La posible presencia de terópodos carcarodontosaurios en el Jurásico Superior de Portugal en el XV Annual Meeting de la EAVP

En el XV encuentro de la European Association of Vertebrate Paleontology celebrado en Munich se discutió en formato póster la posible presencia de dinosaurios terópodos alosauroides estrechamente relacionados con el clado Carcharodontosauria en el Jurásico Superior de la cuenca lusitánica (Portugal). Este clado podría estar representado por dos ejemplares, SHN.019 y SHN.036, recientemente descritos en este registro y que comparten con otros terópodos carcarodontosaurios diversas sinapomorfias, incluyendo la presencia de crestas bien desarrolladas en la superficie ventral de las vértebras caudales anteriores y la superficie articular iliaca del pubis fuertemente cóncava. Estos ejemplares podrán representar la evidencia más antigua de terópodos carcharodontosaurianos en el registro da Laurasia añadiendo importante información para el conocimiento de la evolución temprana del grupo. El resumen es el siguiente:

A new carcharodontosaurian theropod from the Upper Jurassic of the Lusitanian Basin is here discussed. This new carcharodontosaurian could be represented by two specimens, SHN.019 and SHN.036, collected in sediments from the upper Tithonian and upper Kimmeridgian–lower Tithonian, respectively. These specimens share with other carcharodontosaurian theropods some synapomorphies, including the presence of well-developed ventral ridge in the anterior caudal centra, the anteroposterior length of pubic distal expansion more than 60% of pubic shaft length, the iliac articular surface of ischium deeply concave, and the ventrally rather than anteroventrally oriented pubic peduncle. In addition, they share an unusual combination of features with some carcharodontosaurians such as Neovenator and Acrocanthosaurus, including the presence of a robust suboval eminence on the lateral surface of the lesser trochanter and the well-developed and rugose depression in the medial surface adjacent to the fourth trochanter.

With exception of some isolated teeth, these specimens represent the oldest evidence of carcharodontosaurian theropods in the Laurasian record and provide relevant information to fill the gap on the early radiation of the group. The presence of Carcharodontosauria, in the Iberian Peninsula and the apparent absence of this clade in correlative North American strata contrasts with the recognized faunal similarity among both sides of the proto-North Atlantic during the Late Jurassic. Similar situation also occur with other groups of dinosaurs such as dacentrurines and turiasaurs. These differences in the higher-taxonomic composition of the theropod dinosaur faunas may be explained by differential patterns of regional extinction and/or local environmental preferences.

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Referencia:

• Malafaia, E., Mocho, P., Escaso, F., Ortega, F. 2017. Carcharodontosaurian evidences in the Upper Jurassic of Portugal: filling the gap. 15th Annual Meeting of the European Association of Vertebrate Palaeontologists, 56-57.