Glossotherium, OWEN, 1840

Mcafee, Robert K., 2009, Reassessment of the cranial characters of Glossotherium and Paramylodon (Mammalia: Xenarthra: Mylodontidae), Zoological Journal of the Linnean Society 155 (4), pp. 885-903 : 888-889

GENUS GLOSSOTHERIUM OWEN, 1840

Type species: Glossotherium robustum ( Owen, 1842)

Other species: Glossotherium chapadmalense ( Kraglievich, 1925) Robertson, 1976

Synonymy: Based on the cranial material studied, the following taxonomic names are considered to be junior synonyms of Glossotherium robustum :

Mylodon robustus Owen, 1842

Mylodon gracilis Burmeister, 1865

Pseudolestodon lettsomi Gervais & Ameghino, 1880 Pseudolestodon myloides Gervais & Ameghino, 1880 Pseudolestodon morenoii Gervais & Ameghino, 1880 Glossotherium wegneri Spillmann, 1931

Revised diagnosis

This South American mylodontid is distinguished from its closest relatives, Mylodon and Paramylodon , by the following characters:

Skull: Dental formula 5/5, with C1 always present; C1 length along long axis of tooth-row greater than 20 mm; M1 length shorter than in Paramylodon , and more similar to width of M1 and to length of M2; M2 triangular in section with well-defined posterior lobe in early forms that disappears in Pleistocene forms; M4 bilobate with posterior lobe narrower than anterior lobe, which is anteroposteriorly compressed; molariform tooth-row accounts for less than 80 per cent of the total tooth-row length; palatine length posterior to M4 less than 30 mm; ratio of palate length posterior to M4 versus total maxillary– palatine length less than 0.15; skull somewhat domeshaped in lateral profile; posterior skull higher between the postorbital processes than posteriorly; rostrum narrows posteriorly toward the lacrimals, and skull widens thereafter toward posterior portion; width of nasal cavity greater than height; ratio of lacrimal to postorbital width less than 1: 1, with postorbital processes greatly widened in later forms; pterygoid sinuses strongly inflated medially and narrowly spaced; parasagittal crest wide and temporal fossa less developed than in Paramylodon .

Mandible: Shorter than in Paramylodon , and condyle is lower in proportion to height of coronoid; anterior edge of coronoid process more curved along upward slope; predental spout wide, with lateral flare at anterior margins creating a pronounced concavity along lateral margins.

Distribution: Specimens are recorded from Chapadmalan – Lujanian (Pliocene–Pleistocene) localities throughout South America in Argentina, Bolivia, Brazil, Chile, Columbia, Ecuador, Paraguay, Peru, and Uruguay ( Cabrera, 1936; Cartelle & Fonseca, 1981; Figini et al., 1987; Esteban, 1996).

Referred specimens: See Appendix.