Tomarctus
Name: Tomarctus
(Cut bear).
Phonetic: Toe-mark-tus.
Named By: Edward Drinker Cope - 1873.
Synonyms: Aelurodon francisi, Aelurodon
simulans.
Classification: Chordata, Mammalia, Carnivora,
Canidae, Borophaginae.
Species: T. brevirostris
(type), T. hippophaga.
Diet: Carnivore.
Size: About 1.2 meters long.
Known locations: Across North America.
Time period: Aquitanian through to Langhian of the
Miocene, possibly later into the Miocene.
Fossil representation: Multiple individuals.
A
relative of such genera as Aelurodon
and Borophagus,
Tomarctus is
another one of the hyena-like ‘bone crushing’ dogs of the Miocene.
This description comes from the attachments for powerful jaw closing
muscles and short muzzle which means that when borophagine canids like
Tomarctus bit on something, it was closer to the
point of jaw
articulation. This in turn means that the force from the muscles is
focused so that it is concentrated upon a smaller area so that more
damage could be done to whatever is being bitten. This is exactly the
same with a modern hyena.
The
high bite force of Tomarctus is beyond that
necessary to kill an
animal, which leads to speculation that scavenging was just as an
important part of the diet as was hunting, perhaps even more so.
Scavengers however usually get to a carcass after most if not all of
the fleshy parts have been devoured, probably by the animal or animal
that made the kill. This would be no problem for an animal with jaws
like those of Tomarctus however since it had the
necessary jaw
adaptations for cracking open the bones so that it could get at the
marrow within. Bone marrow by itself is one of the most nutritious
things in the natural world, and when encased in bone under the right
conditions it can last for months and even years after the death of an
animal. However, just because Tomarctus was
well suited to being a
scavenger, it does not mean that they never killed their own prey.
Tomarctus
is known to have existed for at least the first half of the Miocene,
and seems to have disappeared with the appearance of later borophagine
forms like Aelurodon. During the early half of the Miocene Tomarctus
would have lived amongst other groups of carnivores such as false
sabre-toothed cats, bear
dogs and entelodonts.
Further reading
- Small mammal fossils from the Barstow Formation, Califonia. - E. H. Lindsay - 1972.
- Phylogenetic systematics of the Borophaginae. - X. Wang, R.
H. Tedford & B. E. Taylor - 1999.
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