A new species of Allodaposuchus (Eusuchia, Crocodylia) from the Maastrichtian (Late Cretaceous) of Spain : phylogenetic and paleobiological implications
Blanco, Alejandro (Institut Català de Paleontologia Miquel Crusafont)
Fortuny, Josep (Institut Català de Paleontologia Miquel Crusafont)
Vicente, Alba 1985- (Universitat de Barcelona. Departament d'Estratigrafia, Paleontologia i Geociències Marines)
Hernández Luján, Àngel (Institut Català de Paleontologia Miquel Crusafont)
García-Marçà, Jordi Alexis (Institut Català de Paleontologia Miquel Crusafont)
Sellés, Albert G. (Institut Català de Paleontologia Miquel Crusafont)

Data:	2015
Resum:	Background. The Late Cretaceous is a keystone period to understand the origin and early radiation of Crocodylia, the group containing all extant lineages of crocodilians. Among the taxa described from the latest Cretaceous of Europe, the genus Allodaposuchus is one of the most common but also one of the most controversial. However, because of its fragmentary record, several issues regarding its phylogenetic emplacement and its ecology remain unsolved or unknown. The discovery of a single specimen attributed to Allodaposuchus, represented by both cranial and postcranial remains, from the Casa Fabà site (Tremp Basin, NE Spain) in the lower red unit of the Tremp Fm. (early Maastrichtian, Late Cretaceous) offers a unique opportunity to deepen in the phylogenetic relationships of the group and its ecological features. Methods. The specimen is described in detail, and CT scan of the skull is performed in order to study the endocranial morphology as well as paratympanic sinuses configuration. In addition, myological and phylogenetic analyses are also carried out on the specimen for to shed light in ecological and phylogenetic issues, respectively. Results. The specimen described herein represents a new species, Allodaposuchus hulki sp. nov. , closely related to the Romanian A. precedens. The CT scan of the skull revealed an unexpected paratympanic sinuses configuration. Allosaposuchus hulki exhibits an "anterodorsal tympanic sinus" not observed in any other extant or extinct crocodilian. The caudal tympanic recesses are extremely enlarged, and the expanded quadratic sinus seems to be connected to the middle-ear channel. Phylogenetic analyses confirm the emplacement of the informal taxonomic group 'Allodaposuchia' at the base of Crocodylia, being considered the sister group of Borealosuchus and Planocraniidae. Discussion. Although this is a preliminary hypothesis, the unique paratympanic configuration displayed by A. hulki suggests that it could possess a high-specialized auditory system. Further, the large cranial cavities could help to reduce the weight of the cranium. Concerning the postcranial skeleton, Allodaposuchus hulki shows massive and robust vertebrae and forelimb bones, suggesting it could have a bulky body. The myological study performed on the anterior limb elements supports this interpretation. In addition, several bone and muscular features seem to point at a semi-erected position of the forelimbs during terrestrial locomotion. Taking all the above results into consideration, it seems plausible to suggest that A. hulki could conduct large incursions out of the water and have a semi-terrestrial lifestyle.
Ajuts:	Ministerio de Economía y Competitividad CGL2011-30069-C02-01 Ministerio de Economía y Competitividad CGL2011-27869 Agència de Gestió d'Ajuts Universitaris i de Recerca FI-DGR/2013/FI_B01059 Agència de Gestió d'Ajuts Universitaris i de Recerca FI-DGR/2012/FI_B01221 Ministerio de Economía y Competitividad BES-2012-05783
Drets:	Aquest document està subjecte a una llicència d'ús Creative Commons. Es permet la reproducció total o parcial, la distribució, la comunicació pública de l'obra i la creació d'obres derivades, fins i tot amb finalitats comercials, sempre i quan es reconegui l'autoria de l'obra original.
Llengua:	Anglès
Document:	Article ; recerca ; Versió publicada
Matèria:	Crocodylia ; Endocranial morphology ; Locomotion ; Allodaposuchus ; Paleoecology ; Late Cretaceous
Publicat a:	PeerJ, Vol. 3 (August 2015) , article e1171, ISSN 2167-8359

DOI: 10.7717/peerj.1171
PMID: 26339549

35 p, 60.9 MB

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