Chapter 35.5, Problem 1CS

Core Skill: Modeling The goal of this modeling challenge is to draw a reptilian phylogenetic tree that distinguishes the four recognized taxa based on critical innovations that are morphological traits.

Modeling Challenge: Turtles, lizards and snakes, crocodiles, and birds are all considered reptilians, yet we recognize them as distinct taxa. Construct a model of a phylogenetic tree using six critical innovations: three- or four-chambered heart, scales, endothermy, a hard protective shell, a kinetic skull, and feathers. Be sure to show these critical innovations on your phylogenetic tree with black bars and labels. The four taxa have the following combinations of traits: Crocodilia (four-chambered heart, scales, not endothermic, no protective shell, no kinetic skull, no feathers); Squamata (three-chambered heart, scales, not endothermic, no protective shell, kinetic skull, no feathers); Testudines (three-chambered heart, scales, not endothermic, hard protective shell, no kinetic skull, no feathers); Aves (four-chambered heart, scales, endothermic, no protective shell, no kinetic skull, feathers).