Dinosaurs evolved from earlier reptiles called archosaurs and first appeared during the Triassic Period, over 230 million years ago, probably in what was then part of the southern supercontinent Gondwana (areas that include today’s South America and Africa).

What does “where did dinosaurs come from” mean?

When people ask “where did dinosaurs come from,” they’re usually asking two things at once:

  • In time : When did they first appear in Earth’s history?
  • In evolution : What kind of animals did they evolve from?

Scientists answer this using fossils, rock dating, and comparisons between dinosaur bones and those of related reptiles.

Their deep family roots

Dinosaurs belong to a big reptile group called archosaurs, which also includes crocodiles and the ancestors of birds.

Within this group, dinosaurs split off from crocodile‑line reptiles and developed their own distinctive body plan: upright legs under the body, special hip and ankle structures, and specific skull features.

Before true dinosaurs, there were “dinosauromorphs” – small, lightly built reptiles that already had some dinosaur‑like traits but were not yet full dinosaurs.

These early relatives show that dinosaurs didn’t appear out of nowhere; they gradually evolved over millions of years from earlier archosaurs.

When and where they first appeared

Most researchers place the first definite dinosaurs in the Late Triassic , roughly 230 million years ago.

Key fossil sites in Argentina and Brazil (Ischigualasto and Santa Maria formations) and in Zimbabwe preserve some of the oldest clear dinosaur remains.

Recent research suggests dinosaurs may actually have started evolving a bit earlier than the oldest fossils we’ve found, meaning the true origin is slightly older but not yet directly recorded in rock.

One modeling study argues that the very first dinosaur ancestors probably lived in low‑latitude Gondwana regions that would now correspond to parts of the Amazon, Congo, or Sahara, although fossils from those exact areas are still missing.

How dinosaurs took over

At first, dinosaurs were rare and small, living alongside many other reptiles and early mammal relatives rather than dominating.

They seem to have been mainly carnivores or omnivores early on, not large plant‑eaters.

After a major extinction event near the end of the Triassic, many competing reptile groups disappeared, and dinosaurs spread and diversified rapidly.

Over the next 135–170 million years or so, they evolved into everything from huge long‑necked sauropods to horned and armored herbivores and fast, bird‑like hunters.

Where dinosaurs fit in today

Non‑bird dinosaurs died out about 66 million years ago, but one branch survived as birds , which are considered living dinosaurs by most scientists.

So in evolutionary terms, dinosaurs came from earlier archosaurs, arose in the Triassic on the supercontinent Pangaea, flourished across the globe, and are still with us today in the form of birds.

TL;DR: Dinosaurs came from earlier archosaur reptiles, evolved into true dinosaurs in the Triassic more than 230 million years ago—likely in southern Pangaea (Gondwana)—and only later became the dominant land animals after other reptiles died out in mass extinctions.

Information gathered from public forums or data available on the internet and portrayed here.