(Piveteau’s lizard - after the French palaeontologist Jean
Named By: P. Taquet & S. P. Welles - 1977.
Synonyms: Eustreptospondylus divesensis, Proceratosaurus divesensis.
Classification: Chordata, Reptilia, Dinosauria, Saurischia, Theropoda, Megalosauridae, Afrovenatorinae.
Species: P. divesensis (type).
Size: Uncertain due to lack of remains, though comparisons to other theropod fossils indicates that it was at least a large theropod, possibly around the nine meter mark.
Known locations: France, Lower Normandy - Marnes de Dives Formation.
Time period: Upper Callovian of the Jurassic.
Fossil representation: Braincase.
history of Piveteausaurus is one that is littered
with comparisons to
other theropod genera. The braincase that is the holotype fossil of
Piveteausaurus was first described in 1923 by
Fossils of other dinosaurs had been discovered in the same region as
this braincase all the way back to 1808 when fossils began to be
studied by Georges Cuvier (though the fossils were actually collected
many years before this). In 1861 another palaeontologist named
Richard Owen created a new species for the genus Streptospondylus
S. cuvieri from some of these fossils. To
Piveteau it seemed a
logical conclusion that the braincase he was studying belonged to this
species of Streptospondylus.
The above remained unchallenged until 1964 when Alick Walker studied the braincase (referenced as MNHN 1920-7) and declared it to belong to a new species of Eustreptospondylus, E. divesensis. However the additional skeletal remains previously assigned to Streptospondylus cuvieri were also assigned to the new species of Eustreptospondylus. In 1977, a new study by Taquet and Welles found the braincase to be unique enough to require its own genus and hence the genus Piveteausaurus was created. A 2001 study by R. Allain also found that there was no definitive link between the braincase and other fossils, the result being that now only the braincase is a valid specimen of Piveteausaurus. Since this creation Gregory S. Paul has considered the brain case to actually represent a species of Proceratosaurus, though thus far everyone else continues to credit Piveteausaurus as a valid genus.
As an actual living dinosaur Piveteausaurus was your classic theropod, bipedal, reduced fore arms, large skull mounted on a relatively short S-curved neck. The brain case that is now the holotype of Piveteausaurus has been considered to be comparable to the brain cases of larger specimens of Allosaurus. Most larger specimens of Allosaurus are just under the ten meter mark for length (some specimens suggest bigger but these are already discussed on the Allosaurus page), so an estimate of around nine meters long, give or take one meter could be a realistic proposition for Piveteausaurus. It should also be remembered that there are other theropods from the Jurassic of France such as Poekilopleuron and Dubreuillosaurus that do seem to have comfortably grown to nine meters long as well.
While Piveteausaurus has been considered to be similar to Eustreptospondylus, Proceratosaurus and Ceratosaurus, a 2004 study of another dinosaur named Piatnitzkysaurus has found that this was possibly one of the closest relatives of Piveteausaurus.
- L'arrière-crâne d'un dinosaurien carnivore de l'Oxfordien de Dives [The braincase of a carnivorous dinosaur from the Oxfordian of Dives], Jean Piveteau - 1923.
- Redescription du crâne de dinosaure théropode de Dives (Normandie) [Redescription of a theropod dinosaur skull from Dives (Normandy)], P. Taquet & S. P. Welles - 1977.
- Triassic reptiles from the Elgin area: Ornithosuchus and the origin of carnosarus, A. D. Walker - 1964.
- Braincase structure of the Middle Jurassic theropod dinosaur Piatnitzkysaurus, Rauhut - 2004.
- Redescription de Streptospondylus altdorfensis, le dinosaure théropode de Cuvier, du Jurassique de Normandie [Redescription of Streptospondylus altdorfensis, Cuvier's theropod dinosaur from the Jurassic of Normandy], R. Allain - 2001.