The geological time scale is divided up and organized according to what life forms existed on earth.
a. true
b. false

The given statement is True.

The geological time scales are divided into epochs and the era. The geological timelines are divided into many division depending on the condition of life and the organism, which existed at that particular time period. There is one exception Hadean period, this is not actually a geological time, in this period, the formation of the solar system occurred, and no life form existed.

tsd is temerature dependent sex determination.

tsd: it is a type of environmental sex determination in which the temperature experienced during embryonic/ larval development (ambient temperature for development) determine the sex of the offspring.

crocodile displays the tsd where the ambient temperature of the developing egg determines the individual's sex. for example in the american alligator's eggs, incubation at 33 ºc produces mostly males, while incubation at 30 ºc produces mostly females. so if the american alligator's egg will get the ambient temperature (33 degree celcius)during embryonic development from egg, the offspring will be male and same for the female sex determination.

the fossil record provides evidence of a common ancestor to many species.