Glossary

109 terms across paleontology, anatomy, taxonomy, and behavior.

Adaptation: A feature shaped by evolution because it helps an animal survive or reproduce. Adaptations develop over many generations through natural selection — a longer neck for reaching higher leaves, a thicker skull for head-butting rivals, hollow bones for saving weight.
Apex Predator: The top predator in an ecosystem — nothing hunts it. Apex predators like T. rex and Giganotosaurus shaped everything around them by controlling prey populations. Remove one, and the whole ecosystem shifts.

Bipedal: Walks on two legs. Most meat-eating dinosaurs were bipedal, freeing up their front limbs for catching prey, grasping, or — eventually — flying.
Brooding: Sitting on eggs to keep them warm. Fossils of oviraptorosaurs found draped over their nests — arms spread, just like a modern bird — are some of the most moving evidence of parental care we have.

Cursorial: Built for running. Cursorial animals have long, slender legs and lightweight feet designed to cover ground quickly — the ornithomimids (ostrich-mimic dinosaurs) are a classic example.

Display: Using a visual feature — a tall sail, a sweeping frill, a brightly colored crest — to communicate. Display structures may have helped dinosaurs recognize their own species, attract mates, or intimidate rivals.

Facultative: Can do it either way. A facultative biped, for example, is capable of walking on two legs or dropping to all fours depending on the situation — not locked into one mode.

Gregarious: Social — living or traveling in groups. Some dinosaurs left behind bone beds (sites where dozens of the same species died together), suggesting they traveled in herds like wildebeest or bison.

Hatchling: A baby animal just out of the egg. Some dinosaur hatchlings were tiny and helpless; others were up and moving almost immediately. Argentinosaurus — potentially the largest animal ever — hatched from an egg no bigger than a rugby ball.

Pack Hunting: Working together as a group to bring down prey. It's a popular idea for raptors, but the fossil evidence is thin — most paleontologists now think it's possible but far from proven.

Quadrupedal: Walks on all four legs. The heaviest dinosaurs — sauropods, ankylosaurs, ceratopsians — needed four legs to carry their weight, and their forelimbs were often nearly as long as their hind legs.

Scavenger: An animal that feeds on animals that are already dead rather than hunting live prey. T. rex was famously debated as hunter vs. scavenger — the evidence now points to both, opportunistically, depending on what was available.

Terrestrial: Land-dwelling. Used to distinguish animals that lived on land from aquatic or semi-aquatic ones. Even fish-eating dinosaurs like Baryonyx were terrestrial — they just hunted at the water's edge like a grizzly bear.
Thermoregulation: How an animal controls its body temperature. Cold-blooded animals rely on the sun; warm-blooded ones generate heat internally. Dinosaurs were probably somewhere in between — and the debate is still very much alive.