 |
| Eosphorosuchus lacrimosa Margulis-Ohnuma, Ruebenstahl, Meyer & Bhullar, 2026 Art by Julio Lacerda |
Abstract
The early evolution and diversification of Crocodylomorpha is a key component of vertebrate evolution on land but is somewhat poorly understood as a result of limited data. We describe Eosphorosuchus lacrimosa gen. et sp. nov., an early crocodylomorph from the Late Triassic of Ghost Ranch, New Mexico, whose cranial anatomy is divergent from that of other early crocodylomorphs (including Hesperosuchus agilis, to which it had been tentatively assigned), featuring an unusually short and osteologically reinforced facial region. A robust upper temporal arch and prominent surangular ridge indicate the presence of well-developed superficial external adductor musculature, which is divergent relative to pseudosuchians generally. These autapomorphies suggest specialization for a powerful bite. Bayesian and maximum parsimony phylogenetic analyses find E. lacrimosa outside of an H. agilis clade, near the base of Crocodylomorpha. The specializations of E. lacrimosa therefore represent the beginnings of ecological diversification within Crocodylomorpha among animals of a similar size, predating the Late Triassic appearance of Crocodyliformes and the Jurassic radiation of mesoeucrocodylians. Coexistence in the same single-event death assemblage of E. lacrimosa and H. agilis—two small early crocodylomorphs with functionally significant anatomical differences—suggests partitioning of terrestrial carnivorous niches within the ‘sphenosuchian’ grade.
Keywords: Crocodylomorpha, Sphenosuchia, Triassic, Hesperosuchus agilis, phylogenetics
 |
| Photographs and line drawings of the skull of Eosphorosuchus lacrimosa as preserved and prepared in right ventrolateral view (a, c) and left dorsolateral view (b, d). Grey shading represents matrix or bones of other individuals; halftone represents areas of breakage. Abbreviations: an, angular; e, ectopterygoid; f, frontal; j, jugal; l, lacrimal; m, maxilla; n, nasal; pa, prearticular; pb, palpebral; pl, palatine; pm, premaxilla; po, postorbital; pt, pterygoid; sa, surangular; tpt, transverse process of the pterygoid. Scale bar is 2 cm. |
ARCHOSAURIA Cope, 1869 (Gauthier & Padian [2020])
PSEUDOSUCHIA Zittel, 1887
CROCODYLOMORPHA Hay, 1930 (emend. Walker [1970])
Eosphorosuchus lacrimosa gen. et sp. nov.
Etymology: Eosphorosuchus derives from ‘Eosphoros,’ one of two Greek gods representing the planet Venus and the counterpart of Hesperos. As Eosphoros was the ‘dawn-bringer’, this name highlights both the dawning of crocodylomorph ecological diversity and the close historic association of this specimen with the genus Hesperosuchus. ‘Suchus’ derives from ‘soukhos’, Greek for crocodile. The specific epithet lacrimosa refers to the distinctive lacrimal region.
Miranda Margulis-Ohnuma; Alexander A. Ruebenstahl; Dalton L. Meyer and Bhart-Anjan S. Bhullar. 2026. A Short-snouted ‘sphenosuchian’ with unusual Feeding Anatomy demonstrates that Ecological Specialization occurred early in Crocodylomorph Evolution. Proc Biol Sci . 293 (2069): 20260130. DOI: doi.org/10.1098/rspb.2026.0130 [15 Apr 2026]
