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Mosasaurs And Crocodylomorphs


megabass22

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I´ve always been slightly obsessed with mosasaurs, as they´re pretty cool, and when i was browsing around the web for inspiration of what to draw (i draw paleoart) i came across a picture of Dakosaurus. Dakosaurus was part of the family Metriorhynchidae (fully aquatic crocodylomorphs alive during the Jurassic and early cretaceous).

Even though classified differently, Dakosaurus and other metriorhynchids look awfully similar to mosasaurs, especially now with the discovery that mosasaurs, like metriorhynchids had a tail fluke.

One of the things that separate them is the secondary set of teeth that can be found in mosasaurs, and i suspect because of anatimical likeness, mosasaurs are classified as closely related to varanids. I don´t know much about varanid anatomy, but do they have secondary teeth? Also i do agree on that mosasaur skulls resemble varanids very much, but couldn´t that be convergent evolution (as metrorhycnhids and mosasaur likeness is explained today)?.

Here´s some images better explaining what i´m trying to say here:

Geosaurini.pngAs you can see, the larger, more primitive forms of metriorhynchids look more like crocodiles, while the smaller forms start to get a very mosasaurish appearance, compare Dakosaurus and Geosaurus to Mosasaurus (imagine it with a tail fule similar to theirs):

Mosasaurus_21copy.jpgOf course, i´m not a palaeontologist, and i don´t know enough about reptile anatomy, so if anything i say here is wrong, please correct me and prove this "hypothesis" to be wrong (even though i must say i don´t quite believe it myself), also i did not really look into the transitional species from varanids to mosasaurs before writing this (so don´t bash my head in too hard).

/Sebastian

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Nope, varanids do not have teeth on their palatine bone, like mosasaurs. But a variety of other reptiles and even fish do. As for convergent evolution... good question. You have to look at the bigger picture.. there is a whole lot of other stuff in both the skull and the skeleton that makes mosasaurs very similar to varanids.

Nice drawings. Is Dakosaurus from one of the Dakotas?

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(They're not my drawings, even though i've drawn some mosasaurs they're yet to be scanned in)

It was just a hypothesis anyway (weirder things have been proposed).

Dakosaurus is pretty much known from all over the world with fossils found in England, France, Switzerland, Germany, Poland, Russia, Argentina and Mexico, but not in any of the Dakotas (not in the US at all), dakosaurus means "biter lizard" ;)

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Now that I've seen those drawings, I think I would run into a great white shark at sea than a hungry Plesiosuchus!

Looking forward to meeting my fellow Singaporean collectors! Do PM me if you are a Singaporean, or an overseas fossil-collector coming here for a holiday!

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