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. - Andrés 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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