I found this vertebral column on the beack on St Martin's Isles of Scilly a few years ago. I don't know if it is a porpoise, seal or dolphin - I assume it's one of these - and wonder if you can help?
Great find! I dont think its Seal though - I have a dozen or so Seal vertabrae (definately Seal - I extracted them myself after finding most of one washed up) and they dont look like yours.
This is the spine from a small cetacea, most probably a porpoise
Dolphin - I have a dozen or so vertabrae that I removed from a very dead and stinky one washed up on the Harris in the Hebrides
The thickness of porpoise vertebra is about 18-20mm and the diameter of the bodies about 25mm. Dolphin have a simillar thickness but the diameter is larger at 50-55mm. It is very difficult to identify exact species from morphology alone because all british dolphin species are very simillar. Size then becomes very important. If the diameter of the vertebra is around 25mm it can only be porpoise. If it is around 50mm then it could be a number of dolphin species.