(Named after the palaeontologist Eberhard Fraas who discovered the
Named By: Peter M. Galton - 1973.
Synonyms: Sellosaurus fraasi, Teratosaurus minor, Thecodontosaurus diagnosticus.
Classification: Chordata, Sauropsida, Dinosauria, Sauropodomorpha.
Species: E. minor (type).
Size: About 6 to 7 meters long.
Known locations: Germany - Löwenstein Formation.
Time period: Norian of the Triassic.
Fossil representation: Partial skull and post cranial remains of juveniles.
early study of Efraasia was to say the least one
born out of
misconceptions. The first remains of this sauropodomorph
were being found way back in the latter half of the nineteenth
century, but they were being assigned to different genera. Some of
these genera were sauropodomorphs too, such as Sellosaurus
though later revisions of the species created when
these fossils were added found the species did not actually compare
well to the type species of those genera. A species of
Thecodontosaurus, T. diagnosticus
has now been found to be
synonymous (the same as) the Efraasia type
species, while a
Sellosaurus species, S. fraasi
synonymous. On a quick
side note the Sellosaurus type species is also now
treated as a synonym
to the famous Plateosaurus
which means that the whole Sellosaurus genus
is no longer valid. Perhaps most bizarre of these early mix-ups was
the adding of sauropodomorph remains that would later be identified as
belonging to Efraasia as to the rauisuchian
creating a then new species called T. minor,
which is now a
synonym to Efraasia, though the actual Teratosaurus
genus is still
treated as valid thanks to the earlier named type species.
So far Efraasia is only known from partial skull and post cranial skeletal remains, and probably those of juveniles, meaning that they were not fully grown. This is why early size estimates of the genus credit Efraasia as being between two and three meters long, they were being based upon the size of the known juvenile remains. Needless to say, juveniles grow up into adults and adults would have been larger than this two to three meter estimate. The first realistic adult size estimate for Efraasia came to light in 2003 in a subsequent study of the genus by Adam Yates which suggested six and a half meters.
There is still debate over whether Efraasia was bipedal or quadrupedal. The development of the wrists suggest that Efraasia may have been able to put weight on the forelimbs, but others have pointed out that the forelimb bones (ulna and radius) could not pronate to point straight down. The latter hints at a more bipedal mode of locomotion, and the hands that were capable of grasping branches also suggest that the forelimbs were of more use in feeding instead of bearing weight. A middle ground could be Efraasia being bipedal when walking around, but then balancing upon the forelimbs when browsing upon low growing vegetation or bending forward to drink. Balancing though may only mean light weight bearing, with the majority of the body weight being counterbalanced by the tail with the force of the weight transmitted to the hips and down the rear legs.
As a sauropodmorph Efraasia already shows signs of an elongated neck though not even close to the extremes of later sauropods. Despite the slight elongation, the neck was still thin, with the bones indicating only the minimum of necessary muscle support. With this in mind Efraasia may have been at its developmental limit before the more radical skeletal changes of later sauropodomorphs. Gastroliths found in association to Efraasia also indicate a more exclusively herbivorous diet for this dinosaur.
- Die Dinosaurier der Europäischen Triasformation mit berücksichtigung der Ausseuropäischen vorkommnisse. - Geologische und Palaeontologische Abhandlungen Suppl. 1(1): 1-419 - Friedrich von Huene - 1908.
- On the anatomy and relationships of Efraasia diagnostica (Huene) n.gen., a prosauropod dinosaur (Reptilia: Saurischia) from the Upper Triassic of Germany - Paläontologische Zeitschrift 47(3/4): 229-255. - Peter M. Galton - 1973.
- The cranial anatomy of the prosauropod dinosaur "Efraasia diagnostica", a juvenile individual of Sellosaurus gracilis from the Upper Triassic of Nordwürttemberg, West Germany - Stuttgarter Beiträge zur Naturkunde B, 117: 1-15 - P. M. Galton & R. T. Bakker - 1985.
- The species taxonomy of the sauropodomorph dinosaurs from the Löwenstein Formation (Norian, Late Triassic) of Germany - Palaeontology 46(2): 317-337. - Adam M. Yates - 2003.