Named By: E. Buffetaut, V. Suteethorn, G. Cuny, H. Tong, J. Le Loeuff, S. Khansubha, & Jongautchariyakul - 2000.
Classification: Chordata, Reptilia, Dinosauria, Saurischia, Sauropodomorpha, Sauropoda.
Species: I. attavipachi (type).
Size: Estimated to about 6.5 meters long.
Known locations: Thailand - Nam Phong Formation.
Time period: Norian/Rhaetian of the Triassic.
Fossil representation: Partial post cranial remains including vertebrae, partial ribs, left femur (thigh bone), right sternum and shoulder blade, possibly from a juvenile.
is recognised as being one of the first sauropods
to appear on the
planet, replacing the previous earliest sauropod title holder
It should be mentioned here that at the time Vulcanodon
was thought to have lived in the early Hettangian stage of the
Jurassic, just after the Triassic/Jurassic boundary, though a
2004 study by Adam Yates covering the Vulcanodon
location led to the realisation that Vulcanodon
lived much later in the
Jurassic during the Toarcian stage.
Back to Isanosaurus, the genus is noted to have been one of the first to adapt to an exclusive quadrupedal form of locomotion. Evidence for a quadrupedal posture comes from the femur which in Isanosaurus is straight, while in known sauropodomorph genera which were at least partially bipedal, the femur is always curved. Isanosaurus is also noted for having vertebrae that had high neural spines, whereas the neural spines on the vertebrae of sauoropodomorphs usually have low neural spines.
Because the neural arches were not fused to the centra (the circular central part) of the vertebrae, it’s a fairly safe bet that the holotype remains of Isanosaurus are those of a juvenile, or at the very oldest a subadult. Whichever, it is fairly certain that Isanosaurus could grow quite a bit larger than the six and a half meters that the holotype individual is estimated to have been.
Isanosaurus means ‘Isan lizard’, and Isan is the name used to refer to Northeast Thailand. The type species name, I. Attavipach, is in honour of P. Attavipach, a prominent supporter of palaeontological research in Thailand. Thailand has been kind of late coming to the party in terms of fossil discoveries, and those that are found are often very fragmentary. However with known fossil locations ranging from the Triassic to Cretaceous, and remains of pterosaurs, spinosaurs, ornithopods, ceratopsians and sauropods already being discovered, Thailand is will likely be one of the key locations to be keeping an eye on in the near future.
- The earliest known sauropod dinosaur - E. Buffetaut, V. Suteethorn, G. Cuny, H. Tong, J. Le Loeuff, S. Khansubha, & Jongautchariyakul - 2000.
- A Review of the Sauropod Dinosaurs of Thailand.
- Eric Buffetaut, Varavudh Suteethorn, Jean Le Loeuff, Gilles Cuny, Haiyan Tong & Sasidhorn Khansubha - 2002.
-The earliest known sauropod dinosaur and the first steps towards sauropod locomotion - A. M. Yates & J. W. Kitching - 2003.