Tlatolophus galorum, gen. et sp. nov., a parasaurolophini dinosaur from the upper Campanian of the Cerro del Pueblo Formation, Coahuila, northern Mexico

Abstract

In 2013, a joint team of INAH and UNAM paleontologists launched a project to recover a semi-articulated tail of a putative hadrosaur, that was discovered in 2005, on the superficial upper Campanian deposits of the Cerro del Pueblo Formation, in General Cepeda Municipality, Coahuila, northern México. Currently, this specimen is the most complete lambeosaurine so far found in México. Herein, Tlatolophus galorum gen. et sp. nov. is erected based on features shown in the head of this specimen. The distinctive characters of this new species are the skull high, with a length/height ratio equals to 1.79; the premaxilla wide, in which maximum/minimum width ratio is about 2.4; the maxillary ascending ramus has a low dorsal apex; the pterygoid dorsal crest is high and convex; the supracranial crest is high, spatula-shaped and similar to an inverse-comma; the occipital condyle is inclined 56° ventrally; the supraoccipital crest is laminar, wide and located inside a deep nuchal fossa; the squamosal shelf is moderately long, as long as the foramen magnum diameter; the dorsal margins of the infratemporal fenestra and orbit are located at the same level; and the nasal is elongated, caudally expanded, and bilobed. The phylogenetic analysis performed here recovers Tlatolophus within the Tribe Parasaurolophini; in this result, the supracranial crest spatula-shaped of this new parasaurolophini represent a plesiomorphic condition within the tribe.