Oregon Coast Rib ID

[Oregon Coast Agates]

So this was one of my first fossil finds from last winter on the Oregon Coast and I still need help identifying it further. It was tossed up on the rocky shoreline one day after a winter storm in the Stonefield Beach State Rec area (Central Oregon Coast). 

 

I've sent photos to the Burke Museum's ID dept along with a few other museums that's offer opinions on fossils based on photo's and they've all said its definitely a rib, and but the debate is now between a Baleen/Whalebone or the Steller's Sea Cow. I've gotten mixed opinions from several museum experts but I would like to know or see if anyone else has come across ones like this on here and maybe has a more definitive answer. 

 

Thank you for taking a look!

 

Specs: 

 

Weight: 3.7lbs

Length: 15"

Width: 3.5"

Depth: 2"

[RJB]

  My youngest son when he was about 6 or 7 found a hunk of fossil rib bone walking the surfline along capitola.  I didnt know he had been listening to his dad with all the scientific names.  He told me it was "honkus ribis".   You can use that kid made Genus and species if you want.   But really, I wish I could help.  I do wish good luck in your IDing endeavor.

 

RB

[Fossildude19]

@Boesse

[Lorne Ledger]

It's from a big animal - my guess is whale of some kind or a huge walrus.