Question

1) __________________ and _____________________ are early tetrapods that do not have features unique to fish. Describe how these two species differ anatomically and what that means about where they each lived.

Answer 1

1->The last major group of Animal kingdom is Phylum chordata.It is largest Deuterostome phyla.It is highest and most important phylum comprising a vast variety of living and extinct animals including man itself.Phylum chordata divided in to 2 group-Protochordata and Euchordata or Vertebrata. Subphylum vetebrata include 2 superclass--PISCES and TETRAPODS.Superclass PISCES include all fishes and Superclass TETRAPODS include class Amphibia,Reptilia,Aves and Mammalia.ERYOPS , ICHTHYOSTEGAand DIPLOCAULUS are early tetrapods .They are called stem amphibians .

In which, ERYOPS are salamander or crocodile like .Teeth large with much folded dentine.They dominate in Carboniferous to Triassic period.ICHTHYOSTEGA are small salamander like .In which head is large ,flat and vertebrae tubular.Notochord and spinal cord housed in common cavity .So ICHTHYOSTEGA believed to be ancestor of modern Salientia and Urodela and they dominate in Carboniferous to Permian Period .DIPLOCAULUS are small salamander or eel like .They consist cylindrical vertebrae ,and each made of a single piece and ribs articulating intervertebrally.They dominate in carboniferous to Permian period.