Glossotherium robustum
- 演化之聲
- Mar 11
- 2 min read
Updated: Mar 18
Age
Quaternary（Late Pleistocene）
0.129-0.0117 Ma
Taxonomy
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Pilosa
Family: Mylodontidae
Subfamily: Mylodontinae
Genus: Glossotherium
Species: Glossotherium robustum
Morphological description
The anterior portion of the maxilla in Glossotherium robustum is broad, producing an approximately triangular outline. The palate is likewise wide in its anterior region and gradually narrows posteriorly along the tooth row. The teeth are large, and the molariform teeth display pronounced lobulation, which constitutes an important diagnostic feature of this species. The anterior end of the mandible expands into a spatulate shape and is more inflated than in related taxa. This configuration provides powerful and stable chewing forces capable of processing tough grasses and coarse ground vegetation. The arrangement of the mandibular teeth corresponds to that of the upper dentition.
The cranial roof is relatively flat, and the occipital region possesses broad areas for muscular attachment, reflecting strong jaw function and well-developed neck musculature. The orbits are positioned laterally, and the zygomatic arches are robust. Endocasts of the braincase indicate that although the brain was proportionally modest in size, its internal organization was clearly differentiated, with distinct separation between the forebrain and midbrain regions.
Etymology
Genus name Glossotherium: from glosso- meaning "tongue", and -therium meaning "beast".
Species name robustum: meaning "strong" or "robust".
Biological description
Glossotherium robustum was a large ground sloth widely distributed across South America during the Pleistocene. Its geographic range extended roughly between 20° and 40° south latitude, including Argentina, Uruguay, Brazil, Bolivia, Chile, and Paraguay. These regions were dominated by temperate grasslands, open landscapes, and relatively dry environments.
Certain aspects of its lifestyle can be inferred from cranial and neurological features. The pronounced dorsal expansion of the olfactory bulbs suggests that the sense of smell was well developed, likely aiding the animal in locating food or detecting environmental chemical signals across open landscapes. The nasal cavity shows considerable dorsoventral expansion, which may have been related to thermoregulation, climate adaptation, or possibly vocalization mechanisms. The combination of large, strongly lobulated teeth and a shovel-shaped expansion at the anterior mandible indicates that this species functioned as a large herbivore specialized in processing coarse, fibrous vegetation, well suited to the high-abrasion diets typical of Pleistocene grasslands and sparse woodland-steppe environments.
（Author: Shui-Ye You）
References
Boscaini A et al. (2020). Digital Cranial Endocasts of the Extinct Sloth Glossotherium robustum (Xenarthra, Mylodontidae) from the Late Pleistocene of Argentina: Description and Comparison with the Extant Sloths. Journal of Mammalian Evolution.
Pitana VG et al. (2013). Cranial and dental studies of Glossotherium robustum (Owen, 1842) (Xenarthra: Pilosa: Mylodontidae) from the Pleistocene of southern Brazil. Alcheringa: An Australasian Journal of Palaeontology.
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