Name: Isanosaurus ‭(‬Isan lizard‭)‬.
Phonetic: I-san-o-sore-us.
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)‬.
Diet: Herbivore.
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.

       Isanosaurus is recognised as being one of the first sauropods to appear on the planet,‭ ‬replacing the previous earliest sauropod title holder Vulcanodon.‭ ‬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 holotype fossil 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.

Further reading
-‭ ‬The earliest known sauropod dinosaur‭. - Nature. 407 (6800): 72–74. ‬-‭ ‬E.‭ ‬Buffetaut,‭ ‬V.‭ ‬Suteethorn,‭ ‬G.‭ ‬Cuny,‭ ‬H.‭ ‬Tong,‭ ‬J.‭ ‬Le Loeuff,‭ ‬S.‭ ‬Khansubha,‭ & ‬Jongautchariyakul‭ ‬-‭ ‬2000.
-‭ ‬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. Proceedings of the Royal Society of London B: Biological Sciences 270: 1753-1758. ‬-‭ ‬A.‭ ‬M.‭ ‬Yates‭ & ‬J.‭ ‬W.‭ ‬Kitching‭ ‬-‭ ‬2003.


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