Tarchia

MAIN INFORMATION: Tarchia (meaning "brainy one") is a genus of herbivorous ankylosaurid dinosaurs from the late Cretaceous of Mongolia.

PHYSICAL APPEARANCE: Like many other Ankylosaurs, Tarchia was quadruple, had an armor on its head, large pit of nostril skin, many rows of spikes on its shell-like body infrastructure, tiny spikes grown at the sides of its legs, having smaller sets of spikes on its long tail and a club at the tip of its tail used for defense. Tarchia was more slimmer, its body slightly thinner than most Ankylosaurus.

APPEARANCE: Tarchia had a darker, more grim look. Its head, body, tail, skin and armor was colored dark brown with streaks of dark gray, saturated light brown colored its spikes, and it had a de-saturated color of light brown at the belly.

PALEONTOLOGY: A rump with tail and club, specimen ZPAL MgD I/113, once referred to Dyoplosaurus giganteus and subsequently to Tarchia gigantea, was by Arbour seen as different from the D. giganteus holotype.[5] The study by Arbour also concluded that specimen PIN 3142/250, in 1977 referred to Tarchia by Tumanova, probably belonged to Saichania instead. This would radically change the common image of Tarchia as this exemplar had been by far the best preserved and most illustrations, museum mounts and indeed scientific research had been based on it. Arbour discovered that the holotype of Tarchia shared distinguishing traits with that of Minotaurasaurus Miles & Miles 2009, concluding that the latter is a junior synonym of Tarchia.[6]

As an ankylosaurid, Tarchia would have had a broad, low-slung body, positioned on strong short legs. The body would have been protected by skin ossifications, named osteoderms. It probably had a bony tail club, for active defence against predators.

Tarchia had previously been distinguished from Saichania on the basis of its relatively larger basicranium, an unfused paroccipital process-quadrate contact and, based on PIN 3142/250, the fact that the premaxillary rostrum is wider than the maximum distance between the tooth rows in the maxillaries. In 2014, Arbour reported two distinguishing traits apart from those known exclusively from the holotype of Minotaurasaurus; the back of the head is visible in top view; and a deep groove runs along the front and outer side of the squamosal horn, and at the front it surrounds around an accessory osteoderm placed on the rear supraorbital, forming a deep furrow

Tarchia was, like other Mongolian ankylosaurines, herbivorous and a low-level bulk feeder based on its sub-rectangular broad muzzle.[8] Instead of oral processing, ankylosaurids living in dry environments such as Tarchia may have relied more on hindgut fermentation for digestion or, alternatively, consumed succulent plants that did not require complex chewing. These ankylosaurids may have also been restricted to simple orthal pulping and might have had to deal with more grit during feeding compared to ankylosaurs that lived in tropical to subtropical climates, as indicated by the microwear pits.[15] Park et al. (2021) suggested that there was a shift from bulk feeding to selective feeding in Mongolian ankylosaurines during the Campanian and Maastrichtian stages which may have either been caused by the change in habitat, as the climate changed from semi-arid and arid to humid, or interspecific competition with saurolophine hadrosaurids that immigrated from North America to Central Asia during the Campanian stage.

SETTINGS: Nemegt Formation, Mongolia

SIZE: Tarchia was overall 5.5 to 6.7 meters long on average, its head and body together 5.2 meters long, while its tail was 0.9 meters long. Tarchia was tall as 1.8 meters, either slightly more bigger than a human or equally matching the height of a human.