Josephoartigasia monesi

Taxobox
name = †"Josephoartigasia monesi"

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fossil_range = Pliocene to Pleistocene
regnum = Animalia
phylum = Chordata
classis = Mammalia
ordo = Rodentia
subordo = Hystricomorpha
familia = Dinomyidae
genus = †"Josephoartigasia"
species = †"J. monesi"
binomial = †"Josephoartigasia monesi"
binomial_authority = Rinderknecht & Blanco, 2008

"Josephoartigasia monesi" is the largest known rodent, and lived approximately 4 to 2 million years ago in South America during the Pliocene or Pleistocene [According to Rinderknecht & Blanco (2008) recent studies indicate that some strata of the San José Formation in which the specimen was found are Pleistocene, instead of Pliocene as was traditionally assumed. In any case, they do give a date range of 4–2 Mya.] . The species may have weighed convert|1000|kg|lb|abbr=on, considerably larger than its closest living relative, the pacarana. The rodent may have lived in an estuarine environment or a delta system with forest communities, and may have eaten soft vegetation.cite web | author = Brahic, Catherine | url = http://www.newscientist.com/channel/life/dn13188-onetonne-rodent-discovered-in-south-america.html | title = One-tonne rodent discovered in South America | work = New Scientist | date = 2008-01-16 | accessdate = 2008-01-16] .

Classification

"J. monesi" is known from an almost complete skull, which was recovered from the San José Formation on the coast of Río de la Plata in Uruguay. Discovered in 1987 (though not scientifically described until 2008), the specimen belongs to Uruguay's National History and Anthropology Museum. [cite web | last = Satter | first = Raphael G. | title = Fossil remains of 2,000-pound rodent found | url = http://www.msnbc.msn.com/id/22684589/?GT1=10755 | work = MSNBC | date = 2008-01-16 | accessdate = 2008-01-17] The species is one of two in the "Josephoartigasia" genus, the other being "J. magna".

Size

The skull of the holotype is convert|53|cm|in|0|abbr=on long, and the remaining incisor is more than convert|30|cm|in|0|abbr=on in length. The total estimated body length is convert|3|m|foot|0|abbr=on, with a height of convert|1.5|m|foot|0|abbr=on.

By comparing the skull with various with extant species of rodent, the authors of the original paper estimated a mass between convert|468|kg|lb|abbr=on and convert|2586|kg|lb|abbr=on, with a median estimate of convert|1211|kg|lb|abbr=on. cite journal | last = Rinderknecht | first = Andrés | authorlink = | coauthors = Blanco, R. Ernesto | year = 2008 | month = Jan | title = The largest fossil rodent | journal = Proceedings of the Royal Society B | volume = | issue = | pages = 923–928 | doi = 10.1098/rspb.2007.1645 | url = http://journals.royalsociety.org/content/34j867846u164624/fulltext.pdf | format = pdf | accessdate = 2008-05-27 | quote = ] A later researcher revisited the numbers and came up with a more conservative estimate of convert|350|kg|lb|abbr=on to convert|1534|kg|lb|abbr=on, with a median of convert|900|kg|lb|abbr=on. cite journal | last = Millien | first = Virginie | authorlink = | coauthors = | year = 2008 | month = May | title = The largest among the smallest: the body mass of the giant rodent "Josephoartigasia monesi" | journal = Proceedings of the Royal Society B | volume = | issue = | pages = | doi = 10.1098/rspb.2008.0087 | url = http://journals.royalsociety.org/content/pg31525230323q27/?p=35f8c90fe97d44c9b32766e547837566&pi=0 | format = | accessdate = 2008-05-27 | laysummary = http://news.bbc.co.uk/2/hi/science/nature/7408743.stm | quote = ]

There is no dispute that "J. monesi" replaces "Phoberomys pattersoni", a related and somewhat older species that lived in Venezuela during the Late Miocene, as the largest rodent. However size comparisons are difficult because previous estimates of convert|400|kg|lb|abbr=on and convert|700|kg|lb|abbr=on for "P. pattersoni" are based on forelimb and hindlimb elements, which are not present in the "J. monesi" specimen.

References