Bones

I always experience a little burst of excitement when I find a skeleton.  This may be a carryover from my Elementary School days when I had visions of becoming a paleontologist, or it could be from my Junior High period of reading everything I could about adventurous archaeologists/treasure hunters searching for amazing discoveries.  In the books, treasure usually wasn’t far behind the discovery of a skeleton.  I found this wonderful specimen in the midst of a cedar thicket.

Many times you can identify the species, or at least the genus, from the shape of the skull.  Opossum was the first animal that came to mind when I saw the shape of this skull.

The size however, indicated a much smaller animal.  This is only about half the size of a typical Opossum skull.

The skull holds the key to identification in the form of a dental record.  Using the pattern of dentition, the range of possible animals can be narrowed considerably.  Step one is to determine the total number of teeth.  Here we have a total of 20 teeth in the upper jaw.

A check of the lower jaw shows 10 teeth on one side, so doubling that gives us a total of 20 lower teeth.  That tells us to suspect mammals with 40 total teeth.

There is only one native Ohio mammal with a total tooth count of 40.  That is the Raccoon.  The trouble is that this doesn’t look like the skull of a Raccoon.  Total tooth count helps narrow your search, but to fine tune or verify a choice, you need to look at the dental formula.  That formula takes the total number of teeth and breaks it down into the number of incisors, canines, premolars and molars in the upper or lower jaws.  One side of this upper jaw appears to have five incisors in front of the long canines.

A closer examination confirms that fact.  The jaw clearly contains five incisors on each side.  Raccoons only have three incisors per side, so this is clearly not a Raccoon.  Browsing through the dental formulae reveals only one mammal with five incisors to a side and that is the Opossum.  So, why the small size and only 40 teeth?

This is apparently the skeleton of an immature Opossum.  A close examination of the lower jaw reveals undeveloped teeth that have not yet emerged.  Many mammals do not get their full complement of teeth until maturity.  Had this little fellow survived a few more months, it would have acquired all 50 teeth characteristic of the species.  Proper identification of most living things requires consideration of many details.  Don’t be eager to make an identification based on just a single point.

Skull

The skull seems to be the most common skeletal part found decorating the Blue Jay Barrens landscape.  At least half of my bone finds are skulls.  I suppose the head yields little of interest to most predators and scavengers.  Meat laden bones from the rest of the animal are carried off and either chewed or consumed.  The tough bones of the skull are also more resistant to decomposition, so they remain recognizable for a longer period of time.  This Raccoon skull was hidden beneath the leaves before I brought it back into the light.

Dentition is important in the proper identification of the skull.  By counting the teeth, you can narrow the range of possible species.  The upper jaw tooth count in this case is 20, which is normal for several genera in this area.  It’s easy to eliminate smaller mammals like moles or shrews and you certainly wouldn’t mistake this little skull for a bear.   Those species that might have a similar size are foxes and dogs.  These are ruled out because their cranial ridges begin at the eye sockets and travel back to merge somewhere near the back part of the skull.  In Raccoons, the ridges quickly merge between the eye sockets and continue back across the top of the skull as a single ridge.

The profile also tells you this isn’t a fox or a dog.  With a little bit of imagination you can put fur, ears and nose in place and make a good guess.  It’s easier when all the teeth are in place.  I’ve had enough dogs growl at me that I’ve gotten pretty good at recognizing that tooth grin.  I would point out that the snout is shorter than the normal dog, but there are so many specialized dog breeds that canine snout lengths and shapes can vary considerably.

I left the skull on top of the leaves.  It’ll be interesting to see how long it stays in place.

I have to end with the image of an alien face emerging from the toothless jaw.  It would be interesting to take a skull and see just how many faces I could find hidden there.

Snake Bones

Yesterday’s weather was moderately warm and very sunny, so I thought I would check out one of the Archaeological Sites to see if any snakes were out and about. Battery cages were once used for pheasant production a couple of generations ago. They were dumped here when the family decided to get out of the pheasant business. The steel covers on the cages become warm with the sunlight and attract Black Racers and Black Rat Snakes.

I didn’t find any snakes, but I did find some evidence of their presence.

There’s no mistaking snake bones. The long spinal column and accompanying rib bones can’t come from anything else that lives around here. Dead snakes are usually eaten by larger animals, so it’s unusual to find a skeleton just out in the open like this.

Much of the skeleton was missing. Several pieces were scattered on the ground near the cage.

A snake has an amazingly flexible spinal column. From the head to the tail it bends in just about any direction. When you see it exposed, it’s hard to imagine how it manages that flexibility. Finding a skeleton is fun, but I’d much rather find the bones surrounded by live snake.

Bones

This would have been great for my Halloween post. It looks like some type of ceremonial mask.

It’s actually the hip bone of a deer. The deer are so numerous that their bones are scattered all over the landscape. Sometimes I wonder how there can be so many live deer around when so many are dieing to provide a continuous supply of bones.

I normally don't find entire deer skeletons. I usually find single bones like this leg bone. One of the larger scavengers probably carried the bone here when it still had some meat attached. Large scavengers can quickly disassemble a carcass and scatter the parts for a great distance.

Bones rarely last long enough to become old. Once the meat is gone, other animals begin the process of breaking them down. Rodents use the bones as a source of calcium. It’s hard to find any bones that haven’t been gnawed by rodents.

Squirrels, mice, voles and ground hogs seem to be the major bone eaters. Rabbits are probably the greatest non-rodent consumers of bone. Most of the bone chewing occurs at night when rodents are most active. Fresh gnaw marks are usually evident every morning. The bright white color is an indicator of recent activity.

Smaller bones, like this vertebra, are carried by many animals. I’ve seen squirrels carry these up trees and have watched crows fly off with small bones. The speed with which animals consume the bones makes we wonder how they were satisfying their calcium needs 30 years ago when deer were still relatively scarce.