Homologous Traits
a. I am going to be describing the tailbone of the Human and the Monkey.
b. A humans "tailbone" is left only as the bone known as the coccyx where the monkey's continues as a longer line of bone as well as fur, muscle, nerves, etc. I would imagine that based on some force of evolution, it was no longer necessary for one line of the ancestor to possess a tail causing a species without tails.
c. They both came from primates which has the lesser evolved version of the tail as the human and monkey.
Analogous Traits
a. I am going to be describing a trait between a lizard, a small reptile, and a rhino, a very large mammal.
b. An analogous trait of these species is a horn grown by both animals. The rhino has a large horn above its nose while the lizard has several horns on different locations of its head and face. They are structurally the same and used against predators and prey.
c. The common ancestor of the two is the Vertebrata. I don't think the common ancestor possessed that specific trait as the mammal, the ancestor of the rhino, does not include a horn and is a direct descendant of the vertebrata.
Love your homologous trait! No student has use this example before. Now, can you speculate a little further on why we (and other apes) don't have longer tails? Baboons are also missing the length, though they do have short stubby tails. Ancestor wise, most mammals do possess some form of tail and the rodent ancestor of all primates, something akin to a shrew, also possessed a tail.
ReplyDeleteGood analogous trait. "Vertebrata" is really referring to organisms with a vertebral system, so that goes all the way back to fish. The common ancestor for these two would be found during the era of lizards, which gave rise to mammals but you are correct that these two traits arose independently, mainly because we can follow the evolution of rhinos and know that their horns arose during their evolutionary history.
Other than this point, good post.