The End Ordovician Extinction seems weird to paleontologists. There’s a lot of agreement on the earth cooling at the end of the Ordovician, right up to evidence of major glaciation and a harsh ice age, but there are serious suggestions that will boggle your mind.
Thalattosuchians are an under-rated clade of mesozoic animals. Part of Pseudosuchia, the crocodile-like archosaurs, they were completely adapted to a marine lifestyle.
That’s the shoulder and pelvic girdle of the plesiosaur (elasmosaur maybe) skeleton cast that the Fort Collins Museum of Discovery has on display.
Looks like three groups of marine diapsids, ichthyosaurs, mosasaurs, and thalattosuchians, all evolved “hypocercal” tail fins.
If you happen to be in Casper, Wyoming, you should visit Tate Geological Museum. It’s a small, but very well done geology and paleontology museum. There’s interesting things for most family members, even well-informed 4-year-olds could have fun and learn things.
