IV. Diapsids and the rise and reign of the reptiles!
A. Lepidosaurs and Archosaurs
1. Lepidosaurs mostly small, poor fossil record
a. Transverse cloacal slit
b. Loss of single penis, evolution of hemipenes
c. Shedding cycle (ecdysis)
2. Archosaurs robust – the dinosaurs
a. lack the above adaptations
b. develop huge body size, bipedalism (many)