Named By: Newberry - 1857.
Classification: Chordata, Sarcopterygii, Onychodontida, Onychodontidae.
Species: O. sigmoides (type), O. eriensis, O. jaekeli, O. jandemarrai, O. yassensis.
Size: Between 0.5 and 4 meters long depending upon individual and species.
Known locations: Australia - Gogo Formation. Canada - Dundee Formation. England. Germany. Norway. Russian Federation. USA.
Time period: Eifelian to Famennian of the Devonian.
Fossil representation: Numerous individuals of varying levels of completeness.
is a genus of large predatory fish that seems to have had a near global
distribution during the Devonian period. Onychodus
was a lobe-finned
fish with a pair of tooth whorls that grew large tusk-like teeth.
Onychodus was probably an ambush predator that
would quickly dart out
from cover to snatch unsuspecting fish as they swam by. One specimen
of Onychodus has been found with a placoderm fish
within its throat,
confirming that these types of fish perhaps among others formed part
of the diet of Onychodus.
Onychodus also had what is known as a kinetic skull. This means that the skull bones were not fused, but capable of moving around. The lower jaw also lacked a hard bony joint with the skull, and was instead connected by cartilage. These features would suggest that Onychodus may have tried for very large prey, perhaps even larger than the mouth would normally be. Once caught, the jaw would loosen up and work its way over the prey in a similar manner to how we would see a snake swallow an animal today.
- On the Occurrence of the Devonian Ganoid Onychodus in Spitzbergen. - Geological Magazine. 6 (3): 499–500. - Aerthur Smith Woodward - 1889.
- Onychodus jaekeli Gross (Crossopterygii, Oberdevon) Bau des Symphysenknochens und seiner Zähne. - Senckenbergiana Lethaea. 46a: 123–131. - Walter R. Gross - 1965.
- Die Crossopterygier des Oberen Plattenkalkes (Devon) der Bergisch-Gladbach-Paffrather Mulde (Rheinisches Schiefergebirge) unter Berücksichtigung von amerikanischem und europäischem Onychodus-Material. - Arkiv för Zoologi. Series 2. 18: 305–389. - Hans L. Jessen - 1966.
- Arthrodire predation by Onychodus (Pisces, Crossoptergii) from the Late Devonian Gogo Formation, Western Australia. - Records of the Western Australian Museum. 15: 479–481. - John Long - 1991.
- The structure of the sarcopterygian Onychodus jandemarrai n. sp. from Gogo, Western Australia: with a functional interpretation of the skeleton - Transactions of the Royal Society of Edinburgh Earth Sciences 96:197. - Mahala Andrews, John Long, Per Ahlberg & Richard Barwick - 2005.
- Morphological innovation through gene regulation: an example from Devonian Onychodontiform fish. - The International Journal of Developmental Biology. 50 (4): 371–375. - Ken Campbell & Ricahrd Barwick - 2006.
- A large onychodontiform (Osteichthyes: Sarcopterygii) apex predator from the Eifelian-aged Dundee Formation of Ontario, Canada. - Canadian Journal of Earth Sciences 54:233-241. - A. Mann, D. Rudkin, D. C. Evans & M. Laflamme - 2017.