AP BIOLOGY

Detailed explanation-1: -Phyletic gradualism. Phyletic gradualism holds that morphological evolution is gradual and occurs independently of speciation. Most of the studies supporting this mode of evolution involve organisms that can be minutely sampled through continuous rock sequences.

Detailed explanation-2: -The first turtle-like reptiles are thought to have evolved about 250 million years ago. Ancestral crocodilians evolved at least 220 million years ago. Tuataras may have diverged from squamates (snakes and lizards) not long after that. Finally, lizards and snakes went their separate ways about 150 million years ago.

Detailed explanation-3: -Snakes are thought to have evolved from either burrowing or aquatic lizards, perhaps during the Jurassic period, with the earliest known fossils dating to between 143 and 167 Ma ago. The diversity of modern snakes appeared during the Paleocene epoch ( c.

Detailed explanation-4: -Found in the early 2000s after 240 million years embedded in the mountains of northern Italy, a fossil known as Megachirella wachtleri has claimed the title of oldest-known species of the reptilian order Squamata, making it an ancestor of all the world’s lizards and snakes, as The Washington Post explains.