Earlier this week I had a chance to look through some specimens that were recently donated to the Dead Zoo. Most were well identified and labelled by the gifted naturalist who collected them, the late Dr Don Cotton, but this specimen was lacking a label:
Do you have any thoughts about what it might be from? As usual you can leave your observations, questions and suggestions in the comments box below. Have fun!
Zygoma 
Mysteriously thin…a well-wave-washed cetacean cervical? Possibly something of a corpse-whale?
don’t know why, but called cetacean to me too….
Yes cetacean, but I would say a T-1 with that broken rib. Clueless as to which critter.
Supposing it is Cetacean (I’m still on the fence about that)… I think of Cetacean centra as a bit longer in proportion than this… except for cervicals. Now, cervicals are often fused, but in some species there are at least a few that look (in a whole skeleton) as if they might be separate. And they have very short (compressed) centra. And the absence of any obvious place for a rib to attach suggests this as well.
Look at the second picture. It looks like there is an articular facet for a rib. But no facets on the first picture. And the pictures of the rib. I think that was a clue.
… A few minutes of image search and…
I’m feeling a good deal more confident of the Cetacean identity of the specimen. So also still feeling it’s probably a cervical. (Compressed length of centrum I think would be unexpected elsewhere.)
… Maybe too big to be one of the smallest dolphins or porpoises, but too small to be a big whale? So maybe in the large dolphin area? Caviar to someone who can find a smallish but not too small whale with unfused vertebrae.
I will agree on cetacean- and the atlas vertebrae. Now… who’s?
Maybe from a bubble-headed or unicorn cetacean? I even considered the grazing Florida native.
Very definitely an odontocete cervical ( I’m assuming its too small to a baleen whale of any sort), Definitely not an atlas, those have distinctive double facets on the anterior face to cup the twin occipital condyles. I found a picture of a narwhal cervical that indicates a centrum height of approximately 7-8 cm which is roughly in range of this bone, so perhaps too big to be anything but the largest of delphinids. The squarish centrum and slender downwardly projecting capitulum seem to be distinctive but I can find no match so far.
Hmmm… Narwhals and my nominee are each other’s closest relatives, so I’ll be pretty happy if it turns out to be either. … The collector, Don Cotton, seems to have been based in Ireland for much of his career, so there might be a geographical clue: which species would have to stray further from its normal range to die and leave bones on an Irish beach?
About monodons, wiki says, “their neck vertebrae are jointed like those of most other mammals, not fused as in dolphins and most whales.” Is that what we’re seeing here?
Sallie Reynolds– That was what I was guessing, but I haven’t looked at actual specimens. So: guessing.
Compare pictures here:
https://www.researchgate.net/figure/Cervical-vertebrae-of-four-marine-mammals-Scale-bars-5-cm-a-Narwhal-Monodon_fig6_273805616
The centrum at researchgate is a bit squarish, but not as squarish as Paolo’s specimen: still, there are six cervicals to choose from (given that it’s not an atlas) and they may not all be exactly the same shape.
And Paolo’s specimen is definitely not from a seal!