Deinotherium is an extinct genus of large, elephant-like proboscideans that lived from the Middle Miocene until the end of the Early Pleistocene. Although its appearance is reminiscent of modern elephants, Deinotherium differered considerably from modern elephants in several anatomical details: it possessed a notably more flexible neck, proportionally more slender limbs, tapir-like teeth, as well as tusks which grew down and curved back from the lower jaw (mandible), and lacked tusks growing from the upper jaw. Several species of Deinotherium grew larger than modern elephants, not uncommonly reaching shoulder heights of and body masses of , making them among the largest land mammals ever. Deinotherium was a widespread genus: during the Miocene they ranged across East Africa, and Eurasia from Western Europe to the Indian subcontinent. They were browsing animals, with a diet largely consisting of leaves. The genus most likely went extinct due to environmental changes, such as forested areas gradually being replaced by open grasslands, during the latter half of the Neogene. Deinotherium thrived the longest in Africa, where they survived until the end of the Early Pleistocene, around 1 million years ago.
History and naming In 1613, a gravestone engraved with the name "Theutobochus Rex" was reputedly excavated from a sand pit in the vicinity of Langon, near Montrigaud in southeast France, also reputedly alongside enormous bones, and silver coins depicting the Roman Republic leader Gaius Marius, who had defeated the Germanic king Teutobod (who by the 17th century was often mythologised as a giant) and his army in southern France around 100 BC. A French surgeon named Mazurier exhibited these relics across France, and for some time they were located in apartments owned by Queen of France Marie de' Medici. However, the veracity of the story was quickly questioned and subject to much controversy, with a long-running dispute via an exchange of pamphlets between the University of Paris surgeon Nicholas Habicot, who argued for a giant identity, and botany student and anatomist Jean Riolan who argued based on comparative anatomy that the bones represented some kind of large animal (in Riolan's opinion likely an elephant), and that the supposed discovery was either mistaken or a fraud.
21 years later in 1634, French polymath Nicolas-Claude Fabri de Peiresc asked the physician Nivolet to investigate the site and the relics (except the tombstone, which was now missing). Following the details of a report that Nivolet sent to him Peiresc concluded that the story was a hoax (based on the fact that the coins were actually from Massalia and did not depict Marius, and that it was unlikely a Germanic leader would have a gravestone written in Latin which he and his people did not speak) and later after another discovery of another supposed giant within the vicinity of Montrigaud, like Riolan concluded the remains represented those of an elephant. The bones were eventually handed over to the French National Museum of Natural History, and were centuries later recognised as belonging to Deinotherium.In 1715, French scholar René de Réaumur investigated turquoise mines in southern France, and realised that the ores used were not rocks like those from turquoise mines from the Middle East, but were blue-green stained fossilised teeth. In his memoir he included a plate with an image of one of these teeth, which was later recognised as being the earliest depiction of a Deinotherium tooth. Other confirmed and probable Deinotherium remains including lower jaws, teeth and ivory fragments, were reported from across France from the 1750s to the 1780s, including a lower jaw with teeth broken into two halves found near Beinc in Haute-Garonne, southwest France in 1783. In 1822, based on the similarity of the teeth to those of tapirs, Georges Cuvier, widely regarded as the father of vertebrate paleontology, gave the name "Tapirs gigantesques" to the remains, primarily based on the Bienc jaw, concluding that they belong to giant elephant-sized tapir relatives.
The genus Deinotherium and the species D. giganteum was coined in 1829 by German paleontologist Johann Jakob von Kaup based on a complete but broken mandible (lower jaw) discovered in sands near Eppelsheim, southwest Germany. Kaup originally incorrectly reconstructed the jaw's tusks as being upward facing, but corrected this several years later. A second species D. bavaricum was named in 1831 by German paleontologist Christian Erich Hermann von Meyer based on remains found in Bavaria, which von Meyer regarded as comparable to rhinoceroses, but is now recognised to belong to the separate deinotheriid genus Prodeinotherium. In 1834 French paleontologist Édouard Lartet studied additional remains of Deinotherium that had been recovered in France. In 1836, Kaup's friend August von Klipstein found a skull of Deinotherium also within the Eppelsheim area, which was later in 1837 exhibited in France.The fragmentary and unusual nature of known Deithotherium remains sparked much speculation as to its appearance and relationships with other animals. French anatomist Henri Marie Ducrotay de Blainville in an 1837 paper regarded Deinotherium as being closely related to sirenians (manatees and dugongs), though this view was contested by other scholars. While Kaup originally assumed that Deinotherium had large, armadillo or anteater-like claws based on erroneously interpreting a large ungual claw (later recognised as belonging to a chalicothere) found near the Epplesheim jaw as belonging to Deinotherium, by 1837 he came to regard Deinotherium as a "pachyderm" (an obsolete zoological term to describe large terrestrial mammals with thick skin, such as elephants, hippos and rhinoceroses). French zoologist Hercule Eugène Straus-Dürckheim in an 1837 publication assumed that the head was too heavy to have belonged to a terrestrial animal and argued that Deinotherium was a marine mammal intermediate between cetaceans (whales, dolphins, etc) and pachyderms. An aquatic ecology was also supported by British paleontologist William Buckland in an 1838 publication, who also suggested that it used its tusks to cling to river banks and was a burrowing animal.
Later finds of Deinotherium remains at various localities in France in the 1840s and 1850s clarified its anatomy, which by 1859 had led it to be widely accepted for Deinotherium to be placed within the Proboscidea (the broader group which contains elephants and their extinct relatives), and finds in India described as D. indicum extended the range of the genus outside of Europe. Fossils of an exceptionally large specimen found in Manzati, Romania between the late 19th and early 20th century were described as D. gigantissimum. In Bulgaria Deinotherium remains have been found from 1897 onward, with one particular fossil of an almost complete animal found in 1965. These remains were officially described in December 2006 as D. thraceiensis, making it the most recently named species, although later studies synonymize it with the other European species.
The name Deinotherium is derived from Ancient Greek , (), meaning "terrible", and (), meaning "beast". Some authors have on occasion referred to Deinotherium as Dinotherium, following latinization of the first element of the name. Although pronunciation remains unchanged, Deinotherium remains the valid spelling as it was coined first.
Description
Deinotherium is mainly distinguished from its ancestor Prodeinotherium by its considerably larger size. Deinotherium was a large-bodied proboscidean, with some species considerably exceeding modern elephants in size. Two adult males of D. giganteum were around tall at the shoulder and weighed . This is similar to adult males of D. proavum, one of which weighed and was tall at the shoulder. The average male and female D. proavum has been estimated to have had a shoulder height of and a weight of . However, both these species are smaller than a 45-year-old male of D. "thraceiensis", at tall at the shoulder and . The most recent species, D. bozasi, was around tall at the shoulder and weighed . The general anatomy of Deinotherium is similar to that of modern elephants with pillar-like limbs, although proportionally longer and more slender than those of other proboscideans. The bones of the toes are longer and less robust than in elephants and the neck likewise differs notably in that it is relatively longer, though still quite short compared to other modern browsers like giraffes.
The permanent tooth formula of D. giganteum was (deciduous ), with vertical cheek tooth replacement as is typical for mammals, as opposed to the horizontal tooth cheek tooth replacement exhibited by elephantimorph proboscideans. Two sets of bilophodont (two-ridged) and trilophodont (three-ridged) teeth were present. The molars and rear premolars were vertical shearing teeth, and suggest that deinotheres became an independent evolutionary branch very early on; the other premolars were used for crushing. The cranium was short, low, and flattened on the top, in contrast to more advanced proboscideans, which have a higher and more domed forehead, with very large, elevated occipital condyles. The largest skulls of Deinotherium reached a length of . The nasal opening was retracted and large, indicating a large trunk. The rostrum was long and the rostral fossa broad. The mandibular symphysis (the fused frontmost-part of the lower jaw) were very long and curved downward, which along with the backward-curved tusks, are a distinguishing feature of the group.
These tusks are without doubt the most immediately noticeable feature of Deinotherium. Unlike in modern proboscideans, which possess tusks that grow from the upper incisors, the tusks of Deinotherium grow from the lower incisors, with upper incisors and upper and lower canines missing entirely. The curvature is initially formed by the mandible itself, with the teeth themselves erupting at only the halfway point of the curve. The degree to which the tusks follow the direction predetermined by the mandible varies between specimens, with some tusks following the curve and pointing backwards, forming an almost semicircular shape, while in other specimens the tusks continue down almost vertically. The tusks have a roughly oval cross-section and could reach a length of .
Although the presence of an elephant-like proboscis or trunk in Deinotherium is evident thanks to the size and shape of the external nares, the exact shape and size of this trunk is a matter that has long been debated. Historic depictions commonly portray it as very elephantine with a long trunk and tusks breaking through the skin below an elephantine lower lip. In the early 2000s Markov and colleagues published papers on the facial soft tissue of Deinotherium contesting these ideas, instead suggesting an alternative soft tissue reconstruction. In the first of these publications the authors argue that, due to the origin of these animal's tusks, the lower lip should be situated beneath them as they evolved their classic downturned appearance. They further suggest that, while a trunk would be present, it would likely not resemble that of modern elephants and instead be more robust and muscular, which they reason is evidenced by the lack of a proper insertion surface. Although later research concurs that the trunk or proboscis of Deinotherium was likely notably different from those of modern proboscideans, the idea of a short tapir-like trunk is questioned. In particular, it is pointed out that the tall stature and still relatively short neck of Deinotherium would render it very difficult for the animal to drink without assuming a more complex posture. Thus it is suggested that the trunk must have been at least long enough for the animal to effectively drink.
Species