1.12.16

Concavenator y sus relaciones filogenéticas en el 76th Annual Meeting de la SVP


Concavenator, ese dinosaurio conquense que tanto nos mola, tuvo su momento en el 76th Annual Meeting de la SVP, que tuvo lugar en Salt Lake City. El trabajo presentado por Elena Cuesta mostraba los resultados de su tesis doctoral sobre nuevas hipótesis filogenéticas de Concavenator dentro del grupo Carcharodontosauria. El resumen del trabajo (en inglés) presentado para el congreso, es el siguiente:

The holotype of Concavenator corcovatus (MCCM-LH 6666) is an almost complete, articulated skeleton from Las Hoyas fossil site (Lower Cretaceous, Spain). Originally, this specimen was proposed as a member of Carcharodontosauria, and its position was swapped within the group as basal Carcharodontosauridae or basal Carcharodontosauria (Neovenatoridae + Carcharodontosauridae). A new data matrix was compiled to reassess the phylogenetic relationships of Concavenator within Carcharodontosauria. The data matrix is composed of 58 taxa and 381 equally weighted characters, of which 25 are ordered. The characters were rescored and reviewed from direct assessment of fossil material or casts of 19 taxa. The matrix was scored using Mesquite 3.01 and imported into TNT 1.5-beta. A heuristic tree search was performed to find all possible most parsimonious trees (MPTs). This MPTs were examined under strict consensus. Branch support in the hypotheses was tested using Bremer support values and resampling methods. Some constrained analyses were carried out to compare with previous phylogenetic hypotheses. The analysis yielded 12 MPTs with 1138 steps; and Consistency and Retention indices are 0.386 and 0.683, respectively. The strict consensus tree shows an unambiguous basal position of Concavenator inside Carcharodontosauridae. Within this clade, Concavenator is positioned as more derived than Eocarcharia. Concavenator shares several synapomorphies with the carcharodontosaurids, such as an anteroventrally inclined anterior end of the junction between the medial wall and paradental plates in the maxilla, lacrimal contacting the postorbital, ventral process of postorbital anteroventrally angled, rugose dorsal surface of postorbital and a concavity in the middle of the proximal surface of the humeral head. Its position inside Carcharodontosauridae is strongly supported, with the highest values of branch support hitherto obtained. With respect to other carcharodontosaurs, the Argentinean taxa are the most derived carcharodontosaurins, with Carcharodontosaurus as their sister group. Megaraptors are obtained inside Neovenatoridae and not as tyrannosauroids. Sixteen additional evolutionary steps are required to place megaroptors as coelurosaurians. The position of Concavenator as a basal carcharodontosaurid supports the hypothesis of the wide paleogeographic distribution of this group, and the probable existence of palaeogeographic connections between Gondwana and Laurasia at or near the beginning of the Early Cretaceous.

---
Referencia: