Asaphid trilobite
This trilobite reminds us that early animal life was already complex, varied, and successful hundreds of millions of years before dinosaurs, birds, or mammals ever appeared.
Evolution
Argentinosaurus
Argentinosaurus shows how far the sauropod body plan could go. By the Late Cretaceous, some titanosaurs had become the largest land animals known, turning the long-necked dinosaur design into one of evolution’s most extreme achievements.
Diplodocid LCA: The Age of Giant Necked Sauropods
The diplodocid story likely began with an earlier shared ancestor we have not yet found by name, reminding us that evolution is often reconstructed from branching clues rather than a single perfect fossil.
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Brontosaurus
Brontosaurus, in the revived interpretation, looks broadly similar to Apatosaurus but is argued to be less massive and less robust. A bit lighter-built overall.
Apatosaurus
Apatosaurus was the heavier, more robust sauropod — more muscular-looking, with a thicker, lower-set neck and a bulkier frame.
Diplodocus
Diplodocus was the longer, slimmer, more stretched-out sauropod, famous for its especially long neck and whiplike tail. It is one of the longest land animals and generally more slender in build.
Styracosaurus
Styracosaurus was a striking horned ancient cousin of Triceratops, showing that ceratopsids branched into different styles long before the dinosaurs came to an end.
Toothed Birds Go Extinct
At the K–Pg boundary, birds were already diverse, but most of that Late Cretaceous variety died out, leaving only a small toothless slice of the bird world to continue.
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Pteranodons Emerge
Pteranodon was one of the great soaring pterosaurs of the Late Cretaceous, but it was only one branch in a much larger pterosaur story.
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The Last Stegosaurus: Wuerhosaurus
Wuerhosaurus shows that the stegosaur branch survived longer than many people realize, but not all the way to the end of the dinosaurs.
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The Last Theropods
At the end of the Cretaceous, theropods were still a varied and successful branch, not a single fading form.
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The Last Sauropods
The last sauropods were titanosaurs—the final surviving long-necked dinosaurs, still ranging from giants to smaller and even armored forms at the end of the Cretaceous.
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The Last Ornithischians
Even near the end, ornithischians remained a diverse and successful branch of plant-eating dinosaurs.
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The Last Pterosaurs
The last pterosaurs were not all the same, and they were not simply faded leftovers.
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Tyrannosaurus Rex
T. rex lived in western North America about 69 to 66 million years ago. All dinosaurs, except potentially three lines of birds, went extinct 66 million years ago, when the Chicxulub asteroid hit.
Proceratosaurus (T.Rex ancestor)
Proceratosaurus had the same general tyrannosaur-style look: a big head, long tail, strong hind legs, short forelimbs, and a built-for-biting predator shape: D-shaped front teeth and a crest on top of the skull.
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Dinosauria Emerge: True Dinosaurs!
Before the famous branches split into predators, long-necks, horned giants, and birds, there was one early ancestral species. One population eventually led to all dinosaurs: Allosaurus, Styracosaurus, and Diplodocus.
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Triceratops
Triceratops, one of the last great horned dinosaurs, roamed western North America at the very end of the Age of Dinosaurs with its three horns, broad frill, and heavy four-legged build.
Zuniceratops
Zuniceratops shows an earlier stage in the evolution of the horns and frill later made famous by Triceratops.
Bashanosaurus primitivus
Bashanosaurus primitivus is one of the earliest known stegosaurs and a strong candidate for representing an early form close to the ancestry of later plated dinosaurs like Stegosaurus.
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