Gaindatherium

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Gaindatherium
Temporal occurrence
Middle to Upper Miocene
15.97 to 5.333 million years
Locations
Systematics
Higher mammals (Eutheria)
Laurasiatheria
Unpaired ungulate (Perissodactyla)
Rhinocerotoidea
Rhinoceros (Rhinocerotidae)
Gaindatherium
Scientific name
Gaindatherium
Colbert , 1934

Gaindatherium is an extinct representative of the rhinoceros who lived 16 to 5 million years ago in the Middle and Upper Miocene , mainly in South Asia . It represents the predecessor of the genus Rhinoceros living today, which includes the South Asian Indian rhinoceros ( Rhinoceros unicornis ) and the Southeast Asian Java rhinoceros ( Rhinoceros sondaicus ). The long, narrow skull with an elongated snout and the singular horn on the nasal bone werecharacteristic of Gaindatherium .

features

Gaindatherium was a medium-sized rhinoceros, which was slightly smaller than today's Java rhinoceros ( Rhinoceros sondaicus ), but it is largely only known from skull finds and tooth fragments. The skull was 52 cm long and had a wedge-shaped outline. When viewed from the side, it was relatively flat and, like its close relative Rhinoceros, had a clearly saddled forehead line. The occiput was rectangular in shape and thus resembled today's Java rhinoceros, while the more modern Indian rhinoceros ( Rhinoceros unicornis ) had a rather obtuse-angled occiput. The rostrum was much more extensive than that of today's representatives of the genus Rhinoceros . As a result, the orbit was relatively central in the skull above the first molar and not, as in Rhinoceros, above the last premolar . The nasal bone was only slightly curved, at the front end there were roughened surface structures that indicated the position of the single horn. The interior of the nose above the intermaxillary bone reached to the anterior premolar. Also characteristic were the fusions of the small bone cones, which were located below the ear canal.

The lower jaw has only partially survived and had an anteriorly upward symphysis . There were two incisors in the upper jaw , a relatively ancient feature of modern rhinos, but the outer ones were significantly smaller and in the process of being reduced. There were also two incisors in the lower jaw, the outer (I2) were conical in shape, significantly enlarged with a length of 4 cm and, typically for rhinos, directed forward, so that small tusks emerged. There was a diastema to the posterior teeth . The upper molar row consisted of four premolars and three molars, but the first premolar was extremely small. The anterior premolar was missing in the lower jaw. All molars were clearly low-crowned ( brachyodont ), the premolars markedly molarized and, like the molars, had folded enamel.

Fossil finds

Finds of Gaindatherium are mainly known from South Asia , but often only include remains of skulls and teeth. Significant fossils date from the Middle Miocene belonging Chinji formation of the lower Siwaliks in Pakistan , which largely composed of gray colored sandy river deposits. This includes a complete skull near Chinji (Attock District) in the Punjab Province , which was used for the first description of the genus in 1934 . In recent times, too, numerous finds of this representative rhinoceros have come to light in the rock formation, mostly in the form of tooth finds or fragments of the lower jaw, for example in the Dhok Bun Ameer Khatoon fossil site (Chakwal district) in the same province. These are associated with the mighty rhinoceros Brachypotherium , one of the largest known representatives of this odd ungulate group , but also with early giraffes . A comparable range of finds comes from lava near Rawalpindi , also Punjab. More recent finds belonging to the Upper Miocene can be referred to the Nagri Formation of the middle Siwaliks.

Outside of South Asia, fossils from the Mae Moh Basin in northern Thailand are known, which also belong to the Middle Miocene. Further tooth finds were reported from Hanzhong in the Chinese province of Shaanxi . These originate from river deposits, but are relatively young with a date in the Pliocene .

Systematics

The genus Gaindatherium belongs to the rhinoceros family and is part of the Rhinocerotinae subfamily , to which all rhinos living today also belong. Together with Rhinoceros and the also extinct Punjabitherium , it forms the Untertribus Rhinocerotina and is therefore a close relative of today's armored ( Rhinoceros unicornis ) and Java rhinoceros ( Rhinoceros sondaicus ), both of which are endangered. Common features of all rhinocerotina are the fused bone cones below the auditory canal and a clearly saddled course of the skull. In contrast to the gigantic Punjabitherium , which with two horns, a longer front snout area and high-crowned molars was a specialized side branch that emerged around 10 million years ago, Gaindatherium could have been the direct ancestor of today's single-horned rhinos in Asia. The clear basal position of Gaindatherium within the rhinocerotina is evident in some features of the incisors, especially the lower I2, and the molars, which means that there are still connections to Lartetotherium and thus to the Dicerorhinina, the line that leads to today's highly endangered Sumatra Rhinoceros ( Dicerorhinus sumatrensis ).

The following types of Gaindatherium are recognized today:

Originally another species was introduced with G. (Iberotherium) rexmanueli by Miguel Telles Antunes and Léonard Ginsburg in 1983, the description of which was based on an upper jaw fragment from Quinta das Pedreiras north of Lisbon and which should have been restricted to western Eurasia. Another point of discovery was Beaugency in the Loire Valley , the stated age of both sites from the early Middle Miocene around 17 million years ago slightly exceeded the finds from southern Europe. On the basis of recent investigations, essential differences could be worked out, which is why this form is now led under its original subgenus Iberotherium .

The name Gaindatherium was first introduced by Edwin Harris Colbert in 1934 on the basis of an almost complete skull from the Chinji formation in the Siwaliks in today's Pakistan . This skull also includes the holotype specimen (specimen number AMNH 19409). Colbert recognized the close relationship to the genus Rhinoceros in the skull , the ancestor of which he saw Gaindatherium . In 1972 Kurt Heissig put Gaindatherium on the level of a subgenus to Rhinoceros , which is largely not accepted. The term Gaindatherium is derived from the Hindi word gainda , which translates as "rhinoceros" and is also used locally for the Indian rhinoceros , while therium in turn is the Latinized version of the Greek word θήριον ( thêrion ) and means "animal".

Individual evidence

  1. ^ A b c d Edwin H. Colbert: A new rhinoceros from the Siwalik beds of India. American Museum Novitates 749, 1934, pp. 1-13
  2. ^ Edwin H. Colbert: Siwalik mammals in the American Museum of Natural History. Transactions of the American Philosophical Society NS 26, 1935, pp. 1-401 (177-214)
  3. ↑ Khizar Samiullah, Muhammad Akhtar, Muhammad A. Khan and Abdul Ghaffar: Fossil mammals (rhinocerotids, giraffids, bovids) from the miocene rocks of Dhok Bun Ameer Khatoon, District Chakwal, Punjab, Pakistan. International Journal of Research in Engineering, IT and Social Sciences 2 (8), 2012, pp. 124–178
  4. ↑ Muhammad Akbar Khan, Muhammad, Abdul Majid Khan, Akhtar, Abdul Ghaffar, Mehboob Iqbal and Khizar Samiullah: New Fossil Locality in the Middle Miocene of Lava from the Chinji-Formation of the Lower Siwaliks, Pakistan. Pakistan Journal of Zoology 43 (1), 2011, pp. 61-72
  5. ^ A b Abdul Majid Khan: Taxonomy and distribution of rhinoceroses from the Siwalik Hills of Pakistan. Department of Zoology, University of the Punjab, Lahore, 2009
  6. ↑ Thanuchai Silaratana, Benjavun Ratanasthien, Katsumi Takayasu, William S. Fyfe, Pongpor Asnachinda, Wittaya Kandharosa and Minoru Kusakabe: Sulfur Isotopic Implication of Middle Miocene Marine Incursion in Northern Thailand. ScienceAsia 30, 2004, pp. 43-58
  7. ↑ Yingjun Tang and Guanfu Zong: Fossil Mammals from the Pliocene of the Hanzhong Region, Shaanxi Province, and their Stratigraphic Significance. Vertebrata Palasiatica 25 (3), 1987, pp. 222-235
  8. ↑ Colin P. Groves: The Rhinos - Tribal History and Kinship. In: Anonymus (Hrsg.): The rhinos: encounter with primeval colossi. Fürth 1997, ISBN 3-930831-06-6 , pp. 14-32
  9. ↑ Esperanza Cerdeño: Cladistic analysis of the family Rhinocerotidae (Perissodactyla). American Museum Novitates 3143, 1995, pp. 1-25
  10. ^ Miguel Telles Antunes and Léonard Ginsburg: Les Rhinocerotides du Miocene de Lisbonne - Systematique, ecologie, paleobiogeographie, valeur stratigraphique. Ciências da Terra 7, 1983, pp. 17-97
  11. ↑ Pierre-Olivier Antoine, Christian Bulot and Léonard Ginsburg: Les rhinocérotidés (Mammalia, Perissodactyla) de l'Orléanien des bassins de la Garonne et de la Loire (France): intérêt biostratigraphique. Earth and Planetary Sciences 330, 2000, pp. 571-576
  12. ^ Miguel Telles Antunes and Léonard Ginsburg: Les Perissodactyles (Mammalia) du Miocene de Lisbonne. Ciências da Terra 14, 2000, pp. 349-354
  13. ↑ Miguel Telles Antunes, Ausenda C. Balbino and Léonard Ginsburg: Ichnological evidence of a miocene rhinoceros bitten by a bear-dog (Amphicyon giganteus). Annales de Paleontologie 92, 2006, pp. 31-39
  14. ↑ Colin P. Groves: Phylogeny of the living species of rhinoceros. Journal of Zoological Systematics and Evolution Research 21 (4), 1983, pp. 293-313