Reconstrucción esquelética 3D y proporción de extremidades cursoriales de Afrovenator abakensis en las XXXIX Jornadas de la SEP

En las XXXIX Jornadas de la Sociedad Española de Paleontología, celebradas la semana pasada en A Coruña, se presentó una ponencia sobre un nuevo espécimen de Afrovenator abakensis, menos completo y de menor tamaño que el holotipo pero con nuevos restos no presentes en él, incluyendo una tibia y pes mucho más completos. Mediante la fotogrametría y la paleontología digital se reconstruyeron la cola, cadera y patas de ambos especímenes y se infirió en cuestiones ontogenéticas y de capacidad cursorial. Los resultados fueron la posible asignación del espécimen nuevo como un adulto de tamaño pequeño, con menor capacidad cursorial que el holotipo, y presentando este una mayor capacidad respecto a otros terópodos con una masa y longitud similares. El resumen es el siguiente:

We present new specimens from the presumed Late Jurassic age megalosauroid Afrovenator abakensis discovered at the locality of Tawachi in the Tiouraren Formation of Niger. New bones include the premaxillae, dentaries and appendicular skeleton. The new premaxillae have a nasal process with a slight less steep angle than previously reconstructed, resulting in a slightly larger external naris. The new dentaries have a more robust symphysis and a more slender midsection, somewhat reminiscent to the symphyseal expansion in the lower jaw of spinosaurids, albeit not as dramatic. Preserved teeth in situ on the dentaries show characters similar to those on the holotype, compatible with a megalosauroid and different from those expected in a ceratosaur like the contemporary Spinostropheus. The absolute length of the hindlimb of the new specimen of Afrovenator is smaller than the holotype, but the tibia/femur ratio is greater than what was estimated previously. The tibia is longer relative to the femur than previously reconstructed and may have had a length close to that of the femur. Along with the nearly completely pes, only the distal phalanges of Digit II and IV are missing, the hindlimb is almost complete. After digitizing the fossils using computed tomographic scans and SfM photogrammetry we obtained allometric and biomechanical calculations. These indicate that Afrovenator has higher cursorial limb proportion scores than Allosaurus fragilis but lower than the abelisaur Aucasaurus garridoi, all of which are theropods of similar size and body mass. While Afrovenator lacks the cursorial adaptations seen in abelisaurids (e.g., extremely dorsalized caudal ribs for a larger caudofemoralis attachment area) it has a slightly taller iliac blade than its relative Torvosaurus suggesting stronger hip protraction and knee extension.

-----
Más información:

• Referencia: González Pérez, A., Ciudad Real, M., Simarro Cano, A., Vidal, D., Sereno, P. C. Updated 3D skeletal reconstruction and cursorial limb proportion of Afrovenator abakensis (Theropoda: Megalosauridae) with new specimens. In Moncunill-Solé, B., Blanco, A., Grandal d’Anglade, A., González Fortes, G., Santos Fidalgo, L., Bao, R. (Eds.), Libro de Resúmenes de las XXXIX Jornadas SEP. Palaeontological Publications 5, 71.