Phillip Gingrich finds an S-shaped bone in this partial skull, a sigmoid process, which is unique to one particular order of animals in the water today... which one?

A primitive whale which he named Pakicetus.

Explanation:

Philip Gingrich is a vertebrate paleontologist at the University of Michigan. He has performed extensive research on whales at the Egyptian desert of Wadi Hitan. His research team member discovered a skull whose braincase was bigger than that of a walnut. Gingerich was able to link the small-brained animal, to an early whale.

The auditory bulla had an s-shaped bony crest known as the sigmoid process and these two features helped whales to hear in water. The case, however lacked other features that helped whales hear beneath the waves. This led Gingrich to the conclusion that the unknown animal was semi-aquatic. This finding also lent credence to the possibility of whales evolving from terrestrial animals.

he movement of air through earth's or any planet's atmosphere is called wind, and the main cause of earth's winds is uneven heating by the sun. this uneven heating causes changes of atmospheric pressure, and winds blow from regions with high pressure to those with low pressure.

i hope this : )

a symbiotic relationship with the mitochondria