A lot of the work done by paleontologists and biologists, especially those that work on taxonomy and systematics, is trying to identify general characteristics that various groups of animals have in common and that differ in other groups. The characters are the raw material that we use to define and identify species, to unravel the evolutionary relationships between those species and group them into higher taxa, and to identify sexes, ages, and other features. But, of course, the smallest unit we deal with is the individual animal, and sometimes fossils are emphatically, stubbornly individualistic.The Valley of the Mastodons exhibit has given us a chance to pull lots of mastodon remains out and compare them more easily, which makes some of the individual characteristics more visible. One interesting specimen that is going to merit a close look at some point is a series of relatively small associated neck and back vertebrae. These vertebrae are not associated with teeth or tusks, but their morphology is well within the range for mastodons, if on the small side (I have seen smaller, however).
The unusual thing about these vertebrae is the texture of the bone, particularly the vertebral centra, as can be seen in the 5th vertebra (above). This bone has a strange, lightweight texture that I haven't seen before; it almost looks like strips of bone woven together. It seems to be concentrated on the centra, and seems to present to some degree on all of the vertebrae for which the centrum is preserved.I'm not sure what this is. Could it be some type of taphonomic damage, caused by weathering, or maybe being eaten by insects? Maybe, although the fact that it's found only on the centra but on all the centra makes this less likely. Or could it be some type of bone disease, some type of cancer or osteoporosis-like condition? I lean toward this explanation, but at this point I'm not really very confident in that answer either.If you want to look at the bones yourself and make your own guess, the vertebrae are in the Valley of the Mastodons exhibit until this May.