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.