Cretaceous Period Animals

It happened quickly, like a bright light hurtling across the sky. It came without notice. It hit with such force that it altered the face of planet Earth. A massive asteroid or comet about 6 miles (10 kilometers) in size is thought to have collided with what is now the shore of Mexico 65 million years ago.

The explosion would have created dense clouds of dust and rock that darkened the sky, eventually chilling the planet to its core and killing 70 percent of all existing species, in addition to all the tidal waves, fires, earthquakes, and other random disasters it would have generated.

The Cretaceous Period came to an end with this collision. This era, which started about 145 million years ago, marked the end of the dinosaurs’ era.

Pterosaurs and huge, feathered birds darkened the skies, and it was the age of massive sauropods digging through forests. Tyrannosaurs, as well as triceratops and stegosauruses, bounded across the globe. New coastlines arose, temperatures increased then fell, and ocean currents altered as Pangea, the supercontinent, broke up.

New habitats for new creatures emerged as a consequence. Coniferous forests emerged as flowering plants took hold.

Dinosaurs started sharing the planet with a wider variety of species when this transformation started. During the Cretaceous Period, a variety of creatures that weren’t dinosaurs thrived.

Several of them have survived thousands of millennia of evolutionary development. Others have passed away. You may be taken aback by some of the things listed here. Your skin will crawl at the presence of others. There are ten of them in total.


Pterodactyls were not members of the same family as dinosaurs, despite the fact that they flew above them. Pterodactyls are pterosaurs, a extinct group of reptiles that evolved to fly.

Birds are actually descended from dinosaurs, so they have body structures that are more dinosaur than a pterodactyl could ever hope for.

Pterosaurs had sluggish hind-limbs, which were mostly inactive during take-off. Pterosaurs took to the sky with their tremendous wings, instead of building up speed by running.

Repenomamus – Dinosaur-Eating Cretaceous Mammals

Cretaceous animals belonging to the Repenomamus genus. Repenomamus giganticus and Repenomamus robustus are the two species that have been identified thus far.
One of the biggest known creatures from the Cretaceous era was Repenomamus giganticus. It was roughly 1 meter (3 feet) long and weighed around 13 kilograms (28 pounds). It was likely carnivorous, according to fossil finds.

With the bones of a dinosaur in its belly, a fossilized example of the closely related Repenomamus robustus was discovered. During the Early Cretaceous period, this short-legged, stocky herbivore thrived in China.


Scratch, scratch, scratch! Hats, coats, and sometimes in your hair will have them. The little louse survived the demise of the dinosaurs, perhaps because they were too tiny to perish or there were simply too many of them.

That’s irrelevant. Lice on the downy feathers of ancient monsters that evolved into modern birds most likely lived on the downy feathers of avian-dinosaurs. Parasites may have chowed down on the Shuvuuia, a genus of birdlike, meat-eating theropods that lived between 85 and 75 million years ago [source: Balter].

Two lice fossils were discovered in stone a few years ago by scientists. The first was 44 million years old, and the second was about 100 million. These poor bloodsuckers not only survived the near-annihilation of Earth 65 million years ago, but also prospered afterwards, according to researchers’ findings.


The sail-backed dimetrodon is not a dinosaur, contrary to popular belief. It’s a synapsid, a group of ancient creatures that preceded modern mammals and predates the dinosaurs. Eventually, your forefathers will resemble dimetrodon if you look back far enough in your family tree.

Before the first dinosaurs evolved, Dimetrodon thrived during the Permian period, 35 million years ago. There were numerous distinct species, the most prominent of which was a 10-foot long monster. They were one of the Permian’s most successful predators because they had serrated teeth ideal for eating flesh.

Steropodon – The First Monotreme

Steropodon galmani is one of the earliest-known monotremes (and one of the first known Australian mammals). It may have resembled the platypus of today, growing to around 50 cm (20 in) in length. In the Early Cretaceous, Steropodon galmani existed around 105 million years ago.


Consider this before you reach for the roach spray the next time you hear the crinkling of a potato chip bag in the middle of the night and see an army of cockroaches scurry off the kitchen counter: Cockroaches have been around forever, or at least longer than dinosaurs.

In reality, the biggest-ever fossil of a full cockroach was discovered by a geology student at Ohio State University more than a decade ago. It was 300 million years old and 3.5 inches (9 centimeters) long. Its veins, as well as its legs and antennae, were visible to scientists [sources: CBC News and Ohio State University].

Before the Cretaceous Period began, cockroaches were present, and they continued to exist long after it ended (as we all know). According to some scientists, the insects ate dino droppings throughout the Cretaceous Period.

While investigating the ancient bug’s diet, researchers at the Slovak Academy of Sciences made a surprising find. Researchers created a 3-D replica of a fossilized cockroach embedded in amber using a sophisticated imaging technology known as synchrotron X-ray microtomography.

The bug dates from the Lower Cretaceous Period, about 120 million years ago. They discovered splinters of wood in the roach’s intestines, which they think came from dinosaur droppings [source: Lewis].


These aquatic reptiles did not exist during the Jurassic period and are not genuine dinosaurs, despite their presence in the film Jurassic World. Mosasaurs are supposed to have evolved in the early Cretaceous period, right before the extinction that wiped out most large life forms.

These massive sea-lizards were fierce predators with a strong bite, but they were also highly evolved and intelligent creatures. Mosasaurs were thought to be warm-blooded and capable of giving birth to live youngsters, much like their dinosaur relatives.

Volaticotherium – Carnivorous Gliding Mammal

Although most Cretaceous animals were ground-dwelling, there are reports of several groups that lived in trees. Volaticotherium, like a tiny group of Cretaceous animals, possessed the ability to glide as well as live in trees.

Skin membranes stretched between Volaticotherium’s limbs would have supported the animal in gliding flight.

China was home to this 20 cm (8 in.) creature. It was likely an insectivore (insect-eater), because of the structure of its teeth.

Devil Frogs

It was the biggest, not to mention the fattest, of all frogs that ever leaped across a Cretaceous lily pad at 16 inches (41 centimeters) long. When scientists discovered the bones of this gigantic fossilized frog in Madagascar, they were astounded.

It was 3.5 inches (8.9 centimeters) taller than the world’s largest live frog, and was known as the Beelzebufo ampinga or “devil frog.” It existed during the Cretaceous period, ranging from 65 to 70 million years ago. The mouth and stomach of the devil frog were both enormous.

It was so large that it most likely waited until its victim passed by before doing any hunting on its own. What did it eat for lunch? Baby dinosaurs [sources: Moskowitz, National Geographic] are possible among smaller frogs, lizards, and mice.

During the Cretaceous, other amphibians flourished as well. Koolasuchus, a half-ton giant with eyes on top of its head, was one of them. It was a tetrapod that lived in colder climes but didn’t survive when the planet warmed [source: BBC]. It was a tetrapod, or four-footed vertebrate.


The absolute behemoth that was Quetzalcoatlus It is the world’s biggest flying animal, and it dominated the skies. The feathered serpent deity Quetzalcoatl, a Mayan god associated to control the earth and the sea, inspired the name of this magnificent pterosaur.

About 68 million years ago, this massive reptile flourished near the end of the Cretaceous period. They were believed to weigh about 600 pounds and had a huge 36-foot wingspan. The Andean condor, the world’s heaviest bird today, weighs just about 33 pounds. To put that in perspective

They were too big to flap their wings, so instead of flapping, they soared high and let natural and physics do the hard work. Pterosaurs were thought to have hollow bones, similar to modern birds, which aided in their lightness.


The Early Cretaceous saw the existence of Nemicolopterus crypticus, the smallest-known pterosaur. It had a wingspan of around 25 centimeter (10 inch). About 120 million years ago, it lived in China.

Ancient Lobsters

When you walk into a seafood restaurant for the first time, what do you see? Lobsters — an aquarium with lobsters. Have a nice meal by picking one out. Just keep in mind that what you’re eating is an evolutionary miracle and a survivor named T. All of the others, including rex.

Lobsters are one of the most delectable dishes on today’s menu, surviving the Late Cretaceous extinction.

The fossilized record actually contains the forebears of today’s lobsters. A new species of Late Cretaceous lobster was discovered in Iran by scientists in 2009. Paraclytia valashtensis was the name given to the creature. This is unique because it’s the first time scientists discovered this species outside of Europe.

The well-preserved fossil was discovered by researchers at the southern bank of Valasht Lake in northern Iran [source: McCobb and Hairapetian] in a limestone bed.

Decapoda (10-legged) crustaceans, such as lobsters, crayfish, and shrimp thrived throughout the Cretaceous Period. Scientists have discovered evidence of 22 decapoda crustacean species in British Columbia, Canada, for example.

By the end of the Cretaceous, less than half of the species had gone extinct, and most were found in North America and Central America. Their forefathers are still alive today [sources: Schweitzer et al.], and they were able to climb the evolutionary ladder.


Long-necked plesiosaurs, a collection of marine reptiles with an unusual appearance that had a significant impact on the collective unconscious, were the inspiration for the Loch Ness monster.

Plesiosaurs were a diverse collection of creatures with shorter necks than the most often depicted one. Since it was one of the first fossils to be found, the plesiosaurus has a lengthy history in the paleontological community.

These animals are thought to have evolved their lengthy necks in order to feed on the sea bottom more easily. Plesiosaur necks were rather inflexible, despite numerous erroneous depictions. These unusual creatures are also thought to have swum in a manner that was fairly similar to what modern penguins do.


Pteranodon, a pterosaur genus that consists of two species, Pteranodon longiceps and Pteranodon sternbergi, first appeared in the Late Cretaceous.

Pteranodon has been found in greater numbers than any other pterosaur type. Pteranodon was a big pterosaur, as the name implies. North America was the location of their lives.

Sea Turtles

The oceans of the Late Cretaceous Period were populated by enormous marine reptiles, whether they were mosasaurs or long-necked plesiosaurs. Plesiosaurs, for example, may reach lengths of up to 60 feet (18 meters). The sea turtle, on the other hand, was one of the few enormous creatures that survived the great extinction.

Over 245 million years ago, the first sea turtles emerged. Land animals that evolved to become sea dwellers during the Cretaceous period, according to most scientists. They had longer necks and were much bigger than current sea turtles.

The now-extinct Atlantochelys mortoni was one of the biggest ancient sea turtles. It existed in North America some 75 million years ago. It looked like a contemporary loggerhead [sources: Sci-News, Amos, and SCISTP] and was 10 feet (3 meters) long.


One of the most peculiar pterosaurs ever known is Dimorphodon. The head of a tyrannosaurus appears to be merged with the body of a bat and a pterodactyl.

Dimorphodon is thought to be one of the earliest huge vertebrates to take to the sky, terrorizing the skies nearly 200 million years ago. They were tiny creatures, roughly three feet in length when fully grown. A very small brain was hidden inside their unusually large skulls.

Studying the tree-dwelling gliders they may have evolved from has resulted in a lot of investigation to try and comprehend how they were capable of flying. These wings were thought to be hefty, similar to those of current birds, and they may have flapped them while flying.


While the dinosaurs dominated, they were not alone in their efforts; early crocodiles like Sarcosuchus, which preyed on both dinosaurs and other Cretaceous creatures, showed that they were formidable predators.
In the Early Cretaceous, Sarcosuchus imperator lived in Africa.

It grew to a length of 11.65 m (38.2 ft.) and might weigh 8 tonnes, making it one of the world’s biggest crocodile-type creatures ever to exist.

Lizards, Lots of Them

It’s just a description, despite the fact that “dinosaur” means “terrible lizard.” Despite what Hollywood screenwriters might lead you to believe, dinosaurs are not related to reptiles. Each group is unique. Many lizard species, on the other hand, lived alongside the giant beasts. Many of them died out with the dinosaurs at the end of the Cretaceous period, like as dinosaurs.

Scientists believed that the majority of lizard species would survive the asteroid collision. They didn’t manage to do so. The difficulty, it appeared, was in determining how to categorize lizard fossils discovered by paleontologists. When the space rock hit, up to 85% of all snake and lizard species vanished, according to Prostak [source: Prostak].

Polyglyphanodontia, a group of lizards that included over 40% of all North American lizard species, was one of the most widespread groups wiped out. The bigger the lizard, the scientists discovered, the less likely it was to live. Lizard re-emergence took roughly 10 million years after the Cretaceous Period [sources: Prostak, CBC News].


The reptile equivalent of dolphins were ichthyosaurs. In a remarkable display of convergent evolution, they were marine lizards that had evolved to be at home in the sea, mirroring the body shapes of other aquatic animals like fish and dolphins.

Slow swimmers, ichthyosaurs could reach rapid speeds by utilizing short bursts of energy. They may have slowly stalked their prey until the time came for them to rush in and attack. They were the oceans’ top predators for a while, until the Plesiosaurs came and topped them.