Blunt-toothed giant hutia-Amblyrhiza inundata
Dec 16, 2014 2:03:00 GMT 5
Life and creature386 like this
Post by Infinity Blade on Dec 16, 2014 2:03:00 GMT 5
Blunt-toothed giant hutia-Amblyrhiza inundata
Amblyrhiza inundata. Painting by Dan Bruce->.
Temporal range: Quaternary (Pleistocene; ~500ka-123ka[1])
Scientific classification:
Life
Clade: Neomura
Domain: Eukarya
(unranked): Unikonta
(unranked): Opisthokonta
(unranked): Holozoa
(unranked): Filozoa
Kingdom: Animalia
Subkingdom: Eumetazoa
Clade: Bilateria
Clade: Nephrozoa
Superphylum: Deuterostomia
Phylum: Chordata
Subphylum: Cephalochordata
Clade: Craniata
Subphylum: Vertebrata
Infraphylum: Gnathostomata
Clade: Eugnathostomata
Clade: Teleostomi
Superclass: Tetrapoda
Clade: Reptiliomorpha
Clade: Amniota
Clade: Synapsida
Clade: Eupelycosauria
Clade: Sphenacodontia
Clade: Sphenacodontoidea
Clade/Order: Therapsida
Clade: Neotherapsida
Clade: Theriodontia
Clade: Eutheriodontia
Clade/Suborder: Cynodontia
Clade: Epicyonodontia
Infraorder: Eucynodontia
Clade: Probainognathia
Superfamily: Chiniquodontoidea
Clade: Prozostrodontia
Clade: Mammaliformes
Class: Mammalia
Subclass: Theria
Infraclass: Placentalia
Subcohort: Exafroplacentalia
Magnorder: Boreoeutheria
Superorder: Euarchontoglires
(unranked): Glires
Order: Rodentia
Suborder: Hystricomorpha
Infraorder: Hystricognathi
Parvorder: Caviomorpha
Superorder: Chinchilloidea
Family: †Heptaxodontidae
Genus: †Amblyrhiza
Species: †Amblyrhiza inundata
Amblyrhiza inundata, colloquially known as the blunt-toothed giant hutia[2], was a large species of caviomorph rodent that lived on the islands of Anguilla, St. Martin, and St. Barthélemy from about 500,000 to about 123,000 years ago.[1]
Phylogeny:
According to MacPhee (2011)’s review, Heptaxodontidae may not be a monophyletic grouping, and Amblyrhiza seems to emerge as a chinchilloid on the basis of basicranial features. Although Heptaxodontinae remains a monophyletic subfamily containing Elasmodontomys obliquus, Amblyrhiza turns out to not be particularly close to Elasmodontomys, and so cannot be considered a part of this subfamily.[3]
Description:
Amblyrhiza was a large rodent; body size estimates based off of 14 isolated (5 femoral, 9 humeral) adult or near adult specimens range from <50 kg to >200 kg. Mass estimates based off of humeral measurements are lower than those based off of femoral measurements. It seems that Amblyrhiza had elongated and gracile forelimbs in comparison to the seemingly disproportionately large head, trunk, and hindlimbs.[4]
Four possible explanations are given to explain the massive size variation in Amblyrhiza individuals: 1.) multiple coeval species (regarded as unlikely), 2.) heterochroneity (also not regarded as the likeliest explanation), 3.) limb heterogeneity (i.e. the gracile forelimbs in comparison to the massive hindlimbs), and 4.) sexual dimorphism. Further testing would seem to be required to determine which proposal is most likely.[4]
Ecology:
The evolutionary pressures leading to gigantism in Amblyrhiza do not appear to be well understood. It does not appear to have been a result of competition (for Amblyrhiza outweighed the largest endemic herbivores on Anguilla by several factors) or predation (no predators with a confirmed presence on Anguilla would have been capable of preying on Amblyrhiza).[4]
Empirical data and predictive equations suggest that the Anguilla bank islands could only have been inhabited by a few thousand Amblyrhiza at any given time during the late Quaternary.[4]
Extinction:
Decades of research have failed to uncover any Amblyrhiza specimens dating after the MIS5e (around 123,000 years ago). This supports suggestions that Amblyrhiza became extinct during the last interglacial period.[1]
References:
[1] McFarlane, D.A.; Lundberg, J.; Maincent, G. (2014). New specimens of Amblyrhiza inundata (Rodentia: Caviomorpha) from the Middle Pleistocene of Saint Barthélemy, French West Indies. Caribbean Journal of Earth Science, 47, 15-19. Geological Society of Jamaica.
[2] www.itis.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value=584891#null
[3] MacPhee, R.D.E. (2011). Basicranial Morphology and Relationships of Antillean Heptaxodontidae (Rodentia, Ctenohystrica, Caviomorpha). Bulletin of the American Museum of Natural History.
[4] Biknevicius, A.R.; McFarlane, D.A.; MacPhee, R.D.E. Body Size in Amblyrhiza inundata (Rodentia, Caviomorpha), and Extinct Megafaunal Rodent From the Anguilla Bank, West Indies: Estimates and Implications. American Museum Novitates.
Amblyrhiza inundata. Painting by Dan Bruce->.
Temporal range: Quaternary (Pleistocene; ~500ka-123ka[1])
Scientific classification:
Life
Clade: Neomura
Domain: Eukarya
(unranked): Unikonta
(unranked): Opisthokonta
(unranked): Holozoa
(unranked): Filozoa
Kingdom: Animalia
Subkingdom: Eumetazoa
Clade: Bilateria
Clade: Nephrozoa
Superphylum: Deuterostomia
Phylum: Chordata
Subphylum: Cephalochordata
Clade: Craniata
Subphylum: Vertebrata
Infraphylum: Gnathostomata
Clade: Eugnathostomata
Clade: Teleostomi
Superclass: Tetrapoda
Clade: Reptiliomorpha
Clade: Amniota
Clade: Synapsida
Clade: Eupelycosauria
Clade: Sphenacodontia
Clade: Sphenacodontoidea
Clade/Order: Therapsida
Clade: Neotherapsida
Clade: Theriodontia
Clade: Eutheriodontia
Clade/Suborder: Cynodontia
Clade: Epicyonodontia
Infraorder: Eucynodontia
Clade: Probainognathia
Superfamily: Chiniquodontoidea
Clade: Prozostrodontia
Clade: Mammaliformes
Class: Mammalia
Subclass: Theria
Infraclass: Placentalia
Subcohort: Exafroplacentalia
Magnorder: Boreoeutheria
Superorder: Euarchontoglires
(unranked): Glires
Order: Rodentia
Suborder: Hystricomorpha
Infraorder: Hystricognathi
Parvorder: Caviomorpha
Superorder: Chinchilloidea
Family: †Heptaxodontidae
Genus: †Amblyrhiza
Species: †Amblyrhiza inundata
Amblyrhiza inundata, colloquially known as the blunt-toothed giant hutia[2], was a large species of caviomorph rodent that lived on the islands of Anguilla, St. Martin, and St. Barthélemy from about 500,000 to about 123,000 years ago.[1]
Phylogeny:
According to MacPhee (2011)’s review, Heptaxodontidae may not be a monophyletic grouping, and Amblyrhiza seems to emerge as a chinchilloid on the basis of basicranial features. Although Heptaxodontinae remains a monophyletic subfamily containing Elasmodontomys obliquus, Amblyrhiza turns out to not be particularly close to Elasmodontomys, and so cannot be considered a part of this subfamily.[3]
Description:
Amblyrhiza was a large rodent; body size estimates based off of 14 isolated (5 femoral, 9 humeral) adult or near adult specimens range from <50 kg to >200 kg. Mass estimates based off of humeral measurements are lower than those based off of femoral measurements. It seems that Amblyrhiza had elongated and gracile forelimbs in comparison to the seemingly disproportionately large head, trunk, and hindlimbs.[4]
Four possible explanations are given to explain the massive size variation in Amblyrhiza individuals: 1.) multiple coeval species (regarded as unlikely), 2.) heterochroneity (also not regarded as the likeliest explanation), 3.) limb heterogeneity (i.e. the gracile forelimbs in comparison to the massive hindlimbs), and 4.) sexual dimorphism. Further testing would seem to be required to determine which proposal is most likely.[4]
Ecology:
The evolutionary pressures leading to gigantism in Amblyrhiza do not appear to be well understood. It does not appear to have been a result of competition (for Amblyrhiza outweighed the largest endemic herbivores on Anguilla by several factors) or predation (no predators with a confirmed presence on Anguilla would have been capable of preying on Amblyrhiza).[4]
Empirical data and predictive equations suggest that the Anguilla bank islands could only have been inhabited by a few thousand Amblyrhiza at any given time during the late Quaternary.[4]
Extinction:
Decades of research have failed to uncover any Amblyrhiza specimens dating after the MIS5e (around 123,000 years ago). This supports suggestions that Amblyrhiza became extinct during the last interglacial period.[1]
References:
[1] McFarlane, D.A.; Lundberg, J.; Maincent, G. (2014). New specimens of Amblyrhiza inundata (Rodentia: Caviomorpha) from the Middle Pleistocene of Saint Barthélemy, French West Indies. Caribbean Journal of Earth Science, 47, 15-19. Geological Society of Jamaica.
[2] www.itis.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value=584891#null
[3] MacPhee, R.D.E. (2011). Basicranial Morphology and Relationships of Antillean Heptaxodontidae (Rodentia, Ctenohystrica, Caviomorpha). Bulletin of the American Museum of Natural History.
[4] Biknevicius, A.R.; McFarlane, D.A.; MacPhee, R.D.E. Body Size in Amblyrhiza inundata (Rodentia, Caviomorpha), and Extinct Megafaunal Rodent From the Anguilla Bank, West Indies: Estimates and Implications. American Museum Novitates.
