Rhinoceros (genus)

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Rhinoceros
Indian rhinoceros (Rhinoceros unicornis)

Indian rhinoceros ( Rhinoceros unicornis )

Systematics
Class : Mammals (mammalia)
Subclass : Higher mammals (Eutheria)
Superordinate : Laurasiatheria
Order : Unpaired ungulate (Perissodactyla)
Family : Rhinoceros (Rhinocerotidae)
Genre : Rhinoceros
Scientific name
Rhinoceros
Linnaeus , 1758

Rhinoceros is a genus of the rhinoceros family, which in turn belongs to the odd-toed ungulate . The genus includes the one-horned rhinos in Asia and, with the rhinoceros and the Javan rhinoceros two still living, but endangered species.

features

The now critically endangered Java rhinoceros at London Zoo (1880).

The genus rhinoceros relatively comprises large rhino representatives, a head-body length from 300 to 380 cm and reach a weight of each of more than 2 t, the Panzernashorn provides thereby the larger of the two recent represent species. The body is of robust construction and has a short and strong limbs . The head, which reaches a length of 50 to 65 cm, is relatively large, but compared to the other recent rhinos, due to cuts in the facial area, smaller than these. The clearly wedge-shaped outline of the skull with a narrow but clearly rounded nasal bone and a short and right to slightly obtuse-angled occiput , which has a strong bulge, is very striking . Due to the shape of the occiput, rhinoceros have a relatively high head posture that surpasses all other rhinoceros species today. In addition, the forehead line between the nose and occiput shows a clear saddle. From the other genera recent rhino differs rhinoceros continue through very clearly pronounced skin folds, which are located in the neck and at the upper ends of the limbs, or lead around the body. Other peculiarities are distinctive skin formations, such as wart-like lumps or pentagonal or hexagonal segment formations, which also do not occur in other rhino lines. A significant difference is the presence of only single horn, which sits on the nose (Nasalhorn) what Rhinoceros apart from the two-horned rhinos in Africa and Asia. The keratin horn is usually the shortest of the rhinoceros species and is a maximum of 60 cm long. It is conical and rises steeply, less often it is curved backwards at the top. In terms of dentition structure, Rhinoceros has the most extensive front dentition with a maximum of two pairs of incisors , the lower outer incisors being elongated like a dagger and protruding forward, the upper ones having a flat shape and standing vertically in the jaw. The other recent rhinoceros species, on the other hand, have a maximum of one pair or no incisors at all. The premolars and molars resemble those of the other rhinos of today, except for individual tooth features. The premolars are clearly molarized so that they largely resemble the posterior molars.

distribution and habitat

The distribution of Rhinoceros is limited today to the northern areas of the Indian subcontinent and the western tip of the island of Java in the Malay Archipelago . The preferred biotopes are tree-lined open landscapes, floodplain forests and dense tropical rainforests . In historical times, the distribution was much wider and the genus also occurred in Indochina . A common area use of the two recent species occurred in the eastern part of India and in Bangladesh . However, the genus reached its greatest extent in the Pleistocene , where it populated large parts of South and Southeast Asia and the southern areas of East Asia with different species and in partially overlapping habitats .

Way of life

Three Indian rhinos in Kaziranga National Park .

Like all rhinos, the representatives of Rhinoceros are crepuscular to nocturnal. During the day they rest or wallow and bathe. Furthermore, they are territorial and solitary, group formations predominantly occur between mother and calf. Individual territories are marked with urine and feces . The intra-species communication therefore mostly takes place via the sense of smell , but there are also numerous and different sounds, the intensity of which varies depending on the rhino species. During the rut there are fights among the bulls, which are rarely carried out with the horns but with the sharp lower incisors. The gestation period usually lasts between 16 and 18 months. Only one calf is born at a time and suckled until it is around one year old. This then stays with the mother for a maximum of two years until she drives it away before the next calf is born. Life expectancy is around 40 years.

nutrition

Representatives of the genus Rhinoceros are herbivores and largely specialize in soft vegetable food such as leaves , twigs or bark, which they graze on medium-high bushes or small trees due to the high head posture. The food is plucked off with the help of the pointed upper lip. Only the Indian rhinoceros sometimes use harder grass forage, especially in dry times. As a good swimmer, they can also take food under the surface of the water, something that has not been known from any other rhino species. Salt licks are also very important.

Systematics

Rhinoceros is a genus from the sub-tribus of the Rhinocerotina within the sub-family of the Rhinocerotinae. The sister group of the Rhinocerotina is the Dicerorhinina with the Sumatran rhinoceros . The two lines separated after studying mitochondrial DNA in the late Oligocene , 26 million years ago. The genus Rhinoceros are the species living today rhinoceros ( R. unicornis ) and Javan rhino ( R. sondaicus on). According to the same studies, the split into the two species took place in the late Miocene , almost 12 million years ago.

Fossil around a dozen other species have been described, most of which are now considered to be the Indian rhinoceros. The few remaining fossil species are also subject to strong controversy among experts . The main problem is the status of R. philippinensis , which is known from several jaw fragments from the island of Luzon and was first described by Ralph von Koenigswald in 1956 . However, many paleontologists consider the finds very dubious due to their isolated geographical location outside the islands of the Sunda Shelf . The status of R. sivalensis is also assessed very differently , which is based on a description by Hugh Falconer and Proby Thomas Cautley from 1847 and was originally placed in the ancestral line of the Indian rhinoceros. Today, some researchers would rather assign this species to the recent rhinoceros representatives, depending on the view, it belongs to the Indian rhinoceros or the Java rhinoceros. Also controversial is R. sinensis , which was described by Richard Owen in 1870 on the basis of a few tooth finds from southern China and which is the most common fossil rhino species of the Pleistocene in this region today. The special high crown of the molars suggests a specialized grass eater, but there is still no complete skull. In addition, the taxon was repeatedly used as a "rubbish bin" for all Pleistocene rhinoceros found in southern China, so that the independence of the species has not yet been clarified. Rhinoceros fusuiensis was extracted from this taxon in 2014 and described on the basis of a few isolated teeth from the Yanliang Cave in the southern Chinese Autonomous Region of Guangxi . The finds date to the Lower Pleistocene . Overall, the following species are recognized today: The last remaining specimens are now only on Java, around 63 to 67 animals in the Ujung Kulon National Park (as of 2019).

The genus Rhinoceros was first scientifically named in 1758 by Linnaeus , but the name was already in use, for example through Albrecht Dürer's famous woodcut Rhinocerus from 1515. The Roman poet Martial (40-102) also used the term in his collection of poems Liber Spectaculorum in the year 80, in which, among other things, he extolled the appearance of a rhinoceros in a Roman circus. In his work Systema Naturae, Linnaeus classified the African black rhinoceros ( Diceros bicornis ) in the genus as well as the Indian rhinoceros and separated the two species based on the number of horns. He also saw the home of the black rhinoceros in India. The existence of two rhino species with varying numbers of horns was not fully accepted at the time. Petrus Camper , a Dutch doctor, was able to prove, by examining a two-horned rhinoceros from Africa in 1771, not only on the basis of the number of horns but also on the basis of the differing dentition, that the two species were separate from each other. In 1821, John Edward Gray referred the black rhinoceros to the new genus Diceros .

Tribal history

The genus Rhinoceros was first detected in fossils in the late Pliocene 3.3 million years ago in the Siwaliks in South Asia . The basal form is assigned to R. sivalensis . A possible predecessor form is the gigantic Punjabitherium , which also lived in the Siwaliks in the Pliocene. Punjabitherium differs from Rhinoceros in that it has a less short skull and the presence of a second horn on the forehead. Similarities include the fusion of the bone cones below the auditory canal and the clearly saddled upper skull, which are common to all rhinocerotina. But since Punjabitherium still had a longer snout and, above all, clearly high-crowned teeth, it is probably only a sister taxon with a common ancestor. This may have been for the Middle Miocene occurring Gaindatherium , also from the Siwaliks, which is at the basis of the Rhinocerotina.

R. sivalensis lived largely in the late Pliocene. The earliest records of the Java rhinoceros include finds from Sangiran on Java, both of which belong to the early Pleistocene . Teeth finds from a terrace of the Irrawaddy near Pauk in Myanmar are similarly old and possibly belonging to the same species , but they could also be attributed to Rhinoceros fusuiensis , which is still known from finds from southern China. R. sinensis was also found for the first time in southern East Asia in the late Early Pleistocene or early Middle Pleistocene, for example at the early human site of Yuanmou in the Yunnan province . The first clear evidence of the Indian rhinoceros can be found in India on the Narmada River and on Java from the Middle Pleistocene . In the further course of the Middle and Young Pleistocene, Rhinoceros occurs in the entire area of ​​South and Southeast Asia as well as southern East Asia and also colonizes various islands of the Sunda Shelf . At that time, the different species still share common habitats in Indochina. At the beginning of the Holocene , only armored and Java rhinos can be detected. Due to increased hunting, especially in historical times, these were pushed back more and more to the remaining refuges of today.

Threat and protection

The two recent species of the genus Rhinoceros are threatened with extinction. The IUCN lists the Indian rhinoceros as Endangered , while the Java rhinoceros is considered critically endangered . Currently, both rhino species live freely only in different national parks . Population censuses and estimates at the end of 2019 showed more than 3,600 Indian rhinos in India and Nepal and only around 63 to 67 Java rhinos in the west of the island of Java as the last refuge. A small population of Java rhinos in Cat Tien National Park in southern Vietnam was declared extinct by WWF experts in October 2011 . This makes the Java rhinoceros one of the rarest large mammal species on earth. Special breeding and repopulation projects are intended to stabilize and increase the population of both species.

Individual evidence

  1. ↑ Colin P. Groves: Phylogeny of the living species of rhinoceros. In: Journal for Zoological Systematics and Evolutionary Research. 21 (4), 1983, pp. 293-313.
  2. ↑ Friedrich E. Zeuner: The relationships between skull shape and way of life in recent and fossil rhinos. In: Reports of the Natural Research Society in Freiburg. 34, 1934, pp. 21-80.
  3. ↑ Colin P. Groves: Species characters in rhinoceros horns. In: Journal of Mammals. 36 (4), 1971, pp. 238-252.
  4. ↑ a b c d W. A. ​​Laurie, EM Lang, Colin P. Groves: Rhinoceros unicornis. In: Mammalian Species. 211, 1983, pp. 1-6.
  5. ↑ a b c d e Colin P. Groves and David M. Leslie, Jr .: Rhinoceros sondaicus (Perissodactyla: Rhinocerotidae). In: Mammalian Species. 43 (887), 2011, pp. 190-208.
  6. ↑ Rudolf Schenkel, Ernst M. Lang: The behavior of the rhinos. In: Handbuch für Zoologie. 8 (46), 1969, pp. 1-56.
  7. ↑ Christelle Tougard, Thomas Delefosse, Catherine Hänni, Claudine Montgelard: Phylogenetic Relationships of the Five Extant Rhinoceros Species (Rhinocerotidae, Perissodactyla) Based on Mitochondrial Cytochrome b and 12S rRNA Genes. In: Molecular Phylogenetics and Evolution. 19, 2001, pp. 34-44.
  8. ↑ a b c d Pierre Olivier Antoine: Pleistocene and holocene rhinocerotids (Mammalia, Perissodactyla) from the Indochinese Peninsula. In: Comptes Rendus Palevol. 2011, pp. 1-10.
  9. ^ Gustav Heinrich Ralph von Koenigswald: Fossil mammals from the Philippines (with first description of Rhinoceros philippinensis). Proceedings of the Fourth Far-Eastern Prehistory and the Anthropology Division of the 8th Pacific Science Congresses combined Part 1: Prehistory, Archeology and Physical Anthropology. (Second Fascicle, Section 1) 1956, pp. 339-369.
  10. ↑ Edwin H. Colbert: Notes on the lesser one-horned rhinoceros, Rhinoceros sondaicus - 2. The position of Rhinoceros sondaicus in the phylogeny of the genus Rhinoceros. In: American Museum Novitates. 1207, 1942, pp. 1-5.
  11. ↑ LA Schepartz, S. Miller-Antonio: Taphonomy, life history, and human exploitation of Rhinoceros sinensis at the Middle Pleistocene site of Panxian Dadong, Guizhou, China. In: International Journal of Osteoarcheology. vol. 20, issue 3, 2010, pp. 253-268, doi: 10.1002 / oa.1025
  12. ↑ a b Tong Haowen: Rhinocerotids in China - systematics and material analysis. In: Geobios. 34 (5), 2001, pp. 585-591.
  13. ↑ Tong Haowen, Wu XianZhu: Stephanorhinus kirchbergensis (Rhinocerotidae, Mammalia) from the Rhino Cave in Shennongjia, Hubei. In: Chinese Science Bulletin. 55 (12), 2010, pp. 1157-1168.
  14. ↑ a b Yan Yaling, Wang Yuan, Jin Changzhu and Jim I. Mead: New remains of Rhinoceros (Rhinocerotidae, Perissodactyla, Mammalia) associated with Gigantopithecus blacki from the Early Pleistocene Yanliang Cave, Fusui, South China. In: Quaternary International. 354, 2014, pp. 110–121, doi: 10.1016 / j.quaint.2014.01.004 .
  15. ^ LC Rookmaaker: Early rhinoceros systematics. In: A. Wheeler, A. et al. (Ed.): History in the service of systematics. London, Society for the Bibliography of Natural History 1981, pp. 111-118
  16. ↑ John Edward Gray: On the natural arrangement of vertebrose animals. London Medical Repository 15, 1821, pp. 297-310 (306) ( PDF )
  17. ^ Donald R. Prothero, Claude Guérin, Earl Manning: The history of Rhinocerotoidea. In: Donald R. Prothero and RM Schoch (Eds.): The evolution of the Perissodactyls. New-York, 1989, pp. 321-340.
  18. ↑ Ehsanulian Khan: Punjabitherium, gen. Nov., An extinct rhinocerotid of the Siwaliks, Punjab, India. Proceedings of the Indian National Science Academy 37 (2) A, 1971, pp. 105-109.
  19. ↑ Colin P. Groves: The Rhinos - Tribal History and Kinship. In: The rhinos: encounter with primeval colossi. Fürth 1997, ISBN 3-930831-06-6 , pp. 14-32.
  20. ^ DA Hooijer: New records of mammals from the Middle Pleistocene of Sangiran, Central Java. In: Zoologische Mededelingen. Leiden 40 (10) 1964, pp. 73-87.
  21. ↑ Zin-Maung-Maung-Thein, Thaung-Htike, Takehisa Tsubamoto, Masanaru Takai, Naoko Egi, Maung-Maung: Early Pleistocene Javan rhinoceros from the Irrawaddy Formation, Myanmar. In: Asian Paleoprimatology. 4, 2006, pp. 197-204.
  22. ↑ Bibhab Kumar Talukdar, R. Emslie, SS Bist, A. Choudhury, S. Ellis, BS Bonal, MC Malakar, BN Talukdar, M. Barua: Rhinoceros unicornis. In: IUCN 2011: IUCN Red List of Threatened Species. Version 2011.2.
  23. ^ Nico J. van Strien, R. Steinmetz, B. Manullang, Sectionov, KH Han, W. Isnan, Kees Rookmaaker, E. Sumardja, MKM Khan, S. Ellis: Rhinoceros sondaicus. In: IUCN 2011: IUCN Red List of Threatened Species. Version 2011.2.
  24. ↑ International Rhino Foundation [1]
  25. ^ Sarah Brooks, Peter van Coeverden de Groot, Simon Mahood, Barney Long: Extinction of the Javan rhinoceros (Rhinoceros sondaicus) from Vietnam. (PDF; 2.6 MB) WWF Report VN, 2011, pp. 1–45.
  26. ↑ Bibhab Kumar Talukdar: Asian Rhino Specialist Group report. In: Pachyderm. 49, 2011, pp. 16-19. ( online )

Web links

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