Thursday 5 July 2012

A new species of Tapejarid Pterodactyl from the Early Cretaceous Las Hoyas Lagerstätte of eastern Spain.

The Tapejarid Pterodactyls are a group of bizarre, toothless Pterosaurs known from the Early Cretaceous (Aptian–Albian stages, 125–99 million years ago) of Brazil and China, with a single possible Late Cretaceous specimen from Morocco. The Tapejarids sported large, distinctive crests that varied a great deal between species. The lifestyle and diet of the Tapejarids is unclear, but it has been noted that a number of groups of Pterosaurs independently evolved toothless forms in the Early Cretaceous, implying that a new ecological niche had become available. It has further been suggested that this coincided with the expansion of the Angiosperms (flowering plants), and that this might be connected, possibly implying that these toothless Pterosaurs may have been among the first frugivores. However there is at this time no actual evidence to confirm or contradict this theory, and it is unlikely that it could be resolved without finding Pterosaurs with preserved stomach contents, which is quite a hard requirement.

In a paper published in the journal PLoS One on 3 July 2012, a team of scientists led by Romain Vullo of the Laboratoire Géosciences Rennes at the Université de Rennes 1 and the Unidad de Paleontología at the Departamento de Biología at the Universidad Autónoma de Madrid describe a new species of Tapejarid Pterodactyl from the Early Cretaceous Las Hoyas Lagerstätte of eastern Spain.

The Las Hoyas is a Konservat-Lagerstätten (deposit producing numerous excellently preserved fossils) of Barremian age (125-130 million years old) formed in a stagnant, microbe rich lake. It is noted for its excellently preserved vertebrate fossils, including Fish, Crocodiles, Dinosaurs and Birds.

The new species is named from a single, incomplete, skull and lower jaw from the Las Hoyas deposits. It is named as Europejara olcadesorum, where Europejara is a combination of Europe and Tapejara, the first described genus of Tapejarid Pterodactyls, and olcadesorum derives from the Olcades, a Celtic tribe who inhabited the region in ancient times. It is not well enough preserved to resolve its exact taxonomic position within the group, though it clearly is a Tapejarid, and being Barremian in age it is the earliest known member of the group, and indeed the earliest known toothless Pterosaur from any group, suggesting that whatever ecological niche these Pterosaurs filled had arisen by this time.

Skull of Europejara olcadesorum. (A) Close-up of the crushed left post-orbital region of the skull (acid-prepared counterslab) in lateral view showing the narrowness of the lower temporal fenestra (ltf), the mandibular condyle of the quadrate (cq) and the distal extremities of the hyoid apparatus (hy). (B) Close-up of the posterior area of the palate (main slab under ultraviolet light) in dorsal view showing the thin, elongated vomer (v) septum separating the two choanae (ch). Note the medial surface of the left dentary (ld) and the hyoid apparatus (hy), adjacent to the ventral margin of the mandible. (C) Detail of the posterior area of the palate (acid-prepared counterslab) in dorsal view showing the pterygoid (pt), the ectopterygoid (ec), and the right maxilla (rm). Note the robustness of right mandibular ramus (in lateral view) and its thin, edentulous dorsal edge (arrow). ch, choanae; cq, mandibular condyle of the quadrate; ec, ectopterygoid; hy, hyoid apparatus; j, jugal; lbd, lingual bulge of the dentary; ld, left dentary; lft, lower temporal fenestra; po, postorbital; pt, pterygoid; q, quadrate; rd, right dentary; rm, right maxilla; sq, squamosal; v, vomer. Scale bars: 10 mm. Vullo et al. (2012).

Lower jaw of Europejara olcadesorum. (A) Close-up of the symphyseal area (acid-prepared counterslab) in right lateral view showing the typical step-like dorsal margin of the dentary in tapejarines (arrow). Note the strong lateral compression of the mandible and the trabecular structure of the sagittal crest of the dentary (scd). (B) Close-up of the best preserved margin of the dentary crest (main slab). Note the concave posterior border (arrow) giving the peculiar recurved aspect of the dentary crest of Europejara. scd, sagittal crest of the dentary. Scale bars: 10 mm. Vullo et al. (2012).

Reconstructions of Europejara olcadesorum. (A) Interpretative line drawing of the skull as observed on the acid-prepared counterslab. (B) Reconstruction of the skull (based in part on Tapejara) showing preserved parts in red. Life restoration of the head of Europejara in lateral (C) and frontal (D) views. apj, anterior process of the jugal; aprj, anterior process of the right jugal; d, dentary; ec, ectopterygoid; hy, hyoids; j, jugal; l, lacrimal; ld, left dentary; lj, left jugal; lm, left maxilla; lpo, left postorbital; lq, left quadrate; lsa, left surangular; lsq, left squamosal; ltf, lower temporal fenestra; m, maxilla; naof, nasoantorbital fenestra; o, orbit; pf, postfrontal; po, postorbital; pt, pterygoid; q, quadrate; rap, retroarticular process; rd, right dentary; rm, right maxilla; scd, sagittal crest of the dentary; scp, scleral plates; sq, squamosal. Scale bar: 50 mm. Vullo et al. (2012).

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