1. which grouping in the animal kingdom is the only one that contains organisms with vertebrae?

Vertebrata, which is the largest part of Chordata. Primitive chordates don't have vertebrae.

Because the earth is not round ,but it may seem round when viewed from ,our planet but true some points earth is not round was an oblate spheroid -a square that it squashed as globe however is not even a perfect oblate spheroid.in fact isaac newton's first proposed that earth was not perfectly round but it was an oblate spheroid instead.that mean a square that is squashed as its poles and swollen at the

Gravitational force i believe