Cretaceous Period

The Cretaceous, the last and longest period of the dinosaur age, lasted from about 145.5 million to about 65.5 million years ago. During the Cretaceous, mammals were small, about rat size, and the land was ruled by dinosaurs, including the duck-bills (hadrosaurs), horned dinosaurs (Triceratops), long-neck sauropods (Dreadnoughtus) and the tyrannosaurs (Tyrannosaurus rex). When the 79-million-year-long period ended, largely because of a 6-mile-wide (10 kilometers) asteroid slamming into the Yucatan Peninsula, about 80 percent of all animal species went extinct, including the non-avian dinosaurs.

Related Topics: Archaeology, Fossils, Human Origins, Dinosaurs

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Full-body specimens of Acipenser praeparatorum, a newly described species from the Hell Creek Formation in Wyoming.

'Hell fish' likely killed by dinosaur-ending asteroid is preserved in stunning detail

By Joanna Thompson published

Scientists recently unearthed stunning fossils of sturgeon from Hell's Creek that might have died on the day that the dinosaur-killing asteroid struck.

Tyrannosaurus rex hunting its prey in a lush jungle environment. There are two Parasaurolophus in the background (they have long crests on their heads and walk on their hind legs).

Cretaceous period: Animals, plants and extinction event

By Michael Dhar published

The Cretaceous period lasted approximately 79 million years, and ended with a major extinction event about 66 million years ago.

The aptly named Thanatosdrakon "dragon of death" pterosaur was a flying reptile that lived alongside dinosaurs during the Cretaceous period.

Giant 'dragon of death' with 30-foot wingspan unearthed in Argentina

By Jennifer Nalewicki published

Scientists recently discovered fossils in Argentina that belong to Thanatosdrakon. The specimens are the largest pterosaurs ever found in South America.

An artistic reconstruction of the seiche wave surging into the Tanis river, bringing in fishes and everything in its path — including trees and dinosaurs — while impact spherules rained down from the sky.

'Frozen in place' fossils reveal dinosaur-killing asteroid struck in spring

By Mindy Weisberger published

Around 66 million years ago, springtime in the Northern Hemisphere brought disaster and mass death to Earth in the form of a giant asteroid impact that triggered a global extinction.

Following the asteroid impact that wiped out the dinosaurs, parts of the planet would have been plunged into darkness.

Darkness caused by dino-killing asteroid snuffed out life on Earth in 9 months

By Mindy Weisberger published

After an asteroid struck at the end of the Cretaceous period, debris from wildfires filled the atmosphere and blocked sunlight across Earth, causing ecosystem collapse and extinctions.

Mosasaurs in the Platecarpus genus, like the one pictured here, have blunter, broader heads than the newly described species, which has an elongated snout like a crocodile's.

An 18-foot-long sea monster ruled the ancient ocean that once covered Kansas

By Mindy Weisberger published

A newly described species of mosasaur, an extinct marine reptile, swam through Cretaceous seas 80 million years ago and had a slender snout like a crocodile's.

"Big John" was discovered in 2014 in South Dakota.

Who will buy 'Big John,' the biggest triceratops ever found?

By Mindy Weisberger published

The largest triceratops in the world, scheduled to be auctioned on Oct. 21, will be on display to the public in Paris beginning Sept. 16.

An artist's rendition of an anhanguerian pterosaur. This group of crested and toothed flying reptiles includes the new species Thapunngaka shawi.

'Real-life dragon' in Cretaceous Australia was huge, toothy and a 'savage' hunter

By Mindy Weisberger published

A pterosaur "dragon" that lived in Australia during the Cretaceous was the continent's biggest flying reptile, according to a new analysis of a fossil jawbone.

Oculudentavis naga, as depicted in this artist's reconstruction, was a bizarre lizard that researchers initially struggled to categorize. They are still unsure of its exact position in the lizard family tree.

'Strange beast' in amber is a very weird lizard

By Mindy Weisberger published

A tiny amber-locked skull that looks like a bird's is actually a lizard's, new fossil evidence shows.

Tail muscle reconstruction in a T. rex.

Never mind outrunning a T. rex — you could probably outwalk it

By Mindy Weisberger published

New simulations calculated T. rex speed from the motion of its swaying tail, finding that the massive dinosaur was a mighty slow walker.

An image reconstruction of a Mosasaurus swimming with its mouth open.

Mosasaurus: Apex ocean predator of the dinosaur age

By Patrick Pester published

Mosasaurus was one of the largest members of the mosasaur family, which were the top predators in the oceans during the age of dinosaurs.

A Chilean rose tarantula (Grammostola rosea) strikes a threatening pose.

Tarantulas conquered Earth by spreading over a supercontinent, then riding its broken pieces across the ocean

By Mindy Weisberger published

Around 120 million years ago, tarantulas first appeared on the Gondwana supercontinent in what is now the Americas, and then dispersed into Africa, Australia and India.

A Deinosuchus, an ancient crocodylian with banana-size teeth, lunges at an Albertosaurus dinosaur.

Cretaceous 'terror crocodile' crushed dinosaurs with banana-size teeth

By Mindy Weisberger last updated

New analysis of the ancient crocodylian Deinosuchus confirms that this apex predator had jaws and teeth that were powerful enough to subdue massive dinosaur prey.

Photomicrograph from top view of the hell ant, Ceratomyrmex ellenbergeri, restraining its prey, an extinct cockroach relative called Caputoraptor elegans, preserved in amber.

Scythelike jaws of Cretaceous 'hell ant' clutch a baby cockroach in an amber tomb

By Mindy Weisberger published

The death strike of a Cretaceous "hell ant" from 99 million years ago is preserved in amber, revealing how these demonic-looking ants hunted.

The two-legged crocodile relative, which left the fossil footprints in what is now South Korea, may have looked like this.

Ancient crocodile walked on two legs

By Laura Geggel published

This ancient croc's legs were likely as long as a human's.

Reconstruction of the Cretaceous marine animal Marsupites testudinarius.

First animal 'buckyballs' discovered in 80-million-year-old sea lillies

By Mindy Weisberger published

Buckyballs are geometric shapes previously only seen in nature at the molecular scale. Scientists recently found them in marine animals dating to the Cretaceous.

The giant pterosaur Cryodrakon boreas stands before a sky illuminated by the aurora borealis. It lived during the Cretaceous period in what is now Canada.

Meet 'Cold Dragon of the North Winds,' the Giant Pterosaur That Once Soared Across Canadian Skies

By Mindy Weisberger published

Cryodrakon boreas, a newly described species of giant pterosaur, was recently identified from fossils found in Canada.

Scientists Find an 'Exceptional Specimen' of a Cretaceous Lizard...Inside a Dinosaur's Belly

By Mindy Weisberger published

An ancient lizard was a flying dinosaur's last meal.

Baby Pterosaurs Could Fly. So, Did They Need Their Parents?

By Mindy Weisberger published

Newly hatched pterosaurs may have been more independent than once thought.

A hungry <i>Aristonectes</i> plesiosaur eyes a tasty squid in this illustration.

Ancient 'Loch Ness Monster' from Antarctica Breaks a Record for Body Size

By Laura Geggel published

Paleontologists have discovered the remains of an ancient Loch Ness Monster look-alike in freezing Antarctica. And just like the legendary Nessie, it wasn't the runt of the litter.