Tethyshadros

Name: Tethyshadros ‭(‬Tethys hadrosaur‭)‬.
Phonetic: Tef-iss-had-ross.
Named By: Fabio M.‭ ‬Dalla Vecchia‭ ‬-‭ ‬2009.
Classification: Chordata,‭ ‬Reptilia,‭ ‬Dinosauria,‭ ‬Ornithischia,‭ ‬Ornithopoda,‭ ‬Hadrosauroidea.
Species: T.‭ ‬insularis‭ (‬type‭)‬.
Diet: Herbivore.
Size: About‭ ‬4‭ ‬meters long.
Known locations: Italy‭ ‬-‭ ‬Liburnia Formation.
Time period: Late Campanian of the Cretaceous.
Fossil representation: Holotype almost complete skull and post cranial skeleton preserved on a slab.‭ ‬Remains of several individuals are known.

       Tethyshadros is without doubt one of the more interesting genera of hadrosauroid dinosaurs.‭ ‬For a start hadrosauroids are not particularly well known from Europe,‭ ‬though large ornithopod dinosaurs which were ancestral to them are.‭ ‬Tethyshadros also seems to‭ ‬have been a dwarf hadrosaur,‭ ‬growing to an average length of four meters.‭ ‬This reduction in size seems to have come about from a reduction in the post cranial skeleton,‭ ‬as the skull is notably large in proportion to the rest of the skeleton.‭ ‬The limbs are also relatively long and more gracile than relative genera.‭ ‬This length and a reduction in digits seem to have been adaptations for a greater reliance upon cursorial‭ (‬ground‭) ‬movement.
       The small size of Tethyshadros seems to have been caused by an effect termed‭ ‘‬insular dwarfism.‭ ‬This is where a population of animals that find themselves living on a restricted landmass with limited food resources will progressively grow smaller over successive generations.‭ ‬This is because evolution would favour those individuals which did not have to eat so much,‭ ‬so that they would survive to breed for longer,‭ ‬and by extension a balance would be attained where a population level could stabilise without outstripping the available food resources for a given area.
       How a population of Tethyshadros came to be restricted to an island has already become a matter of debate.‭ ‬We know that ancestral forms of the hadrosauroid dinosaurs,‭ ‬typicially iguanodonts,‭ ‬were present in Europe all the way back to the Jurassic,‭ ‬and that various forms such as Zalmoxes and Rhabdodon were still present at the end of the Cretaceous.‭ ‬However in the original‭ ‬2009‭ ‬description of Tethyshadros,‭ ‬Dalla Vecchia favoured the idea of island hopping.‭ ‬This is a very plausable notion as during the Mesozoic Europe was not one major landmass as it is today‭; ‬instead it resembled a collection of random islands and archipelagos.‭ ‬It is quite possible that as time progressed,‭ ‬sea levels altered,‭ ‬and lands shifted,‭ ‬some creatures were able to exploit these changes to progress into new areas.
       Tethyshadros was named after the Tehthys Ocean,‭ ‬an ancient body of water that once‭ separated the northern continents from the southern continents.

Further reading
-‭ ‬Tethyshadros insularis,‭ ‬a new hadrosauroid dinosaur‭ (‬Ornithischia‭) ‬from the Upper Cretaceous of Italy.‭ ‬-‭ ‬Journal of Vertebrate Paleontology‭ ‬29‭(‬4‭)‬:1100-1116.‭ ‬-‭ ‬Fabio M.‭ ‬Dalla Vecchia‭ ‬-‭ ‬2009.



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