Help Please! (1 Viewer)

[herbie0822]

hey everyone, can someone help me define pentadactyl limb, and why is the study of thus important when studying evolution?

 

[smurfus]

Basically a pentadactyl limb is an arm or leg with five digits
penta = 5
dactyl = digit (fingers, thumbs, toes)

It is the typical limb of the mammals, birds, reptiles, and amphibians (ie vertebrates).

The discovery of the similarity of this suggests that vertebrates descended from a common ancestor, which had limbs with three parts: a ‘hand/foot’ with five digits (fingers/toes), a lower limb containing two bones, and an upper limb containing one bone.


Pentadactyl limbs of different species are an example of homologous organs. That essentially means that because the structure is the same they must be evolutionary related, and the more alike the structure, the closer the relationship.

Hope that helps a bit

 

[herbie0822]

yes it does!! thank u very much!
my half yearly's commence tommorrow and Biology is on tommorrow! so you have helped me just in time =D

 

[moreturyen]

Pentadactyl limbs of different species are an example of homologous organs.

not quite. the pentadactyl limb is not an organ, its a structure. also, the existance of the pentadactyl limb in species does not exactly show similarities in evolution, but rather a common point of evolutionary origin.

 

[Survivor39]

Excellent moreturyen! Remember that the same phenotypes may often have a different genotype?

 

[herbie0822]

thanks guys!! but thank god the exam is over now... four more to go! argh kill me now! LOL

 

[Buiboi]

didnt you haveto mention of it as being a homologous structure which meant that birds, whales, humans etc have similar strucutres however with different functions as opposed to their external environment...wahles have large pendactyl limbs in order to support its overwhelming weight when swimming in water, and bats have light and long pen limbs for flight?

which supports the idea of divergent evolution, and evolution via natural selection of certain characteristics that lead to these changes in functions over time?

 

[xiao1985]

yes... meanwhile, it also support the theory that we have a common ancestor...