Final answer:
The most probable evolutionary sequence from earliest to most recent is Bilaterians, Deuterostomes, Vertebrates, Tetrapods, and Amniotes. Birds evolved from dinosaurs and mammals from reptilian ancestors. The differences between ectothermy and endothermy involve various metabolic and environmental temperature regulation strategies.
Step-by-step explanation:
Bilaterial symmetry is a basic body plan first. The earliest animals are thought to have evolved from marine protists. As multicellularity evolved, cells specialized for different functions, leading to the rise of Bilaterians. Deuterostomes, which include vertebrates, followed in this evolutionary sequence.
The first vertebrates evolved almost 550 million years ago. Amphibians were the first tetrapods, signaling a major step in the evolution of vertebrates as they moved onto land. Eventually, Amniotes evolved, laying amniotic eggs and no longer needing to return to water to reproduce, marking the rise of reptiles, birds, and mammals. Birds evolved from dinosaur ancestors and were some of the later vertebrates to diversify, with mammals also descended from reptilian ancestors.
Ectothermy and endothermy are two different strategies for metabolic temperature regulation found in the animal kingdom. Ectotherms rely on external environmental heat sources to regulate their body temperature, which can be energy-efficient but limits their activity in colder environments. Endotherms generate their own heat through metabolic processes, allowing greater activity and survival in a wider range of temperatures, but requiring significantly more energy.