Mastodon

The Mastodon animals, (genus Mammut), were a group of several extinct elephantine mammals that belonged to the family Mammutidae and appeared for the first time in the early Miocene period (23 million to 2.6 million years ago) and continued to live in various forms throughout the Pleistocene Epoch period (from 2.6 million to 11,700 years ago). In North America, this group of mastodon elephants might have persisted into post-Pleistocene time and were thus found to be contemporaneous with the Paleo-Indian groups. The Mastodon elephants were distributed worldwide and their remains are quite common which are often very well preserved. 

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A common characteristic of these mastodons was that these mammals were often found to feed on leaves, and had distinct grinding teeth. Mastodons were heavily built and were shorter than modern elephants. Although their skull was much lower and flatter and was generally of simpler construction than that of the modern elephants, the mastodon mammals were found to be similar in appearance to the modern elephants. 

This article will provide you with information about the ancient mastodon and their physical characteristics.

The ancient group of Mastodon mammals belonged to the family Mammutidae and were known to have five different species. Given below is a table that provides the general scientific classification of the extinct Mastodon elephants.

Scientific Classification of Mastodon

M. americanum, also commonly known as the American mastodon and M. pacificus, the Pacific mastodon were considered to be the youngest and best-known species of the genus Mammut. 

How Did the Mastodon Elephants Evolve?

Belonging to the genus Mammuth, the entire mastodon range is believed to have diverged from the proboscidean family Elephantidae (mammoths and elephants) about 27 million years ago. Over the years, several fossils of Mastodons were collected from North America, Africa and Asia which were attributed to Mammut. But among them, only the remains collected from North America were named and described, one of them being M. furlongi, whose remains were found in the Juntura Formation of Oregon belonging to the late Miocene period. However, this species is considered no longer to be valid, leaving only five valid species belonging to the family Mammutidae and Genus Mammuth.

• M. americanum, also known as the American mastodon, is considered one of the best known and among the last species of the genus Mammut. The earliest occurrences of this species date back to the early-middle Pliocene period. Initially, they were regarded to have a continent-wide distribution, mainly during the Pleistocene epoch. This information was gathered from the fossil sites that ranged from present-day Alaska, Ontario and New England in the north, to Florida, Southern California, and Honduras in the south. The American mastodon species were initially thought to have resembled a woolly mammoth in appearance but considering their long tail (which was usually found in animals inhabiting warm climates) along with its size, body mass and environment it was concluded that the mastodon animal was not similarly hairy to a woolly mammoth and instead belonged to a semi-aquatic lifestyle). It also had tusks that were more than 5 m (16 ft) in length and were curved upwards.

• M. Matthewi:  This species of Mastodon were found in the Snake Creek Formation of Nebraska which dates back to the late Hemphillian period. Some authors have also found this species to be similar to M. americanum, although there is only one report of it in China.

• M. pacificus also commonly known as the Pacific mastodon were found to consist of the Pleistocene specimens from California and southern Idaho which were transferred from the American mastodon elephants to this new M.pacificus species. It differed from the eastern population and had narrower molars, a thicker femur and lacked the mandibular tusks.

• M. Raki: The remains of this particular species were found in the Palomas Formation, near New Mexico, which dates back to the early-middle Pliocene period. They were known to have coexisted with Equus simplicidens and Gigantocamelus and differed from the M. americanum species as they had a relatively longer and narrower third molar.

• The occurrence of M. cosoensis species dates back to the Late Pliocene period and was found in the Coso Formation of California. They were originally considered to be a species of Pliomastodon but were later placed under the genus Mammut.

General Characteristics of Mastodon

Some of the general characteristic features of Mastodon are as follows:

1. They all consisted of long and prominent upper tusks that grew parallel to each other and had an upward curvature. The male mastodons also had short lower tusks which were absent in the females.

2. The ears were comparatively smaller and were not much prominent as compared to those of the modern elephants. 

3. They had a relatively long body, and the legs were short, massive, and pillarlike. The Mastodon mammals were found to be covered with long reddish-brown hairs.

4. They are low-crowned, large, and strongly rooted, with as many as four prominent ridges separated by deep troughs.

5. The teeth are much smaller and smaller compared to those of the true elephants. 

6. It is assumed that the constant mortality caused by rapid changes in climate combined with several human hunting pressures resulted in the extinction of these species. 

As per the DNA studies conducted upon the North American mastodon (Mammut americanum), it has been concluded that the genetic diversity of mastodons declined as the conditions warmed, resulting in a retreat of the continental ice sheets and the animal’s geographic range.

Ancient Mastodon - What Did They Eat?

The ancient Mastodons were known to survive as predominantly browsing animals and were often found to remain more consistent in browsing rather than grazing. They relied mostly on consuming C3 plants, and largely occupied closed forests rather than open habitats.

This dietary inflexibility in these mastodon elephants also might have prevented them from invading South America during the Great American Interchange, due to the need to cross areas of grassland to do so. 

Various studies on mastodon teeth have stated the presence of microwear patterns in it, indicating that these species were able to adjust their diet as per the changing ecosystem. It also indicates that they had regionally specific feeding patterns corresponding to the boreal forest versus cypress swamps, while a population at a given location was sometimes able to maintain its dietary niche through changes in climate and browse species availability.

Distribution and Habitat

The distribution and habitats of the ancient mastodon range are mostly unknown as their occurrences were restricted to a few localities, except the American mastodon (M. americanum). This particular species of Mastodon mammals was considered one of the most widely distributed Pleistocene proboscideans in North America. The fossil sites of M. americanum range in time starting from the Blancan to Rancholabrean faunal stages and are found in locations ranging from Alaska, Florida, and the state of Puebla in central Mexico. 

A few isolated reports were found stating mastodons being found along the east coast up to the New England region, with high concentrations in the Mid-Atlantic region. There is also a piece of strong evidence indicating that these Mastodon mammals were forest-dwelling proboscideans, predominating in woodlands and forests, and were mostly found browsing on trees and shrubs. They apparently did not disperse southward to South America, as it is assumed that this was because of a dietary specialization on a particular type of vegetation. 

Extinction of the Mastodon Elephants

Fossil evidence indicates that the mastodons probably disappeared as part of the mass extinction of most of the Pleistocene megafauna from North America.  These animals faced extinction about 10,500 years ago and are widely believed to have succumbed to human hunting pressure leading to mass extinction. The latest Paleo-Indians, who entered the Americas and expanded to relatively large numbers 13,000 years ago are believed to have caused gradual attrition of the mastodon population by their hunting. Various analysis of the mastodon tusks from the American Great Lakes region shows a trend of declining age at maturation. 

These analyses were conducted over a span of several thousand years prior to their extinction and were found contrary to the assumptions related to their extinction which stated that they were experiencing stresses from an unfavourable environment. But this analysis is consistent with a reduction in intraspecific competition that would result from a population being reduced by human hunting. On the other hand, studies based on environmental DNA sequencing indicated that the disappearance of megafaunal DNA in North America correlated in time with major changes in plant DNA, suggesting a key role of climate change.