Monday, March 26, 2018

[Paleontology • 2018] Colobops noviportensis • A Tiny Triassic Saurian from Connecticut and the Early Evolution of the Diapsid Feeding Apparatus

Colobops noviportensis
Pritchard, Gauthier, Hanson, Bever & Bhullar, 2018

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 reptileColobops 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.

Systematic palaeontology

Sauria McCartney, 1802
Archosauromorpha von Huene, 1956
Rhynchosauria? Osborn, 1903b

Colobops noviportensis gen. et sp. nov.
“Sphenodontia indet.” Sues & Baird, 1993

Etymology. From the Greek κολοβός (kolobós) for “docked” or “shortened” and ὤψ (ṓps) for “face”. Refers to the abbreviated rostrum relative to most other known Triassic Diapsida. Novus Portus is a Latinized version of “New Haven”, in reference to the discovery of the fossil in the New Haven Arkose in New Haven County, Connecticut, USA.

Holotype. YPM VPPU 18835 (Yale Peabody Museum, Vertebrate Paleontology Princeton Collection), nearly complete cranium and coronoid process of right mandible, lacking tooth-bearing portions of premaxillae, maxillae, palate, and mandible (Fig. 1).

 Locality and horizon. (Based on ref. 9) Near the junction of Routes 6A, 91, and 15 between Meriden and Middletown, CT, USA. The locality is part of the New Haven Arkose, Hartford Basin, Newark Supergroup. ref. 10 dated a section of the New Haven Arkose at 212 ± 2 Ma, indicating a middle Norian age.

Diagnosis. (1) Prominent, symmetrical fontanelle between frontals and parietals in midline (may reflect juvenility); (2) prefrontal and postfrontal contact one another to exclude frontal from orbit; (3) jugal maxillo-palatal junctions transversely broader than postorbital process of jugal; (4) dorsal exposure of postorbital transversely broad, with posteriorly directed process near the transverse midpoint of the supratemporal fenestra (may reflect juvenility); (5) palatine with transversely broad anterior concavity between lateral contact with maxilla and anteromedial contact with vomer.

Reconstruction process for the ancient reptile species Colobops noviportensis.     

illustration: Michael Hanson

Adam C. Pritchard, Jacques A. Gauthier, Michael Hanson, Gabriel S. Bever and Bhart-Anjan S. Bhullar. 2018. A Tiny Triassic Saurian from Connecticut and the Early Evolution of the Diapsid Feeding Apparatus. Nature Communications. 9, Article number: 1213. DOI:   10.1038/s41467-018-03508-1

Paleontologists put the bite on an ancient reptile from New England via @physorg_com

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