A freshwater plesiosaur? Meet Fluvionectes

[Halichoeres]

A new elasmosaurid has been described from the Dinosaur Park Formation (Alberta, Canada). Fluvionectes sloanae ("Sloan's river swimmer"), named for Donna Sloan, who discovered the holotype and does scientific illustration for the Royal Tyrrell Museum. The deposits where it was found are either riverine or estuarine, hinting that maybe plesiosaurs swam up rivers at least occasionally.

A diagram of the holotype:


Campbell et al., open access in PeerJ: https://peerj.com/articles/10720/

And an interview with Campbell: https://peerj.com/blog/post/115284883809/author-interview-a-new-elasmosaurid-sauropterygia-plesiosauria-from-the-non-marine-to-paralic-dinosaur-park-formation-of-southern-alberta-canada/?utm_source=twitter&utm_medium=Social&utm_campaign=BlogAI

[Gothmog the Baryonyx]

Oh, thats an interesting find. Doesn't seem out of the question

[CityRaptor]

Well, river dolphins are a thing, so why not Plesiosaurs?

[Halichoeres]

Why not indeed? But they do seem to be really scarce in freshwater environments for whatever reason, maybe because they have a hard time maintaining ion balance if they're adapted to a particular water chemistry. Transitions from saltwater to freshwater happen, but they're not exactly a typical trajectory.

[Faelrin]

Absolutely fascinating discovery and from one of my favorite formations as well.

[DinoToyForum]

There are quite a lot of plesiosaurs already known from brackish or fresh(ish) water deposits, connected to the ocean. Good to see another one. But still none from truly fresh water deposits (e.g. lakes).

They had to get their gastroliths from somewhere.

[Halichoeres]

Wait, you mean there aren't any fossils from the vicinity of Loch Ness??? 

[DinoToyForum]

Wait, you mean there aren't any fossils from the vicinity of Loch Ness??? 

Weeeell, there was this one time... http://news.bbc.co.uk/1/hi/scotland/3069803.stm
Totally legitimate and not at all suspicious, I'm sure you'll agree.

[Halichoeres]

Bahaha, yes, absolutely compelling.