Elena Cuesta,Â Francisco Ortega & JosÃ L.Sanz (2018)
Axial osteology of Concavenator corcovatus (Theropoda; Carcharodontosauria) from the Lower Cretaceous of Spain.
Cretaceous Research (advance online publication)
We describe by first time the complete and detailed axial osteology of Concavenator corcovatus.
The axial skeleton of Concavenator is one of the most complete among carcharodontosaurids.
Concavenator axial skeleton shows several synapomorphies of Allosauroidea and some synapomorphies of Carcharodontosauridae.
Concavenator shows a primitive axial skeleton among Carcharodontosauridae.
Concavenator bears a substantial number of autapomorphies in its axial skeleton.
Concavenator corcovatus is represented by a single and almost complete and articulated skeleton, MCCM-LH 6666, from the Las Hoyas fossil site (Lower Cretaceous, Spain). The axial skeleton only lacks some caudal vertebrae whereas presacral and sacral regions are totally articulated. Concavenator shows several unusual features associated to the axial skeleton such as some hypertrophied neurapophyses in both dorsal and caudal regions, a development of accessory processes in the neural spines, and a variable morphology of the dorsal neurapophyses. The results show several allosauroid synapomorphies in the axial region such as (1) constriction in all dorsal vertebral centra (2) expanded prezygocentrodiapophyseal fossa in dorsal vertebrae; (3) chevrons with broad and transversally flattened distal ends; and (4) strongly curved, L-shaped middle chevrons. Concavenator shows several autapomorphic features that include: (1) two hypertrophied dorsal and caudal neurapophyses; (2) imbricated dorsal neurapophyses with anterior processes and a morphology that changes from acute and anteroposteriorly short to rectangular and anteroposteriorly wide backwardly; (3) anterior and posterior accessory processes in the anterior caudal neurapophyses; and (4) deeply excavated lateral groove in the posterior caudal vertebrae.