| 词条 | Josephoartigasia monesi |
| 释义 |
| image = Josephoartigasia BW.jpg |image_caption = Life restoration of J. monesi | fossil_range = Pliocene to Early Pleistocene (Chapadmalalan-Uquian) ~{{fossilrange|4|2}} | taxon = Josephoartigasia monesi | authority = {{harvnb|Rinderknecht|Blanco|2008}} }}Josephoartigasia monesi, an extinct species of South American caviomorph rodent, is the largest rodent known, and lived from about 4 to 2 million years ago during the Pliocene to early Pleistocene.[1][1] The species is one of two in the genus Josephoartigasia, the other being J. magna.[1] J. monesi is sometimes called the giant pacarana, after its closest living relative, the pacarana (Dinomys branickii) in the family Dinomyidae.[1] The species may have weighed a ton, considerably larger than any living rodent.[1] DescriptionThe 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}}. Body massJ. monesi replaced 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|and|700|kg|lb|abbr=on}} for P. pattersoni were based on fore and hind limb elements, which are not present in the J. monesi specimen.[1]By comparing the skull with various extant species of rodents, the authors of the original paper estimated a mass between {{convert|468|and|2586|kg|lb|abbr=on}}, with a median estimate of {{convert|1211|kg|lb|abbr=on}}.[2] A later researcher revisited the numbers and came up with a more conservative estimate of {{convert|350|to|1534|kg|lb|abbr=on}}, with a median of {{convert|900|kg|lb|abbr=on}}.[3] Discovery and etymologyJ. 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.[2] Discovered in 1987, but not scientifically described until 2008, the specimen is preserved in Uruguay's National History and Anthropology Museum.[4] Josephoartigasia monesi was named after the paleontologist Álvaro Mones, for his study on the rodent in 1966.[2]PaleobiologyThe rodent's fearsome front teeth and large size may have been used to fight over females for breeding rights and may also have helped defend against predators, including sparassodonts, short-faced bears and terror birds.[5] The rodent may have lived in an estuarine environment or a delta system with forest communities,[2] and may have eaten soft vegetation.[6] It has been stated that J. monesi probably fed on aquatic plants and fruits, because its molars are small and not good for grass or other abrasive (vegetation). Larger mammals also have the advantage of access to low-quality food resources, such as wood, that smaller species are unable to digest.[5] Finite element analysis was used to estimate the maximum bite force of J. monesi.[7] This study concluded that the bite of J. monesi possibly generated up to 4165 N of force, three times as powerful as predicted for modern day tigers.[8] The study also speculated that J. monesi behaved similarly to elephants, utilizing its incisors like tusks for digging or defense.[7]Notes1. ^According to {{harvnb|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 previously assumed. In any case, they do give a date range of 4–2 Mya. 2. ^1 2 3 4 5 6 7 8 {{ cite journal |ref=harv | last1=Rinderknecht |first1=Andrés |last2=Blanco |first2=R. Ernesto |date=January 2008 |title=The largest fossil rodent |journal=Proceedings of the Royal Society B |volume=275 |issue=1637|pages=923–8 |doi=10.1098/rspb.2007.1645 |pmid=18198140 |pmc=2599941}} 3. ^{{ cite journal |last=Millien |first=Virginie |date=May 2008 |title=The largest among the smallest: the body mass of the giant rodent Josephoartigasia monesi |journal=Proceedings of the Royal Society B |volume=275 |issue=1646 |pages=1953–5; discussion 1957–8 |doi=10.1098/rspb.2008.0087 |laysummary=http://news.bbc.co.uk/2/hi/science/nature/7408743.stm |pmid=18495621 |pmc=2596365}} 4. ^{{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}} 5. ^1 {{cite web|last=Owen|first=James|title=Bull-Size Rodent Discovered -- Biggest Yet|url=http://news.nationalgeographic.com/news/2008/01/080116-giant-rodent.html|work=National Geographic News|accessdate=6 December 2013}} 6. ^{{cite web | author = Brahic, Catherine | url = https://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}} 7. ^1 {{cite journal |doi=10.1111/joa.12282|pmid=25652795|title=Predicting bite force and cranial biomechanics in the largest fossil rodent using finite element analysis|journal=Journal of Anatomy|volume=226|issue=3 |pages=215–23|year=2015|last1=Cox|first1=Philip G.|last2=Rinderknecht|first2=Andrés|last3=Blanco|first3=R. Ernesto|pmc=4337660}} 8. ^{{cite journal |doi=10.1126/science.aaa7792|title=Ratzilla: Ancient giant rodent chomped like a crocodile|journal=Science|year=2015|last1=Perkins|first1=Sid}} References{{Reflist|30em}}{{Taxonbar|from=Q133298}} 14 : Prehistoric pacaranas|Pliocene rodents|Pleistocene rodents|Pliocene mammals of South America|Pleistocene mammals of South America|Chapadmalalan|Uquian|Neogene Uruguay|Pleistocene Uruguay|Fossils of Uruguay|Pliocene first appearances|Pleistocene extinctions|2008 in science|Fossil taxa described in 2008 |
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