Evolution

The first exhibit that was viewed upon entering the museum was the dino zone. There, I observed several dinosaurs, but the most noted dinosaur was the Tyrannosaurus Res (T. Rex). The T. Rex that I observed in detail was Sue. Sue was auctioned and bought by the museum. Most notably, Sue's skull is over 5 and a half feet tall. If one were to study the size of the forearm, her forearms are relatively short as it relates to mammalian forelimbs. Notice that at the end of her arms, her nails are extremely short. In an interview with CNN news, Sue Hendrickson, paleontologist, states that the arms "were used to scratch other animals...but they're so short." Sue's shoulder blades are connected from what it appears to be circa 12h vertebrae. The shoulder blades are positioned anterior and inferior to the vertebrate. The clavicle is rigid, which doesn't allow for a wide axis of rotation. As far as movement of the forearm goes, the forearm can only retract and extend. A possible use of the forelimbs would be to possibly grasp/hold food. However, this model doesn't make much sense as it is almost as if the forelimbs are useless for Sue due to size of the forelimbs. Though, Sue was a therapod, and most therapods have 3 "fingers". Sue only had two, so the purpose of her fingers probably served more along the lines of picking small objects, if the forelimbs were used at all.

Sue's leg bones are extremely large given the amount of weight the legs must substantiate. Unlike the forelimbs, which are extremely useless to Sue when it is further studied her legs are large. Stephen Frazier, CNN correspondent in the same interview, argues that due to expansive size of Sue's legs, she can possible run over 40 miles per hour. It appears as if because the leg bones are so large, that most of the power expressed from Sue is exhibited from the legs, just from posture alone. Her pubic bone is relatively small-only 122 cm in size. She places most of her weight on her tibia as most of the femur is expressed on her tibia. Taxonomically, Sue is considered an ungulate and stands on 3 of her toes, though 4 toes are present. The claws are very sharp on the bones of the foot, so possibly the claws may have been used as a sort of grounding mechanism so she can attain the large distances in a short amount of time.

Sue was a homodont. Her teeth are in varying sizes, but for the most part, the size differs, not the actual shape of the tooth itself. This gives us a clear indication that she was indeed a carnivore, no question about it. Sue was not omnivorous, as if she was, then her teeth would be facilitated in a totally different fashion-that of the heterodont. The teeth themselves are very sharp, and this is a necessity for the type of dinosaur Sue is. Being that she was a carnivore, it was necessary to have teeth so sharp to rip through flesh easily.

The next area of the museum that I entered was the North American bird hall and immediately began to search for information on the flamingo. The flamingo is a pink bird with a relatively large beak in comparison to other birds. The reason for their large beak size lies in the diet the flamingo possesses. Because the flamingo spends a large amount of time in areas closest to water or muddy surroundings, the flamingo eats very small creatures, like mollusk shrimp or other small creatures that occupy the mud. If one notices the relative shape of the beak, it is tipped at the end much similar to an inverted shovel. In one dynamic, the way the flamingo eats is much similar to how one may shovel snow after a nice Chicago snowstorm. From an evolutionary standpoint, this beak mechanic is the only way the flamingo can survive. The curved beak allows the flamingo to easily shovel the smaller organisms that lie in the mud into their mouth with ease.

Another interesting property of the flamingo is that the beak is pointed at the tip. Again, this serves a primary evolutionary significance as the pointed beak allows the flamingo to crack open the chitinous exterior that the mollusk shrimp has. The beak is also pointed for penetration of the mud. Much like a jackhammer penetrates cement, the flamingo must also penetrate heavily caked mud to access food easily. The pointed beak serves a dual purpose as far as evolution goes and is a necessity for the flamingo to survive the environment the flamingo lives in.

Further down the North American Bird Hall lies some very common birds most urban people are used to seeing-the pigeon. Often referred to as "rats with wings", these birds offer a lot more than meets the eye. The pigeon raises their offspring by administering milk to their young, which is an unique trait the bird possesses. In one aspect, despite pigeon milk not resembling mammalian milk, pigeon milk is much like mammalian milk in the regard that both mammalian milk and pigeon milk is full of protein that is necessary for growth of the young bird. The reason that the young pigeon needs milk is that, despite fruits, seeds, and in some cases other chicken (at least on the west side of Chicago) offers nourishment and nutritional sustenance to the adult pigeon, the young pigeon cannot survive nutritionally from these sources, as the protein has necessary ingredients for the growth of feathers and for immediate development. Despite most young birds consuming seeds or small insects, the pigeon is unique as it administers milk to their offspring.

The pigeon milk is produced in a specialized area in the bird called the crop. Pigeon's milk begins to be produced a couple of days before the eggs are due to hatch. The parents may cease to eat at this point in order to be able to provide the chicks with milk uncontaminated by seeds, which the very young chicks would be unable to digest. The chicks are fed on pure crop milk for the first week or so of life. It is extremely high in protein and fat and is considered to be one of the richest nutritive substances known. Both male and female adult birds produce crop milk and share in the feeding and care of the young. The milk is fed to their young by means of regurgitation.

The next region of birds that I studied was the ostrich, and other birds similar to the ostrich. The Ostrich is a flightless bird native to African savannas. It is the only living species of its family, Struthionidae, and its genus, Struthio. They are distinct in their appearance, with a long neck and legs and the ability to run at speeds of about 65 km/h (40 mph). Ostriches are the largest living species of bird and are farmed in many areas all over the world. The ostrich belong to the Struthioniformes order (ratites). Other members of this group include rheas of Africa, emus of Australia, the kiwis of New Zealand (found in the swamp forests), the Cassowary of New Guinea, the Rhea of South America, and the largest bird ever, the

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