Josephoartigasia
Name:
Josephoartigasia.
Phonetic: Ho-say-foe-ar-tig-a-se-ah.
Named By: Mones - 1966.
Synonyms: Artigasia magna.
Classification: Chordata, Mammalia, Rodentia,
Dinomyidae.
Species: J. magna (type),
J.
monesi.
Diet: Herbivore.
Size: Skull 53 centimetres long. Body
estimated at 3 meters long, 1.5 meters high, weight around
1000 kilograms.
Known locations: Uruguay.
Time period: Zanclean of the Pliocene through to the
Gelasian of the Pleistocene.
Fossil representation: Skull, teeth.
The
title of biggest known rodent often gets assigned to the related
Phoberomys;
however the discovery of a new skull of
Josephoartigasia revealed that it was quite a bit
larger. These
estimates however have to be based upon comparing the size of the skull
of Josephoartigasia to those of other known rodents
with more complete
remains. Still just like with Phoberomys, Josephoartigasia
was much
bigger than the largest known rodent alive today, the capybara.
Josephoartigasia
was initially known as Artigasia magna, although this species was
only based upon a description of teeth by J. C. Francis and A.
Mones in 1966. Mones later created the genus Josephoartigasia
in
2007, but it was the description of the second species, J.
monesi in 2008 by Rinderknecht & Blanco that
would
confirm Josephoartigasia as the largest known
rodent.
Josephoartigasia
is thought to have lived in a wetland environment where it would use
its thirty centimetre long incisor teeth to crop vegetation, possibly
grasses. No one knows for certain why the larger rodents like
Josephoartigasia died out although the
disappearance of
Josephoartigasia occurred after the event known as
the Great American
Interchange. This is where the joining of North and South America
during the end of the Pliocene allowed previously isolated animals to
intermix with one another. For Josephoartigasia
this would have
involved increased competition from new herbivores as well as new
predators. Climate change is also a factor as towards the end of
Pliocene and early Pleistocene, global temperatures fell and the
climate became drier and this likely caused wetlands to become reduced
in size. Without habitats capable of supporting large rodents, and
unable to adapt to another kind of ecosystem, the large rodents like
Josephoartigasia would vanish, while smaller ones
like the capybara
could continue.
Further reading
- The largest fossil rodent. - Proceedings of the Royal Society B 275
(1637): 923–928. - Andr�s Rinderknecht & Ernesto R. Blanco -
2008.
- The largest among the smallest: the body mass of the giant rodent
Josephoartigasia monesi. - Proceedings of the Royal
Society B 275
(1646): 1953 - Virginie Millien 2008.
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