DOI: 10.5061/dryad.83bk3j9r1
title: Data from: Evolutionary–phylogenetic pathway of the Cretaceous ammonite genus Aegocrioceras and its relationship to Juddiceras spp. and Crioceratites spp.

description: The systematics of ammonoids are complicated by their large degree of
 intra-specific variation, which complicates a stable validation of
 species. Aegocrioceras is a heteromorph ammonite from the Lower Saxony
 Basin in the Hauterivian Boreal, and a prime example of a genus with an
 unstable internal systematic and external relationship to other ammonoids.
 Here, we use quantitative morphometrics on Aegocrioceras species from an
 assemblage collected in the clay pit Resse (north-west Germany) to
 evaluate the systematics and phylogeny of this Cretaceous genus. We
 simplify the systematic of the genus into the three entities
 A. bicarinatum [m]/A. semicinctum [M] complex (which
 potentially contains A. quadratum as well),
 A. raricostatum and A. spathi. The most likely phylogeny
 coincides very well with the stratigraphic record of the species and
 implies anagenetic adaptations in A. raricostatum and
 A. spathi after the origin of the species. Aegocrioceras most
 likely derived from warm-water adapted Tethyan Crioceratites species, and
 Boreal Crioceratites are potentially warm-water adapted descendants of the
 cold-water adapted Aegocrioceras but may alternatively represent renewed
 Tethyan invasions. Our data imply that Aegocrioceras’ success against
 incumbent ammonites in the Boreal was rooted in abiotic change (Court
 Jester) processes due to its high adaptability, while selection within the
 Aegocrioceras clade was more likely based on biotic interaction (Red
 Queen) processes.
description: General abbreviations for morphological parameters
 [m]/[M], small/large antidimorphs (i.e. microconch and
 macroconch); wh, whorl height; wi, whorl interspace; uw, umbilical width;
 dm, conch diameter; ARI, absolute rib index; RDW, ribs per demi-whorl;
 WER, whorl expansion rate; WHER, whorl height expansion rate; UWI,
 umbilical width index; WII, whorl interspace index.
 Fossil material The material was collected
 from the clay pit Resse, 10 km north of Hanover (north-west Germany),
 located at 52° 28′ 47.64″ N and 9° 38′ 6.96″ E. All specimens were
 collected from calcareous concretions, ensuring their 3D-preservation, and
 are deposited in the Naturalis Biodiversity Centre in Leiden, The
 Netherlands and the Landesamt für Bergbau, Energie und Geologie (LBEG),
 Geozentrum Hanover, Germany. The clay pit sediments cover the latest early
 Hauterivian <i>Aegocrioceras</i> beds, dated to belong to the
 nannofossil zones BC 8b–8c (Möller & Mutterlose 2014). The
 <i>Aegocrioceras</i> beds have been dated by Möller &
 Mutterlose (2014) using the index fossils <i>Cruciellipsis
 cuvillieri</i> (132.87 Ma) and <i>Lithraphidites
 bollii</i> (133.53 Ma). Absolute ages are here based on the
 Geological Time Scale 2012 (Gradstein<i> et al.</i> 2012).
 This implies that the <i>Aegocrioceras</i> beds comprise
 <i>c.</i>600 kyrs (Mutterlose 1992). The clay pit Resse was
 situated firmly in the middle of the Lower Saxony Basin during Hauterivian
 times, <i>c.</i>50 km away from the Pompeckj Swell to the
 north and the Rhenish Massif to the south (Möller & Mutterlose
 2014, fig. 1). The sediment profile is comprised of an interlayering
 between thick claystone layers and thinner (10–20 cm), more calcareous
 layers which contain brown-greyish concretions; each calcareous layer
 comprises <i>c.</i>60 kyrs (Möller & Mutterlose
 2014). A total of
 320 specimens of <i>Aegocrioceras</i> spp. from seven
 different beds of the clay pit Resse have been analysed for this work,
 comprised of the following species: 167 specimens of
 <i>Aegocrioceras bicarinatum</i> [m], 37 specimens of
 <i>Aegocrioceras semicinctum</i> [M], 9 specimens of
 <i>Aegocrioceras quadratum</i>, 49 specimens of
 <i>Aegocrioceras raricostatum</i> and 58 specimens of
 <i>Aegocrioceras spathi</i>. Species designation followed
 Rawson (1975). We
 also extracted morphological data from the depiction of the type specimen
 of <i>Aegocrioceras densiradiatum</i> from Rawson (1975, pl.
 6, fig. 2). In addition, we extracted morphometric data from single
 specimens of closely related Boreal species from published images,
 depicting their type specimens/only described specimens or specimens with
 an ‘average’ morphology. These include the Valanginian <i>Juddiceras
 curvicosta</i> from Kemper & Wiedenroth (1987, p. 353, pl.
 9, fig. 2), the Valanginian <i>Crioceratites</i> sp. from
 Kemper & van der Burgh (1992, pl. 30, fig. 1), and the upper
 Hauterivian <i>Crioceratites seeleyi</i> (p. 272, fig. 11I)
 and <i>Emericiceras wermbteri</i> (p. 272, fig. 11A) from
 Mutterlose & Wiedenroth (2009). Morphometric data extraction and
 preparation For
 all specimens, we extracted morphological data of the conch using the
 software CONCH v. 1.0 (Hoffmann<i> et al.</i> 2019a, b). The
 following measurements were taken at radial angles of every 45°, starting
 at 0° in the adult stage of the conch, and numbered consecutively: (1) The
 whorl height (wh); (2) the whorl interspace (wi; i.e. the height of the
 gap between consecutive whorls); (3) the umbilical width (uw); (4) the
 conch diameter (dm); (5) the absolute rib indices
 ARI<sub>20</sub> and ARI<sub>40</sub>, which are
 the number of ribs in a circle of 20 or 40 mm diameter around the
 measurement point (De Baets<i> et al.</i> 2009) and (6) the
 number of ribs per demi-whorl index (RDW), which is the number of ribs on
 the 180°-section of the conch toward the juvenile stage. From these raw
 parameters, we calculated the following derived parameters for every
 measurement point <i>i</i>: (1) The whorl expansion rate
 WER<i><sub>i</sub></i> = [dm<i><sub>i</sub></i>/(dm<i><sub>i</sub></i> − (wh<i><sub>i</sub></i> + wi<i><sub>i</sub></i>))]<sup>2</sup> (Korn 2000); (2) the whorl-height expansion rate WHER<i><sub>i</sub></i> = (wh<i><sub>i</sub></i>/wh<i><sub>i</sub></i><sub>+4</sub>)<sup>2</sup> (Korn & Vöhringer 2004); (3) the umbilical width index UWI<i><sub>i</sub></i> = uw<i><sub>i</sub></i>/dm<i><sub>i</sub></i> (Korn & Vöhringer 2004) and (4) the whorl interspace index WII<i><sub>i</sub></i> = wi<i><sub>i</sub></i>/wh<i><sub>i</sub></i> (De Baets<i> et al.</i> 2009). Because the ammonoid conchs were often only preserved as fragments and, thus, missed parts of the shell, a method to make measurements homologous and thus comparable was needed. For this, we applied the superimposition procedure described by Hoffmann<i> et al.</i> (2019a). In this procedure, all specimens are aligned via rotation in 45°-steps to the largest specimen until the closest possible fit between their respective radial angle–diameter curves is reached. The radial angles of the superimposed specimens are then adjusted according to the degree of rotation, so that measurements that show the same radial angle represent morphologically homologous measurements in all specimens. Data analysis All data have been analysed using R v. 4.0.2 (R Core Team 2020). We developed a method to re-describe the morphological data in a comparable way between all specimens, including the entire preserved ontogeny. We did this by fitting ordinary least-squares linear regression or non-linear regression models to the parameters, with radial angle (deg) as independent variable. The model for every parameter <i>P</i> took either of the two forms <i>P</i> = <i>m</i> × deg + <i>b</i> or <i>P</i> = <i>m</i> × <i>e<sup>b</sup></i><sup> × deg</sup> (the decision of whether to fit a linear or an exponential model was made via visual examination of the plotted parameters). For either model, we extracted three values to describe the <i>Aegocrioceras</i> morphology throughout its ontogeny: (1) The intercept parameter <i>m</i>, which gives a representative indication of the normalized size of the respective parameter (representative for the adult stage); (2) the slope parameter <i>b</i>, which can be interpreted as the ontogenetic trajectory of the parameter, indicating to what degree it changes during the life of the individual and (3) the inverse coefficient of determination 1−<i>R</i><sup>2</sup> of the model, which indicates the individual variation of the parameter throughout ontogeny. These model parameters had been centred at zero and scaled to unit variance before ensuing analyses to ensure their comparability. We used the Greedy Wilks algorithm (Mardia<i> et al.</i> 1979) with a λ-level of 0.05, as implemented in the R-package ‘klaR’ v. 0.6-15 (Weihs<i> et al.</i> 2005), to identify the most important model parameters for a separation between <i>Aegocrioceras</i> species. The thus identified parameters were used for the construction of a phenetic tree for all species based on the Euclidean distances, using the R-package ‘ape’ v. 5.4-1 (Paradis<i> et al.</i> 2004). Tree generation was performed using the balanced FastME algorithm (Desper & Gascuel 2002). For the <i>Aegocrioceras</i> species, we included morphological variation for the phylogram reconstruction. For this, 999 random trees were generated where the morphological parameters for each species were allowed to vary around the mean morphology following a Gaussian distribution with the standard deviation estimated from the measured data. These random trees were then used to calculate a consensus tree based on the Robinson–Foulds distance (Robinson & Foulds 1981), with the phylogeny based on the average morphology as a starting point, using the R-package ‘phytools’ v. 0.7-47 (Revell 2012). References DE BAETS, K., KLUG, C. and KORN, D. 2009. Anetoceratinae (Ammonoidea, Early Devonian) from the Eifel and Harz mountains (Germany), with a revision of their genera. <em>Neues Jahrbuch für Geologie und Paläontologie – Abhandlungen</em>, 252 (3), 361–376. DESPER, R. and GASCUEL, O. 2002. Fast and accurate phylogeny reconstruction algorithms based on the minimum-evolution principle. 357–374. <em>In</em> GUIGÓ, R. and GUSFIELD, D. (eds). <em>Algorithms in Bioinformatics: Second International Workshop, WABI 2002 Rome, Italy, September 17–21, 2002 Proceedings</em>. Lecture Notes in Computer Science, Vol. 2452. Springer-Verlag, Berlin, Heidelberg, 554 pp. GRADSTEIN, F., OGG, J., SCHMITZ, M. and OGG, G. 2012. <em>The Geologic Time Scale 2012</em>. Elsevier, Oxford, Amsterdam, Waltham, 1176 pp. HOFFMANN, R., WEINKAUF, M. F. G., WIEDENROTH, K., GOEDDERTZ, P. and DE BAETS, K. 2019a. Morphological disparity and ontogeny of the endemic heteromorph ammonite genus <em>Aegocrioceras</em> (Early Cretaceous, Hauterivian, NW-Germany). <em>Palaeogeography, Palaeoclimatology, Palaeoecology</em>, 520, 1–17. HOFFMANN, R., WEINKAUF, M. F. G., WIEDENROTH, K., GOEDDERTZ, P. and DE BAETS, K. 2019b. CONCH – Ammonoid Morphometric Software. <em>Figshare</em>. https://doi.org/10.6084/m9.figshare.6287255.v1 KEMPER, E. and VAN DER BURGH, J. 1992. <em>Die tiefe Unterkreide im Vechte–Dinkel-Gebiet (westliches Niedersächsisches Becken), mit einem paläobotanischen Beitrag von J. van der Burgh</em>. Losser, Stichting het Staringmonument, 95 pp. KEMPER, E. and WIEDENROTH, K. 1987. Klima und Tier-Migrationen am Beispiel der frühkretazischen Ammoniten Nordwestdeutschlands. 315–363. <em>In</em> KEMPER, E. and BATTEN, D. J. (eds). <em>Das Klima der Kreidezeit – Mit Beiträgen zur Klima-Analyse der Kreide</em>. Geologisches Jahrbuch Reihe A, Vol. 96. Schweizerbart Science Publishers, Stuttgart, 399 pp. KORN, D. 2000. Morphospace occupation of ammonoids over the Devonian–Carboniferous boundary. <em>Paläontologische Zeitschrift</em>, 74, 247–257. KORN, D. and VÖHRINGER, E. 2004. Allometric growth and intraspecific variability in the basal Carboniferous ammonoid <em>Gattendorfia crassa</em> Schmidt, 1924. <em>Paläontologische Zeitschrift</em>, 78 (2), 425–432. MARDIA, K. V., KENT, J. T. and BIBBY, J. M. 1979. <em>Multivariate Analysis</em>. Probability and Mathematical Statistics. Academic Press, Michigan, 521 pp. MÖLLER, C. and MUTTERLOSE, J. 2014. Middle Hauterivian biostratigraphy and palaeoceanography of the Lower Saxony Basin (northwest Germany). <em>Zeitschrift der Deutschen Gesellschaft für Geowissenschaften</em>, 165 (4), 501–520. MUTTERLOSE, J. 1992. Biostratigraphy and palaeobiogeography of Early Cretaceous calcareous nannofossils. <em>Cretaceous Research</em>, 13 (2), 167–189. MUTTERLOSE, J. and WIEDENROTH, K. 2009. Neue Tagesaufschlüsse der Unter-Kreide (Hauterive–Unter-Apt) im Großraum Hannover–Braunschweig: Stratigraphie und Faunenführung. <em>Berliner paläobiologische Abhandlungen</em>, 10, 257–288. PARADIS, E., CLAUDE, J. and STRIMMER, K. 2004. APE: Analyses of phylogenetics and evolution in R language. <em>Bioinformatics</em>, 20 (2), 289–290. RAWSON, P. F. 1975. Lower Cretaceous ammonites from north-east England: The Hauterivian heteromorph <em>Aegocrioceras</em>. <em>Bulletin of the British Museum (Natural History) – Geology</em>, 26 (4), 129–159. R CORE TEAM 2020. R: A Language and Environment for Statistical Computing. Version 4.0.2. <em>R Foundation for Statistical Computing</em>. REVELL, L. J. 2012. phytools: An R package for phylogenetic comparative biology (and other things). <em>Methods in Ecology and Evolution</em>, 3 (2), 217–223. ROBINSON, D. F. and FOULDS, L. R. 1981. Comparison of phylogenetic trees. <em>Mathematical Biosciences</em>, 53 (1–2), 131–147. WEIHS, C., LIGGES, U., LUEBKE, K. and RAABE, N. 2005. klaR analyzing German business cycles. 335–343. <em>In</em> BAIER, D., DECKER, R. and SCHMIDT-THIEME, L. (eds). <em>Data Analysis and Decision Support</em>. Studies in Classification, Data Analysis, and Knowledge Organization. Springer-Verlag, Berlin, Heidelberg, 352 pp.
description: All these information are also included in README.txt to aid
 reusability of the data.
 Weinkauf_2021_Aegocrioceras_AppendixS1.pdf
 .pdf file This file contains additional
 analytical results that are complementing the results presented in the
 manuscript. A description of the
 superimposition procedures and results illustrating the superimposition
 success. A depiction of the ARI40 data trajectories
 between species. The unrooted phylogenies.
 A metric multidimensional scaling to compare our consensus tree
 with the random trees. A comparison for different
 phylogenetic tree rootings. Phenotypic
 reconstructions of remaining conch character traits not presented in the
 manuscript. 
 Weinkauf_2021_Aegocrioceras_CollectionNumbers.xlsx
 .xlsx file This file contains the collection
 numbers of specimens used in this study in the Naturalis Biodiversity
 Centre in Leiden, The Netherlands and the Landesamt für Bergbau, Energie
 und Geologie (LBEG), Geozentrum Hanover, Germany.
 Weinkauf_2021_Aegocrioceras_Morphology_Resse.csv
 Comma-separated .txt file This file contains
 extracted morphometric data of <em>Aegocrioceras</em> spp.
 from the clay pit Resse. 
 Bed Bed number 
 Specimen number  Specimen number
 within bed Specimen
 name Unique specimen name 
 Species Species the specimen
 belongs to Radial
 degrees Radial degree of measurement along conch,
 corrected for superimposition 
 Diameter (mm) Conch diameter dm
 (mm) Whorl height
 (mm) Conch whorl height wh (mm)
 Whorl interspace (mm)
 Conch whorl interspace wi (mm) 
 Umbilical width (mm) Conch umbilical width
 uw (mm) WER
 Whorl expansion rate
 [dm<sub>i</sub>/(dm<sub>i</sub>−(wh<sub>i</sub>+wi<sub>i</sub>))]<sup>2</sup> WHER Whorl height expansion rate (wh<sub>i</sub>/wh<sub>i+4</sub>)<sup>2</sup> RDW (n) Ribs per demi-whorl (# ribs along 180 deg. segment toward juvenile) ARI 40 (n) ARI<sub>40</sub> (# ribs within 40 mm circle) ARI 20 (n) ARI<sub>20</sub> (# ribs within 20 mm circle) UWI Umbilical width index uw<sub>i</sub>/dm<sub>i</sub> WII Whorl-interspace index wi<sub>i</sub>/wh<sub>i</sub>                               Weinkauf_2021_Aegocrioceras_Morphology_TypeSpecimens.csv Comma-separated .txt file This file contains extracted morphometric data of the type specimen of <em>Aegocrioceras densiradiatum</em>, as depicted in Rawson (1975). Species Species the specimen belongs to Radial degrees Radial degree of measurement along conch, corrected for superimposition Diameter (mm) Conch diameter dm (mm) Whorl height (mm) Conch whorl height wh (mm) Whorl interspace (mm) Conch whorl interspace wi (mm) Umbilical width (mm) Conch umbilical width uw (mm) WER Whorl expansion rate [dm<sub>i</sub>/(dm<sub>i</sub>−(wh<sub>i</sub>+wi<sub>i</sub>))]<sup>2</sup> WHER Whorl height expansion rate (wh<sub>i</sub>/wh<sub>i+4</sub>)<sup>2</sup> RDW (n) Ribs per demi-whorl (# ribs along 180 deg. segment toward juvenile) ARI 40 (n) ARI<sub>40</sub> (# ribs within 40 mm circle) ARI 20 (n) ARI<sub>20</sub> (# ribs within 20 mm circle) UWI Umbilical width index uw<sub>i</sub>/dm<sub>i</sub> WII Whorl-interspace index wi<sub>i</sub>/wh<sub>i</sub> <br> <br>                         References RAWSON, P. F. 1975. Lower Cretaceous ammonites from north-east England: The Hauterivian heteromorph <em>Aegocrioceras</em>. <em>Bulletin of the British Museum (Natural History) – Geology</em>, 26 (4), 129–159. Weinkauf_2021_Aegocrioceras_Morphology_Outgroup.csv Comma-separated .txt file This file contains extracted morphometric data of ammonoid from literature images to serve as outgroups. Publication  Publication from which the image was taken Specimen name Unique specimen name Species Species the specimen belongs to Radial degrees Radial degree of measurement along conch, corrected for superimposition Diameter (mm) Conch diameter dm (mm) Whorl height (mm) Conch whorl height wh (mm) Whorl interspace (mm) Conch whorl interspace wi (mm) Umbilical width (mm) Conch umbilical width uw (mm) WER Whorl expansion rate [dm<sub>i</sub>/(dm<sub>i</sub>−(wh<sub>i</sub>+wi<sub>i</sub>))]<sup>2</sup> WHER Whorl height expansion rate (wh<sub>i</sub>/wh<sub>i+4</sub>)<sup>2</sup> RDW (n) Ribs per demi-whorl (# ribs along 180 deg. segment toward juvenile) ARI 40 (n) ARI<sub>40</sub> (# ribs within 40 mm circle) ARI 20 (n) ARI<sub>20</sub> (# ribs within 20 mm circle) UWI Umbilical width index uw<sub>i</sub>/dm<sub>i</sub> WII Whorl-interspace index wi<sub>i</sub>/wh<sub>i</sub> <br> <br> <br>                         References KEMPER, E. and VAN DER BURGH, J. 1992. <em>Die tiefe Unterkreide im Vechte–Dinkel-Gebiet (westliches Niedersächsisches Becken), mit einem paläobotanischen Beitrag von J. van der Burgh</em>. Losser, Stichting het Staringmonument, 95 pp. KEMPER, E. and WIEDENROTH, K. 1987. Klima und Tier-Migrationen am Beispiel der frühkretazischen Ammoniten Nordwestdeutschlands. 315–363. <em>In</em> KEMPER, E. and BATTEN, D. J. (eds). <em>Das Klima der Kreidezeit – Mit Beiträgen zur Klima-Analyse der Kreide</em>. Geologisches Jahrbuch Reihe A, Vol. 96. Schweizerbart Science Publishers, Stuttgart, 399 pp. MUTTERLOSE, J. and WIEDENROTH, K. 2009. Neue Tagesaufschlüsse der Unter-Kreide (Hauterive–Unter-Apt) im Großraum Hannover–Braunschweig: Stratigraphie und Faunenführung. <em>Berliner paläobiologische Abhandlungen</em>, 10, 257–288. Weinkauf_2021_Aegocrioceras_Morphology_Mutterlose.csv Comma-separated .txt file This file contains extracted morphometric data of two misidentified <em>Aegocrioceras</em>-species from literature images. Publication Publication from which the image was taken Specimen name Unique specimen name Species Species the specimen belongs to Radial degrees Radial degree of measurement along conch, corrected for superimposition Diameter (mm) Conch diameter dm (mm) Whorl height (mm) Conch whorl height wh (mm) Whorl interspace (mm) Conch whorl interspace wi (mm) Umbilical width (mm) Conch umbilical width uw (mm) WER Whorl expansion rate [dm<sub>i</sub>/(dm<sub>i</sub>−(wh<sub>i</sub>+wi<sub>i</sub>))]<sup>2</sup> WHER Whorl height expansion rate (wh<sub>i</sub>/wh<sub>i+4</sub>)<sup>2</sup> RDW (n) Ribs per demi-whorl (# ribs along 180 deg. segment toward juvenile) ARI 40 (n) ARI<sub>40</sub> (# ribs within 40 mm circle) ARI 20 (n) ARI<sub>20</sub> (# ribs within 20 mm circle) UWI Umbilical width index uw<sub>i</sub>/dm<sub>i</sub> WII Whorl-interspace index wi<sub>i</sub>/wh<sub>i</sub> <br> <br> <br> <br>                         References MUTTERLOSE, J. and WIEDENROTH, K. 2009. Neue Tagesaufschlüsse der Unter-Kreide (Hauterive–Unter-Apt) im Großraum Hannover–Braunschweig: Stratigraphie und Faunenführung. <em>Berliner paläobiologische Abhandlungen</em>, 10, 257–288. Weinkauf_2021_Aegocrioceras_SimpleTree.tree Phylogenetic tree in Newick format This file contains our phylogenetic tree (unrooted) of <em>Aegocrioceras</em> and related species. It is based on the simple mean morphology of <em>Aegocrioceras</em> specimens and was calculated using the FastME algorithm (Desper & Gascuel 2002). References DESPER, R. and GASCUEL, O. 2002. Fast and accurate phylogeny reconstruction algorithms based on the minimum-evolution principle. 357–374. <em>In</em> GUIGÓ, R. and GUSFIELD, D. (eds). <em>Algorithms in Bioinformatics: Second International Workshop, WABI 2002 Rome, Italy, September 17–21, 2002 Proceedings</em>. Lecture Notes in Computer Science, Vol. 2452. Springer-Verlag, Berlin, Heidelberg, 554 pp. Weinkauf_2021_Aegocrioceras_ConsensusTree.tree Phylogenetic tree in Newick format This file contains our phylogenetic tree (unrooted) of <em>Aegocrioceras</em> and related species. It is a consensus tree from 999 random trees (calculated using the FastME algorithm, Desper & Gascuel 2002) where the morphology within each <em>Aegocrioceras</em>-species was allowed to vary around the mean morphology following a Gaussian distribution, with the standard deviation estimated from the data. The consensus tree was calculated based on the Robinson-Foulds distance (Robinson & Foulds 1981), and the base tree (Weinkauf_2021_Aegocrioceras_SimpleTree.tree) was used as the starting point. References DESPER, R. and GASCUEL, O. 2002. Fast and accurate phylogeny reconstruction algorithms based on the minimum-evolution principle. 357–374. <em>In</em> GUIGÓ, R. and GUSFIELD, D. (eds). <em>Algorithms in Bioinformatics: Second International Workshop, WABI 2002 Rome, Italy, September 17–21, 2002 Proceedings</em>. Lecture Notes in Computer Science, Vol. 2452. Springer-Verlag, Berlin, Heidelberg, 554 pp. ROBINSON, D. F. and FOULDS, L. R. 1981. Comparison of phylogenetic trees. <em>Mathematical Biosciences</em>, 53 (1–2), 131–147. Weinkauf_2021_Aegocrioceras_Rawson1975Tree.tree Phylogenetic tree in Newick format This file contains a phylogenetic tree (unrooted) of <em>Aegocrioceras</em> created by Rawson (1975) based on the stratigraphic distribution of species in the Speeton clays (UK). References RAWSON, P. F. 1975. Lower Cretaceous ammonites from north-east England: The Hauterivian heteromorph <em>Aegocrioceras</em>. <em>Bulletin of the British Museum (Natural History) – Geology</em>, 26 (4), 129–159.