Sunda Gavial

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Sunda Gavial
Tomistoma schlegelii fg01.JPG

Sunda Gavial ( Tomistoma schlegelii )

Systematics
without rank: Sauropsida
without rank: Archosauria
Order : Crocodiles (crocodylia)
Family : Gaviale (Gavialidae)
Genre : Tomistoma
Type : Sunda Gavial
Scientific name of the  genus
Tomistoma
Müller , 1846
Scientific name of the  species
Tomistoma schlegelii
( Müller , 1838)

The false gharial or False Gavial ( Tomistoma schlegelii ) is the Southeast Asian of the two extant species of gavials (Gavialidae). It is also the only recent species of the genus Tomistoma .

features

Head of a Sunda Gavial

The Sunda Gavial reaches a length of up to five meters. The snout is elongated and has numerous narrow and pointed teeth in both the upper and lower jaw . Its largely light to dark brown body is marked by darker bands and spots, which are very clearly recognizable in both the young and the adults.

Spread and endangerment

Distribution of the Sunda Gavial. It should be noted that the species does not populate the entire color-coded area, but occurs spotty within this area.

Sunda gavials live exclusively in fresh water in lakes, rivers and swamps. Brackish water occurrences are not known. The distribution area includes the south of the Malay Peninsula as well as the islands of Borneo , Sumatra and possibly also the extreme west of Java . Subfossil finds in Guangdong ( Kwatung ) in China suggest that its distribution area also included southern China at the beginning of the Ming Dynasty ( 1368 ).

The Sunda Gavial is threatened with extinction today . The “Tomistoma Task Force” of the “ IUCN / SSC Crocodile Specialist Group” estimates the number of Sunda Gaviale still living in the wild at a maximum of 2,500 animals. The reason for the threat is the destruction of natural habitats through logging and the draining of peat bogs, fishing and poaching.

Way of life and reproduction

In dorsal view

Sunda-Gaviale live withdrawn and shy mainly in peat bog forests and inhabit rivers, lakes and ponds there.

There they feed mainly on fish, but also smaller amphibians, reptiles, birds and mammals (e.g. monkeys) belong to the food spectrum. Wherever the habitat or hunting grounds of Sunda gavials and humans overlap, humans can also fall victim to them. In 2008, a four-meter-long female attacked a fisherman in central Kalimantan and devoured him. This was the first verified fatal attack by a Sunda Gavial on a human. As of June 2014, there had been at least three other verified fatal attacks on people. However, the estuarine crocodile , which occurs in the same region, is significantly more dangerous, with well over 100 fatalities between 2007 and 2014.

The females of the Sunda Gavial build mound nests from plant material to lay their eggs, mainly at the foot of jungle trees. The breeding period is comparable to that of other crocodile species and is around 90 days at an incubation temperature of around 31 degrees Celsius. Sunda Gaviale lay the largest eggs of all crocodiles.

Systematics

The Sunda Gavial owes its second common name , "False Gavial", to the fact that it has a long, slender snout like the Gangetic Gavial ( Gavialis gangeticus ), but is based on a number of other body features (including the shape of the skull) has traditionally been assigned to the real crocodiles (Crocodylidae) and is still partially assigned today. However, this assignment was always controversial and part of the research community has long favored a close relationship with the Ganges gavial and thus an assignment to the family Gavialidae. With the advent of molecular genetic methods for determining relationships in the 1980s, the evidence supporting the latter hypothesis increased. Meanwhile, a sister group relationship of Ganges Gavial and Sunda Gavial within the recent crocodiles is considered relatively secure.

The Sunda Gavial, Tomistoma schlegelii , is the only recent species of the genus Tomistoma , which in turn is the only recent genus of the subfamily Tomistominae . However, the fossil record shows that the tomistomines were evidently more diverse and also significantly more widespread in the geological past. Crocodiles, interpreted as representatives of this subfamily, are known from Tertiary Asia, North and South America and Europe, among other things through finds in the Eocene of the Messel Pit .

literature

  • Charles A. Ross (Ed.): Crocodiles and Alligators - Evolution, Biology and Distribution. Orbis Verlag, Niedernhausen 2002.
  • Joachim Brock: Crocodiles - A life with armored lizards . Natur und Tier Verlag, Münster 1998.
  • Ludwig Trutnau: Crocodiles: alligators, caimans, real crocodiles and gavials. (= Die Neue Brehm-Bücherei. Volume 593). Westarp Sciences, Magdeburg 1994.
  • Ludwig Trutnau, Ralf Sommerlad: Crocodiles - biology and husbandry. Chimaira publishing house, Frankfurt 2006.

Individual evidence

  1. ^ A b c Robert B. Stuebing, Mark R. Bezuijen, Mark Auliya, Harold K. Voris: The Current and Historic Distribution of Tomistoma schlegelii (The False Gharial) (Müller, 1838) (Crocodylia, Reptilia). The Raffles Bulletin of Zoology. Vol. 54, No. 1, 2006, pp. 81-197, PDF
  2. ↑ Mark R. Bezuijen, BM Shwedick, R. Sommerlad, C. Stevenson, Robert B. Stuebing: Tomistoma schlegelii. Pp. 133-138 in SC Manolis, C. Stevenson (Eds.): Crocodiles. Status Survey and Conservation Action Plan. Third Edition, Crocodile Specialist Group, Darwin 2010, PDF
  3. ↑ Devis Rachmawan, Stephen Brend: Human-Tomistoma interactions in central Kalimantan, Indonesian Borneo . IUCN Species Survival Commission - Crocodile Specialist Group Newsletter. Vol. 28, No. 1, 2009, pp. 9–11, PDF (6.5 MB, complete issue)
  4. ↑ a b Brandon M. Sideleau, Adam RC Britton: An Analysis of Recent Crocodile Attacks in the Republic of Indonesia - a Case Study on the Utility of the CrocBITE Database. Pp. 332-335 in: Crocodiles. Proceedings of the 23nd Working Meeting of the IUCN SSC Crocodile Specialist Group. International Union for Conservation of Nature, Gland (CH) 2014, PDF (460 kB)
  5. ↑ For a brief overview, see Ralph E. Molnar: Biogeography and Phylogeny of the Crocodylia . In: CG Glasby, GJB Ross, PL Beesley (Eds.): Fauna of Australia. Volume 2A: Amphibia and Reptilia. AGPS Canberra, 1993, PDF
  6. ↑ Llewellyn D. Densmore III, Robert D. Owen: Molecular Systematics of the Order Crocodilia. American Zoologist. Vol. 29, No. 3, 1989, pp. 831-841, doi: 10.1093 / icb / 29.3.831
  7. ↑ John Gatesy, George D. Amato: Sequence Similarity of 12S Ribosomal Segment of Mitochondrial DNAs of Gharial and False Gharial. Copeia. Jhrg. 1992, No. 1, 1992, pp. 241-243, doi: 10.2307 / 1446560
  8. ↑ RK Aggarwal, KC Majumdar, JW Lang, L. Singh: Generic affinities among crocodilians as revealed by DNA fingerprinting with a Bkm-derived probe. PNAS. Vol. 91, No. 22, 1994, pp. 10601-10605, PMC 45069 (free full text)
  9. ↑ John Harshman, Christopher J. Huddleston, Jonathan P. Bollback, Thomas J. Parsons, Michael J. Braun: True and false gharials: a nuclear gene phylogeny of crocodylia. Systematic Biology. Vol. 52, No. 3, 2003, pp. 386-402, doi: 10.1080 / 10635150390197028
  10. ↑ Axel Janke, Anette Gullberg, Sandrine Hughes, Ramesh K. Aggarwal, Ulfur Arnason: Mitogenomic Analyzes Place the Gharial ( Gavialis gangeticus ) on the Crocodile Tree and Provide Pre-K / T Divergence Times for Most Crocodilians. Journal of Molecular Evolution. Vol. 61, No. 5, 2005, pp. 620–626, doi: 10.1007 / s00239-004-0336-9 (free full text: Researchgate )
  11. ↑ Ray E. Willis, L. Rex McAliley, Erika D. Neeley, Llewellyn D. Densmore III: Evidence for placing the false gharial ( Tomistoma schlegelii ) into the family Gavialidae: Inferences from nuclear gene sequences. Molecular Phylogenetics and Evolution. Vol. 43, No. 3, 2007, pp. 787-794, doi: 10.1016 / j.ympev.2007.02.005
  12. ↑ Ray E. Willis: Transthyretin Gene (TTR) Intron One Elucidates Crocodylian Relationships. Molecular Phylogenetics and Evolution. Vol. 53, No. 3, 2009, pp. 1049-1054, PMC 2787865 (free full text)
  13. ^ Jamie R. Oaks: A time-calibrated species tree of Crocodylia reveals a recent radiation of the true crocodiles. Evolution. Vol. 65, No. 11, 2011, pp. 3285-3297, doi: 10.1111 / j.1558-5646.2011.01373.x

Web links

Commons : Sunda-Gavial  - album with pictures, videos and audio files