Gogo formation

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The Gogo Formation is a fossil deposit , consisting of a former coral reef , which contains exceptionally well-preserved fossils from the Devonian Mountains. It is located in the Australian state of Western Australia in the Kimberley region (Australia) .

The former reef is located inland in the desert of Western Australia. It is the main attraction of the Windjana Gorge National Park . Time and again, spectacular fossil finds are made in the up to 100 meter high rock faces. About 45 species of fish have been discovered so far.

Parts of the go-go formation consist of siltstone , slate and tufa with numerous concretions of limestone . These concretions are very weather-resistant, which explains the large number of fossil finds.

The sediments of the Gogo Formation were created in the Upper Devonian by deposits on the anoxic seabed. The limestone mineral masses formed on objects in shallow water, which then sank into deep, anoxic areas. Due to the fossilization conditions in the deposit, namely the rapid coating with minerals and the slow rotting in the oxygen-poor environment of the reef, many extinct fish, especially plate-skins (placodermi) are so well preserved that their entire three-dimensional structure can be reconstructed. In many specimens, the head areas, and in some even soft parts such as muscles, nerve fibers and the olfactory system, can be reconstructed very well.

The reef was described in 1940 by the paleontologist Curt Teichert , who also discovered the first fossil fish in this region.

Gogonasus andrewsae (in German "Die Schnauze von Gogo"), an approx. 380 million year old meat fin (Sarcopterygii), was discovered in 1985 in the Gogo formation. Like Panderichthys (370 to 360 million years old) and Tiktaalik (375 million years old), it belongs to a taxon that also contains the precursors of the later terrestrial vertebrates (tetrapods).

The plate- skinned Mcnamaraspis kaprios was discovered in 1986 by the Australian paleontologist John Long in the Gogo formation and described by him in 1995. These fish have cartilage rings in the mouth region, which prove that placoderms are closely related to sharks in evolution. Due to its spectacular properties, the approximately 25 cm long Mcnamaraspis became. named the fossil emblem of Western Australia.

In 2008, an approximately 375 million year old specimen of the placoderma Materpiscis attenboroughi was discovered, inside of which a well-preserved embryo with umbilical cord was found. At least some of the placoderms thus already showed viviparity .

In 2009, an embryo was also described in another plate membrane , the Arthrodiren Incisoscutum ritchiei , in an approx. 365 million year old female specimen and paired clusters in a male specimen and thus further characteristics for reproduction by mating in placoderms. Internal fertilization therefore arose very early in the evolution of vertebrates .

literature

  • John Long: Swimming in Stone. The Amazing Gogo Fossils of the Kimberley . Fremantle Arms Center Press, Fremantle WA 2006, ISBN 1-921064-33-1 .

Web links

Individual evidence

  1. ↑ Gogo Reef Formation ( Memento from March 7, 2018 in the Internet Archive )
  2. ↑ K. Trinajstic, E. Marshall, J. Long, K. Bifield: Exceptional preservation of nerve and muscle tissues in Devonian placoderm fish and their phylogenetic implications. In: Biology Letters. 3, 2007, pp. 197-200.
  3. ^ Obituary for Curt Teichert, in English [1]
  4. ↑ C. Teichert: Actinosiphonate cephalopods (Cyrtoceroida) from the Devonian of Australia. In: Royal Society of Western Australia Journal. 26, 1940, pp. 59-75.
  5. ^ JA Long: A new osteolepidid fish from the upper devonian Gogo formation of Western Australia. In: Recs WA Mus. 12, 1985, pp. 361-377.
  6. ↑ JA Long, GC Young, T. Holland, TJ Senden, EMG Fitzgerald: An exceptional devonian fish from Australia sheds light on tetrapod origins. In: Nature . 444, 2006, pp. 199-202. doi: 10.1038 / nature05243
  7. ↑ J. Long: Gogo fish. Fossil emblem of the state of Western Australia. In: J Roy Soc Western Australia. 82, 1999, p. 51. (PDF) ( Memento from February 21, 2011 in the Internet Archive )
  8. ^ JA Long: A new plourdosteid arthrodire from the upper devonian Gogo formation of Western Australia. In: Palaeontology. 38, 1995, pp. 39-62.
  9. ↑ Aussie fish fossil gives birth to history. May 29, 2008.
  10. ↑ JA Long, K. Trinajstić, Z. Johanson: Devonian arthrodire embryos and the origin of internal fertilization in vertebrates. In: Nature. 457, 2009, pp. 1124-1127. doi: 10.1038 / nature07732
  11. ↑ P. Ahlberg, K. Trinajstić, Z. Johanson, J. Long: Pelvic claspers confirm chondrichthyan-like internal fertilization in arthrodires. In: Nature. 460, 2009, pp. 888-889. doi: 10.1038 / nature08176