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Anatomical Evidence for Evolution
Transcript of Anatomical Evidence for Evolution
Definition: A branch of biology dealing with the study of the form and structure of organisms and their specific structural features.
Example of Morphology:
Embryology is the study of embryos (the unborn/unhatched organism in its earliest stage of development). By comparing the embryos of various species anatomical similarities become evident that are not shown in the adult animals. For instance, all vertebrate embryos develop a tail at some point in their development, even if they don’t always keep it when they are born. Vertebrate embryos also develop a structure called pharyngeal (or throat) pouches. Despite the similarities during development however these similar structures will ultimately develop into structures with very different functions. The pharyngeal throat pouches will develop into gills for fish and parts of the ears and throat in mammals.
Vestigial structures are what remain of ancestral features that were once important. They no longer aid the organism in survival, but they don’t inhibit survival either. Animals with Vestigial structures are still able to mate and reproduce, passing on these features to the next generation and so on. Scientists use vestigial structures to link animals to a common ancestor by comparing the similar skeletal structures.
Example of Vestigial Structures
Anatomical Evidence for Evolution
If a genetic mutation were to occur in the part of the gene that codes for protein it could change the function of the protein, and if it occurs in the gene’s control elements the time or place that the gene is expressed could change. Either of these can lead to a change in the morphology of an animal.
Mammalian forelimbs, which all have similar bone structure (one large bone, two smaller bones, several small bones, attached to metacarpals, attached to approximately five digits or phalanges).
Similar Skeletal Features
By comparing the skeletal structure of species Scientists can determine if they are descendant from a common ancestor. In the case of the primates shown above they have very similar structures, although you will notice variability and differing functionality of these similar structures. The human skeleton has a less pronounced jaw, shorter arms, longer legs, and a thinner chest cavity. Obviously the legs are longer and arms shorter because it walks on two legs rather than switching between two and all fours. The thin human chest cavity can also be attributed to this shift in gravity.
Animals that Bridge the Connection
Archaeopteryx and the hoatzin chick: Archaeopteryx was found in 1860 near Solnhofen, Germany. It is one of the strongest pieces of fossil evidence to support evolution, as it shows characteristics of both birds and reptiles. It is also considered to be the first bird, though it is unlikely that it was able to fly so much as glide. Archaeopteryx has a very distinct toothed jaw rather than beak and a tail coupled with feathers. Yet it still has three fingers attached to its wings, each ending in a hooked claw. This wind structure is much like that of the hoatzin bird which makes its home in the amazon of South America. The chicks are often very adventurous and enjoy climbing around on nearby branches when they are merely a few days old. Dangerous predators live in the nearby water and it is beneficial for the featherless chicks to be able to cling to the branches using the extra set of claws on their wings.
The Hoatzin Bird