DOI: 10.5061/dryad.dg25nt5
title: Cranial morphology of a new phytosaur (Diapsida, Archosauria) from the Upper Triassic of India: implications for phytosaur phylogeny and biostratigraphy

description: Detailed description and phylogenetic assessment of a phytosaur skull
 collected from the Tiki Formation of the Rewa Gondwana Basin of India and
 earlier diagnosed as Parasuchus hislopi, shows that it pertains to a new
 genus and species, Volcanosuchus statisticae. The new taxon is
 characterized by marginal overlapping of the nostrils by the antorbital
 fenestrae, external nares situated on a bulbous and raised dome, the
 lateral surface of the jugal ornamented by a prominent ridge defined by
 multiple tubercles and radiating thread-like structures, and distinct
 ornamentation patterns on the rostrum and skull table. Phylogenetic
 analysis nests Volcanosuchus within Mystriosuchinae where it forms a
 sister taxon to (Rutiodon + Leptosuchomorpha) and marks the transition
 between the basal Parasuchidae and more derived Mystriosuchinae
 phytosaurs. Evolution of the phytosaur skulls resulted in changes from
 non-overlapping nostril and antorbital fenestra to an overlapping state,
 anteroposterior elongation of the exoccipital and supraoccipital shelf,
 appearance of a median ridge on the basioccipital, and reduction of the
 supratemporal fenestra. Considerable faunal overlap of the Tiki Formation
 is evident with the lower Maleri Formation, which is late Carnian based on
 Hyperodapedon, Parasuchus, and Exaeretodon. The Tiki Formation correlates
 with the Ischigualasto Formation of Argentina, the upper part of the Santa
 Maria Formation, and the overlying lower Caturrita Formation of Brazil,
 the Isalo II Beds of Madagascar, Lossiemouth Sandstone of Scotland, and
 the lower Tecovas Formation of the Chinle Group of North America, and
 ranges from late Carnian to early/middle Norian.
description: Datta et al. Appendix
 S2 Appendix S2.
 <em>Parasuchus</em> <em>hislopi</em> Lydekker
 (1885). A, neotype, ISIR 42, actual photograph of a nearly complete skull
 in right lateral view. B–C, boxed area I of A at higher magnification,
 showing right lateral surface of the jugal between the antorbital and the
 infratemporal fenestra; B, actual photograph; C, line drawing. D, neotype,
 ISIR 42, actual photograph of a nearly complete skull in left lateral
 view. E–F, boxed area II of D at higher magnification, showing left
 lateral surface of the jugal between the antorbital and the infratemporal
 fenestra; E, actual photograph; F, line drawing. Abbreviations: afn,
 antorbital fenestra; afo, antorbital fossa; asc, ascending maxillary
 process; dsc, descending maxillary process; ec, ectopterygoid; en,
 external nare; f, frontal; itf, infratemporal fenestra; j, jugal; l,
 lacrimal; mx, maxilla; n, nasal; pmx, premaxilla; prf, prefrontal; q,
 quadrate; qj, quadratojugal. Scale bars represent 30 mm.
  
 
 Datta et
 al._Appendix S3 Appendix S3. Cranial
 characters used in the phylogenetic analysis. A brief explanation follows
 the new characters used, whereas for the characters already used in
 previous literature, its citation follows the last character state of
 each. The citations are abbreviated as follows: H, Hungerbühler (2002); S,
 Stocker (2010); K, Kammerer et al. (2016); J, Jones & Butler
 (2018), whereas the numerals indicate the character number of each
 citation.   
 Datta et al._Appendix
 S4 Appendix S4. Character
 matrix used for phylogenetic analysis.   
 Datta et al_Appendix
 S5 Appendix S5. TNT file of
 <em>Volcanosuchus statisticae</em>.   
 Datta et al._Appendix
 S1 Appendix S1.
 <em>Volcanosuchus statisticae</em> gen et sp. nov. Measured
 parameters (in mm).