It’s a rattlesnake! – Answer to Freak of the Week # 11
Congrats to Juli and to our intern Micayla, who recognized these as snake vertebrae! The distinctive feature that identifies these as reptilian is the “ball and socket” type joint between the vertebrae (termed procoelous). The “ball” structure is on the posterior end of the body of the vertebra and the corresponding “socket” is on the anterior end. Some types of reptiles will have this reversed but it’s this way for snakes. This structure gives the joint much more mobility and strength. Think of the other common ball and socket joint in the body, the femur and pelvis. It’s much harder to dislocate the femur than it is to dislocate a shoulder or knee!
We can also tell these are vertebrae from a rattlesnake as opposed to some other species of large snake based on the presence of the elongated ventral spine (haemal spine). This is distinctive for the pit vipers (Viperidae -Crotalinae). In Ohio this would narrow down the species to the timber rattlesnake, eastern massasauga (swamp rattlesnake), and copperhead. Based on the large size of these vertebra I would say these are from the timber rattlesnake (Crotalus horridus), the largest of Ohio’s venomous snakes.
Fortunately each major group of vertebrates has a distinctive morphology of the body of the vertebrae which allows us to readily identify them to at least mammal, bird, reptile, or fish. Mammals have a flat surface on the body of the vertebra (see the skunk vertebra in the photo) called amphiplatyan, while birds have an unusual saddle-shaped body of the vertebra (termed heterocoelus) which allows great mobility of the neck. Many people have seen fish vertebrae, with their distinctive concave surface on both ends. I remember opening a can of tuna once and seeing a complete fish vertebra lying on top of the meat! Being the dork that I am, I said “Oh cool, a procoelous fish vertebra!”