Paraceratherium

Taxobox
name = "Paraceratherium"
fossil_range = middle Oligocene to early Miocene


image_width = 250px
image_caption = "Paraceratherium" by Charles R. Knight
regnum = Animalia
phylum = Chordata
classis = Mammalia
ordo = Perissodactyla
familia = †Hyracodontidae
subfamilia = †Indricotheriinae
subfamilia_authority = Borissiak, 1923
genus = †"Paraceratherium"
genus_authority = Forster Cooper, 1911
subdivision_ranks = Species
subdivision =
*"P. bugtiense"
*"P. orgosense"
*"P. prohorovi"
*"P. transouralicum"
*"P. zhajremensis"
synonyms=
*"Baluchitherium" Forster Cooper, 1913
*"Indricotherium" Borissiak, 1916
*"Thaumastotherium" Forster Cooper, 1913
*"Aralotherium" Borissiak, 1939
*"Dzungariotherium" Xu and Wang, 1973 [Lucas & Sorbus (1989).]

"Paraceratherium", also commonly known as "Indricotherium" or "Baluchitherium" or just "Indricothere" (see taxonomic discussion below), is an extinct genus of gigantic hornless rhinoceros-like mammals, belonging to the family of the Hyracodontidae. Their fossils have been found in many parts of Asia, including Kazakhstan, Pakistan, India, Mongolia, and China. It lived from the middle Oligocene to the early Miocene, roughly from 30 to 20 million years ago, when this region of Asia was covered in lush subtropical forests and woodlands.

"Paraceratherium" is the largest land mammal known, probably even larger than the largest species of mammoths, though the largest species of mammoth, such as the steppe mammoth ("Mammuthus trogontherii") may have approached it in size and weight. Adult "Paraceratherum" are estimated to have been 5 - 5.5 m (18 ft) tall at the shoulder, over 8 m (27-28 ft) in length without the tail, a maximum raised head height of about 7.5 m (24-25 ft), and a skull length of 1.35 m (4.5 ft). Different weight estimates vary greatly, but most realistic and reliable weight estimates are from over 10 up to about 20 (metric) tons.Fact|2008|date=July 2008. This puts it in the weight range of some medium sized sauropod dinosaurs.

It was a herbivore that stripped leaves from trees with its down-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 evidentlyFact|date=August 2008 extremely mobile. The neck was very long, the trunk robust, and the limbs long and thick, column-like.

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 and species of "Paraceratherium"

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 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".

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, 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".

Lucas and Sobus recognise four valid species of "Paraceratherium". One more (P. zhajremensis) has been tentatively added. The "Paraceratherium" species are: "Paraceratherium bugtiense" (Pilgrim, 1908) from the early Miocene 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.

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

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

"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" means "near horn animal" in old Greek, indicating the fact that is was hornless, but related to the rhinoceroses.

"Indricotherium" is named after a mythical Russian beast called the Indrik-Beast, considered the most powerful creature and the father of the animals.

"Baluchitherium" means "beast of Baluchistan", as it was first discovered in Baluchistan, western Province of Pakistan.

Baluchitherium in Literature

In Science Fiction/Fantasy author Piers Anthony's book Balook, a young boy befriends a genetics project named Balook, who is a reconstructed Baluchitherium born in a laboratory through gene manipulation.

External links

* [http://dsc.discovery.com/convergence/beasts/photo/photo2/slide_05.html Indricotherium]
* [http://dsc.discovery.com/convergence/beasts/know/fortelius.html Discovery Channel - Answers from Dr. Mikael Fortelius]
* [http://www.fmnh.helsinki.fi/users/haaramo/Metazoa/Deuterostoma/Chordata/Synapsida/Eutheria/Perissodactyla/Hyracodontidae/Indricotheriinae.htm Hyracodontidae: Indricotheriinae] and [http://www.fmnh.helsinki.fi/users/haaramo/Metazoa/Deuterostoma/Chordata/Synapsida/Eutheria/Perissodactyla/Hyracodontidae/Synonyms_of_Paraceratherium.htm Synonyms of Paraceratherium transouralicum] - Mikko's Phylogeny Archive - follows Lucas and Sorbus
* [http://groups.google.com/group/sci.bio.paleontology/browse_thread/thread/ed7f9819563b739d/14a0dfbf0982f0d7?q=indricotherium+paraceratherium&rnum=3&hl=en#14a0dfbf0982f0d7 sci.bio.paleontology newsgroup ] 20 July 1999

References

* Lucas, S. G. & Sobus, J. C., (1989), The Systematics of Indricotheres. 358-378 in Prothero, D. R. & Schoch, R. M., (eds.) 1989: "The Evolution of Perissodactyls", Oxford University Press, New York, New York & Oxford, England, ix-537 - argues that "Indricotherium" should be included under "Paraceratherium"