terça-feira, 2 de agosto de 2016

Megalossáurideos do Jurásico Superior Português no XIV Meeting da EAVP

No mês passado decorreu o XIV Annual Meeting of the European Association of Vertebrate Palaeontologists (EAVP) em Haarlem (Holanda). Neste encontro houve a possibilidade de falar de dinossáurios terópodes provenientes do Jurásico Superior de Portugal, numa comunicação liderada pela paleontóloga Elisabete Malafaia (IDL/SHN). Os representantes do grupo Megalosáuridea são o principal alvo de este estudo. Estes correspondem às maiores formas de dinossáurios carnívoros presentes durante o Jurásico Superior Ibérico. Apesar de pouco abundantes, o registo conhecido revela uma existência cada vez mais consistente do género Torvosaurus.

The Portuguese record of Late Jurassic megalosaurids includes a set of cranial and postcranial elements traditionally interpreted as closely related to the North American species Torvosaurus tanneri, but more recently reinterpreted as a species so far exclusive of the Lusitanian Basin: T. gurneyi. Herein it is reported a set of unpublished axial and appendicular elements collected in Praia da Corva (Torres Vedras) that present a combination of shared characters with megalosaurid theropods including Torvosaurus and Megalosaurus. These remains, which show evidences of long weather exposure, were collected from surface along the cliff, in an area composed by upper Kimmeridgian sediments. Thus, and despite these elements present compatible morphology and size, it is not possible to determine if they belong to the same individual. The axial elements include three centra of posterior dorsal vertebrae, a fragment of the neural arch of a dorsal vertebra, and eight partial caudal vertebrae. Appendicular skeleton is represented by an almost complete left fibula and fragments of the tibial diaphysis. The general morphology of the dorsal centra is similar to that of Megalosaurus sharing a flat and transversely broad ventral surface. The great development of the pleurocoels is comparable with that of Torvosaurus, occupying almost the entire anteroposterior length of the lateral surface the centra. The caudal vertebrae present broad ventral grooves, a character sometimes considered as an autapomorphy of Ceratosaurus, but having a much wider distribution among theropods. These vertebrae share with Torvosaurus the wider than high articular facets and the presence of well-marked neurocentral depressions. The fibula is significantly more robust than those of any other known theropod from the Lusitanian Basin and more similar to Torvosaurus and to an indeterminate megalosauroid from the Tendaguru Formation. In summary, the specimens of Praia da Corva are assigned to Megalosauridae, with several elements suggesting a close relationship with Torvosaurus. Some distinct characters would be interpreted as autapormorphies of the skull-based species T. gurneyi or belonging to an unknown non-Torvosaurus megalosaurid taxon.
  • Malafaia E, Mocho P, Escaso F, Ortega F. 2016. New postcranial elements of megalosaurids (Dinosauria, Tetanurae) from the Upper Jurassic of Portugal, p 210. In: Holwerda F, Madern A, Voeten D, van Heteren A, Meijer H, den Ouden N (eds.), XIV Annual Meeting of the European Association of Vertebrate Palaeontologists, 6-10 July 2016, Haarlem, The Netherlands, Programme and Abstract Book Haarlem.