Name: Segisaurus ‭(‬Segi lizard‭ ‬-‭ ‬after Tsegi Canyon‭)‬.
Phonetic: Seg-e-sore-us.
Named By: Lewis Camp‭ ‬-‭ ‬1936.
Classification: Chordata,‭ ‬Reptilia,‭ ‬Dinosauria,‭ ‬Saurischia,‭ ‬Theropoda,‭ ‬Coelophysidae.
Species: S.‭ ‬halli‭ (‬type‭)‬.
Diet: Insectivore/Carnivore.
Size: Estimate about‭ ‬1‭ ‬meter long,‭ ‬but since this was a sub-adult,‭ ‬full size would have been a little larger.
Known locations: USA,‭ ‬Arizona,‭ ‬Tsegi Canyon‭ ‬-‭ ‬Navajo Sandstone Formation.
Time period: Pliensbachian to Toarcian of the Jurassic.
Fossil representation: Partial post cranial remains of a sub adult.

       Segisaurus was once considered to be a very important link in the evolution of theropods because it was thought to have had solid bones instead of the hollow bones of other earlier genera such as Coelophysis.‭ ‬However a later study into the holotype remains that took place in‭ ‬2005‭ (‬Carrano,‭ ‬Hutchinson‭ & ‬Sampson‭) ‬found that Segisaurus does actually have hollow bones,‭ ‬meaning that it is not quite as unique as it was once thought.
       Segisaurus was a small theropod for the early Jurassic,‭ ‬and was probably restricted to hunting insects and small vertebrates like lizards.‭ ‬However it could have also supplemented its diet by scavenging the left over carcases of dead animals,‭ ‬perhaps those killed by large predators.‭ ‬Although not known from the same Formation,‭ ‬a much larger theropod by the name of Dilophosaurus was already hunting in what is now the United States at an earlier period than Segisaurus,‭ ‬and it‭’‬s very likely that other theropod dinosaurs similar to Dilophosaurus in size were also around when Segisaurus was alive.‭
       The full adult size of Segisaurus is unknown because the holotype is of a sub adult,‭ ‬which means that it was reproductively mature,‭ ‬yet not fully grown.‭ ‬However as a sub adult already,‭ ‬it‭’‬s likely that Segisaurus did not grow that much bigger,‭ ‬perhaps only as much as half as long again at the very most.
       One of the closest relatives of Segisaurus is thought to be Procompsognathus.

Further reading
-‭ ‬A new type of bipedal dinosaur from the Navajo Sandstone of Arizona,‭ ‬Lewis Camp‭ ‬-‭ ‬1936.
-‭ ‬New information on Segisaurus halli,‭ ‬a small theropod dinosaur from the Early Jurassic of Arizona,‭ ‬M.‭ ‬T.‭ ‬Carrano,‭ ‬J.‭ ‬R.‭ ‬Hutchinson‭ & ‬S.‭ ‬D.‭ ‬Sampson‭ ‬-‭ ‬2005.


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