Name: Tarchia ‭(‬Brainy one‭)‬.
Phonetic: ‭Tar-chee-ah.
Named By: Teresa Maryańska‭ ‬-‭ ‬1977.
Synonyms: Dyoplosaurus giganteus,‭ ‬Tarchia kielanae.
Classification: Chordata,‭ ‬Reptilia,‭ ‬Dinosauria,‭ ‬Ornithischia,‭ ‬Thyreophoroidea,‭ ‬Ankylosauridae,‭ ‬Ankylosaurinae.
Species: T.‭ ‬gigantea‭ (‬type‭), T. teresae‬.
Diet: Herbivore.
Size: Estimated between‭ ‬8‭ ‬and‭ ‬8.5‭ ‬meters long.‭ ‬Skull‭ ‬40‭ ‬centimetres long,‭ ‬45‭ ‬centimetres wide.
Known locations: Mongolia,‭ ‬Nemegt Basin‭ ‬-‭ ‬Barun Goyot Formation.
Time period: Campanian to Maastrichtian of the Cretaceous.
Fossil representation: Multiple specimens and further referred fossils,‭ ‬together revealing the skull and post cranial skeleton.

       Estimated at over eight meters long,‭ ‬Tarchia is one of the largest ankylosaurids currently known,‭ ‬rivalling even the more famous Ankylosaurus.‭ ‬In fact given that Ankylosaurus is still known only from partial remains,‭ ‬Tarchia may one day actually prove to be the biggest.‭ ‬Tarchia was named along with another large,‭ ‬but slightly smaller ankylosaurid called Saichania,‭ ‬and although quite similar to one another,‭ ‬there are a number of identifiable differences between the two,‭ ‬particularly differences associated with the skull proportions.‭ ‬Despite these differences however,‭ ‬both Tarchia and Saichania both share bulbous bone growths that are present across the tops of their skulls.‭ ‬A North American ankylosaurid called Nodocephalosaurus also has these bumps,‭ ‬strongly‭ ‬suggesting a possible relationship with Tarchia and Saichania.
       Tarchia possessed a wide cropping beak across its mouth that allowed large amounts of vegetation to be indiscriminately pulled into the mouth.‭ ‬These plants would have likely been quite tough considering that Tarchia lived in an arid climate that was near desert in places,‭ ‬and would have required a large degree of processing in the mouth.‭ ‬Evidence for this comes from the teeth which show occlusion wear,‭ ‬basically meaning that the teeth of the upper and lower jaws regularly made contact.‭ ‬Like other ankylosaurids Tarchia had teeth more suited to chopping,‭ ‬and with every up and down movement of the jaw,‭ ‬the food in the mouth would be chopped into smaller and smaller pieces.‭ ‬This was not just to help swallowing but to increase the efficiency of digestion as the teeth chopping the food would provide a greater surface area to be exposed to the digestive acids of the stomach,‭ ‬greatly enhancing the nutritional gain.
       Tarchia also had a hard palate and a network of air passages in the snout which would have helped to moisten the dry air of its ecosystem before it reached its lungs.‭ ‬This would greatly reduce the amount of water lost through the process respiration,‭ ‬a vital adaptation considered the climate that Tarchia lived in.‭ ‬Additionally the presence of the hard palate‭ (‬unknown in most dinosaurs,‭ ‬but seemingly common in ankylosaurids‭) ‬meant that Tarchia could still breathe while it processed food in its mouth.

Further reading
- Ankylosauridae (Dinosauria) from Mongolia - Palaeontologia Polonica 37:85-151 - Teresa Maryanska - 1977.
- New data on the ankylosaur Tarchia gigantea - Paleontological Journal 11: 480-486. - T. A. Tumanova - 1978.
-The cranial morphology and taxonomic status of Tarchia (Dinosauria: Ankylosauridae) from the Upper Cretaceous of Mongolia. - Cretaceous Research - Paul Penkalski & Tatiana Tumanova - 2016.


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