Cranial morphology of a new phytosaur (Diapsida, Archosauria) from the Upper Triassic of India: implications for phytosaur phylogeny and biostratigraphy

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.