>>49843215Endothermic vs exothermic are not these absolute mutually exclusive categories we once thought that were, animals can exist between the two extremes and it's really just not as defining a characteristic as once thought. Certain lizards also have the ability to exhibit endothermy for reproductive purposes.
Birds have scales (not only on their feet, feathers are just really complexly shaped scales essentially), birds lay eggs, beaks have evolved in reptiles a bunch (turtles, triceratops, birds).
A basic adult understanding of dinosaurs makes birds and reptiles inseperable.