Species Basics / Ages 5+ / 5 min
Dinosaurs are a special group of reptiles defined by a specific arrangement of their hip and leg bones - a feature called an erect stance. Many famous prehistoric creatures like Dimetrodon and pterosaurs are not actually dinosaurs.
A true dinosaur has its legs positioned directly underneath its body, like a horse or a person - not splayed out to the side, like a lizard. This is one of the simplest tests paleontologists use.
Pterosaurs (flying reptiles), mosasaurs (sea reptiles) and Dimetrodon (a sailed mammal-relative) lived during dinosaur times but are different groups. Today's birds are actually a surviving branch of dinosaurs.
Videos matched to this lesson, with a quick discussion question for families.
A friendly starter video about what makes dinosaurs different from other prehistoric animals.
Ask: what prehistoric animal is not actually a dinosaur?
A fun bridge between feathered dinosaurs, flight, and the birds kids see today.
Ask: what do birds and theropod dinosaurs have in common?
Yes - Tyrannosaurus rex is one of the most famous theropod dinosaurs and lived at the very end of the Cretaceous period.
No - mammoths were Ice Age mammals that lived tens of millions of years after the dinosaurs went extinct.
More dinosaur guides connected by topic, category, or editorial picks.
Geology & Time / 6 min
The Mesozoic Era: When Dinosaurs Lived
Three periods, 165 million years, and one giant change in life on Earth.
Behavior & Biology / 5 min
Feathered Dinosaurs
Most dinosaurs had feathers, fuzz or quills. Here's what science says now.
Species Basics / 4 min
The Biggest Dinosaurs
Sauropods like Argentinosaurus and Patagotitan were so big it's hard to picture.