Skulls

[seabat]

Does anyone know what type of skulls these are?

Took a dive last Sunday at Ediz Hook, WA and found skull3 behind a submerged log. Its about 4 inches in length, and was pretty fragile. Sorry about the sharpness of the photo, was having some bouyancy control difficulties.

Skull4 was found on the beach at Dungeness Spit. I am guessing either a bear or a seal due to the teeth pits but as I never seen either I thought I would ask. It was about 1-1/2 ft long.

 

[Scubaroo]

I'm thinking a freshwater turtle?

 

[archman]

Turtle skulls are massive affairs, thick-boned and lacking "holes" for muscle attachments. I forget the anatomical descriptor for being "hole-less", but it separates anapsids (turtles) from other reptiles, including dinosaurs. Once you see a turtle skull it sticks out in your mind forever. Look at this link.
http://www.nhc.ed.ac.uk/collections/reptiles/skulls.html

I would guess the first skull is from a fish.

The second skull is definitely a large carnivorous mammal. I don't see enough bear or seal skulls to know the key differences. That would be a honking big seal, however! Go to this link and see if you can find the appropriate looking skull.
http://animaldiversity.ummz.umich.edu/site/accounts/specimens/Carnivora.html

 

[Scubaroo]

That picture is of a saltwater turtle. I was thinking more along the lines of a freshwater type creature. Look at the last skull on this page - much different to the ocean going turtles or land tortoises.

http://www.azdrybones.com/testudines.htm

 

[archman]

The last photo on this page, described as ... "A chelid, or side-necked, turtle, this is the strangest turtle skull of any, living or extinct". Is THAT what you're referring to? Ack. In any case it's still displays an anapsid cranial structure.

Turtle evolution is extremely conservative. The overall cranial structure has not altered significantly since before the Mesozoic. Differences between freshwater, saltwater, and terrestrial species are few and mostly dietary in nature, which concerns the mandible primarily (which is not present in the mystery photo).