Humans first appeared in the cenozic era?

The period of time, also known as an eon, between the end of the Precambrian and today, The Phanerozoic begins with the start of the Cambrian period, 544 million years ago. It encompasses the period of abundant, complex life on the Earth.

Since a female is both xx chromosome and the male passes down the x chromosome, than the offspring would be female since a female is xx.