A Mosasaur From Hell Creek

[suspsy]

https://escholarship.org/uc/item/8v08w2d6

Either Mosasaurus itself or Prognathodon. Pretty cool to imagine it hunting dinosaurs in the shallows like an orca!

[Dynomikegojira]

Several Deviantart users were aware of this for years from what I remember.

[Reuben03]

best news i've had in awhile. thanks for sharing.

[suspsy]

I'd love for it to be a species of Prognathodon instead of Mosasaurus for the simple reason that the former is a really awesome predator that gets overshadowed by the latter and Tylosaurus.

[Faelrin]

Honestly any mosasaur that isn't Mosasaurus and Tylosaurus gets overshadowed, so it would be interesting if it belongs to Prognathodon.

Regardless of what this is though, it is a great find and helps flesh out Hell Creek's coastal environment, although I do wonder how long this find has been known of, since if I recall right, I think the Saurian team justified having Mosasaurus in the game because of some unspecified remains discovered, or some such, other then needing a border guard to encourage the player to not go out of bounds. I'll have to dig for it because I think it was explained in a blog post years back.

[Reuben03]

I'd love for it to be a species of Prognathodon instead of Mosasaurus for the simple reason that the former is a really awesome predator that gets overshadowed by the latter and Tylosaurus.

Tim Haines' Masterpiece, the immersive exhibition 'Dinosaurs in the Wild' depicted a group of researchers in hell creek on what I believe was called 'timebase 67'
I was lucky enough to experience Dinosaurs in the Wild, and their depiction of this then undescribed mosasaur was the standout to me. They depicted it as a Prognathodon and it was shown leaping from the water to drag a drinking baby triceratops to its watery demise.

later on when a tyrannosaur became curious and begin to bump its head into the glass of the viewing dome, we had to evacuate and enter an underwater chamber below the facility for safety.

The prognathodon seemed curious and swam over to the glass as shutters closed over us, it looked through the glass right at me, making eye contact and almost looking through me. it was fantastic to see the animal portrayed like that. a marine monitor, with the mind of a killer whale.

Hopefully Dinosaurs in the Wild returns to london again, so other people can experience what i did.

[andrewsaurus rex]

interesting to think of, at least some mosasaurs, as having a nile crocodile-like lifestyle, picking off drinking and wading fauna.  It may just have been one of the environments mosasaurs patrolled for food, rather than its only hunting ground.

And I agree with the comments about Prognathodon.  A very cool animal that barely gets a mention, which is curious.  It was large, nearly as large as Mosasaurus itself, with a much heavier built and more robust skull.  Very interesting animal.

[stargatedalek]

Hell Creek had a lot of freshwater fauna, and it seems far more likely mosasaurs that could fit into the marshes and rivers were hunting the numerous giant turtles and crocodiles than risking their lives trying to snatch drinking dinosaurs. They may have even chased marine prey into shallow marshes to corner them like some dolphins do, or the young may have sheltered in fresh or brackish water like some sharks.

[andrewsaurus rex]

this brings up an interesting question: could mosasaurs live in fresh water and salt water or just one or the other?  Perhaps they would live in one and venture briefly into the other?   Crocodiles can live in both, but alligators much prefer fresh.  So perhaps diff't species of mosasaur had similar diverse preferences.

[stargatedalek]

this brings up an interesting question: could mosasaurs live in fresh water and salt water or just one or the other?  Perhaps they would live in one and venture briefly into the other?   Crocodiles can live in both, but alligators much prefer fresh.  So perhaps diff't species of mosasaur had similar diverse preferences.

It's a lot easier for reptiles than for fish due to breathing air. The issue then comes down to drinking, drinking salt water and eating only foods laced heavily with salt adds a lot and marine reptiles need special adaptations for removing that salt from their bodies. So freshwater reptiles can have a very hard time in saltwater, though depending on what they're eating they can still hunt there and return to freshwater to rest and drink which IIRC is what most crocodiles do. Saltwater reptiles (and cetaceans) however tend to do just fine in freshwater, and its not uncommon to find marine turtles feeding in brackish or even fresh water. In theory they could develop salt related deficiencies due to forcing out so much of it, but that would take a very long time, months if not years, to develop.