Deinotheriidae - Evolutionary History

Evolutionary History

The oldest known deinothere is Chilgatherium harrisi from the late Oligocene. Its fossil remains have been found in the district of Chilga in Ethiopia (hence the name). This indicates that, like other proboscideans, deinotheres evolved in Africa. Chilgatherium was quite small, about midway between a large pig and a small hippopotamus in size.

By the early Miocene, deinotheres had grown to the size of a small elephant, and had migrated to Eurasia. Several species are known, all belonging to the genus Prodeinotherium.

During the late middle Miocene these modest-seized proboscideans were replaced by much larger forms across Eurasia. In Europe, Prodeinotherium bavaricum appeared in the early Miocene mammal faunal zone MN 4, but was soon replaced by Deinotherium giganteum in the middle Miocene. Likewise in Asia, Prodeinotherium is known from the early Miocene strata in the Bugti Hills, and continued into the middle Miocene Chinji Formation, where it was replaced by Deinotherium indicum.

While these Miocene deinotheres were dispersed widely and evolved to huge elephant size, they were not as common as the contemporary (but smaller) euelephantoidea. Fossil remains of this age are known from the France, Germany, Greece, Malta, and northern India and Pakistan. These consist chiefly of teeth and the bones of the skull.

After the extinction of the indricotheres at the end of the early Miocene, the deinotheres were (and remained) the largest animals walking the Earth.

The late Miocene was the heyday of the giant deinotheres. D. giganteum was common from Vallesian and Turolian localities in Europe. Prodeinotherium, which was reasonably well represented in the early Miocene of Africa, was succeeded by D. bozasi at the beginning of the late Miocene. And in Asia, Deinotherium indicum was most common in the late Miocene Dhok Pathan Formation.

Fossil teeth of D. giganteum, from the late Miocene Sinap Formation at the Turkish site of Kayadibi are larger than those from older localities, such as Eppelsheim, Wissberg and Montredon, indicating a tendency for increasing size of members of the species over time. These were the biggest animals of their day, protected from both predators and rival herbivores by virtue of their huge bulk. Not until the Pleistocene would the largest mammoths approach them in size.

With the end of the Miocene, deinothere fortunes declined. Deinotherium indicum died out about 7 million years ago, possibly driven to extinction by the same process of climate change that had previously eliminated the even more enormous Indricotherium. While in Europe, Deinotherium giganteum continued, albeit with dwindling numbers, until the middle Pliocene; the most recent specimen is from Romania.

In its original African homeland, Deinotherium continued to flourish throughout the Pliocene, and fossils have been uncovered at several of the African sites where remains of hominids have also been found.

The last deinothere species to become extinct was Deinotherium bozasi. The youngest known specimens are from the Kanjera Formation, Kenya, about one million years ago (early Pleistocene). The causes of the extinction of such a successful and long-lived animal are not known, although a small number of other species of African megafauna also died out at this time.