[2] The holotype skull of Colobops, YPM VPPU 18835, is mostly complete, although flattened and missing tooth-bearing portions of the cranial bones.
The Newark supergroup is a collection of Late Triassic formations along the eastern coast of North America, and the New Haven Arkose has specifically been Uranium-Lead dated to the mid Norian age, about 214.0 to 209.8 million years ago.
[4] The skull was not described in an academic context until 1993, although photographs of the specimen had been featured in "A pictorial guide to fossils", a natural history book published by G.R.
A formal study of the specimen by Hans-Dieter Sues and Donald Baird in 1993 offered a discussion of its classification, but did not provide a scientific name for the reptile in question.
This study considered the skull to lack a lacrimal bone, and noted that it originally possessed supposed fang-like premaxillary teeth at the tip of the snout which were accidentally destroyed during preparation.
[3] The specimen finally received a formal name in early 2018, when a group led by Adam Pritchard provided new preparation and discussion of the skull, as well as giving it the name Colobops noviportensis.
This study also included CT-scans of the specimen, proportional and numerical analyses of the enlarged temporal region, and a phylogenetic analysis in order to determine its relations.
[1] A 2020 reinterpretation by Torsten Scheyer et al. argued that the skull was crushed and several bones were displaced, and that it more closely resembled a rhynchocephalian once these issues were rectified.
All of these features exist to strengthen the front part of the skull, which explains how they convergently evolved in multiple different types of reptiles.
This means that the frontals (bones of the skull roof between the eyes) are separated from the orbit, a feature which is known to a lesser degree in Sphenodon and Clevosaurus, but not rhynchosaurs.
[2] Another diagnostic feature of Colobops is the fact that the skull roof possesses a very large, diamond-shaped gap between its bones, referred to as a fontanelle.
Colobops would have been the smallest known reptiles to possess such a powerful and expanded supratemporal area,[1] although uncertainty in the shape of the skull may oppose this interpretation.
Unlike some lepidosaurs, Colobops possesses a fully ossified thin and tall plate-like bone known as a parasphenoid rostrum, which extends forward along the midline of the rear part of the roof of the mouth.
A phylogenetic analysis constructs thousands of family trees, each of which include hundreds of "steps" in evolution where analyzed traits are evolved, lost, or reacquired.
The MPT given by Pritchard et al. (2018) is given below:[1] Squamata Rhynchocephalia Protorosaurus Trilophosauridae Tanystropheidae Prolacerta Archosauriformes Boreopricea Kuehneosauridae Pamelaria Azendohsaurus Colobops Mesosuchus Howesia Eohyosaurus Rhynchosauridae Prior to receiving a formal name and description, the holotype of Colobops noviportensis was actually believed to be a rhynchocephalian upon its discovery and preliminary description by Sues & Baird (1993).
In this expansion, Colobops is positioned as a rhynchocephalian next to Sphenodon (the tuatara), with a minimum of 17 steps required to place it back as a basal rhynchosaur.
Most modern reptiles enlarge their jaw musculature by two methods, either developing large muscle receptor areas on the parietals bones in the middle of the skull, or by the supratemporal fenestrae being widened.
[1] However, Scheyer et al. (2020) reinterpreted the supratemporal fenestrae as much narrower in life, with crushing and bone displacement artificially expanding the fossil.