Air sacs and lightweight bones helped some dinosaurs grow to enormous sizes

Birds are living dinosaurs that evolved from feathered theropods

Traits associated with birds, including feathers, laying eggs, and hollow bones, were first present in dinosaurs and carried through to their descendants. Fossils of these dinosaurs have been found in a sleeping posture, resembling roosting behavior.

Why have birds never become as large as a T. rex?

Birds are descended from dinosaurs, but none have ever reached the gigantic size of their Jurassic ancestors. Some birds in the fossil record, like the "terror birds" of South America, have reached as large as ten feet, but the energy-intensive act of flying disallows birds much larger than that. Researchers claim a lack of evolutionary pressure and predatory bird behavior likely limit bird size.

Dinosaurs ranged from the size of chickens to multistory buildings, with one of the largest, Argentinosaurus, spanning about 39 meters (128 feet) and weighing more than a Boeing 737.

Dinosaurs’ feathers and greater metabolism helped them survive polar conditions

Studies of dinosaur footprints alongside ice-deposited rock fragments indicate that early dinosaurs adapted to cold weather before the volcanic winters of the Triassic-Jurassic extinction event. These geological events helped dinosaurs to flourish by wiping out their amphibious competitors.

Variations in beak shape helped birds survive the dinosaur extinction event

The asteroid that struck Earth 66 million years ago killed some avian dinosaurs. The smaller species endured by reproducing more quickly and adapting to the environment. Their different beaks allowed them to eat more varied foods for survival.

Uncovering the evolution of history's largest dinosaurs

This article details how sauropods—the dinosaurs that Little Foot would call longnecks—repeatedly evolved to attain such colossal sizes, towering over other land critters, including tyrannosaurs and mammoths. Sauropods were giant, long-necked...

Mammals thrived under the feet of dinosaurs

An explosion of fossil finds reveals that ancient mammals evolved a wide variety of adaptations allowing them to exploit the skies, rivers and underground lairs.

Mammals gradually expanded in size and diversity after the dinosaur extinction

After an asteroid impact caused a mass extinction event 66 million years ago, small mammals were among the few surviving species. With fewer predators, mammals steadily grew larger as new habitats emerged.

Dinosaurs suffered from cancer, arthritis, and infections seen in modern animals

Using CT scans and advanced pathology techniques, paleopathologists have identified respiratory illnesses, malignant osteosarcoma, and other diseases in dinosaurs. The research has helped show how many of these ailments are not exclusively modern phenomena.

Dinosaurs emerged 245 million years ago when Earth’s continents were still conjoined

Once the supercontinent split apart, dinosaurs evolved into thousands of species as they adapted to their changing environments. All non-avian dinosaurs went extinct about 66 million years ago following an asteroid impact, while avian dinosaurs evolved into today’s birds.

Without dinosaurs, plants could produce fleshy fruits with bigger seeds

Previously disturbed by massive herbivores, denser and darker forests shifted plant evolution, reaching the greatest diversity of seed sizes, fruit sizes, and fruit types about 50 million years ago.

Some dinosaurs evolved night vision and acute hearing for nocturnal hunting

Paleontologists analyzed the fossilized eye and ear structures of 16 theropods, finding that some had owl-like hearing and huge pupils. These characteristics are consistent with modern-day nocturnal species, including nightjars and geckos.

Pterosaurs were dinosaur cousins that ruled the skies

Giant flying lizards or massive leathery birds? Pterosaurs were neither. What they were were the first vertebrates to fly through the skies. This National Geographic video discusses the anatomical features that made their flight possible, how big these awesome creatures could get, and which species was named after a legendary vampire.

Dinosaurs are defined by specific traits that many dinosaur-like creatures lack

Although pterodactyls, mosasaurs, crocodilians, and other organisms are mistaken for dinosaurs, they do not have upright legs or specific hip structures characteristic of the terrestrial reptiles. Some, like the Dimetrodon, are more closely related to humans than dinosaurs.

Richard Owen coined the term ‘Dinosauria’ to group three giant reptiles

Identifying similarities in the fossils of Megalosaurus, Iguanodon, and Hylaeosaurus, Owen surmised that they were all part of a broader group of large terrestrial reptile species. The name “Dinosauria” came from combining the Greek words for “fearfully great” (deinos) and “lizard” (sauros).

Unlike the roars in movies, dinosaurs likely cooed, rumbled, and boomed

Fossil evidence and CT scans suggest that many dinosaurs produced low-frequency sounds using resonating crests, closed-mouth vocalizations, or organs similar to those of birds and crocodiles. Larger sounds would not have been helpful for sneakily hunting prey.

Civilizations of the past mistook dinosaur fossils for dead mythological creatures

Without knowledge of evolution or extinction, people believed such fossils were the bones of massive animals no one had ever seen alive, including dragons and giants. It was not until the science of paleontology and studies of extinction that these ideas were overturned definitively.

The ancestors of ostriches and emus could fly

The discovery of a 56 million-year-old fossil bone helps explain how this (mostly) flightless family of birds spread to so many different continents.

Millions of years of evolution produced dinosaurs with bizarre features

This list of the 17 weirdest dinosaurs includes a cross between a parrot and a porcupine, a dinosaur whose arms each ended with one finger, a vampire dinosaur, a dinosaur with wings on its legs instead of its arms, and a Harry Potter-inspired “dragon king of Hogwarts.”

T. rex didn't stomp, it walked on tiptoes like a bird

A new biomechanical study analyzing four T. rex specimens, including the famous "Sue" at Chicago's Field Museum, found the dinosaur used a "distal-first" foot strike, described as landing on its toes before its heel, similar to a modern ostrich. The technique improved stride efficiency and shock absorption, letting adults reach speeds up to 14 mph, while younger, lighter T. rexes could sprint closer to 25 mph.

The first dinosaur bone ever discovered in Antarctica—a tail bone from a titanosaur—sat in storage for over 40 years before scientists realized what it was.

Fossilized bite marks suggest some dinosaurs may have engaged in cannibalism

An excavation site near the Colorado-Utah border contained Allosaurus bones with tooth marks of other Allosaurus, which may have occurred in response to a dry season in the area. The Tyrannosaurus and Majungasaurus have also been shown to eat their own.

View a directory of more than 300 dinosaurs

This resource details each dinosaur's taxonomy, type, diet, and habitat, from Aardonyx to Zuniceratops. More well-researched dinosaurs include information on when they were discovered alongside their size, behaviors, and other noteworthy findings.

Explore an interactive timeline and map of dinosaurs across the globe

This tool maps dinosaur habitats based on fossil sites around the world. It includes short articles and additional information—including size, diet, and weight—about each dinosaur. A timeline and data table also allow users to compare dinosaur emergence and extinction dates.

Herd behavior has been seen in 193-million-year-old dinosaur fossils

Scientists excavated eggs, juveniles, and adult remains in Patagonia, all arranged by age group. The organization into structured groups may have contributed to evolutionary success by consolidating eggs in one location to make defending them easier.

Dinosaurs thrived in the Arctic year round

The Arctic in the Cretaceous Period was a rough place to live, especially in winter. And yet, the fossils of many kinds of dinosaurs have been discovered there. So how were they able to survive in this harsh environment?

T. rex needed the same amount of calories as 80 people every day

Tyrannosaurus rex is the most extensively studied fossil creature ever known. Every year, new research is added to the towering list of papers that try to draw …

Estimates say 2.5 billion total T. rexes lived on Earth

Roughly 68 million years ago, the Tyrannosaurus rex was king of the North American ecosystem. Researchers used the dinosaur's size, metabolic rate, age of sexual maturity, and other factors to determine 20,000 individuals likely were alive at any given time, more than 120,000 20-year generations. This piece breaks down how they arrived at those numbers.

T. rex hunted for prey but wasn't above scavenging rotting meat

Despite possessing a huge head full of serrated teeth the size of rail spikes, the Tyrannosaurus rex had puny, rigid arms, and scientists think it enjoyed scavenging.

Huge tyrannosaur wore a fuzzy coat

It’s not your dad’s tyrannosaur: Yutyrannus huali, a newly discovered ancestor of Tyrannosaurus rex, was covered from head to tail in downy feathers.

Dinosaur names have shifted from ancient languages to pop culture references

Early dinosaur names used Greek and Latin roots, often just attaching “-saurus” (lizard) to another word describing a notable trait. Over time, this convention has evolved to incorporate the names of where the discovery was made, local languages, and even celebrities.

There are lots of weird ideas about dinosaur extinction, like hungry, hungry caterpillars

One of the great historical puzzles is this: why did the dinosaurs go extinct? Whether an asteroid, poison plants, volcanos and climate change, or something else, it's still a mystery. Scientists have been debating this question for almost a hundred years. One insect scholar suggests that caterpillars are the culprits.

How snake biology allows them to eat prey larger than they are

Possessing flexible skulls with elastic ligaments and unfused jaw bones, snakes can open their mouths to engulf much larger prey, and adjustable airways enable them to continue breathing while their teeth grip onto their food. Through slow digestion and specialized cells that decompose bones, some snakes can survive on a single large meal for over a year.

Spinosaurus had the weirdest dinosaur tail of all time

A new fossil of one of the most unusual dinosaurs, Spinosaurus aegyptiacus, suggests it was a swimming predator powered by a fin-like tail.

Human anatomy provides evidence for evolution

Throughout history, scientists have used anatomy to support the Theory of Evolution in three main ways. Homologous structures, or similar physical features in organisms that serve different functions, can help scientists understand common ancestors....

Watch animations of the creation and excavation of dinosaur tracks

The discovery of a dinosaur trackway in the UK emerged from a controlled explosion that removed limestone from an Oxfordshire quarry. The footprints provide unique insights into dinosaur behavior and movement, with marine fossils suggesting a lagoon-like environment.

Dinosaurs would likely still roam Earth if the Chicxulub asteroid had hit elsewhere

Some scientists argue that the asteroid's impact would have been less severe if it had struck the ocean instead of shallow seas. In this scenario, small dinosaurs might have become urban survivors, living in cities alongside humans, much like pigeons or rats do today.

The resulting climate change, not the asteroid impact itself, killed most dinosaurs

Although the Chicxulub impact caused widespread destruction through earthquakes and tsunamis, the subsequent nuclear winter, acid rain, and eventual greenhouse warming drove mass extinction. Roughly 70% of species, including all non-avian dinosaurs, went extinct.

What did the world of the dinosaurs look like?

Mesozoic means "middle life" and this is the time of the dinosaurs. This era includes the Triassic, Jurassic, and Cretaceous Periods, names that may be familiar to you. It ended with a massive meteorite impact that caused a mass extinction, wiping out the dinosaurs.

Metamorphosis evolved over millions of years as species that hatched as smaller versions of adults started exhibiting genetic mutations that differentiated juvenile and adult bodies.

Dinosaur portrayals in film mistakenly limit them to only living in tropical climates

The ancient creatures have been brought to life in cinema by combining animatronics and CGI. However, creative liberties have created misconceptions about dinosaurs for audiences, including that the Tyrannosaurus rex could not see stationary prey.

Instead of bones, shark skeletons have 200 to 400 structures composed of cartilage—the same material that makes up human ears.

The Age of Dinosaurs ended in fiery disaster

How did dinosaurs become extinct? Explore the Cretaceous extinction event and the role of the Chicxulub impact in the death of dinosaurs (except birds).

The tongue evolved in animals roughly 350 million years ago

Creatures like fish rely on suction to consume food, flexing their gills to create water currents that vacuum up their meals. The evolution of the tongue enabled vertebrates to completely cut ties with the sea, moving onto land where they could sample new foods and ways to eat them.

About 66 million years ago, an asteroid larger than Mount Everest struck Earth off the coast of the Yucatán Peninsula and wiped out at least 75% of all species, including nearly all dinosaurs.

The halting of human bone growth helps manage heat produced from metabolism

While fish, amphibians and reptiles get bigger throughout their lives until they die, their slower metabolisms allow their bodies to regulate the resulting smaller temperature increases. In humans, hormones triggered during puberty harden growth plates, ending bone lengthening.

Studies show the asteroid that killed the dinosaurs was from the outer asteroid belt

Isotopic evidence confirms the rock was a carbon-rich asteroid, likely born beyond Jupiter and later knocked into Earth's path after billions of years of orbital drift and gravitational nudges. Its path spanned over 4 billion years and ended in the extinction of 75% of life, including all nonavian dinosaurs.

Large animals like giraffes and elephants have evolved unique cancer defenses.

Georges Cuvier used his knowledge of anatomy to prove extinction had occurred

Extinction had been viewed as impossible because a divine plan for the world would not rationally involve the loss of any of God’s creations. However, mammoth and mastodon bones differed from elephants’, and it seemed impossible that such creatures could be hiding elsewhere on Earth.

How paleos dig up dinosaurs

Follow Kelsie Abrams and the dig team from the field to the lab, as they unravel mysteries from the end of the age of dinosaurs.