Dinosaurs: From First Footprints to Rediscovery

Key chronological milestones marking the origin, rise, diversification, and ultimate demise of non-avian dinosaurs, spanning the Mesozoic Era and their scientific rediscovery.

Events in this Collection

252000000 BC

Great Dying

Also known as Permian–Triassic Extinction, this event wiped out 90 % of species, clearing ecological space for dinosaur ancestors.
mass-extinction triassic-start ecosystem-clearing
249000000 BC

Earliest dinosaur footprints in Poland

Trackways in Poland preserve the oldest known dinosaur footprints, indicating small, bipedal, social species.
ichnology early-jurassic gregarious-behavior
233000000 BC

First dinosaurs

Fossils such as Eoraptor and Herrerasaurus mark the earliest undisputed dinosaurs.
late-triassic small-bipedal argentina-brazil
201000000 BC

Triassic–Jurassic extinction

This event eliminated many competitors, allowing dinosaurs to become dominant land vertebrates in the Jurassic Period.
mass-extinction dinosaur-expansion jurassic
200000000 BC

First soft-shelled dinosaur eggs

Fossil eggs from ~200 Ma display thin, flexible shells, showing that early dinosaurs laid soft-shelled eggs.
reproduction microstructure jurassic eggs
155000000 BC

Theropods

Archaeopteryx preserves flight feathers, documenting dinosaur–bird transition.
archaeopteryx feathered-dinosaurs germany
145000000 BC

Cretaceous period begins

Spread of angiosperms and diversification of duck-billed and horned dinosaurs.
flowering-plants hadrosaurs ceratopsians
145000000 BC

Hard-shelled dinosaur eggs

By 145 Ma thick, calcified eggshells evolve in theropods, permitting open-nest incubation and brooding behaviors.
eggs calcite-shells jurassic theropods
76000000 BC

First evidence of mixed-species herds

Canadian tracks show ceratopsians moving with other herbivores, the earliest direct proof of multi-species herding.
ceratopsians trackways alberta social-complexity
75000000 BC

Maiasaura nesting colonies reveal parental care

Maiasaura nesting grounds show adults tending multiple age classes of young, documenting post-hatchling care.
montana hadrosaur colonial-nests parental-care
68000000 BC

Tyrannosaurus Rex appears

Emergence of T-Rex, one of the largest terrestrial carnivores
late-cretaceous apex-predator north-america t-rex
66000000 BC

Chicxulub Asteroid Impact & K–Pg Extinction

An asteroid strike ends the reign of non-avian dinosaurs and ~75 % of marine species.
asteroid iridium-layer non-avian-dinosaurs-end
1676

First scientific dinosaur fossil

Discovery of a giant femur of a Megalosaurus; Robert Plot illustrates it but does not identify it as a dinosaur.
england femur earliest-recognition
1842

Coining of “Dinosauria” by Richard Owen

Owen groups Megalosaurus, Iguanodon, and Hylaeosaurus under the new clade “Dinosauria”.
taxonomy british-museum formal-naming
1854

First public dinosaur sculptures

Life-size concrete models of Iguanodon and allies open in London’s Crystal Palace Park, the world’s first dinosaur-themed public display.
crystal-palace victorian-england public-outreach
1868

First mounted Dinosaur skeleton

Exhibit at the Academy of Natural Sciences sparks worldwide dinosaur enthusiasm.
philadelphia public-display cretaceous-herbivore
1969

Dinosaur Renaissance

A monograph presents Deinonychus, revitalizing ideas of active, bird-like dinosaurs.
bird-hipped warm-blooded john-oster
1996 September 1

Discovery of Sinosauropteryx

Fossils of Sinosauropteryx, the first feathered non-avian dinosaur, preserve filamentous feathers, confirming widespread feathery coverings among coelurosaurian theropods.
china protofeathers theropod
1996

Feathered dinosaur fossils from China

Discoveries cement the dinosaur–bird link via direct feather impressions.
sinosauropteryx liaoning preserved-feathers
2007

First dinosaur protein sequences

Mass-spec analysis recovers 68 Ma collagen peptides, confirming endogenous biomolecules.
collagen t-rex molecular-paleo