a) Both chimpanzees and humans have opposable thumbs, which makes them different than other mammals on this earth.
b)The main difference in structure is that the chimpanzees’ thumbs are covered in hair and are smaller and a different color than humans’. Chimpanzees also use their thumbs to help them climb and pick food, whereas humans use it for things like driving cars, making food, holding cell phones, etc.
c) The common ancestor of the two species is Hominidae, which lived 14 million years ago. The ancestor possessed this homologous trait because it is made up of a taxonomic family which includes chimpanzees, gorillas, humans and orangutans, who all have opposable thumbs.
d)
2. Analogous trait
a)Both cats and dogs possess nails.
b) They both look similar, with their thin long nails. Both cats and dogs use their nails as tools: dogs use them for digging and cats use them for climbing and defending themselves.
c) The common ancestor between dogs and cats is called Maelestes gobiensis. There are little resources about this ancestor, as only the skull has been found, but they probably had nails of some sort. According to the Scientific American, the Maelestes gobiensis lived in the Gobi Desert over 70 million years ago. The shrew-like animal is an ancestor to all mammals. http://www.scientificamerican.com/podcast/episode.cfm?id=4B1665EC-E7F2-99DF-332752A3D3E23B03
d)
I like how you used the fact that both cats and dog have nails as your analogous trait example. It always makes it easier to understand when someone uses an example that people are familiar with. In addition to your stating that cats use their nails for “climbing and defending themselves”, I found that they also use their nails (claws) for marking their territory, stabilizing themselves while they stretch and exercise, and to catch their prey. Nice post.
ReplyDeleteI enjoyed reading your post especially about cats and dogs. I always knew they had come sort of connection. I googled a picture of their common ancestor "Maelestes gobiensis" and was surprised to see how it looks like a cat and a dog.
ReplyDeleteGood discussion on the thumb.
ReplyDeleteI don't think claws (not nails) in cats and dogs are analogies, though. What evidence suggests that the common ancestor of the two groups wouldn't have claws? Even reptiles have claws, so I'm would argue that the early mammalian ancestor of dogs and cats would have them as well.