| A | B |
|---|
| vertebra | bones that make up the backbone |
| agnathan | the earliest fishes with no jaws or paired fins |
| acanthodian | spiny fishes with strong jaws with jagged bony edges that served as teeth |
| cartilage | a lightweight, strong, flexible tissue |
| terrestrial | animals that lived on land |
| thecodont | dinosaurs evolved from these crocodile-like reptiles |
| Pangea | Earth's super-continent |
| ectothermic | animals that must absorb heat from their environment |
| endothermic | animals that can maintain a constant body temperature |
| therapsid | the descendants of mammals |
| primate | member of the phylum, Mammals, includes prosimians, monkeys, apes, and humans |
| prosimian | a primate that is active at night and lives in trees |
| diurnal | a pattern where primates are active during the day and sleep at night |
| hominid | primates that walk upright on two legs |
