CONICET | Buscador de Institutos y Recursos Humanos

INVESTIGADORES

POL Diego

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Título:

The postcranial anatomy of Yacarerani boliviensis and the evolution of the notosuchian postcranial skeleton

Autor/es:

LEARDI, J.M.; POL, D.; NOVAS, F.E.; SUAREZ RIGLOS, M.

Lugar:

Los Angeles

Reunión:

Congreso; 73° Annual Meeting of the Society of Vertebrate Paleontology; 2013

Resumen:

Yacarerani boliviensis is a bizarre notosuchian whose remains were recovered from the Upper Cretaceous of Bolivia. This taxon is diagnosed by its peculiar cranial and, in particular, dental morphology. The block containing the holotype material also included several other individuals. The material studied belongs to at least three different individuals. This record is the first well-preserved and represented postcranial skeleton of any sphageasaurid notosuchian known. Few differences in the size of the elements recovered suggest a similar ontogenetic state of these individuals. The objective of this contribution is to study the postcranial skeleton of Yacarerani boliviensis and to evaluate the distribution of several postcranial characters among basal mesoeucrocodylians. The abundance of specimens allows a deep knowledge of the postcranial skeleton of Yacarerani, as a great number of elements are known. The axis is short and bears an anteroposteriorly short neural spine, as in most notosuchians. All cervical centra bear hypapophyses. As in other notosuchians, there is an abrupt migration of the parapophyses almost at the level of the diapophyses on the fifth dorsal vertebra. Knob-like hypapophyses are observed up to the seventh dorsal vertebra. There are forelimb characters shared with other notosuchians such as a greatly expanded scapular blade, the medially displaced deltopectoral crest of the humerus, the structure of the proximal end of the ulna, and the presence of an additional articular surface in the ulnare. Additionally, the hind limb also bears relevant characters like a reduced fourth femoral trochanter on the femur that lacks an anterior flange, two additional depressions on the anterior hollow of the astragalus, and a posteroventral tuber on the calcaneum. Many postcranial characters have been previously identified as notosuchian synapomorphies, and new ones have been recovered as such in this contribution. This situation highlights the relevance of incorporating postcranial characters to the study of fossil crocodyliforms, as they can be phylogenetically informative.

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