Gogonasus
Encyclopedia
Gogonasus was a lobe-finned fish known from 3-dimensionally preserved 380 million-year-old fossils found from the Gogo Formation
in Western Australia
. It lived in the late Devonian period, on what was once a 1400 kilometre coral reef
off the Kimberley coast surrounding the north-west of Australia. Its skeleton shows several features that were like those of a four-legged land animal (tetrapod
). They included the structure of its middle ear
, and its fins show the precursors of the forearm
bones, the radius
and ulna
. Researchers believe it used its forearm-like fins to dart out of the reef to catch prey.
Gogonasus was first described from a single snout (ethmosphenoid) by John A. Long (1985). On Long's 1986 expedition to Gogo the first relatively complete skull of Gogonasus was found by Chris Nelson and after being prepared solved a scientific controversy by showing that the inner large fang
s of the coronoid bones did not insert into the choana
of the palate
(Long 1988) as had been suggested by Rosen et al. (1981) for Eusthenopteron
. In 1990 a combined expedition from the Western Australian Museum
and the Australian National University
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 3 specimens. In 2005 Long lead 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
. It was Dr Senden's first field trip with the other researchers.
The specimen (NMV P221807) is now held at Museum Victoria
, after nearly 4 months of acetic acid
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-covered lamina of bone present on the tabular bone. This indicated its spiracle
s were almost as large as in the elpistostegalian
fishes (like Tiktaalik
) and early tetrapods (e.g. Acanthostega
). Secondly, after preparation of its pectoral fins, the internal limb skeleton showed closer resemblances to that of the elpistostegalians than to other more generalised tetrapodomorph fishes like Eusthenopteron
. For almost 100 years Eusthenopteron had been the well-used role model for demonstrating stages in the evolution of lobe-finned fishes to tetrapod
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). Gogonasus is in superficial look 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 almost 45 species of 3-dimensionally preserved fishes from the Gogo Formation deposit. It is the only Devonian
site in the world to yield whole complete fishes in perfect uncrushed preservation in some specimens.
Gogo Formation
The Gogo Formation in the Kimberley region of Western Australia is a Lagerstätte that exhibits exceptional preservation of a Devonian reef community.- Sedimentology :...
in Western Australia
Western Australia
Western Australia is a state of Australia, occupying the entire western third of the Australian continent. It is bounded by the Indian Ocean to the north and west, the Great Australian Bight and Indian Ocean to the south, the Northern Territory to the north-east and South Australia to the south-east...
. It lived in the late Devonian period, on what was once a 1400 kilometre coral reef
Coral reef
Coral reefs are underwater structures made from calcium carbonate secreted by corals. Coral reefs are colonies of tiny living animals found in marine waters that contain few nutrients. Most coral reefs are built from stony corals, which in turn consist of polyps that cluster in groups. The polyps...
off the Kimberley coast surrounding the north-west of Australia. Its skeleton shows several features that were like those of a four-legged land animal (tetrapod
Tetrapod
Tetrapods are vertebrate animals having four limbs. Amphibians, reptiles, birds and mammals are all tetrapods; even snakes and other limbless reptiles and amphibians are tetrapods by descent. The earliest tetrapods evolved from the lobe-finned fishes in the Devonian...
). They included the structure of its middle ear
Middle ear
The middle ear is the portion of the ear internal to the eardrum, and external to the oval window of the cochlea. The mammalian middle ear contains three ossicles, which couple vibration of the eardrum into waves in the fluid and membranes of the inner ear. The hollow space of the middle ear has...
, and its fins show the precursors of the forearm
Forearm
-See also:*Forearm flexors*Forearm muscles...
bones, the radius
Radius
In classical geometry, a radius of a circle or sphere is any line segment from its center to its perimeter. By extension, the radius of a circle or sphere is the length of any such segment, which is half the diameter. If the object does not have an obvious center, the term may refer to its...
and ulna
Ulna
The ulna is one of the two long bones in the forearm, the other being the radius. It is prismatic in form and runs parallel to the radius, which is shorter and smaller. In anatomical position The ulna is one of the two long bones in the forearm, the other being the radius. It is prismatic in form...
. Researchers believe it used its forearm-like fins to dart out of the reef to catch prey.
Gogonasus was first described from a single snout (ethmosphenoid) by John A. Long (1985). On Long's 1986 expedition to Gogo the first relatively complete skull of Gogonasus was found by Chris Nelson and after being prepared solved a scientific controversy by showing that the inner large fang
Fang
Fang is a mammal's canine tooth.Fang may also refer to:* A snake's poison-injecting tooth: see snake venom* Fang people, in Central Africa* Fang language, spoken by Fang people...
s of the coronoid bones did not insert into the choana
Choana
Choana is the posterior nasal aperture.The choanae are separated by the vomer.- Boundaries :It is the opening between the nasal cavity and the nasopharynx....
of the palate
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 separate. The palate is divided into two parts, the anterior...
(Long 1988) as had been suggested by Rosen et al. (1981) for Eusthenopteron
Eusthenopteron
Eusthenopteron is a genus of prehistoric lobe-finned fish which has attained an iconic status from its close relationships to tetrapods. Early depictions of this animal show it emerging onto land, however paleontologists now widely agree that it was a strictly aquatic animal...
. In 1990 a combined expedition from the Western Australian Museum
Western Australian Museum
The Western Australian Museum is the state museum for Western Australia.The Western Australian Museum has seven main sites: two in Perth within the Perth Cultural Centre, two in Fremantle , and one each in Albany, Geraldton, and Kalgoorlie-Boulder...
and the Australian National University
Australian National University
The Australian National University is a teaching and research university located in the Australian capital, Canberra.As of 2009, the ANU employs 3,945 administrative staff who teach approximately 10,000 undergraduates, and 7,500 postgraduate students...
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 3 specimens. In 2005 Long lead 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
Tail
The tail is the section at the rear end of an animal's body; in general, the term refers to a distinct, flexible appendage to the torso. It is the part of the body that corresponds roughly to the sacrum and coccyx in mammals, reptiles, and birds...
. It was Dr Senden's first field trip with the other researchers.
The specimen (NMV P221807) is now held at Museum Victoria
Museum Victoria
Museum Victoria is an organisation which operates three major state-owned museums in Melbourne, Victoria, Australia; these are: the Melbourne Museum, the Immigration Museum and Scienceworks. It also manages the Royal Exhibition Building and a storage facility in Melbourne's City of Moreland.Museum...
, after nearly 4 months of acetic acid
Acetic acid
Acetic acid is an organic compound with the chemical formula CH3CO2H . It is a colourless liquid that when undiluted is also called glacial acetic acid. Acetic acid is the main component of vinegar , and has a distinctive sour taste and pungent smell...
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-covered lamina of bone present on the tabular bone. This indicated its spiracle
Spiracle
Spiracles are openings on the surface of some animals that usually lead to respiratory systems.-Vertebrates:The spiracle is a small hole behind each eye that opens to the mouth in some fishes. In the primitive jawless fish the first gill opening immediately behind the mouth is essentially similar...
s were almost as large as in the elpistostegalian
Elpistostegalia
Elpistostegalia or Panderichthyida is an order of prehistoric lobe-finned fishes which lived during the Late Devonian period . They represent the advanced tetrapodomorph stock, the fishes more closely related to tetrapods than the osteolepiform fishes...
fishes (like Tiktaalik
Tiktaalik
Tiktaalik is a genus of extinct sarcopterygian from the late Devonian period, with many features akin to those of tetrapods . It is an example from several lines of ancient sarcopterygian "fish" developing adaptations to the oxygen-poor shallow-water habitats of its time, which led to the...
) and early tetrapods (e.g. Acanthostega
Acanthostega
Acanthostega is an extinct labyrinthodont genus, among the first vertebrate animals to have recognizable limbs. It appeared in the Upper Devonian about 365 million years ago, and was anatomically intermediate between lobe-finned fishes and the first tetrapods fully capable of coming onto...
). Secondly, after preparation of its pectoral fins, the internal limb skeleton showed closer resemblances to that of the elpistostegalians than to other more generalised tetrapodomorph fishes like Eusthenopteron
Eusthenopteron
Eusthenopteron is a genus of prehistoric lobe-finned fish which has attained an iconic status from its close relationships to tetrapods. Early depictions of this animal show it emerging onto land, however paleontologists now widely agree that it was a strictly aquatic animal...
. For almost 100 years Eusthenopteron had been the well-used role model for demonstrating stages in the evolution of lobe-finned fishes to tetrapod
Tetrapod
Tetrapods are vertebrate animals having four limbs. Amphibians, reptiles, birds and mammals are all tetrapods; even snakes and other limbless reptiles and amphibians are tetrapods by descent. The earliest tetrapods evolved from the lobe-finned fishes in the Devonian...
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). Gogonasus is in superficial look similar to the generalised tetrapodomorph fishes like Osteolepis
Osteolepis
Osteolepis is an extinct genus of lobe-finned fish from the Devonian period. It lived in the Orcadian Lakes of northern Scotland....
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 almost 45 species of 3-dimensionally preserved fishes from the Gogo Formation deposit. It is the only Devonian
Devonian
The Devonian is a geologic period and system of the Paleozoic Era spanning from the end of the Silurian Period, about 416.0 ± 2.8 Mya , to the beginning of the Carboniferous Period, about 359.2 ± 2.5 Mya...
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 kapriosMcnamaraspis kapriosMcnamaraspis kaprios is an arthrodiran placoderm of the Family Plourdosteidae that inhabited the ancient reef system of north Western Australia during the Late Devonian period . The type specimen was found and described by John A. Long from the Gogo Formation near Fitzroy Crossing...
, another fish found by Long in the Gogo Formation. - TiktaalikTiktaalikTiktaalik is a genus of extinct sarcopterygian from the late Devonian period, with many features akin to those of tetrapods . It is an example from several lines of ancient sarcopterygian "fish" developing adaptations to the oxygen-poor shallow-water habitats of its time, which led to the...
- EusthenopteronEusthenopteronEusthenopteron is a genus of prehistoric lobe-finned fish which has attained an iconic status from its close relationships to tetrapods. Early depictions of this animal show it emerging onto land, however paleontologists now widely agree that it was a strictly aquatic animal...
- PanderichthysPanderichthysPanderichthys is a 90–130 cm long fish from the Devonian period 397 million years ago, of Latvia. It is named after the german-baltic palaeontologist Christian Heinrich Pander. It has a large tetrapod-like head...
- Coelacanthimorpha
- MaterpiscisMaterpiscisMaterpiscis is a genus of ptyctodontid placoderm from the Late Devonian located at the Gogo Formation of Western Australia...
External links
- Ancient Gogonasus advances evolution, Museum Victoria.
- Photographs and x-ray micro-tomography animation of Gogonasus from ANUAustralian National UniversityThe Australian National University is a teaching and research university located in the Australian capital, Canberra.As of 2009, the ANU employs 3,945 administrative staff who teach approximately 10,000 undergraduates, and 7,500 postgraduate students...
- Gogonasus andrewsae by PZ MyersPZ MyersPaul Zachary "PZ" Myers is an American biology professor at the University of Minnesota Morris and the author of the Pharyngula science blog. He is currently an associate professor of biology at UMM, works with zebrafish in the field of evolutionary developmental biology , and also cultivates an...
- Ancient Fish Fossil May Rewrite Story of Animal Evolution (National Geographic)
- Livescience.com: "Discovery Points to Our Fishy Heritage." (Accessed 10/21/06)
- Fox News: Primitive Fish Skeleton May Link Land, Sea
- Interview with Dr John Long, curator at the Museum of Victoria