Eotrachodon

Name: Eotrachodon Eotrachodon‭ (‬Dawn Trachodon/Dawn rough tooth‭)‬.
Phonetic: E-oh-trak-oh-don.
Named By: Albert Prieto-Marquez,‭ ‬Gregory M.‭ ‬Erickson‭& ‬Jun A.‭ ‬Ebersole‭ ‬-‭ ‬2016.
Classification: Chordata,‭ ‬Reptilia,‭ ‬Dinosauria,‭ ‬Ornithischia,‭ ‬Ornithopoda,‭ ‬Hadrosauridae.
Species: E.‭ ‬orientalis‭ (‬type‭)‬.
Diet: Herbivore.
Size: Holotype skull reconstructed to be about‭ ‬42‭ ‬centimetres long.‭ ‬Total body length estimated at between six and nine meters long,‭ ‬but this is highly speculative.
Known locations: USA,‭ ‬Alabama‭ ‬-‭ ‬Mooreville Chalk Formation.
Time period: Santonian-Coniacian of the Cretaceous.
Fossil representation: Almost complete skull,‭ ‬lower jaws,‭ ‬some vertebrae and fragmentary limb bones.

       By the start of the Late Cretaceous the central portion of North America had been submerged by a shallow sea.‭ ‬This created two landmasses out of the North American continent,‭ ‬Laramidia in the west and Appalachia in the east.‭ ‬Most Cretaceous era dinosaurs from North America have been found in what was once Laramidia,‭ ‬but a few are known from Appalachia.‭ ‬With respect to the hadrosaurs‭ (‬a.k.a.‭ ‬the duck billed dinosaurs‭)‬,‭ ‬for over one hundred and fifty years the only known member of this group of dinosaurs present in Appalachia was the Hadrosaurus genus itself‭ (‬discovered in New Jersey in‭ ‬1858‭)‬.‭ ‬Then in‭ ‬2016,‭ ‬a second genus of hadrosaur was identified as living in Appalachia:‭ ‬Eotrachodon.
       Eotrachodon is so far known from an almost complete skull,‭ ‬lower jaws as well as some vertebrae and fragmentary elements of the limbs.‭ ‬The genus is actually the first hadrosaurid dinosaur from Appalachia to be known from skull material,‭ ‬with the earlier named Hadrosaurus only known from very partial post cranial fossils.‭ ‬Eotrachodon was discovered in the Mooreville Chalk Formation of Alabama,‭ ‬a fossil bearing formation that is actually best known for marine animals such as sharks,‭ ‬bony fish and mosasaurs.‭ ‬This may well suggest that the holotype individual of Eotrachodon was actually washed out to sea,‭ ‬which in turn might mean that this animal lived elsewhere from Alabama.
       Eotrachodon means‭ ‘‬dawn rough tooth‭’ ‬and is a reference to the earlier appearance of Eotrachodon compared to the genus Trachodon‭ (‬today regarded as a highly dubious hadrosaurid dinosaur genus‭)‬.‭ ‬The authors of the description have speculated that Eotrachodon may have been amongst the first true hadrosaurs to appear upon the face of the planet,‭ ‬suggesting that the hadrosaurid dinosaurs may have first appeared in Appalachia.‭ ‬However,‭ ‬with a growing number of hadrosauroid dinosaurs‭ (‬evolutionary close to true hadrosaurs,‭ ‬though not quite them‭) ‬being discovered in other parts of America,‭ ‬Asia as well as possibly Africa,‭ ‬it may well be too soon to jump to a conclusion as to where the first true hadrosaurs appeared.

Further reading
-‭ ‬A primitive hadrosaurid from southeastern North America and the origin and early evolution of‭ '‬duck-billed‭' ‬dinosaurs.‭ ‬-‭ ‬Journal of Vertebrate Paleontology:‭ ‬e1054495.‭ ‬-‭ ‬Albert Prieto-Marquez,‭ ‬Gregory M.‭ ‬Erickson‭& ‬Jun A.‭ ‬Ebersole‭ ‬-‭ ‬2016.





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