Name: Onychodus ‭(‬claw tooth‭)‬.
Phonetic: On-e-ko-dus.
Named By: Newberry‭ ‬-‭ ‬1857.
Classification: Chordata,‭ ‬Sarcopterygii,‭ ‬Onychodontida,‭ ‬Onychodontidae.
Species: O.‭ ‬sigmoides‭ (‬type‭)‬,‭ ‬O.‭ ‬eriensis,‭ ‬O.‭ ‬jaekeli,‭ ‬O.‭ ‬jandemarrai,‭ ‬O.‭ ‬yassensis.
Diet: Piscivore/Carnivore.
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.

       Onychodus 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.

Further reading
-‭ ‬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.


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