SSCE VCE Biology Evolution and Species Relationships: Mammals are considered to have b

Question

Mammals are considered to have been extremely successful in evolutionary terms. One reason for this may be their well-developed sense of hearing.

a. Suggest one reason why a well-developed sense of hearing would contribute to the evolutionary success of mammals.

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This well-developed sense of hearing is partly due to three tiny bones in the middle ear.
Scientists believed that the middle ear probably developed from small bones in the jaw of an early mammal. This early mammal then evolved into the three modern mammal groups: monotremes (the platypus and echidna), marsupials (such as kangaroos and placental mammals (such as humans, mice, gorillas).

b. What term describes the evolution of the three mammalian groups from the early mammal?

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In February 2005 scientists reported the discovery of a jawbone from Teinolophos trusleri that lived 115 million years ago and is thought to be the world’s oldest known monotreme. It is believed that by 115 million years ago the monotremes had split off on their own evolutionary line from marsupial and placental mammals. This jawbone provides evidence that the transformation of the small bones from the jaw to the middle ear occurred in all three groups of modern evolutionary lineages of living mammals, and that today’s monotremes are a different branch of the mammalian family tree from the marsupial and placental mammals.

c. What type of evolution describes the formation of the middle ear bones in the two mammalian lines?

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d. In the spaces alongside 1, 2 and 3 show the possible evolutionary relationships between placental mammals, marsupials and monotremes suggested by this discovery.

1      
          E  D
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          |         
          2  ---- A ----  3 
          |         
          |        
          C  B

e. Based on this discovery in Teinolophos trusleri, along which branches (A, B, C, D and E) in the above diagram could the lower jawbone have evolved into the middle ear?

Mammals are considered to have been extremely successful in evolutionary terms - VCE - SSCE Biology - Question 9 - 2005 - Paper 1

Worked Solution & Example Answer:Mammals are considered to have been extremely successful in evolutionary terms - VCE - SSCE Biology - Question 9 - 2005 - Paper 1

a. Suggest one reason why a well-developed sense of hearing would contribute to the evolutionary success of mammals.

b. What term describes the evolution of the three mammalian groups from the early mammal?

c. What type of evolution describes the formation of the middle ear bones in the two mammalian lines?

d. In the spaces alongside 1, 2 and 3 show the possible evolutionary relationships between placental mammals, marsupials and monotremes suggested by this discovery.

e. Based on this discovery in Teinolophos trusleri, along which branches (A, B, C, D and E) in the above diagram could the lower jawbone have evolved into the middle ear?

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