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Anatomists

Anatomists. GROUP 1. Homologous and Vestigial Structures. How are homologous (homologies) and vestigial structures different?

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Anatomists

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  1. Anatomists GROUP 1

  2. Homologous and Vestigial Structures • How are homologous (homologies) and vestigial structures different? • Vestigial structures are those that are not necessarily used by an organism for a bodily function, but are often used as evidence that those organisms evolved from animals who do use those structures. For example, the human tailbone is not used for a particular function, but it may serve as evidence that humans evolved from creatures with tails, which are functional structures.

  3. Vestigial Structures • Remnant of a structure that may have had an important function in a species’ ancestors, but has no clear function in the modern species. • An example of a vestigial structure would be the pelvis of a whale. The pelvis may have been used by their four footed ancestors, but has no function in the whale of today. • As previously mentioned, another example would be the tailbone of a human and the tail of a monkey. Humans have no “function” for the tailbone, but it may have once been a tail. • Source: Prentice Hall Biology Textbook

  4. Homologous Structures • Homologous structures (homologies) are those that are similar between two organisms. For example, the arm of a monkey can be considered “homologous” to the fin/flapper of a whale. Both of these organisms are mammals, so this similarity is logical and is to be expected. • Another example would be a bat’s wing and an ape’s arm. These are also considered homologous structures. • Source: http://evolution.berkeley.edu/evolibrary/article/0_0_0/lines_04

  5. Arm Structures Source: http://upload.wikimedia.org/wikipedia/commons/3/38/Arm_skeleton_comparative_NF_0102.5-2.png

  6. Comparative Anatomy All of these animals have four legs, and all four legged animals have limbs with five digits, at least at some stage in development. The bird doesn’t have 5 digits because it lost some of these digits during development. Even though the birds do not need all 5 digits, they represent a genetic artifact inherited from ancient ancestors that did use all 5 digits.

  7. Comparative Anatomy

  8. Development Biology • As embryos, human and fish look the same at the first stage but as they develop the differences start to appear. A human starts to take on human characteristics while the fish starts to take on the fish like structure, with fins ect. This is also true with most other embryos. In stage one, they all seem to be very similar but as they develop, there are obvious changes, such as a chicken embryo and a human embryo. As the embryo changes it starts to look as it would when it is fully developed.

  9. Developmental Biology

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