 2.0* x Glenoid L: 14.9,

glenoid D: 10.8

Left scapula MAD 07746 128.2 21.0 3.9 x Glenoid L: 14.7,

glenoid D: 11.2

Left coracoid MAD 07213 38.0 66.1 3.1* x x

Right humerus MAD 07213 94.3 6.9 9.6 x x

Left ilium MAD 07218-1 187.2 x x 43.2 a x

Left pubis MAD 07218 206.0 14.1 6.8 x Boot L: 48.5†

Right pubis MAD 07218 179.3† 8.9† ? x ?

Right femur MAD 07493 193.6* 20.5 15.6* x x

Right tibia MAD 07476 195.8 10.9 17.0 x x

Left tibia MAD 07687 196.9 12.5 18.0 x x

Right fibula MAD 07487 189.6 8.3 4.7 x x

Left fibula MAD 07523 ? 8.2 4.7 x x

Right astragalus MAD 07216 x x 24.7 b 9.9 b Asc proc W: 12.1, 

asc proc H: 17.1
n u m b e r 9 5 • 2 7

PR 2485 humerus is about two-thirds the size of FMNH 

PR 2143 and is correspondingly less rugose, whereas the 

FMNH PR 2481 humerus is approximately equivalent in 

size to FMNH PR 2143.

Manus: UA 9146 appears to be the proximal part 

of a metacarpal, perhaps the fourth judging by its mediolaterally thin proportions. The slender shaft bears an elliptical, concave proximal articular facet. The shaft is also 

oval in cross-section, and so thin that the dorsal and ventral edges taper to ridges.

Several manual phalanges have been found (Figure 

20). They are uniformly short in proportions, and are 

characterized by a proximal articular facet that is deeper 

dorsoventrally than the distal articular surface, weak or 

absent collateral fossae, and pronounced attachment 

marks on the lateral and medial surfaces. In addition, the 

TABLE 1. (continued)

Element Field number L AP ML H Other

Larger Individual (FMNH PR 2481)

Left astragalus MAD 07440 x x 25.2 b 10.4 b ?

Right metatarsal II MAD 05585 93.2 7.5 3.8 x x

Left metatarsal II MAD 07700 ? 7.7 3.6 x x

Right metatarsal III MAD 07833 112.0 10.3 11.6 x x

Pedal phalanx III-1 MAD 07537 28.2 9.6 10.0 x x

Pedal phalanx III-x MAD 07685 18.2 7.1 10.8 x x

Smaller Individual (FMNH PR 2485)

Cervical vertebra 4 MAD 05443-1 24.7 x 10.7 7.8 36.9 (prz–poz)

Cervical vertebra ~6 MAD 05616-1 25.4 x 10.5 8.3 ?

Cervical vertebra ~7 MAD 05467-2 23.4 x 10.5 9.1 ?

Dorsal vertebra 4 (arch) MAD 05459-1 ? x ? ? 21.3 (prz–poz)

Dorsal vertebra (arch) MAD 05460-27 ? x ? ? 30.5 (prz–poz)

MAD 07682 ? x ? ? 22.5 (prz–poz)

Sacral 1 (centrum) MAD 07475 22.2 x 14.4 16.8 ?

Anterior caudal vertebra MAD 05593-3 28.3 x 11.9 13.7 ?

Mid-caudal vertebra MAD 05459-1 23.2 x 9.2 9.7 ?

Posterior caudal vertebra MAD 05386 25.4 x 10.5 8.5 ?

Posterior caudal vertebra MAD 07882-2 27.3 x 9.1 6.9 ?

MAD 07474 25.5 x 6.7 5.2 ?

Left humerus MAD 05418 80.8 5.6 7.6 ? x

Left ilium MAD 05460-3 146.3 ? ? 42.5 a Acetabulum

L: 29.0

Left ischium MAD 05444 ? 9.4 9.8 ? Boot L: 23.2

Right ischium MAD 05444 ? 9.0 10.5 ? ?

Right femur MAD 05456 160.7 16.7 14.8 ? x

Left femur MAD 05467-2 159.8 16.3 14.5 ? x

Right tibia MAD 05456 173.7 11.3 14.4 ? x

Left tibia MAD 05419 171.7 11.0 14.4 ? x

Right fibula (proximal) MAD 05456 ? 6.9 3.9 ? x

Left fibula (proximal) MAD 05419 ? 7.2 4.1 ? x

Right metatarsal III MAD 05460-27 96.4 7.8 9.6 ? x

Right metatarsal IV MAD 05593-2 ? 7.7 7.6 ? x

Pedal phalanx MAD 05593-1 14.8 7.5 8.1 ? x

a Height to apex of acetabulum.

b Measurement of body.
2 8 • smithsonian contributions to paleobiology

vertical ridge separating the two halves of the proximal 

articular facet tends to be well developed and quite visible 

in mediolateral view, particularly near the dorsal process 

(Figure 20D).

Different morphologies are evident among the specimens, but with few comparative materials among other 

ceratosaurs, precise identifications remain tenuous. They 

vary in overall proportions, shape of the proximal articular surface, and development of collateral fossae. Nonetheless, they bear distinct similarities to the manual phalanges 

of Aucasaurus and Majungasaurus.

Specimens FMNH PR 2225 (Figure 20A) and 2227 

(Figure 20B) are proportionally the longest phalanges, 

with lengths 50%–70% greater than their dorsoventral 

depth; UA 9194 has proportions similar to these although 

a much larger ventral extension of the proximal articular 

surface.

Specimens FMNH PR 2132 (Figure 20C) and 2224 

(Figure 20D) are extremely short, about as long as they are 

dorsoventrally deep. They have faint or absent collateral 

fossae, a very pronounced ventral extension proximally, 

and oblique, asymmetrical distal condyles.

Specimens FMNH PR 2136 and 2217 (originally 

referred to the pes; Carrano et al., 2002) share similarly 

oblique distal condyles with the preceding elements, but 

the vertical axes of these condyles are not parallel and 

converge dorsally. The short proportions of these elements 

suggest that they may be penultimate phalanges, and they 

resemble the penultimate “pedal” phalanx of Noasaurus. 

Thus we interpret this phalanx in Noasaurus as a manual 

element, along with the supposedly “raptorial” ungual 

that articulates with it (Carrano and Sampson, 2004b; 

Agnolin and Chiarelli, 2010). No similar manual unguals 

are yet known for Masiakasaurus.

Pelvic girdle: The pelvic girdle is now completely 

known. Three ilium specimens together preserve everything except the anteroventral corner of the preacetabular 

process.

In lateral view (Figure 21A), the ilium exhibits long, 

deep pre- and postacetabular processes, both of which 

extended well beyond their respective peduncles. The lateral surface is concave but lacks a centrally placed vertical 

ridge. A thin, striated scar for the origination of M. iliotibialis extends along the dorsal border (Carrano and Hutchinson, 2002). The acetabulum is open and is overhung by a 

prominent supraacetabular crest, best seen in FMNH PR 

2481. This crest is contiguous with the lateral brevis shelf 

via a marked ridge, as in Majungasaurus and most other 

abelisaurids. A smaller left ilium (FMNH PR 2485) has a 

complete postacetabular blade and confirms the very wide 

brevis fossa. The notched profile of the posterior edge is 

similar to the condition in Ceratosaurus and abelisaurids.

In dorsal view the supraacetabular crest flares posterolaterally, with the greatest overhang located just anterior to the ischial peduncle. As seen in ventral view (Figure 

21B), the broad brevis fossa is not particularly deep and 

widens posteriorly. Both peduncles are similar in size, as 

in other theropods, but possess prominent pegs that would 

have lodged into sockets in the pubis and ischium. Similar pegs are also known in abelisaurids, and an ischial 

peg-and-socket articulation is present in the carcharodontosaurids Giganotosaurus (personal observation) and Ma‐

pusaurus (Coria and Currie, 2006).

The medial surface of the ilium (Figure 21C) bears 

distinct rugosities that mark the attachment sites for the 

sacral ribs and transverse processes. Six sacral rib attachments are visible on the ilium associated with FMNH PR 

2485, as confirmed by the articulated sacrum of FMNH 

Figure 20. Manual phalanges of Masiakasaurus knopfleri: (A) FMNH PR 2225 in medial/lateral (left) and dorsal (right) views; (B) FMNH 

PR 2227 in medial/lateral view; (C) FMNH PR 2132 in medial/lateral (left) and dorsal (right) views; (D) FMNH PR 2224 in medial/lateral view. 

Abbreviations: cf = collateral fossa; dp = dorsal process. Not to scale.
n u m b e r 9 5 • 2 9

PR 2481. In medial view, the acetabular opening is an ogival arch with a smooth, thin rim. The remainder of the 

medial surface is smooth and unornamented.

Additional remains of the pubis clarify the morphology of its proximal and distal ends (Figure 22A–C). The 

right pubis UA 9162 shows evidence of fusion to the 

articulated ilium and ischium. Much of the exact articulation line has been overprinted by rugose bone growth, 

although parts of the original path remain discernible, if 

indistinct. Fusion was also apparently complete along the 

puboischial contact, although the ventral portion of this 

area is missing in this specimen. Here again, the suture 

Figure 21. Left ilium (FMNH PR 2485) of Masiakasaurus knopfleri in lateral (A), ventral (B), 

and medial (C) views. Abbreviations: bf = brevis fossa; ip = ischial peduncle; ito = origin for M. ilio‐

tibialis; lbs = lateral brevis shelf; mbs = medial brevis shelf; pp = public peduncle; sac = supraacetabular crest; sr1–6 = attachment sites for sacral ribs 1–6; st1–6 = attachment sites for sacral transverse 

processes 1–6. Scale bar = 1 cm.
3 0 • smithsonian contributions to paleobiology

has been largely obliterated but its original path remains 

evident. The contact between these bones tapers from a 

maximum thickness (8 mm in this specimen) at the acetabular border to a minimum thickness (less than 2 mm) 

at the most ventral preserved part.

The distal end is preserved in two specimens (FMNH 

PR 2470, 2481), both of which document the fusion of 

left and right elements into a “boot” (Figure 22A–C). This 

structure is fully fused along the ventral and dorsal edges, 

as well as both anteriorly and posteriorly. In ventral view 

Figure 22. Ventral pelvic elements of Masiakasaurus knopfleri. Pubes (FMNH PR 2470) in left lateral 

(A), posterior (B), and distal (C; anterior is to the left) views. Note that a midshaft break has artificially 

exaggerated the shaft curvature in A. (D) Proximal left ischium (FMNH PR 2468) in lateral view. Distal 

left and right ischia (FMNH PR 2485) in left anteroventral (E), posterior (F), and distal (G) views. Abbreviations: ac = acetabular opening; ap = apex of pubic boot; apr = anteroproximal ridge; ds = dorsal shelf; 

fti3i = insertion for M. flexor tibialis internus 3; lr = lateral ridge on ischial boot; mi = midline invaginations; on = obturator notch; pc = contact for pubis; pdr = posterior distal ridge; pr = posterior ridge; r = 

rugose area. Scale bars = 1 cm.
n u m b e r 9 5 • 3 1

(Figure 22C), the boot is long and roughly triangular, with 

the apex directed posteriorly. At the anterior end, the left 

and right halves are demarcated by a shallow invagination.

The pubic shaft exhibits distinct morphological 

changes as it approaches the boot (Figure 22A). The lateral 

surface of the shaft transforms from rounded to shelf-like, 

extending distally to form a thin rim along the anterodorsal margin of the boot. The flattened dorsal surface of the 

shaft merges almost imperceptibly into the boot. Posteriorly, a thin ridge arises from the concave surface of the 

ventral one-quarter of the shaft, eventually meeting its 

opposite to form a central ridge along the posterodorsal 

margin of the boot (Figure 22B). A conical cavity leads 

into the dorsal part of the boot between the two ridges. It 

exits anteriorly via a thin slit, in contrast to Carnotaurus

where the anterior opening is large and rounded (Carrano 

and Sampson, 2008: fig. 12).

The ischium is now represented by several specimens 

that effectively preserve the entire element (Figure 22D–

G). It is fairly straight-shafted, with a striated scar near the 

(presumed) midshaft marking the origin of M. adductor 

femoris 2 (Carrano and Hutchinson, 2002). The proximal 

portion of the ischium is also striated near the pubic contact and bears a discrete, oblong bump, which was probably the origin of M. flexor tibialis internus 3 (Hutchinson, 

2001; Carrano and Hutchinson, 2002).

The proximal ischium bears an obturator notch—

best seen in FMNH PR 2468—that is located in the ventralmost portion of the puboischial plate (Figures 22D). 

There does not appear to be a ventral notch setting off 

an “obturator flange,” as in many tetanurans (Rauhut, 

2003). Some variation is evident in the morphology of 

the notch, which was broadly open in FMNH PR 2468 

but more nearly closed in UA 9168. The iliac contact is 

quadrangular and bears a distinct medial socket, as in the 

proximal pubis, that would have received an iliac “peg.” 

It overhangs the acetabular opening slightly. The pubic 

contact is an inverted triangle with a laminar ventral segment. The dorsal end of the puboischial contact is rugose 

and extends into the acetabular opening. The acetabular 

rim is tightly curved. Medially, the ischial shaft is marked 

by a low ridge that disappears proximally at the obturator notch. Presumably this ridge either contacted the same 

ridge on the opposite ischium or anchored an interischial 

membrane.

The distal ischium is best observed in FMNH PR 

2485, which includes fused distal two-thirds of the contralateral elements (Figure 22E–G), thereby illustrating 

several proximodistal changes in shaft morphology. Near 

the proximal end, the ischia are triangular in cross-section, meeting along a flat medial contact that is enhanced 

anteriorly by a ridge formed by rugosities along the contact edge. The posterior shaft is transversely peaked at 

this point, whereas the anterior shaft is transversely concave. The midshaft becomes slightly convex anteriorly and 

concave posteriorly, with each ischium exhibiting a more 

elongate, D-shaped cross-section. The contact surface is 

no longer rugose at this point, and the posterior shaft is 

flattened, marking the origination area of M. flexor tibialis 

internus 3 (Carrano and Hutchinson, 2002). Most distally, 

the medial contact forms a thin ridge on the posterior surface. Anteriorly the bone remains strongly concave, creating an inverted triangular cross-section.

Distally, the two ischia are fused into an expanded 

“boot,” like the pubes (Figure 22G). This fusion is complete posteriorly but not anteriorly, where a narrow incisure remains between the two elements. Each ischium is 

teardrop-shaped in distal view, giving the boot a triangular appearance. In lateral view, a thickened rim is visible 

along the lateral edge, marking where the distal surface 

curves up onto the lateral side of the bone.

Fibula: The fibula is generally long and slender, 

slightly shorter than the tibia. In proximal view, the proximal end of the fibula describes a broad, medially concave 

curve. The anterior and posterior ends are rounded, although the anterior end is broader. The proximal articulation is convexo-concave from anterior to posterior, 

becoming almost flattened toward its posterior edge (Figure 23A,B). A thickened rim along the proximal end likely 

marks the original extent of a cartilaginous cap.

Laterally, the fibula shows little discrete surface morphology aside from a large flange for the insertion of M. 

iliofibularis along the anterior edge of the shaft (Figure 

23A,C). As in other ceratosaurs, this flange is well-developed, textured, and sinuous, curving from anterior to 

lateral as its descends. In addition, a second attachment 

surface is more proximally placed along the anterior 

edge; this surface is smaller and more vertically oriented, 

and was probably associated with the tibial articulation. 

Otherwise the anterior surface is smoothly rounded. In 

contrast, the posterior shaft is more acuminate and lacks 

flanges or tubercles. The anteroposterior breadth of the 

proximal fibula is approximately three times greater than 

at midshaft, and continues to narrow distally.

Medially, the fibula shows several ceratosaur characteristics, including the development of a large, posterodistally open fossa (Figure 23A,B). This opening is bordered 

by a tall anterior wall that turns posteriorly near the proximal end. The medial surface is concave proximal to this 

wall, forming a second shallow fossa. The long, flat facet 

for the interosseous membrane appears just distal to the 

M. iliofibularis tubercle and continues toward the distal 
3 2 • smithsonian contributions to paleobiology

end; it occupies more than one-half of the medial shaft 

surface (Figure 23A,C).

The fibula appears to exhibit dimorphism, as has previously been noted for the femur and tibia (Carrano et 

al., 2002). For example, UA 9167 exhibits exceptionally 

pronounced muscle scars and ligament attachment surfaces, yet it is not substantially larger than other specimens 

lacking these qualities. In particular, the medial surface of 

the proximal end shows well-developed rugosities along 

the edges of the medial fossa, and the floor of this fossa 

is strongly ridged. The M. iliofibularis scar is strongly 

textured, and the scar for the interosseous membrane is 

roughened and swollen (Figure 23A,C).

Tarsus: Disarticulated astragali show several aspects of morphology not visible in the fused specimens described previously (Figure 24; Carrano et al., 2002). The 

ascending process is very tall and has straight lateral and 

proximal edges; the medial edge is straight along the basal 

two-thirds but then angles slightly laterally (Figure 24A,C). 

The process is well inset from the body of the astragalus, 

and nearly twice as tall as the body is deep. The lateral contact for the calcaneum, though not well preserved, is fairly 

flat with a distal C-shaped portion that connects to a more 

proximal triangular part that lies adjacent to a corresponding bulge in the astragalar body (Figure 24B).

The tibial facet bears two concave fossae, one posterior to the ascending process and a second placed medially 

(Figure 24C). Both have deep portions close to the base of 

the ascending process that may relate to the hollow (?) interior of the bone, along with the corresponding fossae at 

the base of the process externally. A thick ridge separates 

these two tibial facet fossae.

Distal tarsal 3 was found articulated on the proximal 

surface of its corresponding metatarsal III in two specimens 

(FMNH PR 2481, UA 9102; Figure 25A–B). The element 

has the rounded triangular shape that is typical for most 

basal theropods and is not fused to the metatarsal. The 

proximal surface is slightly convex, and a small lip from 

Figure 23. Right fibula (UA 9167) of Masiakasaurus knopfleri in medial (A) and posteromedial (B) views, 

with a close-up anteromedial view of the midshaft region (C). Abbreviations: ifis = scar for M. iliofibularis

insertion; ims = scar for interosseous membrane; mf = medial fossa; ptc = proximal tibial contact surface. 

Scale bar = 1 cm for A, B.)
n u m b e r 9 5 • 3 3

this tarsal overhangs the posterior edge of the metatarsal. In 

UA 9102 distal tarsal 3 is completely fused to metatarsal III.

Pes: A complete left metatarsal III (UA 9102) 

reveals this element to be long and slender, with a very 

straight shaft. The large proximal end is squared but 

slightly hourglass-shaped to accommodate the articulations for metatarsals II and IV. The medial and lateral 

invaginations on this end are considerably smaller than 

those of Allosaurus and other tetanurans, but similar to 

the condition in Ceratosaurus and Majungasaurus. This is 

especially true of the expanded proportions of the proximal end of metatarsal III when compared to those of II 

and IV. The distal end is a squared, dorsoventrally compact roller with two condyles that are approximately symmetrical. The groove between them is weak, as it is on 

most of the phalanges of digit III. Posteriorly, the shaft of 

metatarsal III bears prominent muscle scars.

Metatarsal IV is now completely known. It bears the 

narrow distal condyles that have been highlighted as a noasaurid synapomorphy (Sereno et al., 2004), but this feature is barely evident in some specimens (e.g., UA 9101), 

which show distal condyles with proportions similar to 

those of other theropods. The shaft of UA 9101 is also less 

strongly curved than in other specimens, diverging from its 

contact with metatarsal III at an angle of about 15° (versus about 30° in FMNH PR 2214). This difference may 

be attributed to postmortem damage of the latter specimen, or alternatively may represent natural population 

variation between gracile and robust extremes, as has been 

Figure 25. Metatarsals of Masiakasaurus knopfleri. Proximal end 

of right metatarsal III with articulated distal tarsal 3 (FMNH PR 

2687) in lateral (A) and medial (B) views. Proximal view (C) of left 

metatarsals III (UA 9102) and IV (UA 9101); anterior is toward the 

top. Note that the latter two specimens were not associated, and so 

have been scaled to show the reconstructed articulations between 

these elements. Abbreviations: dt3 = distal tarsal 3; mt2c = metatarsal II contact surface; mt3 = metatarsal III; mt4 = metatarsal IV; mt4c 

= metatarsal IV contact surface. Scale bar = 1 cm.

Figure 24. Right astragalus (FMNH PR 2481) of Masiakasaurus knopfleri in anterior (A), medial (B), and posterior (C) views. (Abbreviations: 

ap = ascending process; cf = calcaneal facet. Scale bar = 1 cm.
3 4 • smithsonian contributions to paleobiology

observed in the femora, tibiae (Carrano et al., 2002), and 

fibulae. The posterior shaft of metatarsal IV bears very 

pronounced scars for the insertion of M. gastrocnemius, 

especially along its lateral and medial edges. The proximal 

end of the bone has a broadly D-shaped outline with a 

convex anterolateral edge, a concave posterior edge, and a 

slightly undulating medial edge.

DISCUSSION

Noasaurid Morphology

These new materials greatly clarify several important 

aspects of noasaurid anatomy, particularly the skull and 

cervicodorsal vertebral series. Although most of the present fossils probably derive from numerous individuals of 

Masiakasaurus, the presence of at least two associated 

skeletons at locality MAD 05-42 (FMNH PR 2481, 2485) 

permits a more accurate assessment of skeletal proportions 

(Table 1; Figure 26). In addition, there is now a greater 

overlap with the associated materials of Noasaurus and 

other noasaurids, allowing clarification of the anatomy of 

related forms. In Noasaurus, for example, all preserved 

elements (maxilla, quadrate, cervical 4, dorsal centrum, 

cervical ribs, manual phalanx, and metatarsal IV) except 

the manual ungual can be compared directly.

It is now apparent that the noasaurid skull was not 

especially modified relative to those of other ceratosaurs 

except with regard to the anterior portions of the jaws. 

Figure 26. Associated individuals of Masiakasaurus knopfleri from locality MAD 05-42, illustrating size and proportional differences and 

showing recovered (white) and missing (gray) elements. (Top) Larger individual (FMNH PR 2481); (bottom) smaller individual (FMNH PR 

2485). See Table 1 for measurements.

one meter 

FMNH PR 2481 

FMNH PR 2485 
n u m b e r 9 5 • 3 5

The remainder of the facial skeleton, the posterior mandible, and the braincase do not show highly derived morphologies with respect to other ceratosaurs and more 

primitive theropods. In some cases (e.g., external element 

sculpturing, lacrimal morphology) noasaurids exhibit an 

intermediate condition between more basal ceratosaurs 

and abelisaurids.

The neck of noasaurids was relatively longer than 

in abelisaurids, which exhibit anteroposterior vertebral 

shortening similar to that seen in other large theropods 

such as allosauroids and tyrannosaurids. However, the noasaurid neck was not especially lengthened relative to that 

of other small theropods, and was composed of vertebrae 

that were proportionally shorter than those of coelophysoids, Elaphrosaurus, Limusaurus, and Spinostropheus. 

More unusually, there is virtually no change in centrum 

proportions across the pectoral region, unlike the condition in other ceratosaurs and nearly all other theropods. 

This implies that the neck would have curved downward 

from the head, then straightened from the middle cervicals 

through the anterior trunk before arching slightly upward 

through the posterior trunk and sacrum.

The pectoral girdle shares with other ceratosaurs the 

development of an expanded coracoid and ventral scapula 

and the lack of any constriction posterior to the acromion. Whereas in Abelisauridae (and to a more restricted 

extent in Ceratosaurus and Limusaurus) this morphology 

is paired with a reduction in the length of the forelimb, 

in noasaurids the forelimb is not appreciably reduced in 

length. The humerus is long and slender, as may be some 

of the manual elements. Several features of the humerus 

are shared with Elaphrosaurus and abelisaurids, including the globular head, reduced deltopectoral crest height, 

and flattened distal condyles (some of these features may 

also be present in Limusaurus). No reduction in functionality is evident from the preserved remains. In contrast, 

the morphology of the humeral head and the expanded 

muscle origination areas on the ventral pectoral girdle suggest that mobility was significant and perhaps enhanced 

over the primitive theropod condition.

The manus remains poorly known, but seems to have 

been less transformed in noasaurids than in Limusaurus 

or abelisaurids. Although it is possible that some of the 

manual phalanges were short in noasaurids, the metacarpals apparently retained more primitive proportions. 

The phylogenetic placement of Noasauridae suggests a 

four-fingered manus, but we cannot yet confirm this with 

fossil evidence. Regardless, the manus would likely have 

had a prehensile function similar to those of other basal 

theropods.

The hind limb resembles that of abelisaurids, except 

in its more gracile proportions. No major differences in 

structure or articulation can be observed between these 

two groups, especially now that the supposed “raptorial” 

pedal ungual of Noasaurus has been reidentified as a manual ungual (Carrano and Sampson, 2004b; Agnolin and 

Chiarelli, 2010). Likewise, the overall pelvic structure is 

shared between most abelisauroids (Carrano, 2007), suggesting similarity of the placement and relative sizes of attached muscles.

It is not clear why abelisauroids might have retained 

(or reevolved) caudal ribs, a condition that contrasts with 

all other theropods. However, the overall organization of 

the axial column in abelisauroids suggests an emphasis of 

hypaxial relative to epaxial musculature, opposite of what 

is seen in most theropods. If this trait was also evident 

in the tail, then the presence of caudal ribs could be interpreted as a means to enhance transverse tail flexibility, 

the ribs providing increased moment arms for the attached 

muscles.

Comparative Anatomy

Masiakasaurus remains the best-known noasaurid, 

but the incompleteness of other taxa greatly reduces the 

opportunities for substantive comparisons. However, the 

new materials described here do allow for increased anatomical resolution of some existing specimens, particularly those from the Lameta Formation of India (Huene 

and Matley, 1933; Novas et al., 2004).

Four vertebrae were originally assigned to Laevisu‐

chus indicus (Huene and Matley, 1933), and identified 

as cervicals and dorsals without further specification. We 

can now identify GSI K27/696 as C6 (see “Cervical Vertebrae” above), but the remaining vertebrae can only be 

imperfectly placed because they have not been located in 

the GSI collections. Specimen GSI K20/613 is a more posterior cervical, approximately C7–C8 based on comparison with Masiakasaurus. Specimen GSI K20/614 is shown 

only in ventral view (Huene and Matley, 1933: pl. XX, fig. 

4), but its proportions are very close to those of C5 in Ma‐

siakasaurus. Specimen GSI K27/588 has a lateral centrum 

fossa but no foramen. The centrum faces are not offset, 

and the neural arch is long at its base but tapers toward 

the apex. Based on these features, we assign this vertebra 

to the mid-dorsal region.

Jubbulpuria tenuis also appears to comprise noasaurid 

materials. Both specimens (GSI K20/612, K27/614) were 

described as dorsal vertebrae, but “almost without any 

indications of buttresses” (Huene and Matley, 1933:61). 
3 6 • smithsonian contributions to paleobiology

They have long, low centra with transverse processes, as 

well as posteriorly placed neural spines. Together these features suggest that the specimens are midcaudal vertebrae.

Although it is approximately twice the size of the 

largest specimen of Masiakasaurus, the holotype axis of 

Compsosuchus solus (GSI K27/578) is otherwise very similar in morphology. Like Masiakasaurus, it bears a large, 

rounded pneumatic foramen adjacent to the parapophysis. 

It differs in exhibiting a slightly more upturned atlantal intercentrum and a proportionally less projected odontoid.

The dorsal (GSI K27/541, K27/531) and midcaudal? 

(GSI K27/604) vertebrae assigned to Ornithomimoides? 

barasimlensis also resemble those of Masiakasaurus in 

size, general proportions, and disposition of laminae, but 

are too incomplete to be placed more specifically in the 

axial column.

A number of other Lameta specimens, not assigned 

to particular taxa, can also be more specifically identified, 

including a number of “coelurosaurs” (Table 2; see also 

Novas et al., 2004). For taxonomic purposes, these can 

be assigned to Noasauridae indet., but it is very possible 

that all the materials mentioned above pertain to a single 

noasaurid taxon. Overall, the Lameta specimens are approximately twice as large as those from the Maevarano 

Formation, and are proportionally more robust. However, 

even the largest Masiakasaurus specimens may derive 

from individuals that were not fully grown, so this size 

difference may reflect ontogenetic effects.

Noasaurus leali (Bonaparte and Powell, 1980) is the 

namesake taxon for the family Noasauridae, but is only 

represented by a few disassociated elements. As noted 

above, we have reidentified the putative squamosal as a cervical rib, and the “pedal” phalanx and ungual as belonging 

to the manus. Although there are strong similarities between Noasaurus and Masiakasaurus, the two taxa exhibit 

significant differences as well. For example, the maxilla of 

Noasaurus has a narrower antorbital fossa, and the anterior margin of the antorbital fenestra reaches to the fifth alveolus (versus the fourth in Masiakasaurus). The quadrate 

shaft is much more strongly curved in Noasaurus than in 

Masiakasaurus. Finally, the medial collateral ligament pit 

on metatarsal IV is internally subdivided in Noasaurus and 

connects to a more distinct distal intercondylar sulcus.

A second form from Argentina, Velocisaurus unicus

(Bonaparte, 1991) is known only from limb elements. 

These are more poorly preserved than the corresponding 

elements in either Noasaurus or Masiakasaurus, but exhibit enough morphology to confirm the taxon’s status as a 

noasaurid. Although the astragalus is damaged, it is similar to the same element in Masiakasaurus and likely had a 

laminar ascending process (as evidenced from the broken 

base on the astragalar body and flat contact area on the 

anterior surface of the distal tibia). The pedal elements of 

Velocisaurus are generally similar to those of Masiakasau‐

rus but are more slender; this is particularly evident in the 

proportions of the phalanges of digits III and IV.

Finally, Genusaurus sisteronis (Accarie et al., 1995) 

from the Early Cretaceous of France also shows many similarities to Masiakasaurus, and has been recently recovered as a noasaurid (Carrano and Sampson, 2008). The 

ilium, in particular, bears a peg-shaped articulation for 

the ischium and shows a similar pattern of sacral rib attachments to Masiakasaurus, although it is proportionally 

TABLE 2. Isolated noasaurid specimens from the Lameta Formation, Bara Simla, Jabalpur, India. Identifications are based on 

comparison with materials of Masiakasaurus knopfleri. Many of 

these were identified as Abelisauroidea indet. (and tentatively as 

Noasauridae and/or Laevisuchus) by Novas et al. (2004).

Original 

taxonomic 

assignment, 

and Specimen 

no. reference Element Original 

Coelurid

GSI K27/587 Distal mid-caudal vertebra pl. XXIII, fig. 5

Coelurosaur

GSI K27/589 Distal mid-caudal vertebra pl. XXIII, fig. 3

GSI K27/599 Mid-caudal vertebra pl. XXIII, fig. 4

GSI K27/526 Right tibia pl. XXIII, fig. 7

GSI K27/665 Right metatarsal III pl. XXIV, fig. 2

GSI K27/697, 

 K27/681 Metatarsal III pl. XXIV, fig. 3

GSI K27/666 Right metatarsal IV pl. XXIV, fig. 4

GSI K27/667 Right metatarsal II pl. XXIV, fig. 5

GSI K20/337 Right metatarsal IV pl. XXIV, fig. 6

GSI K20/626B Left pedal phalanx IV-1 pl. XXIV, fig. 7

GSI K27/637 Left pedal phalanx IV-4 pl. XXIV, fig. 9

GSI K27/638 Pedal phalanx IV-3 pl. XXIV, fig. 10

GSI K27/648 Right pedal phalanx IV-1 pl. XXIV, fig. 13

GSI K27/646 Pedal phalanx III-2/3 pl. XXIV, fig. 14

GSI K27/647 Right? pedal phalanx IV-4 pl. XXIV, fig. 15

GSI K20/337 Pedal phalanx IV-2 pl. XXIV, fig. 16

GSI K27/524 Left pedal phalanx II-1 pl. XXIV, fig. 17

GSI K27/644 Right pedal phalanx III-1 pl. XXIV, fig. 18

GSI K27/632 Pedal phalanx II-3/IV-5 pl. XXIV, fig. 19

GSI K27/629 Pedal phalanx III-4 pl. XXIV, fig. 20
n u m b e r 9 5 • 3 7

shallower dorsoventrally. The proximal pubis is fused to 

the ilium in a manner similar to that in UA 9162, and 

bears the broken remnants of an obturator foramen. It is 

approximately 1.5 times the size of the largest specimen of 

Masiakasaurus.

Relationships within Noasauridae

One of the most frustrating aspects of interrelationships within Ceratosauria involves the high degree of 

uncertainty that surrounds the placement of individual 

species in the group, and particularly within the clades 

Abelisauridae and Noasauridae (Carrano and Sampson, 

2008). This is partly because many ceratosaur taxa are 

known from incomplete specimens, thus when large numbers of taxa are analyzed, many most parsimonious trees 

are produced.

One problem has been the labile placement of several incompletely known abelisauroids (e.g., Genusau‐

rus, Ligabueino, Velocisaurus). Ligabueino is extremely 

fragmentary, represented by a handful of elements. These 

include a cervical neural arch, a mid to posterior dorsal 

neural arch, a posterior dorsal centrum, the left femur, 

left ilium (visible only in medial view), articulated pubic 

shafts, and two pedal phalanges. The shorter of the latter two elements appears to represent a manual phalanx, 

and resembles the corresponding bones in Masiakasaurus

and Noasaurus. The specimen is from a tiny individual, 

and the separation of the cervical and dorsal vertebral 

centra from their neural arches indicates that it represents 

a juvenile (contra Bonaparte, 1996). There do not appear 

to be any definitive noasaurid synapomorphies preserved, 

but there are enough features (e.g., anteroposteriorly 

short cervical neural spine, cervical prezygapophyseal–

epipophyseal lamina, and marked but not hypertrophied flange on mediodistal femoral shaft) to confidently 

place Ligabueino within Abelisauroidea (Carrano and 

Sampson, 2008).

On the other hand, it now seems clear that Velocisau‐

rus represents a true noasaurid. Although in many respects 

less complete than Ligabueino, the holotype of Velocisau‐

rus (comprising most of the hind limb distal to the knee) 

does preserve several noasaurid and abelisauroid features. 

In particular, the cnemial crest is incomplete but shows the 

distinctive ceratosaur morphology at its base, curving far 

anterior to the tibial shaft. Metatarsal III is much larger 

than the flanking elements (i.e., an “antarctometatarsus”), 

and metatarsal II is extremely slender, as in Noasaurus

and Masiakasaurus. However, there does not appear to be 

any compelling morphological reason to ally Velocisaurus

with Masiakasaurus to the exclusion of Noasaurus into 

the clade Velocisauridae (Bonaparte, 1991), as has been 

suggested (Agnolin et al., 2003). The purported similarities and distinctions rest entirely on the differential preservation of elements, and we can offer no positive support 

for Velocisauridae, which we therefore consider a junior 

synonym of Noasauridae.

Similarly, the fragmentary Genusaurus also appears to 

be a noasaurid based on the presence of a hypertrophied 

flange along the anteromedial edge of the femoral shaft 

and a bulbous fibular condyle on the femur (Carrano and 

Sampson, 2008). Genusaurus is slightly larger than Ma‐

siakasaurus and Noasaurus, perhaps approaching three 

meters in length. Its early geological appearance (Albian) 

provides the oldest definitive evidence of noasaurids, antedating the final Laurasia–Gondwana split (Hay et al., 

1999), and the undescribed form from the Elrhaz Formation of Niger may be even older (Sereno et al., 2004.)

It is not yet possible to shed much light on Laevisu‐

chus or the other very fragmentary small-bodied theropods 

from the Upper Cretaceous Lameta Formation of India. 

Carrano et al. (2002) noted that the holotypic vertebrae 

of Laevisuchus share some synapomorphies with those of 

Masiakasaurus and Noasaurus, and grouped these three 

taxa into Noasauridae. Numerous additional small theropod specimens are known from the Lameta Formation, but unfortunately it is not possible to determine 

how many discrete taxa are represented (see discussion in 

Novas et al., 2004). Huene and Matley (1933) almost certainly overstated the taxonomic diversity of their sample 

in naming four small theropods: Compsosuchus solus, 

Laevisuchus indicus, Jubbulpuria tenuis, and Ornithomi‐

moides? barasimlensis. If the Lameta fauna is very similar 

to the Maevarano fauna in composition, then all four taxa 

may represent a single noasaurid species, to which most 

of the currently unassigned small theropod specimens 

might also be allocated. Even if this were so, such a taxon 

would still be too incomplete for its relationships within 

Noasauridae to be highly resolved without the addition of 

new specimens. We note, however, that the proportions of 

the individual pedal phalanges are much closer to those of 

Masiakasaurus than to those of Velocisaurus.

In summary, we can now more confidently assign 

several small theropod taxa (Genusaurus, Velocisaurus, 

Lameta forms) to Noasauridae, but we cannot determine 

their interrelationships with any greater certainty. Liga‐

bueino should be excluded from Noasauridae and considered an indeterminate abelisauroid. Until more complete 

specimens of existing taxa are found, noasaurid phylogeny will remain in flux, but there is some evidence for 
3 8 • smithsonian contributions to paleobiology

a close relationship between the Lameta noasaurid and 

Masiakasaurus.

Evolutionary Implications for Ceratosauria

Noasaurids

Genusaurus appears to be the earliest definitive noasaurid (Albian), although an additional form from the 

late Early Cretaceous of Niger (Sereno et al., 2004) may 

be coeval with or slightly older than it. Abelisauridae, the 

sister taxon to Noasauridae within Abelisauroidea, has its 

earliest known appearance in the late Early Cretaceous of 

Niger (Sereno and Brusatte, 2008). Neither group is yet 

known from pre-Cretaceous rocks, nor from rocks earlier 

than Aptian–Albian. This represents the minimum divergence time for these two main abelisauroid clades (Carrano and Sampson, 2008).

Subsequent diversification of noasaurids took place at 

least in South America (Velocisaurus, Noasaurus), Africa 

(one unnamed form; Sereno et al., 2004), India (Laevi‐

suchus, Compsosuchus, O? barasimlensis, Jubbulpuria), 

Madagascar (Masiakasaurus), and Europe (Genusaurus). 

Sereno et al. (2004) proposed that an additional taxon, 

Deltadromeus, represented a gigantic noasaurid. We have 

not found independent support for this hypothesis and 

consider Deltadromeus to be a more primitive member of 

Ceratosauria, close to Spinostropheus and Elaphrosaurus

(Carrano and Sampson, 2004a, 2004b, 2008). Thus there 

is currently a maximum of 10, and perhaps as few as 6, 

noasaurid taxa spanning more than 55 million years on at 

least 5 continental landmasses. Certainly this represents 

a vast undersampling of the true history of the noasaurid 

lineage.

It is therefore highly speculative to attempt to decipher 

biogeographic patterns within Noasauridae. The group 

appears to be legitimately absent from the Late Cretaceous 

of eastern Asia and western North America, but may yet 

prove to have had a wider distribution, particularly in the 

Early Cretaceous prior to maximum Mesozoic continental 

separation. Patterns within Noasauridae are impossible 

to determine without a well-resolved phylogeny, which is 

lacking and will remain so without additional materials. 

Furthermore, the fact that more noasaurids are known 

from South America than elsewhere predisposes many 

analyses to determine this as the “center of origin” for the 

group, in spite of their highly incomplete record. (A corresponding problem also exists for taxa in poorly sampled 

regions, which are predisposed to sister taxon relationships 

with forms from other areas, leading to an overemphasis 

on “dispersal” [Carrano and Sampson, 2004a].) We note 

that there is at least a superficial resemblance between the 

distributional patterns of Late Cretaceous abelisaurids 

and noasaurids (Carrano et al., 2002), which may herald 

some deeper paleobiogeographic significance. However, 

given the extremely fragmentary record of noasaurids and 

the lack of fossils from several important regions (Carrano 

et al., 2002; Carrano and Sampson, 2002, 2004a, 2008), 

we are skeptical of even these broad conclusions.

Despite this incomplete record, a few features of noasaurid evolution are apparent. First, all definitive noasaurids are medium- or small-bodied forms, less than 

four meters in length and weighing perhaps hundreds but 

certainly not thousands of kilograms. All seem to share 

proportionally slender hind limbs, with elongate distal 

segments and reduced lateral digits that suggest some degree of cursoriality (e.g., Carrano, 1999). Most specializations were confined to the skull (although this is only 

partly known, and only in Masiakasaurus and Noasaurus); 

primitive ceratosaurian features dominated the appendicular skeleton. Vertebral morphologies are similar to those 

of abelisaurids, and do not imply any major axial changes 

in Noasauridae aside from development (or retention) of 

a relative elongation neck. Noasaurids thus appear to primarily represent a divergence in feeding habits from the 

primitive ceratosaur, and theropod, condition. The overall 

distribution of body sizes within Ceratosauria further suggests that small-bodied noasaurids underwent a size reduction during their evolution (Carrano et al., 2002).

Character Distributions

The addition of many new anatomical observations 

for Masiakasaurus has resolved much of the uncertainty 

surrounding character distributions within Ceratosauria. 

Specifically, it has been unclear whether numerous features were abelisauroid or abelisaurid synapomorphies, 

because they had not yet been preserved in any noasaurid 

specimens. New character codings are detailed elsewhere 

(Carrano and Sampson, 2008), but certain features are 

emphasized below.

In the skull, it is now clear that sculpturing on the dermal skull elements is limited to the postorbital and lacrimal 

in abelisauroids; this trend is elaborated in abelisaurids 

to include the premaxilla and maxilla (the distributions 

for the jugal and quadratojugal remain unknown). Similarly, pnematization and elaboration of the frontals and 

nasals is an abelisaurid, not abelisauroid, characteristic. 

It is interesting to note that the sculpturing of the skull 

roof and facial skeleton are considered to indicate distinct 
n u m b e r 9 5 • 3 9

anatomical structures in the overlying dermis (Hieronymus and Witmer, 2008).

In contrast, most vertebral characters of abelisaurids 

(including the presence of hyposphene-hypantrum articulations in at least the anterior caudals) are also found in 

noasaurids, and thus characterize Abelisauroidea. This is 

also the case for the unusual proportions of the cervical 

vertebrae, in which the epaxial musculature occupied a 

broad, deep space adjacent to the neural spine and was 

separated from the hypaxial musculature by a distinct 

prezygapophyseal–epipophyseal lamina. This division is 

marked in the tail by the presence of caudal ribs, which 

significantly expanded the attachment areas for lateral tail 

musculature well into the distal half of the tail. Highly 

shortened manual phalanges are also shared between noasaurids and abelisaurids. Aspects of some of these features are also found in more basal ceratosaurs.

CONCLUSIONS

The small-bodied noasaurid ceratosaur Masiakasau‐

rus knopfleri is described in detail, focusing on many 

newly discovered specimens that now document approximately 65% of the cranial and postcranial skeleton. These 

new elements demonstrate that the skull of Masiakasaurus

was similar in proportions to those of other small, primitive theropods. The most significant modifications occurred in the anterior dentition and jaws, while aspects 

of skull texturing, braincase morphology, and the lower 

jaw are shared with other abelisauroids and ceratosaurs. 

In the axial column, the most unusual characteristic is the 

relatively horizontally articulated posterior cervical series, 

which does not undergo proportional changes into the 

trunk. The rib cage seems to have been fairly narrow, and 

the tail may have retained caudal ribs. The pectoral girdle 

and forelimb include a very broad scapulocoracoid and a 

long, slender humerus but at least some shortened phalanges. In the pelvic girdle, the ilia articulate against six 

sacral vertebrae, while both the pubes and ischia terminate 

distally in fused “boots.”

Comparisons with other noasaurids are limited by 

incomplete materials, but some forms were substantially 

larger than Masiakasaurus. Many of the small theropod 

specimens from Bara Simla in the Lameta Formation appear to pertain to at least one species of noasaurid. The 

group primarily differs from other abelisauroids in feeding specializations, as well as body-size reduction, but the 

many derived characters shared between noasaurids and 

abelisaurids indicate a great deal of functional similarity 

in the lower jaw, axial column, shoulder girdle, and hind 

limb between these groups.

The following list of Masiakasaurus knopfleri specimens (Table A.1) supplements that given in Carrano et al. (2002) and emends the following information 

therein: (1) UA 8682 was listed as a dentary, but is actually a pedal phalanx; 

(2) FMNH PR 2198, 2226, and 2228 have been re-identified as juvenile Ma‐

jungasaurus teeth; (3) FMNH PR 2204 has been re-identified as pertaining to 

a crocodyliform; (4) FMNH PR 2183 and 2124 were inadvertently switched in 

the captions for figs. 3 and 4; and (5) FMNH PR 2147 was substituted for 2146 

in the caption for fig. 19 (Carrano et al., 2002).

Appendix
4 2 • smithsonian contributions to paleobiology

TABLE A.1. Complete list of Masiakasaurus knopfleri specimens from the Upper Cretaceous Maevarano Formation of Madagascar 

collected through 2007. All specimens are from the Anembalemba Member of the Maevarano Formation except those marked with 

an asterisk (*), which are derived from the underlying Masorobe Member. Other symbols and abbreviations (in order of appearance): 

NA = not applicable; ND = position not determined; ? = data uncertain; tilde (~) = approximately; ?? = element identification uncertain; 

NFN = no field number; NR = exact locality not recorded. A dash (-) serves as visual placeholder only; no data were intended.

Element(s) Notes and comments Position Specimen number a Field number b Locality

Skull

Premaxilla - Left FMNH PR 2453 03056 MAD 93-18

Maxilla - Right FMNH PR 2183 98199 MAD 93-18

Lacrimal - Right FMNH PR 2473 03584 MAD 93-18

Postorbital - Right UA 9090 01026 MAD 93-18

Right FMNH PR 2456 03120 MAD 93-18

Frontal - Left FMNH PR 2475 03586-8 MAD 93-18

- Left UA 9095 01032-1 MAD 93-18

Quadrate - Right FMNH PR 2496 05322 MAD 05-42

Braincase - NA FMNH PR 2457 03174 MAD 03-03*

Basioccipital - NA UA 9178 03592 MAD 93-18

Laterosphenoid? - ND FMNH PR 2495 03280 MAD 93-18

Dentary - Left FMNH PR 2471 03471+03472 c MAD 93-18

- Left UA 9177 03587 MAD 93-18

- Left FMNH PR 2222 95246 MAD 93-18

- Left FMNH PR 2178 98103 MAD 93-18

- Left FMNH PR 2177 98315 MAD 93-18

- Right UA 9145 03204 “East of Mammal”

Anterior 2/3 Right UA 8680 (holotype) 95248 MAD 93-18

- Right FMNH PR 2179 98093 MAD 93-18

Splenial - Left FMNH PR 2124 98070 MAD 93-18

Angular - Left UA 9147 03232 MAD 93-18

- Left FMNH PR 2455 03119 MAD 93-18

Prearticular - Left FMNH PR 2454 03118 MAD 93-18

- Left UA 9149 03257 MAD 93-18

Prearticular, articular - Right UA 9166 03420 MAD 93-18

Tooth - Anterior FMNH PR 2180 99181 MAD 93-18

- Anterior FMNH PR 2165 95358 MAD 95-05

- Anterior FMNH PR 2200 95244-1 MAD 93-18

- Anterior FMNH PR 2220 96068-4 MAD 93-35

- Anterior FMNH PR 2818 07126 MAD 05-42

- Posterior FMNH PR 2170 99279 MAD 99-06

- Posterior FMNH PR 2221 98446 MAD 98-26

- Posterior UA 9159 03356 MAD 93-18

- Posterior FMNH PR 2476 03593 MAD 93-18

2 elements Posterior FMNH PR 2181 93008-2, 93008-4 MAD 93-09

- Posterior FMNH PR 2199 93086-4 MAD 93-35

- Posterior FMNH PR 2182 98073 MAD 93-18

- Posterior FMNH PR 2164 98203 MAD 93-18

- Posterior FMNH PR 2201 99016 MAD 93-01

- Posterior UA 9091 01027 MAD 93-18

- Posterior UA 9123 03055 MAD 93-18

- Posterior UA 9126 03068 MAD 93-18

- Posterior UA 9128 03101 MAD 93-18

- Posterior UA 9183 07028 MAD 93-35

- Posterior FMNH PR 2696 07882-1 MAD 05-42

- Posterior UA 9734 07909-1 MAD 93-35

Ceratobranchial - FMNH PR 2481 07449 MAD 05-42
n u m b e r 9 5 • 4 3

Atlantal intercentrum - C1 FMNH PR 2477 03594 MAD 93-18

- C1? FMNH PR 2481 07508 MAD 05-42

Axis - C2 FMNH PR 2462 03409 MAD 93-18

- C2 FMNH PR 2466 03420-1 MAD 03-40

Arch C2 UA 9130 03579+03580 c MAD 93-18

Cervical vertebra - C3 UA 9121 03031 MAD 93-18

- C4 UA 9189 07225 MAD 07-16

- C4 UA 9106 01099 MAD 93-18

- C4 FMNH PR 2485 05443-1 MAD 05-42

- C5 FMNH PR 2465 03417 MAD 93-18

- C6 FMNH PR 2481 07436 MAD 05-42

- C7 FMNH PR 2481 07219 MAD 05-42

- C7 FMNH PR 2139 95322 MAD 93-18

- C7 UA 9111 01120 MAD 93-18

- C8 UA 9171 03454 MAD 93-18

- C8 UA 9181 03605 MAD 93-18

- C8 FMNH PR 2141 98180 MAD 93-18

- C9 FMNH PR 2481 07212 MAD 05-42

- C9–10 UA 9150 03273 MAD 93-18

- C10 FMNH PR 2491 98154-1 MAD 93-18

- C10 FMNH PR 2140 98172 MAD 93-18

- ND FMNH PR 2485 05467-2 MAD 05-42

- ND FMNH PR 2485 05616-1 MAD 05-42

- ND FMNH PR 2464 03414 MAD 93-18

- ND FMNH PR 2481 07494 MAD 05-42

- ND FMNH PR 2630 07439 MAD 05-42

Centrum ND UA 9859 98218-3 MAD 93-18

Dorsal vertebra - D1 FMNH PR 2837 07214 MAD 05-42

Arch D2 UA 9107 01100 MAD 93-18

- D2 FMNH PR 2485 07682 MAD 05-42

- D3 FMNH PR 2684 07789 MAD 05-42

Arch D4 FMNH PR 2144 95283 MAD 93-18

Arch D4 FMNH PR 2485 05459-1 MAD 05-42

- D4 FMNH PR 2636 07446 MAD 05-42

- D5 FMNH PR 2481 07215 MAD 05-42

- D6 FMNH PR 2481 07445 MAD 05-42

- D7 FMNH PR 2481 07213 MAD 05-42

- D11? FMNH PR 2481 07494-2 MAD 05-42

- D12? FMNH PR 2481 07494-3 MAD 05-42

- D13? FMNH PR 2481 07494-4 MAD 05-42

- D14? FMNH PR 2481 07494-5 MAD 05-42

- Posterior UA 9175 03582 MAD 93-18

- Posterior UA 9103 01087 MAD 93-18

- Posterior UA 9176 03604 MAD 93-18

- Posterior UA 9092 01028 MAD 93-18

- Posterior UA 9097 01036 MAD 93-18

Arch ND FMNH PR 2458 05460-28 MAD 05-42

Arch ND UA 9164 03413 MAD 93-18

Centrum ND FMNH PR 2114 95339 MAD 93-18

Transverse process ND UA 9108 01102 MAD 93-18

- ND FMNH PR 2207 96023 MAD 93-18

- ND FMNH PR 2113 98235 MAD 93-18

- ND FMNH PR 2229 98313-1 MAD 93-18

- ND UA 8701 99162 MAD 93-18

- ND FMNH PR 2171 99262 MAD 99-38

Element(s) Notes and comments Position Specimen number a Field number b Locality

Axial Column
4 4 • smithsonian contributions to paleobiology

- ND FMNH PR 2458 05593-3 MAD 05-42

- ND FMNH PR 2137 95334 MAD 93-18

- ND FMNH PR 2138 95334-1 MAD 93-18

- ND FMNH PR 2145 95283-1 MAD 93-18

- ND FMNH PR 2610 07085 MAD 05-42

Sacral vertebra - 1 UA 9115 01135 MAD 93-18

- 5–6 UA 9098 01043 MAD 93-18

- 3–6 FMNH PR 2460 03407 MAD 03-66

- 3–5 FMNH PR 2142 98243 MAD 93-18

Centrum 1 FMNH PR 2485 07475 MAD 05-42

- 1–6 FMNH PR 2481 07218-3 MAD 05-42

Caudal vertebra - Anterior FMNH PR 2469 03453 MAD 93-18

Arch Anterior FMNH PR 2481 07218-4 MAD 05-42

2 elements Anterior FMNH PR 2481 07494-1 MAD 05-42

- Anterior FMNH PR 2481 07779 MAD 05-42

- Anterior UA 9112 01129 MAD 93-18

- Anterior FMNH PR 2133 93061-2 MAD 93-30

- Anterior FMNH PR 2481 07690 MAD 05-42

Centrum Anterior UA 9173 03474 MAD 93-18

- Anterior/middle FMNH PR 2481 07507 MAD 05-42

- Anterior/middle FMNH PR 2482 05389 MAD 05-42

- Middle UA 9190 07073 MAD 05-04

- Middle UA 8692 95331 MAD 93-18

- Middle FMNH PR 2125 95332 MAD 93-18

- Middle FMNH PR 2110 95195-4 MAD 93-18

- Middle UA 9179 03597 MAD 93-18

- Middle UA 8688 98075 MAD 93-18

- Middle UA 9197 98191 MAD 93-18

- Middle FMNH PR 2126 98394 MAD 93-18

- Middle FMNH PR 2485 05459-1 MAD 05-42

- Middle FMNH PR 2481 07503 MAD 05-42

+ Rib Middle/posterior FMNH PR 2481 07211 MAD 05-42

- Middle/posterior UA 9195 98041 MAD 96-01

- Middle/posterior UA 9858 98218-2 MAD 93-18

- Middle/posterior UA 9120 03017 MAD 93-18

- Middle/posterior UA 9158 03350 MAD 93-18

- Posterior UA 8689 98206 MAD 93-18

3 elements Posterior FMNH PR 2492 98188 MAD 93-18

- Posterior FMNH PR 2485 05386 MAD 05-42

- Posterior FMNH PR 2467 03431-1 MAD 93-18

- Posterior UA 9139 03176 MAD 93-18

- Posterior UA 9119 03015 MAD 93-18

- Posterior FMNH PR 2203 95222-130-1 MAD 93-18

- Posterior FMNH PR 2202 95222-097-1 MAD 93-18

- Posterior UA 8695 95244-6 MAD 93-18

- Posterior UA 8696 95244-7 MAD 93-18

- Posterior UA 8691 95272 MAD 93-18

- Posterior FMNH PR 2162 95275 MAD 93-18

- Posterior UA 8690 96015 MAD 93-18

- Posterior FMNH PR 2156 98165-1 MAD 93-18

- Posterior FMNH PR 2157 98165-2 MAD 93-18

- Posterior FMNH PR 2642 07480 MAD 05-42

- Posterior FMNH PR 2638 07464 MAD 05-42

- Posterior FMNH PR 2163 98169-1 MAD 93-18

- Posterior FMNH PR 2485 07474 MAD 05-42

- Posterior FMNH PR 2481 07213 MAD 05-42

Element(s) Notes and comments Position Specimen number a Field number b Locality

Axial Column
n u m b e r 9 5 • 4 5

- Posterior FMNH PR 2127 98179 MAD 93-18

- Posterior FMNH PR 2128 98179-1 MAD 93-18

- Posterior UA 8703 98415 MAD 93-18

- Posterior FMNH PR 2168 99265 MAD 99-26

- Posterior FMNH PR 2481 07443 MAD 05-42

- Posterior UA 9857 03178 MAD 93-18

- Posterior FMNH PR 2458 05460-26 MAD 05-42

Arch ND UA 9174 03575-2 MAD 93-18

Centrum ND FMNH PR 2230 98236 MAD 93-18

Centrum ND UA 9113 01131 MAD 93-18

Centrum ND UA 9151 03274 MAD 93-18

Centrum ND FMNH PR 2490 98018 MAD 93-18

Centrum ND UA 9110 01119 MAD 93-18

Centrum ND UA 9184 07098 MAD 07-13*

- ND FMNH PR 2481 07838 MAD 05-42

- ND UA 8702 96018 MAD 93-18

- ND FMNH PR 2481 07208-1 MAD 05-42

- ND FMNH PR 2481 07218-4 MAD 05-42

- ND FMNH PR 2485 07882-2 MAD 05-42

- ND FMNH PR 2485 07882-3 MAD 05-42

- ND FMNH PR 2699 07882-4 MAD 05-42

- ND FMNH PR 2700 07882-5 MAD 05-42

- ND UA 9127 03100 MAD 93-18

- ND UA 9140 03179 MAD 93-18

- ND UA 9148 03256 MAD 93-18

- ND FMNH PR 2125 95229 MAD 93-18

- ND UA 9187 95198-4 MAD 93-18

Unidentified vertebra - ND FMNH PR 2485 07465 MAD 05-42

Arch ND UA 9109 01104-2 MAD 93-18

Arch ND FMNH PR 2618 07207 MAD 05-42

Centrum ND UA 9093 01029 MAD 93-18

Centrum ND FMNH PR 2111 95195-5 MAD 93-18

Centrum ND FMNH PR 2677 07775 MAD 05-42

2 elements ND UA 8687 98083 MAD 93-18

Cervical rib - C4 (right) FMNH PR 2485 05384 MAD 05-42

Proximal portion C4 (right) FMNH PR 2481 07787 MAD 05-42

Proximal portion C6 (right) UA 9169 03443 MAD 93-18

- C6 FMNH PR 2485 05414-1 MAD 05-42

Proximal portion C7 (right) FMNH PR 2485 07491 MAD 05-42

Proximal portion C9 (left) UA 9104 01088-1 MAD 93-18

Proximal portion C10 FMNH PR 2481 07435 MAD 05-42

Proximal portion ND FMNH PR 2481 07776 MAD 05-42

- ND FMNH PR 2481 07213 MAD 05-42

Cervicodorsal rib - C10/D1 (right) FMNH PR 2672 07691 MAD 05-42

Dorsal rib - ~D4 FMNH PR 2485 05416 MAD 05-42

Proximal portion ~D4 (right) UA 9160 03394 MAD 93-18

Proximal portion ~D4 UA 9862 03574-2 MAD 93-18

- (Left) FMNH PR 2485 05415 MAD 05-42

- (Right) FMNH PR 2481 07788 MAD 05-42

- ND FMNH PR 2481 07784 MAD 05-42

Proximal portion ND UA 9155 03332-1 MAD 93-18

- ND FMNH PR 2481 07500 MAD 05-42

Unidentified rib - ND FMNH PR 2478 03595 MAD 93-18

Proximal portion ND FMNH PR 2634 07444 MAD 05-42

Proximal portion ND UA 9861 03497 MAD 93-18

Proximal portion ND UA 9863 03590 MAD 93-18

Element(s) Notes and comments Position Specimen number a Field number b Locality

Axial Column
4 6 • smithsonian contributions to paleobiology

Fragments ND FMNH PR 2603 05392 MAD 05-42

Fragment ND FMNH PR 2481 07437 MAD 05-42

Fragment ND FMNH PR 2632 07441 MAD 05-42

Fragment ND FMNH PR 2481 07744 MAD 05-42

Fragment ND FMNH PR 2685 07791 MAD 05-42

- ND FMNH PR 2481 07890 MAD 05-42

5 fragments ND FMNH PR 2485 07222 MAD 05-42

Gastrale - Anterior FMNH PR 2481 07213 MAD 05-42

Chevron - ND UA 9196 98175 MAD 93-18

- Middle UA 9152 03285 MAD 93-18

- ND UA 9180 03602 MAD 93-18

- ND UA 9182 03147 MAD 93-18

- ND FMNH PR 2481 05385 MAD 05-42

- ND FMNH PR 2485 07221 MAD 05-42

- ND FMNH PR 2673 07698 MAD 05-42

Appendicular Skeleton

Scapula - Left UA 9116 01136 MAD 93-18

- Left FMNH PR 2458 03400 MAD 93-18

- Left FMNH PR 2481 07746 MAD 05-42

- Right FMNH PR 2481 07442 MAD 05-42

- Right FMNH PR 2606 05404 MAD 05-42

Scapulocoracoid - Right UA 9160 03394 MAD 93-18

Coracoid - Right UA 9159 03356 MAD 93-18

- Left? FMNH PR 2481 07213 MAD 05-42

Fragment? ND FMNH PR 2481 07522 MAD 05-42

Humerus - Left FMNH PR 2485 05418 MAD 05-42

Proximal 2/3 Right FMNH PR 2143 98007 MAD 93-18

- Right FMNH PR 2481 07213 MAD 05-42

Proximal portion Right UA 9165 03415 MAD 93-18

Shaft Right UA 8693 95244-4 MAD 93-18

Shaft? ND UA 8694 98090 MAD 93-18

Metacarpal IV? Proximal portion ND UA 9146 03213 MAD 93-18

Manual phalanx - ND FMNH PR 2227 98312-6 MAD 93-18

- ND FMNH PR 2224 96353 MAD 93-101

- ND FMNH PR 2132 95244-5 MAD 93-18

2+ elements ND FMNH PR 2225 96392 MAD 96-41

- ND UA 9194 95377 MAD 95-14

Manual ungual - ND FMNH PR 2169 99277 MAD 99-05

- ND FMNH PR 2136 95335 MAD 93-18

Ilium - Left FMNH PR 2485 05460-03 MAD 05-42

- Left FMNH PR 2481 07218-1 MAD 05-42

?? Left? FMNH PR 2472 03496 MAD 93-18

- Right FMNH PR 2481 07218-2 MAD 05-42

Central and posterior portions Right UA 9170 03450 MAD 93-18

Pubis Proximal 2/3 Left FMNH PR 2463 03411 MAD 93-18

Distal 2/3 Left, right FMNH PR 2470 03457 MAD 93-18

- Left FMNH PR 2108 98089 MAD 93-18

Proximal portion Left FMNH PR 2461 03408 MAD 93-18

Proximal portion Left UA 9153 03323 MAD 93-18

- Right FMNH PR 2109 95250-1 MAD 93-18

Proximal 2/3 Right UA 9100 01045 MAD 93-18

Proximal portion Right UA 9162 03445 MAD 93-18

- Left, right FMNH 2481 07218 MAD 05-42

Shaft ND UA 9136 03143 MAD 93-18

Shaft? ND UA 9117 01137 MAD 93-18

Element(s) Notes and comments Position Specimen number a Field number b Locality

Axial Column
n u m b e r 9 5 • 4 7

Ischium - Left UA 9168 03435 MAD 93-18

Proximal 1/2 Left FMNH PR 2468 03439 MAD 93-18

Proximal portion Right UA 9133 03130 MAD 93-18

- Right UA 9172 03470 MAD 93-18

Distal 2/3 Left, right FMNH PR 2485 05444 MAD 05-42

Femur - Left FMNH PR 2123 98317 MAD 93-18

- Left FMNH PR 2117 95194 MAD 93-18

- Left FMNH PR 2120 95256 MAD 93-18

- Left FMNH PR 2115 95234 MAD 93-18

- Left FMNH PR 2485 05467-2 MAD 05-42

Proximal 1/2 Left FMNH PR 2481 07217 MAD 05-42

Proximal portion Left UA 9193 95222-049-1 MAD 93-18

Proximal portion Left FMNH PR 2150 98245 MAD 93-18

Proximal portion Left FMNH PR 2149 95248-1 MAD 93-18

Distal shaft Left UA 9135 03139 MAD 93-18

- Right FMNH PR 2153 96020 MAD 93-18

- Right UA 9170 03450 MAD 93-18

- Right UA 8712 98238-1 MAD 93-18

- Right FMNH PR 2148 98229 MAD 93-18

- Right FMNH PR 2215 98021 MAD 93-18

- Right FMNH PR 2208 95238 MAD 93-18

- Right UA 8684 98212 MAD 93-18

- Right UA 8681 98237 MAD 93-18

- Right FMNH PR 2481 07493 MAD 05-42

Tibia - Left UA 8685 98022 MAD 93-18

- Left FMNH PR 2481 07687 MAD 05-42

- Left FMNH PR 2214 98124 MAD 93-18

Proximal portion Left FMNH PR 2119 98216-1 MAD 93-18

Proximal portion Left FMNH PR 2118 98216 MAD 93-18

Distal portion Left UA 9142 03199 MAD 93-18

Distal portion Left UA 9613 NFN 5 NR

Distal 1/2 Left FMNH PR 2152 95233 MAD 93-18

- Right UA 8687 98083 MAD 93-18

- Right UA 8711 98241 MAD 93-18

- Right FMNH PR 2121 98323 MAD 93-18

- Right FMNH PR 2112 98155 MAD 93-18

Proximal portion Right UA 8710 98125 MAD 93-18

Proximal portion Right UA 9099 01044 MAD 93-18

- Right FMNH PR 2481 07476 MAD 05-42

- Left FMNH PR 2686 07792 MAD 05-42

- Left FMNH PR 2817 05442 MAD 05-42

Femur, tibia, fibula - Right FMNH PR 2485 05456 MAD 05-42

Tibia, fibula - Left FMNH PR 2485 05419 MAD 05-42

Tibia, fibula, tarsus - Left FMNH PR 2122 95325 MAD 93-18

Tibia, fibula, tarsus - Right FMNH PR 2116 98320 MAD 93-18

Fibula Proximal 2/3 Left FMNH PR 2481 07523 MAD 05-42

- Right UA 9167 03421+03269 c MAD 93-18

Proximal 2/3 Right UA 9172 03470 MAD 93-18

Proximal 1/2 Right UA 9143 03201 MAD 93-18

Proximal portion Right UA 9134 03136 MAD 93-18

Proximal 2/3 Right UA 9098 01043 MAD 93-18

Proximal 1/2 Right UA 9132 03128 MAD 93-18

Fibula, astragalus - Right FMNH PR 2481 07216+07487 c MAD 05-42

Astragalus - Left FMNH PR 2481 07440 MAD 05-42

Calcaneum - Right FMNH PR 2235 95124-2 MAD 93-18

Metatarsal I? Distal portion Left UA 9118 03004 MAD 93-18

Element(s) Notes and comments Position Specimen number a Field number b Locality

Appendicular Skeleton
4 8 • smithsonian contributions to paleobiology

Metatarsal II - Left UA 9122 03053-1 MAD 93-18

Distal portion Left FMNH PR 2175 99166 MAD 93-18

Distal 1/3 Left UA 9138 03175 “East of Mammal”

Distal 1/2 Left FMNH PR 2481 07700 MAD 05-42

Distal 1/4 Left UA 9774 07148 MAD 93-72

Distal 1/2 Left FMNH PR 2679 07778 MAD 05-42

- Right FMNH PR 2147 98086 MAD 93-18

- Right FMNH PR 2151 98220 MAD 93-18

- Right FMNH PR 2206 98201 MAD 93-18

- Right FMNH PR 2481 05585 MAD 05-42

Distal portion Right UA 8683 93061-6 MAD 93-30

- Right FMNH PR 2154 95244-10 MAD 93-18

Metatarsal III - Left? FMNH PR 2146 95225 MAD 93-18

+ Distal tarsal 3 Left UA 9102 01086 MAD 93-18

- Left FMNH PR 2155 98165 MAD 93-18

Proximal portion + distal tarsal 3 Right FMNH PR 2687 07833 MAD 05-42

- Right FMNH PR 2485 05460-27 MAD 05-42

Metatarsal IV - Left UA 9101 01085-1 MAD 93-18

- Right FMNH PR 2459 03406 MAD 93-18

- Right FMNH PR 2214 98124 MAD 93-18

Distal portion Right UA 9163 03577 MAD 93-18

Distal portion Left FMNH PR 2485 05593-2 MAD 05-42

Proximal portion Right FMNH PR 2234 98119 MAD 93-18

Unidentified metatarsal Distal portion ND UA 9773 07909-2 MAD 93-35

+ Rib fragments ND UA 9105 01089 MAD 99-33

Pedal phalanx II-1 - Left FMNH PR 2129 98200 MAD 93-18

- Left UA 9154 03327 MAD 93-18

- Left FMNH PR 2160 95122 MAD 93-18

- Left FMNH PR 2616 07186 MAD 05-42

- Right FMNH PR 2161 98196 MAD 93-18

- Right FMNH PR 2709 05433 MAD 05-42

- Right UA 9188 07421 MAD 93-34

Pedal phalanx II-2 - Left FMNH PR 2217 93069 MAD 93-33

- Right FMNH PR 2136 95335 MAD 93-18

- Left FMNH PR 2604 05395 MAD 05-42

Pedal phalanx III-1 - Right FMNH PR 2159 95041 MAD 93-18

- Right UA 8700 NFN 7 NR

- Left FMNH PR 2218 98094-2 MAD 93-18

- Left FMNH PR 2481 07537 MAD 05-42

Pedal phalanx III-2 - Left FMNH PR 2167 98075-1 MAD 93-18

- Left FMNH PR 2480 03609 MAD 93-18

- Left FMNH PR 2176 98280 MAD 93-18

- Right FMNH PR 2173 99120 MAD 99-30

Pedal phalanx III-2/3 - Right FMNH PR 2219 99312 MAD 99-33

- Left UA 9199 99052 MAD 93-35

Pedal phalanx III-4 - Right UA 9094 01030 MAD 93-18

Pedal phalanx III-x - Left UA 9192 07889 MAD 93-26

- Right FMNH PR 2481 07685 MAD 05-42

- Right UA 9186 07416 MAD 93-34

- Right FMNH PR 2617 07191 MAD 05-42

- Right FMNH PR 2613 07123 MAD 05-42

Pedal phalanx IV-1 - Left FMNH PR 2158 98311 MAD 93-18

- Left UA 9156 03337 MAD 93-18

- Right FMNH PR 2614 07135 MAD 05-42

- Right FMNH PR 2172 99270 MAD 93-18

- Right FMNH PR 2605 05397 MAD 05-42

Element(s) Notes and comments Position Specimen number a Field number b Locality

Appendicular Skeleton
n u m b e r 9 5 • 4 9

- Right UA 9185 07543 MAD 93-35

Pedal phalanx IV-2 - Left FMNH PR 2216 96271 MAD 96-01

- Right UA 9096 01035 MAD 93-18

- Left UA 9137 01140 MAD 93-35

Pedal phalanx IV-2/3 - ND FMNH PR 2479 03598 MAD 93-18

Pedal phalanx IV-3 - Left FMNH PR 2130 98200-1 MAD 93-18

- Right FMNH PR 2131 98200-2 MAD 93-18

- Right FMNH PR 2174 99167 MAD 93-18

Pedal phalanx IV-4 - Right UA 8686 95323 MAD 93-18

Pedal ungual III-4 - Left UA 9157 03339 MAD 93-18

Pedal ungual II/IV - Left FMNH PR 2135 95333 MAD 93-18

- ND FMNH PR 2486 05435 MAD 05-42

- Left FMNH PR 2667 07587 MAD 05-42

- Left FMNH PR 2485 07202 MAD 05-42

Pedal ungual - Right FMNH PR 2134 95332-1 MAD 93-18

- Left FMNH PR 2236 95307 MAD 95-14

- Right UA 9144 03203 MAD 93-18

- Left UA 9198 98284 MAD 93-18

Unidentified pedal phalanx - ND FMNH PR 2205 95271 MAD 93-18

2 elements ND FMNH PR 2223 93104-4 MAD 93-38

- ND FMNH PR 2611 07116 MAD 05-42

- ND UA 8682 93174 MAD 93-74

- ND UA 8713 95123 MAD 93-18

- ND UA 8714 93201 MAD 93-81

- ND UA 9132 03128 MAD 93-18

?? ND FMNH PR 2493 98270 MAD 93-18

?? ND FMNH PR 2485 05593-1 MAD 05-42

a

 Elements found in direct association are given the same specimen number. 

b The field number is composed of two initial digits representing the year followed by three digits identifying the specimen; e.g., 03056 is specimen #56 

from the 2003 expedition.

c

 Element is composed of two separately numbered specimens.

Element(s) Notes and comments Position Specimen number a Field number b Locality

Appendicular Skeleton

Accarie, H., B. Beaudoin, J. Dejax, G. Friès, J.-G. Michard, and P. Taquet. 1995. Découverte d’un Dinosaure théropode nouveau (Genusaurus sisteronis n. g., n. sp.) 

dans l’Albien marin de Sisteron (Alpes de Haute-Provence, France) et extension au 

Crétacé inférieur de la lignée cératosaurienne. [Discovery of a New Theropod Dinosaur (Genusaurus sisteronis n. g., n. sp.) in the Marine Albian of Sisteron (Alps 

of Haute-Provence, France) and Extension of the Ceratosaurian Lineage into the 

Lower Cretaceous.] Comptes Rendus de l’Académie des Sciences à Paris, Série IIa, 

320:327–334.

Agnolin, F. L. and P. Chiarelli. 2010. The Position of the Claws in Noasauridae (Dinosauria: Abelisauroidea) and its Implications for Abelisauroid Manus Evolution. 

Paläontologische Zeitschrift, 85:293–300.

Agnolin, F. L., F. E. Novas, and S. Apesteguía. 2003. Velocisaurids in South America and 

Madagascar. Ameghiniana, 40(4, Supplement):77R. 

Allain, R., R. Tykoski, N. Aquesbi, N.-E. Jalil, M. Monbaron, D. Russell, and P. Taquet. 

2007. An Abelisauroid (Dinosauria: Theropoda) from the Early Jurassic of the High 

Atlas Mountains, Morocco, and the Radiation of Ceratosaurs. Journal of Vertebrate 

Paleontology, 27:610–624.

Bonaparte, J. F. 1991. Los vertebrados fósiles de la Formación Río Colorado, de la Ciudad de Neuquén y cercanías, Cretácico Superior, Argentina. [The Fossil Vertebrates 

of the Río Colorado Formation, from Neuquén City and Surrounding Area, Upper 

Cretaceous, Argentina.] Revista del Museo Argentino de Ciencias Naturales “Ber‐

nardino Rivadavia” e Instituto Nacional de Investigación de las Ciencias Naturales, 

Paleontología, 4(3):17–123.

———. 1996. Cretaceous Tetrapods of Argentina. Münchner Geowissenschaftliche Ab‐

handlungen (A), 30:73–130.

Bonaparte, J. F., and F. E. Novas. 1985. Abelisaurus comahuensis, n.g., n.sp., Carnosauria del Cretácico Tardio de Patagonia. [Abelisaurus comahuensis, n.g., n.sp., Carnosauria from the Late Cretaceous of Patagonia.] Ameghiniana, 21(2–4):259–265.

Bonaparte, J. F., F. E. Novas, and R. A. Coria. 1990. Carnotaurus sastrei Bonaparte, the 

Horned, Lightly Built Carnosaur from the Middle Cretaceous of Patagonia. Con‐

tributions in Science, Natural History Museum of Los Angeles County, 416:1–41.

Bonaparte, J. F., and J. E. Powell. 1980. A Continental Assemblage of Tetrapods from the 

Upper Cretaceous Beds of El Brete, Northwestern Argentina (Sauropoda-Coelurosauria-Carnosauria-Aves). Mémoires de la Société Géologique de France, Nouvelle 

Série, 139:19–28.

Brissón Egli, F., and S. Apesteguía. 2008. “Noasaurid remains from the Candeleros 

Formation at ‘La Buitrera’ (early Upper Cretaceous), Río Negro, Argentina.” In 

Actas III Congreso Latinoamericano de Paleontología de Vertebrados, Neuquén, 

Argentina, 22–25 Septiembre, 2008, Libro de Resúmenes, ed. J. O. Calvo, R. Juarez 

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