(*) Herrerasaurus, Eoraptor, and Coelophysis were dinosaurs from this period, during which both theropods and prosauropods appeared.
At 2008 Cardinal Classic, this geologic period was the lead-in clue for a tossup on the Mid-Atlantic Ridge. The term "coal gap" refers to how we have never found coal from the early part of this geologic period. The Crurotarsi, a group that includes modern (+) crocodiles, evolved during this period. The leading herbivore of the early parts of this period was Cynodont, a therapsid synapsid. (*) Herrerasaurus, Eoraptor, and Coelophysis were dinosaurs from this period, during which both theropods and prosauropods appeared. This geologic period followed the Mass Extinction at the end of the Permian, and it was during this period that dinosaurs first evolved. For ten points, name this first period of the Mesozoic Era, which preceded the Jurassic. 
At 2008 Cardinal Classic, this geologic period was the lead-in clue for a tossup on the Mid-Atlantic Ridge.
Triassic [prompt on "Mesozoic"]