Marine mammal bone? Templeton, CA (6”x3” or 15x7.5 cm)

[Slow_BS]

Hi there,

 

I found this in a field in Templeton, CA, in an area surrounded by jasper and chert. I’ve read (including on here, thanks!) that the area is known for marine mammals, but I have no idea what I’m doing when it comes to bone ID. Any help is appreciated, even if you tell me it’s bbq. 
 

Thanks for reading!

[pachy-pleuro-whatnot-odon]

Looks like bone, looks mineralised, appears osteosclerotic... I'd say marine mammal bone is indeed a likely candidate. Unfortunately, I'm not too well versed in mammal material, so wouldn't be able to tell you what it is. The surface on the first photograph makes it look like a whale vertebra, worn down to the absolute core, but we'd probably better hold off to hear from those more experienced with marine mammals to see what it may actually be - if it still can be identified at all. If cetacean, someone like @Shellseeker or @RJB might be able to help...

[Fossildude19]

@Boesse

[Boesse]

This is a very fragmentary baleen whale vertebra - but it is not osteosclerotic. Osteosclerotic means it has reduced marrow cavity and is generally dense; this is completely composed of porous cancellous bone.

Edited October 8, 2021 by Boesse

[Shellseeker]

1 hour ago, Boesse said:

This is a very fragmentary baleen whale vertebra - but it is not osteosclerotic. Osteosclerotic means it has reduced marrow cavity and is generally dense; this is completely composed of porous cancellous bone.

Bobby, I am intrigued.

Can you provide the differentiators that have you leaning toward baleen versus toothed. I am fortunate that I can recognize the porous cancellous bone as marine mammal.

[Boesse]

Based entirely on the size in this case - odontocete vertebrae are typically quite small. Most fossil odontocetes have vertebrae under 10cm long, with the exception of some sperm whales, rare beaked whales, rare globicephaline delphinids, and some giant archaic dolphins like Ankylorhiza.

[Slow_BS]

I hope you guys know what a great ripple effect your contributions on here make. My daughter’s class just had a unit on whales and she’s so excited by this. 

[pachy-pleuro-whatnot-odon]

22 hours ago, Boesse said:

Osteosclerotic means it has reduced marrow cavity and is generally dense; this is completely composed of porous cancellous bone.

 

I hope you don't mind my asking, but I was under the impression that what you're describing is called pachyostosis - a thickening of the layers of lamellar bone towards the cortex that, coincidentally, also leads to a reduced marrow cavity - with osteosclerosis rather being an increase in the density of vascularization of the cancellous bone (which is what I think I'm seeing here). The two conditions together, often seen in marine reptiles, then being referred to as pachyosteosclerosis. But may be I'm getting my terminology mixed up, or my diagnosis about the nature of the vascularization of the bone is wrong...?