Gogonasus
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''Gogonasus'' (meaning "snout from Gogo") was a
lobe-finned fish Sarcopterygii (; )—sometimes considered synonymous with Crossopterygii ()—is a clade (traditionally a class or subclass) of vertebrate animals which includes a group of bony fish commonly referred to as lobe-finned fish. These vertebrates ar ...
known from three-dimensionally preserved 380-million-year-old fossils found from the
Gogo Formation The Gogo Formation in the Kimberley region of Western Australia is a Lagerstätte that exhibits exceptional preservation of a Devonian reef community. The formation is named after Gogo Station, a cattle station where outcrops appear and fossi ...
in
Western Australia Western Australia (WA) is the westernmost state of Australia. It is bounded by the Indian Ocean to the north and west, the Southern Ocean to the south, the Northern Territory to the north-east, and South Australia to the south-east. Western Aust ...
. It lived in the Late
Devonian The Devonian ( ) is a period (geology), geologic period and system (stratigraphy), system of the Paleozoic era (geology), era during the Phanerozoic eon (geology), eon, spanning 60.3 million years from the end of the preceding Silurian per ...
period, on what was once a
coral reef A coral reef is an underwater ecosystem characterized by reef-building corals. Reefs are formed of colonies of coral polyps held together by calcium carbonate. Most coral reefs are built from stony corals, whose polyps cluster in group ...
off the Kimberley coast surrounding north-western Australia. ''Gogonasus'' was a small fish reaching in length. Its skeleton shows several features that were like those of a four-legged land animal (
tetrapod A tetrapod (; from Ancient Greek :wiktionary:τετρα-#Ancient Greek, τετρα- ''(tetra-)'' 'four' and :wiktionary:πούς#Ancient Greek, πούς ''(poús)'' 'foot') is any four-Limb (anatomy), limbed vertebrate animal of the clade Tetr ...
). They included the structure of its
middle ear The middle ear is the portion of the ear medial to the eardrum, and distal to the oval window of the cochlea (of the inner ear). The mammalian middle ear contains three ossicles (malleus, incus, and stapes), which transfer the vibrations ...
, and its fins show the precursors of the
forearm The forearm is the region of the upper limb between the elbow and the wrist. The term forearm is used in anatomy to distinguish it from the arm, a word which is used to describe the entire appendage of the upper limb, but which in anatomy, techn ...
bones, the
radius In classical geometry, a radius (: radii or radiuses) of a circle or sphere is any of the line segments from its Centre (geometry), center to its perimeter, and in more modern usage, it is also their length. The radius of a regular polygon is th ...
and
ulna The ulna or ulnar bone (: ulnae or ulnas) is a long bone in the forearm stretching from the elbow to the wrist. It is on the same side of the forearm as the little finger, running parallel to the Radius (bone), radius, the forearm's other long ...
. Researchers believe it used its forearm-like fins to dart out of the reef to catch
prey Predation is a biological interaction in which one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not ki ...
. ''Gogonasus'' was first described from a single snout (ethmosphenoid) by John A. Long (1985). On Long's 1967 expedition to Gogo the first relatively complete skull of ''Gogonasus'' was found by Chris Nelson and after being prepared by Sheila Mahala Andrews solved a scientific controversy by showing that the inner large
fang A fang is a long, pointed tooth. In mammals, a fang is a modified maxillary tooth, used for biting and tearing flesh. In snakes, it is a specialized tooth that is associated with a venom gland (see snake venom). Spiders also have external fangs, ...
s of the coronoid bones did not insert into the
choana The choanae (: choana), posterior nasal apertures or internal nostrils are two openings found at the back of the nasal passage between the nasal cavity and the pharynx, in humans and other mammals (as well as crocodilians and most skinks). They ...
of the
palate The palate () is the roof of the mouth in humans and other mammals. It separates the oral cavity from the nasal cavity. A similar structure is found in crocodilians, but in most other tetrapods, the oral and nasal cavities are not truly sep ...
(Long 1988) as had been suggested by Rosen ''et al.'' (1981) for ''
Eusthenopteron ''Eusthenopteron'' (from 'stout', and 'wing' or 'fin') is an extinct genus of prehistoric marine lobe-finned fish known from several species that lived during the Late Devonian period, about 385 million years ago. It has attained an iconic ...
''. In 1990 a combined expedition from the
Western Australian Museum The Western Australian Museum is a statutory body, statutory authority within the Culture and the Arts Portfolio, established under the ''Museum Act 1969''. The museum has six main sites. The state museum, WA Museum Boola Bardip, is located i ...
and the
Australian National University The Australian National University (ANU) is a public university, public research university and member of the Group of Eight (Australian universities), Group of Eight, located in Canberra, the capital of Australia. Its main campus in Acton, A ...
yielded another almost complete skull of ''Gogonasus'', this one found by Dr R. E. Barwick. The full description of its cranial anatomy appeared in Long, J. A., Barwick, R. E. & Campbell, K.S.W. (1997), although not all aspects of the skull were clear then even from the three specimens. In 2005 Long led another expedition back to Gogo and on July 11 one of the team members, Dr Tim Senden from the Australian National University, found a very well-preserved skeleton of ''Gogonasus'', containing almost the complete fish down to the tip of the
tail The tail is the elongated section at the rear end of a bilaterian animal's body; in general, the term refers to a distinct, flexible appendage extending backwards from the midline of the torso. In vertebrate animals that evolution, evolved to los ...
. It was Dr Senden's first field trip with the other researchers. The specimen (NMV P221807) is now held at
Museums Victoria Museums Victoria is an organisation that includes a number of museums and related bodies in Melbourne. These include Melbourne Museum, Immigration Museum, Scienceworks, IMAX Melbourne, a research institute, the UNESCO World Heritage-listed Roy ...
, after nearly four months of
acetic acid Acetic acid , systematically named ethanoic acid , is an acidic, colourless liquid and organic compound with the chemical formula (also written as , , or ). Vinegar is at least 4% acetic acid by volume, making acetic acid the main compone ...
preparation by John Long. The new specimen showed some surprising new data not seen in any of the other specimens. Firstly, there were large spiracular openings on top of the skull, with a distinct down-folded
cosmine Cosmine is a spongy, bony material that makes up the dentine-like layers in the scales of the lobe-finned fishes of the class Sarcopterygii. Fish scales that include layers of cosmine are known as cosmoid scales. Description As traditionally d ...
-covered
lamina Lamina may refer to: People * Saa Emerson Lamina, Sierra Leonean politician * Tamba Lamina, Sierra Leonean politician and diplomat Science and technology * Planar lamina, a two-dimensional planar closed surface with mass and density, in mathem ...
of bone present on the
tabular bone The tabular bones are a pair of triangular flat bones along the rear edge of the skull which form pointed structures known as tabular horns in primitive Teleostomi. References Fish anatomy Amphibian anatomy {{vertebrate-anatomy-stub ...
. This indicated its spiracles were almost as large as in the
elpistostegalia Elpistostegalia is a clade containing ''Panderichthys'' and all more derived Tetrapodomorpha, tetrapodomorph taxa. The earliest elpistostegalians, combining fishlike and tetrapod-like characters, such as ''Tiktaalik'', are sometimes called fisha ...
n fishes (like ''
Tiktaalik ''Tiktaalik'' (; ) is a monospecific genus of extinct sarcopterygian (lobe-finned fish) from the Late Devonian Period, about 375 Mya (million years ago), having many features akin to those of tetrapods (four-legged animals). ''Tiktaalik'' is est ...
'') and early tetrapods (e.g. ''
Acanthostega ''Acanthostega'', from Ancient Greek ἄκανθα (''ákantha''), meaning "spine", and στέγη (''stégē''), meaning "roof", is an extinct genus of stem tetrapoda, stem-tetrapod, among the first vertebrates, vertebrate animals to have recogn ...
''). Secondly, after preparation of its
pectoral fin Fins are moving appendages protruding from the body of fish that interact with water to generate thrust and help the fish aquatic locomotion, swim. Apart from the tail or caudal fin, fish fins have no direct connection with the vertebral column ...
s, the internal limb skeleton showed closer resemblances to that of the elpistostegalians than to other more generalised
tetrapodomorph Tetrapodomorpha (also known as Choanata) is a clade of vertebrates consisting of tetrapods (four-limbed vertebrates) and their closest sarcopterygian relatives that are more closely related to living tetrapods than to living lungfish. Advanced for ...
fishes like ''
Eusthenopteron ''Eusthenopteron'' (from 'stout', and 'wing' or 'fin') is an extinct genus of prehistoric marine lobe-finned fish known from several species that lived during the Late Devonian period, about 385 million years ago. It has attained an iconic ...
''. For almost 100 years ''Eusthenopteron'' had been the well-used role model for demonstrating stages in the evolution of
lobe-finned fish Sarcopterygii (; )—sometimes considered synonymous with Crossopterygii ()—is a clade (traditionally a class or subclass) of vertebrate animals which includes a group of bony fish commonly referred to as lobe-finned fish. These vertebrates ar ...
es to
tetrapod A tetrapod (; from Ancient Greek :wiktionary:τετρα-#Ancient Greek, τετρα- ''(tetra-)'' 'four' and :wiktionary:πούς#Ancient Greek, πούς ''(poús)'' 'foot') is any four-Limb (anatomy), limbed vertebrate animal of the clade Tetr ...
s. ''Gogonasus'' now replaces ''Eusthenopteron'' in being a better preserved representative without any ambiguity in interpreting its anatomy (as had been shown for example by Rosen ''et al.'' 1981 when erroneously reconstructing the fit of the lower jaws to the palate). Superficially, ''Gogonasus'' appears similar to the generalised tetrapodomorph fishes like '' Osteolepis'' from Scotland, but in its advanced features shows that even primitive-looking cosmine-covered forms evolved significant specializations towards becoming tetrapod-like. ''Gogonasus'' is just one of the over 45 species of three-dimensionally preserved fishes from the Gogo Formation deposit. It is the only
Devonian The Devonian ( ) is a period (geology), geologic period and system (stratigraphy), system of the Paleozoic era (geology), era during the Phanerozoic eon (geology), eon, spanning 60.3 million years from the end of the preceding Silurian per ...
site in the world to yield whole complete fishes in perfect uncrushed preservation in some specimens.


See also

Other fish found in fossils from the Devonian period: *'' Mcnamaraspis kaprios'', another fish from the Gogo Formation and Western Australia's fossil emblem *'' Elpistostege'' *''
Tiktaalik ''Tiktaalik'' (; ) is a monospecific genus of extinct sarcopterygian (lobe-finned fish) from the Late Devonian Period, about 375 Mya (million years ago), having many features akin to those of tetrapods (four-legged animals). ''Tiktaalik'' is est ...
'' *''
Eusthenopteron ''Eusthenopteron'' (from 'stout', and 'wing' or 'fin') is an extinct genus of prehistoric marine lobe-finned fish known from several species that lived during the Late Devonian period, about 385 million years ago. It has attained an iconic ...
'' *''
Panderichthys ''Panderichthys'' is a genus of extinction, extinct Sarcopterygii, sarcopterygian (lobe-finned fish) from the late Devonian period, about 380 Myr, Mya. ''Panderichthys'', which was recovered from Frasnian (early Late Devonian) deposits in Latvia, ...
'' *
Actinistia Coelacanths ( ) are an ancient group of lobe-finned fish (Sarcopterygii) in the class Actinistia. As sarcopterygians, they are more closely related to lungfish and tetrapods (the terrestrial vertebrates including living amphibians, reptiles, bi ...
*''
Materpiscis ''Materpiscis'' (Latin for ''mother fish'') is a genus of ptyctodontid placoderm from the Late Devonian located at the Gogo Formation of Western Australia. Known from only one specimen, it is unique in having an unborn embryo present inside the ...
''


References

* * * * * *


External links


Ancient Gogonasus advances evolution
Museum Victoria.
Photographs and x-ray micro-tomography animation of ''Gogonasus''
from ANU
''Gogonasus andrewsae''
by PZ Myers
Ancient Fish Fossil May Rewrite Story of Animal Evolution
(
National Geographic ''National Geographic'' (formerly ''The National Geographic Magazine'', sometimes branded as ''Nat Geo'') is an American monthly magazine published by National Geographic Partners. The magazine was founded in 1888 as a scholarly journal, nine ...
)
Livescience.com: "Discovery Points to Our Fishy Heritage." (Accessed 10/21/06)
* ttp://www.abc.net.au/rn/inconversation/stories/2007/1876587.htm#transcript Interview with Dr John Long, curator at the Museum of Victoria {{Taxonbar, from1=Q136413, from2=Q20718210 Tetrapodomorpha Prehistoric lobe-finned fish genera Late Devonian sarcopterygians Devonian sarcopterygians of Australia Gogo fauna Fossil taxa described in 1985 Symbols of Western Australia