Una de terópodos (o no) en la XXII Bienal de la RSEHN

La semana pasada se presentó en la XXII Bienal de la Real Sociedad de Historia Natural celebrada en la ciudad portuguesa de Coimbra la reevaluación de unos restos axiales articulados dentro de un bloque de arenisca que han formado parte hasta hace poco de la exposición permanente de dinosaurios del Museu Nacional de História Natural e da Ciência (MUHNAC) en Lisboa.

Los resultados preliminares presentados en este congreso indican que los restos presentes en este bloque de arenisca no pertenecen, como hasta ahora se había creído, al dinosaurio terópodo ‘Megalosaurus insignis’. Por el contrario, esta serie vertebral en articulación muestra una combinación de caracteres que relacionan a esta ejemplar con los dinosaurios ornitópodos cercanamente emparentados con formas como Camptosaurus.

Aquí está el resumen:

“Megalosaurus Buckland (1824) was the first non-avian dinosaur genus described and one of the three genera which Owen defined Dinosauria in 1842. Nevertheless, since its discovery, Megalosaurus is considered a waste-basket taxon for which more than thirty species have been described. Some of these controversial species were described in the Portuguese fossil record during the mid-twentieth century by Lapparent & Zbyszewski (1957) including Megalosaurus insignis, Megalosaurus pannoniensis, Megalosaurus pombali and Megalosaurus superbus.

One of the Portuguese specimen assigned to M. insignis consists of a sandstone block in which five articulated vertebrae are included, three of them having the proximal part of the left ribs in articulation. This specimen comes from the area of Praia de Areia Branca in Lourinhã municipality. Lapparent & Zbyszewski (1957) described and figured the specimen and identified it as a partial articulated set of five anterior caudal vertebrae of a the theropod dinosaur M. insignis. However, an ongoing re-evaluation of the specimen, housed at the Museu Nacional de História Natural e da Ciência in Lisbon, does not support the interpretation of Lapparent & Zbyszewski (1957).

The preserved dorsal series is characterized by low, cylindrical centra, clearly visible neurocentral sutures and parapophyses positioned at the base of the transverse processes. All of these features suggest that this specimen is related to ornithopod dinosaurs because the combination of them is unknown in theropod dinosaurs. In addition, the overall morphology of the vertebrae resembles that of camptosaur-grade ankylopollexians but pending further preparation of the specimen, it is tentatively referred to an indeterminate ankylopollexian.”

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Referencia:

• Escaso, F., Malafaia, E., Mocho, P., Narváez, I., Ortega, F. 2017. ‘Megalosaurus insignis’ from Praia de Areia Branca (Lourinhã, Portugal): is it Theropoda or Ornithopoda?. Livro de Resumos da XXII Bienal da RSEHN - Coimbra, 227.