Dinosaurs rise
A group of reptiles begins a reign of over 180 million years
Quick facts
- First dinosaurs
- Triassic Period, around 245 million years ago
- Length of reign
- More than 180 million years
- Range
- From small feathered hunters to the largest land animals ever
- Living dinosaurs today
- Birds
What happened
Dinosaurs first appeared in the Triassic Period, around 245 million years ago, and went on to dominate life on land for the next 180 million years or so, through the Jurassic and Cretaceous that followed. Over that immense span they ranged from small, fast, feathered hunters to the largest animals ever to walk the Earth. One branch of the dinosaurs survived everything that came later and is still alive all around us: the birds.
Why it matters
The age of dinosaurs is the single longest chapter in the story of large land animals, and it is the one most people picture when they imagine deep time. Because it ran for so long and ended so abruptly, it also sets up the event that follows it. This entry is a doorway: at this scale it is one line, but it opens onto a much more detailed timeline of its own.
How we know
The Natural History Museum dates the first dinosaurs to the Triassic Period, around 245 million years ago, and notes that birds are the living descendants of the dinosaur line.
Sources
- Natural History Museum, London. When did dinosaurs live? (Natural History Museum) (2024) · Reputable sourcenhm.ac.uk · The domain "nhm.ac.uk" is on our Reputable source registry. · Link is live and its text matches the event's key terms (Jul 2026)
- Gnathovorax cabreirai: a new early dinosaur and the origin and initial radiation of predatory dinosaurs (PeerJ, 2019, via PubMed Central) (2019) · Peer-reviewed (author-declared)pmc.ncbi.nlm.nih.gov · Cited as a "journal" source (no stronger domain match). · Link is live and its text matches the event's key terms (Jul 2026)
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Related timelines
- Age of Dinosaurs → · Zoom in: the full 180-million-year story of the dinosaurs