From the Permian through the end of the Triassic, a succession of taxa dominated the terrestrial vertebrate..

..community. Which of the following lists contains the most accurate and complete succession of taxa, starting with the earliest?

a. Amphibians, diapsids, archosaurs.
b. Amphibians, synapsids, diapsids.
c. Amphibians, cynodonts, archosaurs.
d. Amphibians, crocodilians, dinosaurs.
e. Amphibians, crocodilians, synapsids.

The least worst choice would be b.

a. ignores the detail that archosaurs are diapsids.
c. has the problem that cynodonts didn't appear until the Upper Permian and, at that time, other therapsid lineages were more numerous and diverse.
d. and e. fall out as croc relatives never dominated the terrestrial vertebrate fauna.

All options are dubious as amphibians weren't dominant among terrestrial vertebrates during the Permian.