Name:
Eobrontosaurus
(Dawn thunder lizard).
Phonetic: E-owe-bron-toe-sore-us.
Named By: Robert T. Bakker - 1998.
Synonyms: Apatosaurus yahnahpin.
Classification: Chordata, Reptilia, Dinosauria,
Saurischia, Sauropodomorpha, Sauropoda, Diplodocidae,
Apatosaurinae.
Species: E. yahnahpin (type).
Diet: Herbivore.
Size: 21 meters long.
Known locations: USA, Wyoming - Morrison
Formation.
Time period: Kimmeridgian to Tithonian of the
Jurassic.
Fossil representation: Almost complete post cranial
skeleton as well as additional fragmentary remains.
Eobrontosaurus
was initially described as a new species of Apatosaurus
called A.
yahnahpin by James Filla and Patrick Redman in 1994.
However when
the material was re-examined by Robert Bakker in 1998 he found that
it represented a similar but more primitive sauropod
dinosaur to Apatosaurus.
The second species of Apatosaurus, A.
excelsus,
originally went
by the name of Brontosaurus excelsus until it was
declared to be a
synonym to the earlier Apatosaurus by Elmer S.
Riggs in 1903.
This is a clearly definable species to the Apatosaurus
type species of
A. ajax, and in the 1990s Bakker suggested
that A. excelsus is
different enough to resurrect Brontosaurus as its
own genus, although
this was largely refuted by other palaeontologists and to this day
Brontosaurus is still a synonym to Apatosaurus.
This is in part why
Bakkar chose the name Eobrontosaurus instead of Eoapatosaurus,
although it does also help prevent confusion with the Apatosaurus
genus.
Suggestions
have been made that Eobrontosaurus may actually be
a specimen of
Camarasaurus,
although most palaeontologists do
not accept this idea.
Further reading
- Apatosaurus yahnahpin: a preliminary description
of a new species of
diplodocid dinosaur from the Late Jurassic Morrison Formation
(Kimmeridgian-Portlandian) and Cloverly Formation (Aptian-Albian) of
the western United States. - M�moires de la Soci�t� G�ologique de
France (Nouvelle S�rie) 139 (Ecosyst�mes Continentaux du M�sozoique):
87-93. - J. A. Filla & P. D. Redman - 1994.
- Dinosaur mid-life crisis: the Jurassic-Cretaceous transition in
Wyoming and Colorado. - Lower and Middle Cretaceous Terrestrial
Ecosystems, New Mexico Museum of Natural History and Science Bulletin
14:67-77 - R. T. Bakker - 1998.