Sunday, May 27, 2018

[Paleontology • 2018] Bagualosaurus agudoensis • A New Dinosaur (Saurischia: Sauropodomorpha) from the Late Triassic of Brazil Provides Insights on the Evolution of Sauropodomorph Body Plan


Bagualosaurus agudoensis
Pretto, Langer & Schultz, 2018

Illustration: Jorge Blanco  coral.ufsm.br

Abstract
A new sauropodomorph dinosaur from the Late Triassic Candelária Sequence (Santa Maria Formation), south Brazil, Bagualosaurus agudoensis gen. et sp. nov., helps to fill a morphological gap between the previously known Carnian members of the group and younger sauropodomorphs. In some aspects, the skull, lower jaw, and dental anatomy of the new taxon approaches that seen in Norian forms like Pantydraco caducus, Efraasia minor, and Plateosaurus engelhardti. On the contrary, the post-cranial skeleton is broadly reminiscent of coeval, early dinosaurs. Although not reaching the size of most Norian and younger sauropodomorphs, B. agudoensis is significantly larger than coeval forms. The new data thus suggest that modifications in skull anatomy, possibly related to more efficient herbivorous habits, appeared early in sauropodomorph evolution, along with a moderate increase in size, followed in post-Carnian times by further increase in size, accompanied by more radical changes in post-cranial anatomy.

Keywords: Candelária Sequence, Early dinosaurs, Late Triassic, Santa Maria Formation, Sauropodomorpha






SYSTEMATIC PALEONTOLOGY 

Dinosauria Owen, 1842 sensu Padian & May, 1993 
Saurischia Seeley, 1887 sensu Gauthier, 1986 
Sauropodomorpha von Huene, 1932 

Bagualosaurus agudoensis gen. et sp. nov.

Etymology The generic name is derived from the term ‘Bagual’, a term employed regionally in southern Brazil to refer to an animal or person of strong build or valour, plus ‘saurus’, Latin, meaning lizard; the specific name makes allusion to the town of Agudo, where the holotype was collected.

....

CONCLUSION: 
Bagualosaurus agudoensis represents the largest known Carnian sauropodomorph. Indeed, if the material described by Pretto et al. (2015) is regarded as a second specimen of the taxon, its body size would rival that of many other Carnian taxa (e.g. rhynchosaurs and cynodonts, at least from Brazilian faunas). Despite that, B. agudoensis is far from achieving the large body sizes of most post-Carnian sauropodomorphs. Indeed, most traits related to large body masses (such as robust hindlimbs, especially the pes) are not yet present in B. agudoensis, and most traits shared with post-Carnian sauropodomorphs seem to be related to the skull and mandible. This suggests that modification in the skull anatomy, possibly related to more efficient herbivorous habits, appeared earlier in the evolution of sauropodomorphs than their further increase in size. The discovery of Bagualosaurus agudoensis adds to the known dinosaur diversity of the Carnian. It also reinforces the idea that sauropodomorphs had an initial moment of high diversification, prior to their increase in abundance achieved during the Norian and afterwards when the group started to represent a dominant component of many paleoenvironments (Brusatte et al., 2010; Ezcurra, 2010; Langer et al., 2010; Irmis, 2011).


Representação artística da paisagem na região de Agudo no período Triássico. No centro da imagem, uma dupla de Bagualosaurus agudoensis confronta o cinodonte Trucidocynodon riograndensis . No canto inferior direito, um Hyperodapedon, réptil herbívoro do grupo dos rincossauros. Ao fundo, um grupo de cinodontes, Exaeretodon riograndensis, observa a cena.
Arte: Jorge Blanco

Flávio A. Pretto, Max C. Langer and Cesar L. Schultz. 2018. A New Dinosaur (Saurischia: Sauropodomorpha) from the Late Triassic of Brazil Provides Insights on the Evolution of Sauropodomorph Body Plan.  Zoological Journal of the Linnean Society. zly028.  DOI: 10.1093/zoolinnean/zly028

“Tataravô” de gigantes  coral.ufsm.br/arco/sitenovo/?p=3670  
Estudo põe mais um dinossauro na pré-história do País @estadao:   brasil.estadao.com.br/noticias/geral,estudo-poe-mais-um-dinossauro-na-pre-historia-do-pais,70002323449

   

No comments:

Post a Comment