Blunt-toothed giant hutia

Extinct species of rodentTemplate:SHORTDESC:Extinct species of rodent

The **blunt-toothed giant hutia** (*Amblyrhiza inundata*) is an extinct species of giant hutia from Anguilla and Saint Martin that is estimated to have weighed between 50 and 200 kg (110 and 440 lb). It was discovered by Edward Drinker Cope in 1868 in a sample of phosphate sediments mined in an unknown cave (possibly Cavannagh Cave) in Anguilla and sent to Philadelphia to estimate the value of the sediments. It is the sole species of the genus *Amblyrhiza* in the fossil family Heptaxodontidae.

Some authors have suggested that its extinction may have resulted from overhunting by pre-Columbian humans. However, it is unknown whether this species was contemporaneous with human populations. Fossil specimens discovered at the end of the 20th century on Anguilla have been dated to the last interstadial period, while very recent discoveries made on Coco Islet (Saint-Barthélemy) are dated to 400,000 - 500,000 years; no bone has been recovered yet from a pre-Columbian archaeological site. Despite being described as a "giant hutia", it has recently been recovered as a member of the Chinchilloidea.

## Description

Paleontologist A. R. Biknevicius and his team have estimated body size for *Amblyrhiza inundata* based upon 5 femora and 9 humeri from adult *Amblyrhiza* remains. They concluded based upon these specimens that *Amblyrhiza* ranged from just under 50 kg in mass to over 200 kg in mass. These calculations were based on comparisons with extant caviomorphs of 16 different species. The blunt teeth of *Amblyrhiza inundata* suggest an herbivorous lifestyle, consistent with that of the other genera within Heptaxodontidae.

## Taxonomy

Known colloquially as the “Blunt Toothed Hutia,” this animal's scientific name reflects a similar narrative. “*Amblyrhiza*” roughly translates to “blunt root,” and “*inundata*” has been speculated to be in reference to Cope's disbelief that such a large rodent could evolve in an isolated region such as the islands of the northern Lesser Antilles. It is now accepted that Cope thought that the animal was cosmopolitan in nature, moving freely from island to island due to the lowered sea levels of the interval, which enabled *Amblyrhiza* to develop such an impressive body size. *Amblyrhiza* is currently considered to be a close relative of *Elasmodontomys obliquus*, a smaller yet similar rodent found in the Quaternary deposits of Puerto Rico. Although it has yet to be decided exactly where *Amblyrhiza* fits in a phylogenetic context, it is thought that they belong to a paraphyletic group of giant caviomorphs known as Heptaxodontidae. More recent work finds *Amblyrhiza* and *Elasmodontomys* to be members of the Chinchilloidea, with *Amblyrhiza* being most closely related to *Dinomys*.

## Discovery

Paleontology work began in the northeastern area of the Caribbean in the mid nineteenth century, when phosphate mining boomed in the region and fossils were coincidentally found in associated strata. Later, in 1868, samples of fossils and their overlying sediments were sent from the islands to the Philadelphia Academy of Sciences to estimate the potential scientific value of said specimens. These fossils were then given to famed paleontologist Edward Drinker Cope, who was serving as the academy's secretary at that time. Cope is said to have taken particular interest in them and their notably large size.

The fossilized remains of this remarkably large rodent are found solely within Quaternary cave deposits, all of which are located on the islands of the northern Lesser Antilles, specifically Anguilla and St. Martin.

## References

1. ↑ Woods, C.A.; Kilpatrick, C.W. (2005). "Infraorder Hystricognathi". In Wilson, D.E.; Reeder, D.M. *Mammal Species of the World: A Taxonomic and Geographic Reference* (3rd ed.). Johns Hopkins University Press. p. 1600. ISBN 978-0-8018-8221-0. OCLC 62265494.
2. ↑ Biknevicus, A. R.; McFarlane, D. A.; MacPhee, R. D. E. (1993). "Body size in *Amblyrhiza inundata* (Rodentia: Caviomorpha), an extinct megafaunal rodent from the Anguilla Bank, West Indies: Estimates and implications". *American Museum Novitates*. New York: American Museum of Natural History. **3079**: 1–25. hdl:2246/4976.
3. ↑ "Cavannagh Cave, Anguilla". Wondermondo.
4. ↑ "Late Quaternary vertebrate faunas of the Lesser Antilles: historical components of Caribbean biogeography", 1994, Bulletin of the Carnegie Museum of Natural History. Pregill, G. K., D. W. Steadman, and D. R. Watters.
5. ↑ "Body size variability and a Sangamonian extinction model for Amblyrhiza, a West Indian megafaunal rodent", 1998, Quaternary Research, D.A. McFarlane, R.D.E. MacPhee & D. Ford
6. ↑ "New specimens of Amblyrhiza inundata (Rodentia, Caviomoprha) from the Middle Pleistocene of Saint Barthélemy, French West Indies", 2014, Caribbean Journal of Earth Science, D.A. McFarlane, J. Lundberg & G. Maincent
7. ↑ 7.0 7.1 Marivaux, Laurent; Vélez-Juarbe, Jorge; Merzeraud, Gilles; Pujos, François; Viñola López, Lázaro W.; Boivin, Myriam; Santos-Mercado, Hernán; Cruz, Eduardo J.; Grajales, Alexandra; Padilla, James; Vélez-Rosado, Kevin I. (2020-02-12). "Early Oligocene chinchilloid caviomorphs from Puerto Rico and the initial rodent colonization of the West Indies". *Proceedings of the Royal Society B: Biological Sciences*. **287** (1920): 20192806. doi:10.1098/rspb.2019.2806. ISSN 0962-8452. PMC 7031660  Check `|pmc=` value (help). PMID 32075529 Check `|pmid=` value (help).
8. ↑ 8.0 8.1 8.2 8.3 McFarlane, Donald A.; MacPhee, Ross D. E.; Ford, Derek C. (July 1998). "Body Size Variability and a Sangamonian Extinction Model for Amblyrhiza, a West Indian Megafaunal Rodent". *Quaternary Research*. **50** (1): 80–89. doi:10.1006/qres.1998.1977. ISSN 0033-5894.
9. ↑ McFarlane, Donald (1993). "Amblyrhiza and the Vertebrate Paleontology of Anguillean Caves". *El Boletín de la Sociedad Venezolana Espeleología*.

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