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Primitive 'prosauropods' from Triassic of Brazil



From: Ben Creisler
bcreisler@gmail.com

 A new online paper:

Jonathas Souza Bittencourt, Átila Augusto Stock da Rosa, Cesar Leandro
Schultz & Max Cardoso Langer (2012)
Dinosaur remains from the ‘Botucaraí Hill’ (Caturrita Formation), Late
Triassic of south Brazil, and their stratigraphic context.
Historical Biology (advance online publication)
DOI:10.1080/08912963.2012.694881
http://www.tandfonline.com/doi/abs/10.1080/08912963.2012.694881

Vertebrate fossils recovered from sites nearby the Botucaraí Hill and
Candelária (Caturrita Formation) depict a diverse Late Triassic
tetrapod fauna from south Brazil. These records are of key importance
to the biostratigraphy of the upper sections of the Rosario do Sul
Group. A lithological and biostratigraphic survey on the main fossil
localities of the Botucaraí Hill area confirms the occurrence of the
lower Hyperodapedon and the upper Riograndia Assemblage Zones in the
region, the latter yielding early saurischians. In this paper, three
incomplete dinosaur specimens, an isolated sacral vertebra, an
articulated left pubis–ischium and an isolated right ischium, from the
‘Botucaraí Hill’ site are described. A comparative survey suggests
that these specimens have sauropodomorph affinities, but probably more
primitive than typical ‘prosauropods’ from the Norian-Early Jurassic.
Regardless of the phylogenetic position of Guaibasaurus as theropod or
sauropodomorph, their occurrence in the Caturrita Formation, which
also yielded ‘core prosauropods’ from the Santa Maria region, suggests
either the survival of early members of the clade with more derived
‘prosauropods’ or that heterochronous faunas are sampled from that
stratigraphic unit.