''Deuterosaurus'' is an extinct

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

dinocephalia Dinocephalians (terrible heads) are a clade of large-bodied early therapsids that flourished in the Early and Middle Permian between 279.5 and 260 million years ago (Ma), but became extinct during the Capitanian mass extinction event. ...

n therapsids, one of the non-mammalian synapsids dominating the land during the late

Paleozoic The Paleozoic ( , , ; or Palaeozoic) Era is the first of three Era (geology), geological eras of the Phanerozoic Eon. Beginning 538.8 million years ago (Ma), it succeeds the Neoproterozoic (the last era of the Proterozoic Eon) and ends 251.9 Ma a ...

Etymology

''Deuterosaurus'' comes from Greek δευτερος "second" and σαυρος "lizard".

Species

* ''Deuterosaurus biarmicus'', the type species of ''Deuterosaurus'', was named by Eduard Eichwald in 1846 based on a series of vertebrae and ribs. Efremov erroneously listed "Deuterosaurus mnemionalis" as a synonym of ''D. biarmicus'', although no such species was ever named. * ''Deuterosaurus seeleyi'' was named by

Franz Nopcsa Franz may refer to: People * Franz (given name) * Franz (surname) Places * Franz (crater), a lunar crater * Franz, Ontario, a railway junction and unorganized town in Canada * Franz Lake, in the state of Washington, United States – see Fran ...

in 1902, based on a specimen consisting of 13 ribs. * ''Deuterosaurus jubilaei'' was named by Nopcsa in 1928, originally as representing a distinct genus, '' Mnemeiosaurus''. Boonstra and Tchudinov agreed that ''Mnemeiosaurus'' and ''Deuterosaurus'' were distinct genera, whereas Efremov and Ivakhnenko considered ''Mnemeiosaurus'' a synonym of ''Deuterosaurus'', albeit with ''D. jubilaei'' still a distinct species. * ''Deuterosaurus gigas'' was named by Ivan Efremov in 1954 based on teeth. It was later reassigned to ''

Ulemosaurus ''Ulemosaurus'' is an extinct genus of dinocephalian therapsids that lived 265 to 260 million years ago, at Isheevo in Russian Tatarstan. It was a tapinocephalid, a group of bulky herbivores which flourished in the Middle Permian. ''Ulemosauru ...

Anatomy

Skulls of ''Deuterosaurus'' are well known from several finds. It is over high, with a long snout and conical teeth. Like all

anteosaur Anteosaurs are a group of large, primitive carnivorous dinocephalian therapsids with large canines and incisors and short limbs, that are known from the Middle Permian of South Africa, Russia, China, and Brazil. Some grew very large, with skulls ...

s, the skull possessed long, dagger-like

canine teeth In mammalian oral anatomy, the canine teeth, also called cuspids, dogteeth, eye teeth, vampire teeth, or fangs, are the relatively long, pointed teeth. In the context of the upper jaw, they are also known as '' fangs''. They can appear more fl ...

. The skull was rather short for an anteosaur, with a broad cheek region, indicating a very strong bite. The eyes were partly slanted forward, giving it at least partial stereo vision. The

pineal eye A parietal eye (third eye, pineal eye) is a part of the epithalamus in some vertebrates. The eye is at the top of the head; is photoreceptive; and is associated with the pineal gland, which regulates circadian rhythmicity and hormone production ...

, though small, had a well formed opening right atop the brain case. ''Deuterosaurus'' was a very large animal, the size of a modern

grizzly bear The grizzly bear (''Ursus arctos horribilis''), also known as the North American brown bear or simply grizzly, is a population or subspecies of the brown bear inhabiting North America. In addition to the mainland grizzly (''Ursus arctos horr ...

T. H. Huxley Thomas Henry Huxley (4 May 1825 – 29 June 1895) was an English biologist and anthropologist who specialized in comparative anatomy. He has become known as "Darwin's Bulldog" for his advocacy of Charles Darwin's theory of evolution. The stor ...

mistakenly considered it to be a

dinosaur Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic Geological period, period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the #Evolutio ...

.Huxley, T.H. (1869)
"Triassic Dinosauria"
''Nature'' 1: 23-24. Judging from related therapsids, the short but massive legs were held splayed, much like a modern crocodile. When walking, the tail would have swung sideways, like in modern reptiles.

Biology

''Deuterosaurus'' is found in what is now

Siberia Siberia ( ; , ) is an extensive geographical region comprising all of North Asia, from the Ural Mountains in the west to the Pacific Ocean in the east. It has formed a part of the sovereign territory of Russia and its predecessor states ...

, which in the Permian was dominated by temperate lowlands. ''Deuterosaurus'' was among the largest animals of its day, and has variously been interpreted as a

herbivore A herbivore is an animal anatomically and physiologically evolved to feed on plants, especially upon vascular tissues such as foliage, fruits or seeds, as the main component of its diet. These more broadly also encompass animals that eat ...

carnivore A carnivore , or meat-eater (Latin, ''caro'', genitive ''carnis'', meaning meat or "flesh" and ''vorare'' meaning "to devour"), is an animal or plant Plants are the eukaryotes that form the Kingdom (biology), kingdom Plantae; they ar ...

. While the large canines may indicate the ability to kill prey, the short legs and massive body would have made it unsuited as a long distance runner, and better suited to eating plants. Then again, the possible stereoscopic vision again indicates an ambush style carnivore, and the rather blunt, cone-like post canine teeth can be interpreted both ways. Possibly ''Deuterosaurus'' was

omnivorous An omnivore () is an animal that regularly consumes significant quantities of both plant and animal matter. Obtaining energy and nutrients from plant and animal matter, omnivores digest carbohydrates, protein, fat, and fiber, and metabolize ...

, like a modern bear. ''Deuterosaurus'', like all its therapsid cousins, probably laid eggs. A remarkable thickening of the skull above the eyes indicates it may have engaged in head-butting, possibly in connection with mating or territorial disputes.

References

Works cited