A tiny Triassic saurian from Connecticut and the early evolution of the diapsid feeding apparatus

Adam C Pritchard,Gabriel S Bever,Bhart-Anjan S Bhullar,Jacques A Gauthier,Michael Hanson

doi:10.1038/s41467-018-03508-1

Adam C Pritchard, Gabriel S Bever + Show 3 more

Open Access

https://doi.org/10.1038/s41467-018-03508-1

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Abstract

Following the Permo–Triassic Extinction, large-bodied diapsid reptiles—with a body length >1 m—rapidly expanded their ecological roles. This diversification is reflected in enormous disparity in the development of the rostrum and adductor chamber. However, it is unclear how marked the diversity of the feeding apparatus was in contemporary small-bodied diapsids. Here we describe the remarkably small skull (2.5 cm long) of a saurian reptile, Colobops noviportensis, gen. et sp. nov., from the Triassic New Haven Arkose of Connecticut, USA. The taxon possesses an exceptionally reinforced snout and strikingly expanded supratemporal fossae for adductor musculature relative to any known Mesozoic or Recent diapsid of similar size. Our phylogenetic analyses support C. noviportensis as an early diverging pan-archosaur. Colobops noviportensis reveals extraordinary disparity of the feeding apparatus in small-bodied early Mesozoic diapsids, and a suite of morphologies, functionally related to a powerful bite, unknown in any small-bodied diapsid.

Highlights

Following the Permo–Triassic Extinction, large-bodied diapsid reptiles—with a body length >1 m—rapidly expanded their ecological roles
The early Mesozoic Era saw the initial flowering of the major tetrapod clades that dominated terrestrial ecosystems thereafter
In present-day ecosystems, significant morphological and ecological disparity, as well as a substantial proportion of taxonomic diversity, reside in small-bodied animals (

Summary

Introduction

Following the Permo–Triassic Extinction, large-bodied diapsid reptiles—with a body length >1 m—rapidly expanded their ecological roles. In reviews of vertebrate history, there is a long-running assumption that these clades emerged from unspecialized, generalist ancestors during the Triassic[3] This does not mean that the stem taxa from which those crown groups emerged did not produce substantial diversity of their own during the Triassic; recent studies of early pan-archosaur clades have revealed a substantial morphological radiation[4,5]. In present-day ecosystems, significant morphological and ecological disparity, as well as a substantial proportion of taxonomic diversity, reside in small-bodied animals (

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