Wyniki wyszukiwania

Wyszukiwano:
w słowach kluczowych: ornithischian dinosaur

Sortuj według:

Ogranicz wyniki do:

Artykuł dostępny w postaci pełnego tekstu - kliknij by otworzyć plik

New evidence on brain-endocranial cavity relationships in ornithischian dinosaurs

100%

Evans D. C.

Acta Palaeontologica Polonica

2005

tom 50

nr 3

Discussions of brain morphology and relative brain size in nonavian dinosaurs have been complicated by uncertainty in the extent to which the brain filled the endocranial cavity. Recently reported vascular imprints (valleculae) on the endocranial surfaces of the braincase suggest that nonavian maniraptoriform theropods had brains that tightly fit the endocranium. Similar impressions of the intracranial vascular system are reported here in two ornithischian clades, Hadrosauridae and Pachycephalosauridae. These structures are more widespread in dinosaurs than previously thought, and suggest that the brain closely fit the endocranium in some regions of the forebrain through hindbrain in several distantly related dinosaur groups.

The phylogenetic position of the ornithischian dinosaur Stenopelix valdensis from the Lower Cretaceous of Germany and the early fossil record of Pachycephalosauria

80%

Butler R. J., Sullivan R. M.

Acta Palaeontologica Polonica

2009

tom 54

nr 1

21-34

The holotype of Stenopelix valdensis is the most completely known dinosaur specimen from the “Wealden” (Lower Cretaceous) of northwestern Germany, but its phylogenetic position has remained highly controversial. Most recent authors have suggested affinities with the ornithischian clade Marginocephalia, and most commonly to the marginocephalian subclade Pachycephalosauria. A pachycephalosaurian identity would make Stenopelix the only confirmed pre−Late Cretaceous member of this clade, breaking up an extensive ghost lineage which extends to the inferred origin of Pachycephalosauria in the Middle–Late Jurassic. Based upon re−examination of the holotype we here review the characters that have previously been used to assign Stenopelix to either Pachycephalosauria or Ceratopsia. All of these characters are problematic, being based upon inaccurate anatomical interpretations, or having more widespread distributions within Ornithischia than previously realised. We conclude that although the overall anatomy of Stenopelix is consistent with marginocephalian affinities, there is insufficient evidence to support referral to either Pachycephalosauria or Ceratopsia; we consider Stenopelix ?Marginocephalia. A brief review indicates that there is no compelling fossil evidence for pachycephalosaurs prior to the Late Cretaceous.

Ograniczanie wyników

2 Acta Palaeontologica Polonica

1 Butler R. J.

1 Evans D. C.

1 Sullivan R. M.

1 2009

1 2005

Wyniki wyszukiwania

New evidence on brain-endocranial cavity relationships in ornithischian dinosaurs

The phylogenetic position of the ornithischian dinosaur Stenopelix valdensis from the Lower Cretaceous of Germany and the early fossil record of Pachycephalosauria