Mammutidae

Mammutidae is an extinct family of proboscideans belonging to Elephantimorpha. It is best known for the mastodons (genus Mammut), which inhabited North America from the Late Miocene (around 8 million years ago) until their extinction at the beginning of the Holocene, around 11,000 years ago. The earliest fossils of the group are known from the Late Oligocene of Africa, around 24 million years ago, and fossils of the group have also been found across Eurasia. The name "mastodon" derives from Greek, {{#invoke:Lang|lang}} "nipple" and {{#invoke:Lang|lang}} "tooth", referring to their characteristic teeth.

Description

Mammutids are characterised by their zygodont molars, where pairs of parallel cusps are merged into sharp-sided riges, which are morphologically conservative and differ little between mammutid species.<ref name=":0" /> Like other members of Elephantimorpha, mammutids exhibited horizontal tooth replacement like modern elephants. Some authors have argued that horizontal tooth replacement evolved in parallel in mammutids and members of Elephantida (which includes gomphotheres and elephants), though this is uncertain.<ref>Template:Cite journal</ref> Compared to modern elephants, the bones of most mammutids were more robust, with the limb bones in particular being massive,<ref name=":0" /> with the legs being proportionally shorter than living elephants, while their bodies were proportionally more elongate.<ref name=":7" /> Early members of the group like Eozygodon and Zygolophodon had elongate mandibular symphysis (the front-most part) of the lower jaws with lower incisors/tusks (which tend to be flattened and narrow in shape<ref name=":7">Template:Cite journal</ref>), while in later representatives like Sinomammut and Mammut, the lower incisors/tusks were either lost or only vestigially present, and the lower jaws shortened (brevirostrine). This process happened convergently amongst other elephantimorph proboscideans, including gomphotheres, stegodontids, and elephantids.<ref name="Mothe16">Template:Cite journal</ref><ref>Template:Cite journal</ref> Mammutids are thought to have had prehensile trunks like those of living elephants, with those of Mammut suggested to have been possibly long enough to reach the ground.<ref name=":7" /> The upper tusks in primitive mammutids are relatively small as well as being downward (ventrally) and outward (laterally) curving, while those of mastodons (Mammut) are large and upward curving, often reaching around Template:Convert in length.<ref name=":7" /> The mammutid "Mammut" borsoni is one of the largest of all proboscideans with an estimated average male body weight of Template:Convert making it one of the largest land mammals of all time,<ref name="proboscideans">Template:Cite journal</ref> with the tusks of this species being the longest known of any animal, reaching over Template:Convert in length.<ref>Template:Cite journal</ref>

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Ecology

Members of Mammutidae are thought to have been primarily browsers on the foliage and twigs of trees and shrubs.<ref>Template:Cite journal</ref><ref>Template:Cite journal</ref><ref name=":15">Template:Cite journal</ref> The jaws of mammutids are adapted to powerful vertical biting (orthal movement) that served to crush food items and to a considerably lesser extent grind it with side-to side movement.<ref name=":7" /> Analysis of American mastodon (Mammut americanum) remains suggests that mammutids had a similar social structure to modern elephants, with herds of adult females and juveniles, with adult males living solitarily or in bonding groups with other males,<ref name="buesching">Template:Cite journal</ref><ref name="Haynes">Template:Cite journal</ref> with adult males periodically engaging in musth-like fighting behaviour against other males.<ref name="buesching" />

Evolution

Mammutids are the most basal group within Elephantimorpha, with gomphotheres and other members of Elephantida like amebelodonts being more closely related to elephants.<ref>Template:Cite journal</ref><ref name="Baleka et al. 2021">Template:Cite journal</ref> Cladogram after Li et al. (2024).<ref>Template:Cite journal</ref> Template:Clade Mammutids originated in Africa during the Late Oligocene, with the oldest genus Losodokodon dating to around 27.5-24 million years ago.<ref>Template:Cite book</ref> Mammutids belonging to the genus Zygolophodon (as well as possibly other mammutid genera) entered Eurasia across the "Gomphotherium land bridge" during the early Miocene, around 18 million years ago. Mammutid remains are generally rare in Eurasia in comparison to contemporary gomphotheres and deinotheres.<ref name=":0" /> During the late early Miocene, around 16.5 million years ago,<ref name=":3">Koenigswald, Widga & Göhlich (2021): New mammutids (Proboscidea) from the Clarendonian and Hemphillian of Oregon – a survey of Mio-Pliocene mammutids from North America</ref> a population of Zygolophodon entered North America, giving rise to Mammut.<ref name=":0" /> The youngest confirmed records of mammutids in Africa date to around 13 million years ago, though possible Late Miocene fossils have been reported from North Africa.<ref>Pickford, M. 2007. New mammutid proboscidean teeth from the middle Miocene of tropical and southern Africa. Palaeontologia Africana 42: 29–35.</ref> At the beginning of the Pleistocene, around 2 to 2.5 million years ago, the last of the Eurasian mammutids, "Mammut" borsoni became extinct, with members of Mammut persisting in North America until the end of the Pleistocene, approximately 11,000 years ago.<ref name=":0">Template:Cite journal</ref>