Paraceratherium

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Paraceratherium
Temporal range: Oligocene, 34–23Ma
Skeleton of Paraceratherium transouralicum
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Perissodactyla
Family: Hyracodontidae
Subfamily: Indricotheriinae
Borissiak, 1923
Genus: Paraceratherium
Forster Cooper, 1911
Species
  • P. bugtiense
  • P. transouralicum
  • P. prohorovi
  • P. orgosensis
  • P. zhajremensis
Synonyms
  • Baluchitherium Forster Cooper, 1913
  • Indricotherium Borissiak, 1916
  • Thaumastotherium Forster Cooper, 1913
  • Aralotherium Borissiak, 1939
  • Dzungariotherium Xu and Wang, 1973[1]

Paraceratherium, also commonly known as Indricotherium or Baluchitherium (see taxonomic discussion below), is an extinct genus of gigantic hornless rhinoceros-like mammals of the family Hyracodontidae, endemic to Eurasia and Asia during the Oligocene epoch.[2] It was first discovered in 1910 in Balochistan of what is now Pakistan, hence the name, during an expedition by the English paleontologist and Cambridge University Museum of Zoology director Sir Clive Forster Cooper.[3]

Description[edit]

Restoration

Paraceratherium is regarded as the largest land mammal known, with the largest species having an estimated mean adult mass of 11 t (12 tons)[4] and the largest individual known estimated at 4.8 m (16 ft) tall at the shoulders, 8.0 m (26.2 ft) in length from nose to rump, and 16 t (18 tons) in weight.[5]

Paraceratherium was a browsing herbivorous perissodactyl that stripped leaves from trees with its downward-pointing, tusk-like upper teeth that occluded forward-pointing lower teeth. It had a long, low, hornless skull and vaulted frontal and nasal bones. Its front teeth were reduced to a single pair of incisors in either jaw, but they were conical and so large that they looked like small tusks. The upper incisors pointed straight downwards, while the lower ones jutted outwards. The upper lip was evidently extremely mobile. The neck was very long, the trunk robust, and the limbs long and thick, column-like.

It lived in and browsed the forests of Central Asia between 34 and 23 million years ago.

Its type of dentition, its mobile upper lip and its long legs and neck indicate that it was a browser that lived on the leaves and twigs of trees and large shrubs.

Taxonomy[edit]

While more distinct at the species level, there is uncertainty and disagreement with regard to the genus level of taxonomy.

Paraceratherium was first described by Clive Forster Cooper in 1911. The genus Baluchitherium was first described by Forster Cooper in 1913. The genus Indricotherium was first described by Borissiak in 1915.

Baluchitherium is now widely regarded as a synonym of (i.e. the same as) either Paraceratherium or Indricotherium.

Old reconstruction of P. bugtiense
Skeletal restoration

However, there has been disagreement over whether Indricotherium is a distinct genus from Paraceratherium. Lucas and Sobus in their 1989 review of the subfamily Indricotheriinae (see reference below), argue for synonymy, and consider that the differences between the two are of species level at most, and may even be the result of sexual dimorphism in a single species, with the larger more robust Indricotherium with larger incisors being probably the male, and the more gracile Paraceratherium the female. Others,[who?] however, have expressed doubts about this (concerning the interpretation of the shape of the skull). Even if these two do turn out to be distinct genera, they would still be similar in size and appearance.

If they are considered the same genus, then Indricotherium would become a junior synonym of Paraceratherium, because, according to the priority principle of scientific classification, the first publication, and hence the oldest valid name, takes priority and the name Paraceratherium predates the other.

Here Lucas and Sobus are followed. They consider Indricotherium, Baluchitherium, Thaumastotherium Forster Cooper, 1913a, Aralotherium Borissiak, 1939, and Dzungariotherium Xu and Wang, 1973 all as junior synonyms of Paraceratherium.

Paraceratherium transouralicum skull

Lucas and Sobus recognise four valid species of Paraceratherium. One more (P. zhajremensis) has been tentatively added. The Paraceratherium species are:

Skull of Paraceratherium bugtiense.

Paraceratherium bugtiense (Forster Cooper, 1911) from the Oligocene of Pakistan is the type species of Paraceratherium. Baluchitherium osborni Forster Cooper, 1913a is a junior synonym. It was first found in the Chitarwata Formation of the Bugti Hills, Balochistan, after which it was originally named. New specimens of P. bugtiense were unearthed in the last decade by a French-Pakistani team (Antoine et al., 2004; Métais et al., 2009).

Paraceratherium transouralicum (Pavlova, 1922). Also known as Indricotherium transouralicum, this is the best known and most widespread species, known from the middle and late Oligocene of Kazakhstan, Mongolia, and Nei Monggol in northern China. Lucas and Sobus list the following species as synonyms: Baluchitherium grangeri Osborn, 1923, Indricotherium asiaticum Borissiak, 1923, Indricotherium minus Borissiak, 1923.

Paraceratherium orgosensis (Chiu, 1973) is the largest species, the teeth being at least a quarter again as big as P. transouralicum (see Lucas and Sobus p. 363/fig.19.2). It is known from the middle and late Oligocene of Xinjiang, northwest China. The three synonyms are Dzungariotherium orgosensis Chiu, 1973 and (each of the following named after a separate skull) Dzungariotherium turfanensis Xu & Wang, 1978 and Paraceratherium lipidus Xu & Wang, 1978. While there is some variation in details of the proportions of the skull (perhaps due to sexual dimorphism), all occur in a close geographical region and have distinct first and second upper molar crochets.

Paraceratherium prohorovi (Borissiak, 1939) from the late Oligocene or early Miocene of eastern Kazakhstan.

Paraceratherium zhajremensis (Osborn, 1923) from the Middle and late Oligocene of India.

Other remains referable to Paraceratherium or related taxa were found in Southeastern Europe and Asia Minor, notably in Turkey (Antoine et al., 2008).

In popular culture[edit]

Paraceratherium was the main focus in the third episode of the popular BBC documentary Walking with Beasts. In the programme the narrator always calls the creature an Indricothere, not a specific genus. In the accompanying book's information box about the animal, it states that the Indricothere is called Paraceratherium.

According to special effects creator Phil Tippett, Paraceratherium was the inspiration for the AT-AT walkers featured in the 1980 science-fiction film Star Wars: The Empire Strikes Back.[6]

References[edit]

  1. ^ Donald R. Prothero, Robert M. Schoch (1989). "The Systematics of Indricotheres". The Evolution of Perissodactyls. Oxford University Press. pp. 358–378. ISBN 0195060393. 
  2. ^ "Indricotherium: Age range and collections". Paleobiology Database. Retrieved 16 February 2013. 
  3. ^ Forster Cooper, Clive (1911). "Paraceratherium bugtiense, a new genus of Rhinocerotidae from the Bugti Hills of Baluchistan. Preliminary notice.". Ann. Mag. Nat. Hist. 8 (8): 711–716. 
  4. ^ Fortelius, Mikael; Jonh Keppelman (1993). "The largest land mammal ever imagined.". Zoological Journal of the Linnean Society (107): 85–101. 
  5. ^ Gregory S. Paul (1992). "The size and bulk of extinct giant land herbivores". Retrieved 16 February 2013. 
  6. ^ Angela Watercutter (24 May 2012). "35 Years After Star Wars, Effects Whiz Phil Tippett Is Slowly Crafting a Mad God". Wired. Retrieved 16 February 2013. 

Bibliography[edit]

External links[edit]