Metopotoxus
From Wikipedia, the free encyclopedia
| Metopotoxus Temporal range: Santacrucian ~ | |
|---|---|
 | |
| YMP PU 15612, the type specimen (a skull) of M. anceps, from various angles | |
Scientific classification  | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Mammalia |
| Order: | Cingulata |
| Family: | Chlamyphoridae |
| Subfamily: | †Glyptodontinae |
| Genus: | †Metopotoxus Ameghino, 1898 |
| Type species | |
| †Metopotoxus laevatus (Ameghino, 1889) | |
| Species | |
Metopotoxus is a dubious extinct genus of glyptodont known from the Early Miocene (Santacrucian) of Patagonia, Argentina. Two species of Metopotoxus have been described, M. laevatus and M. anceps, both from the Santa Cruz Formation.
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Florentino Ameghino named several new glyptodont genera and species in 1889,[1] based on fossils recovered in the Santacrucian-age[2] Santa Cruz Formation in Patagonia. Among these were the species Asterostemma laevata. The fossil material assigned to this species included plates from the carapace and head shield, as well as two fragments of skulls which preserved some of the upper dentition.[1] In 1891, Alcides Mercerat reassigned A. laevata to the genus Propalaehoplophorus (as P. laevatus) and in 1894, Richard Lydekker considered the fossils to be referrable to the species P. australis.[1]
Ameghino maintained the validity of the species and erected a new genus in 1898, Metopotoxus, with M. laevatus as the type and only species.[1][3] In 1903, William Berryman Scott reviewed the various glyptodonts from the Santa Cruz Formation and considered Metopotoxus to be sufficiently distinguishable to be considered a valid genus.[1] Scott also named a second species of Metopotoxus, M. anceps, based on a skull without a mandible and four cervical vertebrae.[1] Scott suggested that M. anceps was slightly earlier in age than M. laevatus, though a difference in date could not be determined for certain, and that the genus was ancestral to the later glyptodont Panochthus.[1]
The fossil material assigned to Metopotoxus has not been reviewed or revised since Scott's 1903 study.[4] The validity of the genus has been questioned by several scholars since the mid-20th century.[5] Metopotoxus is sometimes used only with quotation marks, e.g. as "Metopotoxus".[4] In 2012, Sergio F. Vizcaíno, Juan C. Fernicola, and M. Susana Bargo suggested that Metopotoxus could be synonymous with Cochlops,[2] though Cochlops is also in need of revision.[4]
