The ribs are pachyosteosclerotic - i.e. pachyostotic (ribs inflated outwards with dense bone) and osteosclerotic (medullary cavity smaller, rimmed by dense bone). This is an adaptation for negative bouyancy - otherwise, they'd have a hard time staying submerged. Sirenian bones are extremely dense, to the point where sometimes fragments of their bones in the field can be mistaken for fragments of teeth.
There's a dugong skull in the local natural history museum, so I'm unfazed by the bizarre appearance of the manatee skull. It's the body that freaks me out- pachyostotic ribs, and check out the fingers! If all sirenians were extinct, I wonder if there are any clues that would prevent us from restoring them with webbed hands instead of flippers.
Those are some sturdy ribs. Is that due to strong muscles attached or for armor?
The ribs are pachyosteosclerotic - i.e. pachyostotic (ribs inflated outwards with dense bone) and osteosclerotic (medullary cavity smaller, rimmed by dense bone). This is an adaptation for negative bouyancy - otherwise, they'd have a hard time staying submerged. Sirenian bones are extremely dense, to the point where sometimes fragments of their bones in the field can be mistaken for fragments of teeth.
There's a dugong skull in the local natural history museum, so I'm unfazed by the bizarre appearance of the manatee skull. It's the body that freaks me out- pachyostotic ribs, and check out the fingers! If all sirenians were extinct, I wonder if there are any clues that would prevent us from restoring them with webbed hands instead of flippers.