Cynognathus

Name: Cynognathus dog jaw‭)‬.
Phonetic: Sy-noe-nay-fuss.
Named By: Harry Govier Seeley‭ ‬-‭ ‬1895.
Synonyms: Synonyms may include Cistecynodon parvus,‭ ‬Cynidiognathus broomi,‭ ‬Cynidiognathus longiceps,‭ ‬Cynidiognathus merenskyi,‭ ‬Cynognathus beeryi,‭ ‬Cynognathus minor,‭ ‬Cynognathus platyceps,‭ ‬Cynogomphius berryi,‭ ‬Karoomys browni,‭ ‬Lycaenognathus platyceps,‭ ‬Lycochampsa ferox and Lycognathus ferox,‭ ‬though not all authors agree to the exact synonymy of these.
Classification: Chordata,‭ ‬Synapsida,‭ ‬Therapsida,‭ ‬Cynodontia.
Species: C.‭ ‬crateronotus‭ (‬type‭)‬,‭ ‬C.‭ ‬seeleyi.
Diet: Carnivore.
Size: Body length up to‭ ‬1‭ ‬meter long,‭ ‬Skull up to‭ ‬30‭ ‬centimetres long.
Known locations: Antarctica,‭ ‬Argentina,‭ ‬China,‭ ‬South Africa.
Time period: Anisian of the Triassic.
Fossil representation: Multiple fossils,‭ ‬Cynognathus is one of the most numerous and completely reconstructed cynodonts.

       Cynognathus seems to be one of the most successful of the cynodonts,‭ ‬with a large number of fossil remains from a wide geographic distribution being all attributed to the genus.‭ ‬There is however some controversy over whether all of these fossils should be labelled as Cynognathus,‭ ‬as the genus does seem to have suffered from the‭ ‘‬wastebasket taxon‭’ ‬effect.
       Despite this the appearance of Cynognathus‭ ‬is known without doubt.‭ ‬In general appearance Cynognathus was a stocky animal with a proportionately large skull that made up thirty per-cent of the total body length.‭ ‬The skull was robust‭ ‬and was likely capable of inflicting powerful bites.‭ ‬The teeth were sharp,‭ ‬and slightly re-curved,‭ ‬and driven by the jaw muscles were easily capable of piercing the tough hides of the known herbivores of the early Triassic.‭ ‬In addition they was some variance in the form of the teeth suggesting that Cynognathus processed food by jaw movement,‭ ‬cutting meat up into smaller bits rather than just trying to swallow chunks whole.‭ ‬The skull also features a hard secondary palate,‭ ‬something that proves that Cynognathus would have still been able to breathe when the mouth was full of food.
       The post cranial skeleton of Cynognathus is also quite interesting.‭ ‬The ribs do not extend into the abdomen which means two things.‭ ‬One is that Cynognathus likely had a diaphragm,‭ ‬a sheet of muscle that separates the lungs from the lower organs,‭ ‬a feature commonly seen in mammals that aids in respiration.‭ ‬Two is that the lower body would have been much more flexible thanks to the absence of the ribs.‭ ‬The rear legs of Cynognathus supported the hind quarters from underneath,‭ ‬but at the same time the front legs sprawled out to the sides like in more primitive therapsids.‭ ‬Although Cynognathus might have been an unusual runner,‭ ‬it was almost certainly fast enough to catch other therapsids.

Further reading
Researches on the Structure,‭ ‬Organization,‭ ‬and Classification of the Fossil Reptilia.‭ ‬Part IX,‭ ‬Section‭ ‬5.‭ ‬On the Skeleton in New Cynodontia from the Karroo Rocks.‭ ‬-‭ ‬Philosophical Transactions of the Royal Society of London B‭ ‬186:59-148‭ ‬-‭ ‬Harry Govier Seeley‭ ‬-‭ ‬1895.



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