So often the traces that animals leave behind are slight or quick to fade. Footprints are washed or melted away, chew marks are grown over and droppings are absorbed into the surroundings. But bones, at least some bones, hang around a bit longer. It’s common to come across the skeleton of a dead animal or at least a skull or vertebrae left behind.
Naturalist Selby M. considers this skull at the front desk of North Chagrin Nature Center. What is it? A Virginia opossum skull.
To whom did it belong? Does it have stories to tell? What will happen to it as time passes? These are all the questions that are sparked by the finding of a bone. Or, finding a bone with a child brings some of my favorite questions. Is it dead? Where did the eyes go? Are my bones like that?
The most common bone brought into a nature center is a skull, or part of a skull. And since we are often familiar with how animals’ heads appear, it can make identification not too difficult. Check first the size. How big might have the live head have been? The muscles, skin, fur and feathers take up more bulk than you might imagine, so skulls can appear surprisingly small. Now you have an idea of how big the animal was.
beaver skull on the left; muskrat skull on the right
Now look at the teeth. Are the front teeth large and flat, built for shearing off plant material or wood? This is how rodents look – with grinding teeth in the back. Carnivore and animals that hunt, have teeth that are made for catching, crushing and tearing. Coyotes, raccoons, weasels and other carnivores have large canines that clearly belong to meat eaters. Deer lack front teeth on their top jaw and the teeth in the back are well suited for chewing up branches and vines.
beaver (herbivore) skull on the left; coyote (carnivore) skull on the right
One of my favorite parts about exploring bones is how similar the bones of different species are to each other and even to human bones. A turtle’s shell is made up of its spine and fused ribs. A bat’s wing is made up of the same bones you’ll find in my hands, only greatly elongated and specialized. At first look it seems like a frog only has one bone where we have two, the tibia and fibula. But upon closer inspection, the two bones that are distinct are fused in the frog. This provides for a stronger support for extreme jumping and landing.
common snapping turtle shell inside of the turtle shell showing spine and fused ribs
white-tailed deer pelvis fragment on the top; mouse pelvis fragment on the bottom
So what happens to the bones when they are left to nature? Call the FBI! No, not law enforcement. Fungus, Bacteria and Invertebrates do a good job of cleaning up nature of its decaying matter. Bones are also eaten by rodents and even carnivores for their high nutritional content. While we know that occasionally bones are left intact for long periods of time, most bones are recycled by nature within a short period of time.
Photo by Jeff Riebe
If you find a bone that captures your interest, bring it by one of the Cleveland Metroparks Nature Centers. We’d be happy to help you solve the mystery of what you’ve found. We may never be hired by The Jeffersonian as a forensic anthropologist, but we can marvel as the wonders left behind by nature.