Palaeomastodon ("ancient mastodon") is an extinct genus within the elephant order Proboscidea. Its fossils have been extracted from Oligocene strata conventionally dated to 33.9-23.03 million years old. Usually considered an ancestor or near-ancestor of elephants or mastodons as a member of Elephantiformes[1] it lived in marshes and fluvial-deltaic environments of what is now Egypt, Ethiopia, Libya, and Saudi Arabia.
| Palaeomastodon Temporal range: Oligocene,
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| P. beadnelli skull | |
Scientific classification 
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| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Mammalia |
| Order: | Proboscidea |
| Family: | †Palaeomastodontidae |
| Genus: | †Palaeomastodon Andrews, 1901 |
| Type species | |
| †Palaeomastodon beadnelli Andrews, 1901
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| Species | |
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Few postcranial remains are known. However, based on the reported 875 mm length of one P. beadnelli femur, a 2016 study estimated an adult shoulder height of about 2.2 metres (7.2 ft) with a mass over 2.5 tonnes (2.8 short tons).[2]
Palaeomastodonts possessed both maxillary and mandibular tusks. The mandibular tusks projected anteriorly and were generally flat and scoop-like. They were probably used to scrape the bark off trees and uproot various plants. By contrast, the sharp maxillary tusks primarily functioned as defensive weapons.[3] Unlike later proboscideans belonging to Elephantimorpha, the teeth erupted vertically rather than horizontally, as shared with other "paleomastodonts" like Phiomia.[4]
The form, size, and capabilities of palaeomastodont nasal structures have long been debated. Though often depicted with a relatively small, prehensile proboscis, Osborn 1909 argued that wear patterns on the lower tusks better favored the presence of a large, retractile upper lip.
References
edit- ^ The genus Palaeomastodon Archived 2008-10-17 at the Wayback Machine
- ^ Larramendi, A. (2016). "Shoulder height, body mass and shape of proboscideans" (PDF). Acta Palaeontologica Polonica. 61. doi:10.4202/app.00136.2014.
- ^ Osborn, H. F. (1909). "The Feeding Habits of Mœritherium and Palæomastodon". Nature. 81 (2074): 139–140. Bibcode:1909Natur..81..139O. doi:10.1038/081139a0.
- ^ Sanders, William J. (2018-02-17). "Horizontal tooth displacement and premolar occurrence in elephants and other elephantiform proboscideans". Historical Biology. 30 (1–2): 137–156. Bibcode:2018HBio...30..137S. doi:10.1080/08912963.2017.1297436. ISSN 0891-2963.
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