Hypsodont is a pattern of dentition characterized by with high crowns, providing extra material for wear and tear. Some examples of animals with hypsodont dentition are cattle and horses; all animals that feed on gritty, fibrous material. The opposite condition is called brachydont.
Evolution
Since the morphology of the hypsodont tooth is suited to a more abrasive diet, hypsodonty was thought to have evolved concurrently with the spread of grasslands. Grass contains phytoliths, silica-rich granules, which wear away dental tissue more quickly. Analysis has shown, however, that the development of this morphology is out of sync with the spread and flourishing of grasslands.
Instead, the ingestion of grit and soil is hypothesized to be the primary driver of hypsodonty, a hypothesis termed the grit, not grass hypothesis.
[Phillip E. Jardine, Christine M. Janis, Sarda Sahney, Michael J. Benton. “Grit not grass: Concordant patterns of early origin of hypsodonty in Great Plains ungulates and Glires.” Palaeogeography, Palaeoclimatology, Palaeoecology. December 2012:365–366, 1–10]
Morphology
Hypsodont dentition is characterized by:
[Flynn, John J., André R. Wyss, and Reynaldo Charrier. “South America’s Missing Mammals.” Scientific American. May 2007: 68-75.]
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high-crowned tooth
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A rough, flattish occlusal surface adapted for crushing and grinding
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Cementum both above and below the line
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Enamel which covers the entire length of the body and likewise extends past the gum line
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The cementum and the enamel Invagination into the thick layer of dentin
A mammal may have exclusively hypsodont molars or have a mix of dentitions.
Examples
Hypsodonty is observed both in the fossil record and the modern world. It is a characteristic of large clades (equids) as well as subspecies level specialization. For example, the Sumatran rhinoceros and the
Javan rhinoceros both have brachydont, lophodont cheek teeth whereas the Indian rhinoceros has hypsodont dentition.
Examples of extant animals with hypsodont dentition include:
At least two lineages of Allotheria, Taeniolabidoidea and Gondwanatheria, developed hypsodont teeth, the latter being probably among the first mammals to be able to process grass.[ Gondwanatheria]
See also
External links
