Monday, February 21, 2011

Museum of Natural History Bone Lab

Museum of Natural History Bone Lab

This lab in the Natural History Museum was able to open the eyes making connections to the texts of Goethe that we have been reading and the physical bone structures under question. It was an experience which helped me better appreciate the things that Goethe accomplished in his studies of the intermaxillary bones also called the premaxillae. It was pretty unreal to see the structures in the skulls of the different species and then compare them to each other. The position of these bones and how they functioned for the specific species was a very interesting spectrum to see.

There were six different skulls of animals that I sketched in this lab, in addition to the human skull that I more completely sketched. The six animal skulls that I observed were a gorilla, a young chimpanzee, an older chimpanzee, a bison, a fox, and a harbor porpoise. These six animals I did not make complete sketches of the entire skull, just ones that better showed where the intermaxillary bones are located and what it looks like. I made sure to sketch the roof of the mouths of the animal and human skulls in order to compare the intermaxillary bones across the different species. There were some very interesting comparisons to be made.

The intermaxillary bones in humans are located on the roof of the mouth one on each side of the centerline of the mouth. They contain the incisors and are very hard to see in humans, if at all. The one skull that I looked at, I was able to barely make out the faint cracks that run along from the center of the mouth to a spot in between the last incisor and the canine. The sutures were very hard to spot because of how thin they were. In humans the intermaxillary bones must fuse earlier in life under a decent amount of pressure in order to be that thin.

I also studied the skulls of some animals that are closely related to humans, the chimpanzees and gorillas. In these species the intermaxillary bones are very easy to spot clearly running from the center of the mouth to a spot in between the canines and the last of the incisors. The line created by the intermaxillary bones and the bones of the rest of the mouth in the chimpanzees ran more perpendicular to the centerline of the mouth than they did in the gorilla. This makes sense because the snout of the gorilla is a little bit more elongated than that of the gorilla. I also looked at the skull of the both a younger and an older chimp to see the differences between them. The sutures created between the intermaxillary bones and the rest of the mouth are more readily seen in the younger chimpanzee. They are more jagged and appear like fissures in the bone. The sutures in the older chimpanzee look as if they have been put under a greater pressure and have been fused together. These lines are much smoother, as compared to the fissures of the younger chimpanzee.

Next I looked at the intermaxillary bones of a bison. These bones were very different then the premaxilla of the chimps and gorillas. The primates use their incisors to a great extent, so a lot of pressure is put on them when eating. In that way the intermaxillary bones are small, compact, and do not extend to far from the skull. This is different with bison though. They do not use their incisors too much because they are more of a grazing animal. Instead the bulk of the force is put on their molars. This seems to be the case at least, because the premaxilla of the bison is very long and protrudes out a great distance from the bulk of the skull, as shown in the sketch. It seems to be very fragile and not take a lot of force. They start at the roof of the mouth, like in the primates, and loop around very intricately, continuing up the front part of the face under the nostrils.

The fox skull that was looked at was almost a combination of the bison and primates in terms of premaxilla shape. The intermaxillary bones were angled a bit forward like the gorilla skull, and also headed up the front of the face like the bison. The interesting features of this skull were two little holes in the roof of the mouth. These are depicted in the sketch and their purpose is unknown.

The last skull that was looked at was that of the harbor porpoise. This skull looked like a mammal skull that had been pulled out long like taffy. This skull was unique because its intermaxillary bones are extremely long. They looked like two white strips on the top of the long snout. They were very thin and looked as if they were not used too much in terms of load bearing during eating.

It seems as if there are differences in the intermaxillary bones that correlate with differences in the types of food that the animal eats. Humans and animals like the primates have very stout intermaxillary bones that are held close to the skull. This would more than likely due to the use of the front incisors when biting into food to tear it. The canine skulls like the fox are similar to the primates except that their premaxillae are lengthened a little bit and not as stout, which might have to do with the fact that they use their canines more when eating. The bovine animals like cows and, in this experiment, bison have very long intricate intermaxillary bones since they do not use their incisors at all. They use their molars to grind up all the plant matter that they eat.

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