Specimen of the Month: Skull Stories

Skulls tell stories. Have you ever looked at the sharp teeth of a large cat at the zoo, or perhaps a mighty dinosaur in a museum, and imagined yourself in the role as that carnivore's prey? Do puncture wounds or other markings on the bone surface share some insight on the animal's last fateful interaction? 

I recently brought a black bear skull along to a children's Halloween program that I led. The miniature scarecrows, princesses, and and other young ones squirmed around with index fingers ready as I passes around a myriad of props for them to feel. A bit to my surprise, they were already well versed in the anatomy of many of the animals we addressed that evening. As I presented the large skull of a black bear to the group, though, speculations as to its identity ranged from a tiger to a shark. 

Although I made sure to preface the guessing game with a note that we might find the mystery animal roaming local forests, the children had a tough time with it. I hypothesize that some of the issue in that came from the teeth. Black bears feed on plant materials as well as the meat of small animals and insects. As omnivores, their teeth characteristics are a combination of those from carnivores and herbivores. Front incisors are well developed and cheek teeth are likewise adapted for handling plant material as they are wide and cusped. Still, those canines are intimidatingly large and pointed which allows them to kill and hold the occasional prey or simply tear open rotting logs for grubs. 

We had enough time between unrelated stories and requests to feel the skull again to squeeze in a few more characteristics of the black bear. I pointed out a fin-like protrusion on the rear top of the bear's skull. "This is called a sagittal crest. It's a fancy science word we use for this part of the skull. Can you all try to say that word with me?"

I admit I had to do a little research on this before the program. A sagittal crest is where chewing muscles on the jaw attach to the back of the skull. A more pronounced crest indicates that an animal has a powerful bite and can also indicate a rougher diet. Most skull characteristics actually relate to eating habits, even if not directly. 

We already know that a bear is an omnivore--thus also a predator. Their eyes are a relatively small part of their skull--smaller than those of a mountain lion, for example--but in a discussion of predator and prey characteristics, we consider the placement rather than size. The orbits of both bears and mountain lions face towards the front of the skull. Most predators rely on their binocular vision which is established by their forward eye placement, but prey look elsewhere. Prey animals, like deer, survive in part because their eyes are instead oriented to the side of their skulls. It's also one way for little humans to investigate the differences in animal bones. 

There wasn't time to go into too much detail before the spooky cake walk was set to begin, but the children and I filled the rest of our time together by observing turtle shells, antlers, and loon sternums. And just like the impressive bear skull, each successive piece told a story.