Question

Ques. fossil X can be considered to be evolved earlier than fossil Y:
1)Y has vestigeal structures that are homologous to functional structures in fossil X
2)Y is structuraly more complex then fossil X
3)Y is in better state of preservation of X
4)X is found in lower stratum of undisturbed sedimentary rock than Y

Answer 1

@exuras @blues @viendra @TranceNova @Frostbite @ebaxter01 @agreene help me -_-

Answer 2

It can be 1 because, Y has been EVOLVED from X so it can have the vestigeal sturctures of X..and the question asks about EVOLUTION of Y from X, even though 4 is correct too, but it doesn't necessarily mean that Y has been evolved from X, it only means that X is older.

Answer 3

and 2 isn't correct because any new fossil species is more developed than the one before, again this doesn't specifically mean that X is an ancestor to Y. here we can think of Y to be any species not necessarily related to X

Answer 4

and it can't be 3 because ANY new fossil can be in a better state as compared to the older ones..

Answer 5

There is a tie between option 1 and 4. Both seem equally correct

Answer 6

not necessary if u see while leeching old foil get in ocean and come to upper layer of soil again wat u ll say abu this :??

Answer 7

all the options seem correct :)

Answer 8

yea thatsthe only prob :(

Answer 9

@heena , the pressure on fossil buried under the sediment layer is very immense and always. The older fossils are always found in deeper layers of the sediment :)

Answer 10

@heena , see this too -> http://answers.yahoo.com/question/index?qid=20100506174456AALoxkG

Answer 11

yea but wbu leeching at that time?

Answer 12

@heena , yes you are right. There is a probability that due to leeching the older fossil may came above the newer fosil . So go ahead with option A

Answer 13

@kma230 @rahulchatterjee

Answer 14

@heena - I'm unfamiliar with what "leeching" means in this context. Mind explaining please?

Answer 15

leeching is the process in which die to heavy rain fossil get burried and later mix with icean water and go to ocean than eaten by fihes which was further eaten by cranes and such fossil omtimes get fall don on soil again which states not necessary that old foil must be deeper in soil compared to newly formed foissl

Answer 16

I see - thanks, @heena.

To be honest, I'd have to go with Answer choice 4. I agree that the process you describe as leeching definitely does occur, but I think the key word is "undisturbed". So it seems that choice is specifically referring to a situation in which the older fossil is located underneath the younger fossil. And I Interpreted the phrase "evolved earlier" to simply mean which is older.

It seems the consensus is that 2 and 3 are wrong, so I won't go into those choices.
In regards to answer choice 1, "Y has vestigeal structures that are homologous to functional structures in fossil X" - although this seems intuitive, I don't think it's necessarily true in every case.

For example, let's say you have an ancestral species A which has features P, Q, and R.
Over the course of time, the offspring of ancestor A begin to diverge, forming two main branches - species Y and X.

Let's say that given the environment Y developed in, features P, Q, and R were rendered redundant and became vestigial structures. However, X lived in roughly the same environment as A, but also changed extensively elsewhere such that it became a new species (though this occurred later than Y branching off). X still therefore possesses features P, Q, and R. Now let's compare fossils of X and Y. Fossil Y has the vestigial structures that are homologous to functional structures in X. However, X still evolved later.

This might be a bit abstract, so I'll try to offer a more realistic example. Take humans as species Y, and baleen (or any other type) whales as species X. The feature in question are legs.

Species Y, or humans, have functional hind legs. Species X, or whales, do not. They have vestigial remains of hind leg bones. This would appear to indicate that whales evolved later than us. In reality, whales developed tens of millions of years before we did.

It's also important to keep in mind: The question asked about which organism evolved earlier - X or Y. The question did not ask if X evolved from Y or Y from X. It only seeks to classify the two organisms relative in terms of time to one another.

Hope this helps!