Derived Characters ( indicates the character is present) rgantsms Mamrnals Croco

Question

Derived Characters ( indicates the character is present) rgantsms Mamrnals Crocoditians Fish Amphibiaps Birds rJaws Feather Two Pairs of Lmbs Kecatin Scales The table above shows derived characters for selketed orpazisms, Bsxed on the inßormation in th tab the following cladograms best represeats the evolationary relationships among the organisms? A)Fis Amphibians Crocodilians Birds Mammals (B) Mammals Birds Crocodilians Amphibians Fish (C) Amphibians Fish Birds Crocodilians Mammals Fish Mammals D) Crocodilians Amphibians Birds

Explanation / Answer

Among all animals listed, we see that all of them have one common characteristic which is the presence of jaws. Hence we can say all of them have evolved from a common jawed ancestor.

All except the fish, have two pairs of limbs. Hence we know that fish was the first one to diverge away from the common path in evolution.

So now we look into the characteristics of mammals, crocodiles, amphibians and birds who all have a common ancestor which has two pairs of limbs. Among these we see except amphibians all have amniotic eggs. Hence next amphibians diverged away from the common line of evolution.

Now among the mammals, crocodiles and birds, who all have a common ancestor with jaws, two-pairs of limbs and amniotic eggs, both crocodiles and birds have beta keratin scales on their bodies. But mammals donot have these, rather they have hair on their bodies. Hence next it was mammals who diverged from the common line.

Lastly among the crocodiles and birds, birds developed feathers, while crocodiles did not. In this way these two also diverged from each other at last.

So the option (A) appropriately supports our observation. Answer is (A).

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