Abrictosaurus

Name: Abrictosaurus ‭(‬Wakeful lizard‭)‬.
Phonetic: Ah-brik-toe-sore-us.
Named By: James A.‭ ‬Hopson‭ ‬-‭ ‬1975.
Synonyms: Lycorhinus consors.
Classification: Chordata,‭ ‬Reptilia,‭ ‬Dinosauria,‭ ‬Ornithischia,‭ ‬Heterodontosauridae,‭ ‬Heterodontosaurinae.
Species: A.‭ ‬consors‭ (‬type‭)‬.
Diet: Herbivore/Omnivore‭?
Size: 1.2‭ ‬meters long.
Known locations: South Africa,‭ ‬Cape Province‭ ‬-‭ ‬Upper Elliot Formation.
Time period: Hettangian to Sinemurian of the Jurassic.
Fossil representation: Two individuals.

       The description of Abrictosaurus was born out of the naming of a species of Lycorhinus earlier in‭ ‬1974.‭ ‬The palaeontologist Richard Thulborn had named Lycorhinus consors,‭ ‬based upon a partial skull and skeleton,‭ ‬UCL B54,‭ ‬of what seemed to be a Lycorhinus angustidens,‭ ‬but lacked the tusk like teeth at the‭ ‬front of the mouth.‭ ‬Then in‭ ‬1975,‭ ‬another palaeontologist named James Hopson was studying UCL A100,‭ ‬another partial skull of a heterodontosaurid that had been assigned to Lycorhinus angustidens by Thulborn.‭ ‬Hopson found the skull to be both different to Lycorhinus angustidens,‭ ‬but also similar to UCL B54,‭ ‬and thus split them from Lycorhinus and placed them within the newly created Abrictosaurus.
       Abrictosaurus is still defined by the remains of two individuals,‭ ‬one with the tusk like front teeth‭ (‬a.k.a.‭ ‬caniniforms‭) ‬the other without.‭ ‬This raises the serious possibility that the front tusks seen in Abrictosaurus,‭ ‬and by extension other heterodontosaurids were simply signs of sexual dimorphism,‭ ‬with the teeth being present in males,‭ ‬but absent in females,‭ ‬just like in many kinds of tusked animals known today.‭ ‬An alternative theory however is that the lack of teeth in one specimen could be because the genus Abrictosaurus is considered to be basal‭ (‬primitive‭) ‬to other heterodontosaur genera,‭ ‬with the teeth in this specimen simply not evolving yet.‭ ‬Alternatively again,‭ ‬the proportions‭ ‬of the skull of UCL B54‭ ‬are similar to those of known juveniles of other genera,‭ ‬and this raises the notion that the tusks had yet to grow in this individual.
       Aside from show,‭ ‬the next popular theory about the tusks is that they were feeding adaptations.‭ ‬This could be either for the digging up of plants such as roots,‭ ‬or even the killing of other small animals.‭ ‬These tusks were the only teeth in the anterior‭ (‬front‭) ‬portion of the mouth which was shaped into a cutting beak.‭ ‬Again this beak could have been used to crop vegetation,‭ ‬or slice flesh from a carcass.‭ ‬A further support for the meat eating theory is that the tusks of Abrictosaurus were serrated on the front half,‭ ‬and in other genera like Lycorhinus,‭ ‬the tusks were serrated upon both sides.‭ ‬The cheek teeth towards the rear of the mouth however overlap one another to provide a grinding surface,‭ ‬something of use for a herbivorous diet.‭ ‬It may simply be that dinosaurs like Abrictosaurus and other heterodontosaurids were omnivores,‭ ‬eating both animals and plants.

Further reading
-‭ ‬On the generic separation of the ornithischian dinosaurs Lycorhinus and Heterodontosaurus from the Stormberg Series‭ (‬Upper Triassic‭) ‬of South Africa,‭ ‬James A.‭ ‬Hopson‭ ‬-‭ ‬1975.
-‭ ‬A new heterodontosaurid dinosaur‭ (‬Reptilia:‭ ‬Ornithischia‭) ‬from the Upper Triassic Red Beds of Lesotho,‭ ‬Richard A.‭ ‬Thulborn‭ ‬-‭ ‬1974.



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