Tapirus augustus

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Tapirus augustus
Skull of Tapirus augustus

Skull of Tapirus augustus

Temporal occurrence
Pleistocene
1.8 million years to 10,000 years
Locations
  • China, Vietnam
Systematics
Order : Unpaired ungulate (Perissodactyla)
Superfamily : Tapiroidea
Family : Tapirs (Tapiridae)
Genre : Tapirs ( tapirus )
Subgenus : Megatapirus
Type : Tapirus augustus
Scientific name of the  subgenus
Megatapirus
Matthew & Granger , 1923
Scientific name of the  species
Tapirus augustus
Matthew & Granger , 1923

Tapirus (Megatapirus) augustus is an extinct, very large member ofthe tapir family , which is listed within the genus Tapirus as a subgenus Megatapirus . Fossils of this odd-toed ungulate , which include several complete skulls, other dentition fragments and remains of the body, originate from the Pleistocene and have largely been found in East and Southeast Asia (China, Vietnam).

features

The typical molars with two enamel strips from Tapirus augustus

Megatapirus was the largest known representative of the tapirs and, according to reconstructions, had a head-trunk length of 3.5 m and a shoulder height of 1.5 m. Megatapirus exceeded the largest tapir species living today, the black- backed tapir, by 25% in each case. In the skeletal structure, especially in the postcranium , Megatapirus was largely similar to the other tapirs, but was characterized by its general size. The skull was up to 53 cm long, but was comparatively shorter than that of the other tapir species, and had a domed forehead area when viewed from the side. Like all tapirs, it had a strongly developed crest . The occiput was only short and rectangular in shape. As in all tapirs , the nasal bone lay far behind the median jawbone and was only poorly formed.

In the upper jaw, the dentition comprised the complete, original mammalian dentition with three incisors , one canine , four premolars and three molars ; in the lower jaw, the first premolar was not formed. The dental formula for the permanent dentition thus read: . In the upper jaw the third incisor was enlarged and had a dagger-like shape. The following canine, which had a small diastema , was only very small. In the lower jaw, the situation was exactly the opposite with a large canine and a small third incisor. The following molars had a much larger diastema. The premolars were characterized by a strong molarization, much stronger than in the other tapir species, and thus clearly resembled the posterior molars. In general, the molars were characterized by two transverse enamel ridges ( bilophodont ), while the tooth crowns were relatively low in height ( brachydont ).

Distribution area

Megatapirus was widely spread in East and Southeast Asia. In China , it has been found predominantly in the southern parts of the country, where more than 20 sites are known, in isolated cases it is also found in northern China during warm climatic phases in the Pleistocene . Significant finds come from Daxin from the Middle Pleistocene, while the remains from Liujiang come from the New Pleistocene and were associated with fossils of an early man ( Liujiang man ). Both sites are in the Guangxi Autonomous Region . Remains of Megatapirus have also been found in Vietnam and Laos . The cave of Tham Khuyen in Northern Vietnam is particularly worth mentioning here, where the tapir species occurred together with the giant monkey Gigantopithecus and Homo erectus .

Paleobiology

The clearly bilophodontic and low-crowned molars of Megatapirus , together with the characteristic grinding patterns on the transverse melting strips, speak for a diet similar to today's tapirs with soft vegetable foods such as leaves , twigs or fruits . The habitat largely comprised tropical rainforests , the occasional occurrence further north could also speak for an acceptance of more seasonal, but still warm climates. Some researchers suggest that megatapirus occupied an ecological niche similar to that of the hippos , which has not been safely proven in China. In more southern parts of Asia, such as Thailand, the hippopotamus genus Hexaprotodon is known from the Pleistocene.

Systematics

The family of tapirs (Tapiridae) is a relatively old representative of the mammals , the earliest known genus is Protapirus that the Oligocene lived. The closest living relatives of the tapirs are the rhinos , but according to molecular genetic analyzes the two groups separated already around 47 million years ago. Together with these and the extinct Hyracodontidae and Amynodontidae, they form the suborder of the Ceratomorpha .

Several lines developed within the tapirs, also due to the separation of the Asian and American representatives. In the Pleistocene of East Asia, among other things, two parallel lines of development emerged. Megatapirus developed via T. peii and T. sinensis and thus contrasts with the developmental sequence from T. sanyuanensis to T. indicus ( black-backed tapir). Both lines are characterized by the increase in body size, differences exist primarily in the structure and shape of the molars. Megatapirus itself formed in a later phase of the Old Pleistocene and is mostly known from the Middle and New Pleistocene. Towards the end of the last Ice Age, the representative tapir largely died out, and data is available from some Chinese sites such as Chonqing and Zheijiang that suggest that some remaining populations survived into the middle Holocene .

Research history

Tapirus augustus was first scientifically described in 1923 by William Diller Matthew and Walter W. Granger based on several skull finds ( holotype number AMNH 18433) from the Chinese province of Sichuan . At the same time, both authors introduced the term Megatapirus and pointed to the status as a subgenus within the genus Tapirus . In a 1953 study, Megatapirus was introduced as a separate genus and it was believed that it might have developed from the form tapirus in East Asia , which was later repeatedly expressed. Due to the resulting paraphyletic origin of the genus Tapirus , Megatapirus was equated with Tapirus again in 1998 and the form was listed as a subgenus. The only known species is Tapirus (Megatapirus) augustus .

literature

  • Malcolm C. McKenna and Susan K. Bell: Classification of Mammals
  • Spencer G. Lucas: Chinese Fossil Vertebrates
  • Edwin H. Colbert, Michael Moral, and Eli C. Minkoff: Colbert's Evolution of the Vertebrates: A History of the Backboned Animals Through Time

Individual evidence

  1. ↑ Darren Naish: The biggest tapir. 2009 ( [1] )
  2. ^ A b c William Diller Matthew and Walter Granger: New fossil mammals from the Pliocene of Sze-chuan, China. Bulletin of the American Museum of Natural History 48, 1923, pp. 563-598
  3. ↑ a b c d e Tong Haowen: Dental characters of the Quaternary tapirs in China, their significance in classification and phylogenetic assessment. Geobios 38, 2005, pp. 139-150
  4. ^ A b c Edwin Harris Colbert and Dirk Albert Hooijer: Pleistocene mammals from the limestone fissures of Szechwan, China. Bulletin of the American Museum of Natural History 102, 1953, pp. 1-134
  5. ^ A b Luke T. Holbrook: Comparative osteology of early Tertiary tapiromorphs (Mammalia, Perissodactyla). Zoological Journal of the Linnean Society 132, 2001, pp. 1-54
  6. ↑ a b Richard C. Hulbert Jr .: Late Miocene Tapirus (Mammalia, Perissodactyla) from Florida, with description of new species Tapirus webbi. Bulletin of the Florida. Museum of Natural History 45 (4), 2005, pp. 465-494
  7. ↑ a b Tong Haowen: Occurrences of warm angepasst mammals in north China over the Quaternary Period and Their paleoenvironmental significance. Science in China, Series D: Earth Sciences 50 (9), 2007, pp. 1327-1340
  8. ↑ a b Julien Louys, Darren Curnoe and Haowen Tong: Characteristics of Pleistocene megafauna extinctions in Southeast Asia. Palaeogeography, Palaeoclimatology, Palaeoecology 243, 2007, pp. 152-173
  9. ↑ C. Tougard: Biogeography and migration routes of large mammal faunas in South-East Asia during the Late Middle Pleistocene: focus on the fossil and extant faunas from Thailand. Palaeogeography, Palaeoclimatology, Palaeoecology 168 (3-4), 2001, pp. 337-358
  10. ↑ Christelle Tougard, Thomas Delefosse, Catherine Hänni and Claudine Montgelard: Phylogenetic Relationships of the Five Extant Rhinoceros Species (Rhinocerotidae, Perissodactyla) Based on Mitochondrial Cytochrome b and 12S rRNA Genes. Molecular Phylogenetics and Evolution 19, 2001, pp. 34-44
  11. ↑ a b Richard C. Hulbert Jr .: A new Early Pleistocene tapir (Mammalia, Perissodactyla) from Florida, with a review from Blancan tapirs from the state. Bulletin of the Florida Museum of Natural History 49 (3), 2010, pp. 67-126

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