Livro de Resumos - Dinossauros do Maranhão

Paleontologia 163
Redescription of a pterosaur lower jaw from the Albian Toolebuc Formation
(Western Queensland, Australia)
1 Setor de Paleovertebrados, Departamento de Geologia e Paleontologia, Museu Nacional (MN/UFRJ),
Quinta da Boa Vista, s/n 0 - São Cristóvão - 20940-040, Rio de Janeiro, RJ, Brasil.
2 Bolsista de Mestrado CNPq.
3 Membro Academia Brasileira de Ciências.
4 Bolsista de Produtividade em Pesquisa do CNPq
5 Bolsista Cientista do Nosso Estado FAPERJ.
Fabiana Rodrigues Costa 1,2, & Alexander W. A. Kellner 1,3,4,5
The fossil record of pterosaurs in Australia is rather poor and has been limited to Early
Cretaceous occurrences. The first remains of these volant creatures from this region were
reported in the Toolebuc Formation, Western Queensland, and included an incomplete
lower jaw deposited at the Queensland Museum (QM F10613), with a cast deposited at
the Museu Nacional/UFRJ, that is redescribed here. The specimen is three-dimensionally
preserved and comprises only the mandibular symphysis, with 88 mm in length. A midline
groove, typical of Anhangueridae, Brasileodactylus and some specimens from the
Cambridge Greensand, is observed. The lateral surfaces of the symphysis are flat and
meet ventrally in a sharp edge without neither expansions nor crests, resulting in a
triangular cross-section that is somewhat deeper than broad. The right dental margin
bears five alveoli, none of them with teeth. The left dental margin bears four complete
alveoli and the remains of a fifth one paired with the fifth of the right margin. Only the
fourth alveolus contains a small replacement tooth. The dorsal margin of the symphysis is
concave, with the highest point at the fifth alveolus. The elongate mandibular symphysis
shows that the specimen represents a Pterodactyloidea (Archaeopterodactyloidea +
Dsungaripteroidea), since non-pterodactyloid pterosaurs either have a very short
mandibular symphysis or no symphysis at all. The size and shape of the alveoli differ from
all archaeopterodactyloids and some dsungaripteroids that are toothless (e.g.,
Tapejaridae, Azhdarchidae), but enable us to classify this specimen in the
Pteranodontoidea (Pteranodon, Istiodactylidae and Anhangueridae). The lack of an
expanded distal end excludes this material from the Anhangueridae. The rather oval
alveoli differ from the Istiodactylidae, but are similar to some taxa from the Cambridge
Greensand closely related to the Anhangueridae. Based on the marked concave dorsal
margin, not present in any other pteranodontoid toothed pterosaur known so far, we
regard this material as representing a new species of Pteranodontoidea.
E-mails: fabiana.costa@ufrj.br, kellner@mn.ufrj.br
Paleovertebrados