Dryadissector

Name: Dryadissector ‭(‬Dryad dissector‭)‬.
Phonetic: Dry-ad-iss-sek-tor.
Named By: Stephen L.‭ ‬Wick,‭ ‬Thomas M.‭ ‬Lehman‭ & ‬Alyson Brink‭ ‬-‭ ‬2014.
Classification: Chordata,‭ ‬Reptilia,‭ ‬Varanoidea.
Species: D.‭ ‬shilleri‭ (‬type‭)‬.
Diet: Carnivore.
Size: Unknown.
Known locations: USA,‭ ‬Texas‭ ‬-‭ ‬Aguja Formation.
Time period: Campanian of the Cretaceous.
Fossil representation: Teeth.

       At the time of the genus description and writing of this,‭ ‬Dryadissector is known only from teeth,‭ ‬but these teeth are nonetheless very interesting indeed.‭ ‬At a glance these teeth are very similar to those of small theropod dinosaurs,‭ ‬laterally compressed and serrated like knives,‭ ‬while recurved so that prey that was impaled upon them could not pull itself free out of the mouth.‭ ‬However,‭ ‬these teeth have a bulge near the base on the inside surface,‭ ‬something that is unheard of in theropod dinosaurs,‭ ‬but common in varanid lizards which would have also been around at this time.‭ ‬This has led the describers to conclude that Dryadissector would have been a varanid lizard‭ (‬possibly similar to a modern day monitor lizard‭)‬,‭ ‬but with teeth exceptionally well adapted to slicing through the flesh of animals.
       Reptiles are known to shed and regrow their teeth throughout their lives,‭ ‬and so far all the teeth of Dryadissector seem to have been shed by living individuals,‭ ‬which by extension helps explain why no actual bones have been so far found.‭ ‬This makes Dryadissector a tooth taxon,‭ ‬and traditionally tooth taxons are problematic because it is very difficult to infer additional non tooth remains to the genus.‭ ‬However it is not impossible,‭ ‬the dinosaur genus Troodon was first named from teeth,‭ ‬and was later attributed skeletal remains thanks entirely to the teeth being so unique.‭ ‬Likewise,‭ ‬because the teeth of Dryadissector are so specialised,‭ ‬it may be easier to attribute skeletal fossil remains to this genus,‭ ‬especially jawbones with teeth still attached.‭
       On a further note about the teeth,‭ ‬when you count up the number of Dryadissector teeth known from lower Aguja Formation,‭ ‬they actually outnumber the teeth of all the known teeth from theropod dinosaurs from the Aguja Formation combined.‭ ‬This raises a speculative but very interesting question,‭ ‬were varanid lizards like Dryadissector actually outcompeting the smaller theropod dinosaur predators,‭ ‬at least in Texas anyway‭?


Further reading
-‭ ‬A theropod tooth assemblage from the lower Aguja Formation‭ (‬Early Campanian‭) ‬of West Texas,‭ ‬and the roles of small theropod and varanoid mesopredators in a tropical lizard predator guild.‭ ‬Palaeogeography,‭ ‬palaeoclimatology.‭ ‬-‭ ‬Palaeoecology‭ ‬-‭ ‬Stephen L.‭ ‬Wick,‭ ‬Thomas M.‭ ‬Lehman‭ & ‬Alyson Brink‭ ‬-‭ ‬2014.





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