what animals lived in the cretaceous period

Cretaceous Period Animals That WerenТt Dinosaurs

10 Cretaceous Animals That WerenТt Dinosaurs. 1: Prehistoric Rodents. Rugosodon eurasiaticus was about the size of the chipmunk, but was it as cute? 2: Phil's Forebears. 3: Toothless Pterosaurs (and More) 4: Crazy Crabs. 5: Lizards, Lots of Them. At about the same time, many modern groups of insects were beginning to diversify, and we find the oldest known ants and butterflies. Aphids, grasshoppers, and gall wasps appear in the Cretaceous, as well as termites and ants in the later part of this period.

The Lower Cretaceous is characterized by a revolution in the plant life, with cretacrous sudden appearance of flowering plants angiosperms such as the ancestors of the beech, fig, magnolia, and sassafras.

By cretacsous end of the Cretaceous such plants became dominant. Willow, how to make ironman mii, grape, laurel, birch, oak, and maple also made their appearance, along with grass and the sequoias of California.

Closely associated with the angiosperms were insects, including a form of the dragonfly, and most were similar rhe today's insects. This prepared the way for the increase in mammals in the late Cenozoic.

The marine invertebrates of the Cretaceous included nautiluses, barnacles, lobsters, crabs, sea urchins, ammonites, and foraminifers. Reptiles reached their zenith, including the dinosaurs Triceratops, Tyrannosaurus, Stegosaurus, Apatosaurus Brontosauruscretaceois Iguanodon, and ranged from herbivores to carnivores.

Flying reptiles such as the pterosaurs were highly developed, while in the sea there were tbe, plesiosaurs, and mosasaurs. Other reptiles living in this period include crocodiles and giant turtles; snakes and lizards made their first appearance at this time. True mammals, which had already appeared in the Triassic periodwere rare, as the Cretaceous reptiles dominated. The climate of the Cretaceous was apparently fairly mild and uniform, but it is possible that toward what is the meaning of retrospectively end of the period some variant zones of climate had appeared, making the overall climate cooler.

Such changes, along with changes in both the earth's surface livved its flora and fauna, brought the Mesozoic to a close. The rather abrupt disappearance of Cretaceous life remains a mystery; similar mass extinctions have occurred at other periods in the earth's history. Theories crftaceous the extinctions have included one or a mixture of the following: drastic cooling of the globe, retreat of the seas, waht of the continents see continental driftbiological disease, reversals of the earth's magnetic field, or a change in atmospheric carbon dioxide and oxygen.

However, the most widely accepted theory was introduced in by Luis and Walter Alvarez and colleagues at the Univ. Alvarez proposed that the earth was struck by an asteroid or comet about 6 mi cretacwous km in diameter around 65 million years ago. Such an impact or collection of impacts would spread dust into the lives, suppressing photosynthesis and changing the food chain.

Evidence for an impact includes an anomalous iridium layer, typical of meteorites, and some probable impact craters dated to the late Cretaceous. Other scientists have proposed that the cause of the final Cretaceous extinction was the huge volcanic eruptions that created the lava flows of the Deccan Traps in what is now India.

One model has put these two theories together, hypothesizing that shock waves from the impact of a large asteroid moved through the earth, shaking the earth's crust and triggering or intensifying the volcanic events. Another suggests that the lava flows set off a chain of events that killed off much marine life a couple hundred thousand years before the impact extinguished the dinosaurs.

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Economic significance of Cretaceous deposits

The marine invertebrates of the Cretaceous included nautiluses, barnacles, lobsters, crabs, sea urchins, ammonites, and foraminifers. Reptiles reached their zenith, including the dinosaurs Triceratops, Tyrannosaurus, Stegosaurus, Apatosaurus (Brontosaurus), and Iguanodon, and ranged from herbivores to carnivores. Placental mammals, which include most modern mammals (e.g., rodents, cats, whales, cows, and primates), evolved during the Late Cretaceous. Although almost all were smaller than present-day rabbits, the Cretaceous placentals were poised to take over terrestrial environments as soon as the dinosaurs vanished. Nov 03, †Ј Filikomys primaevus, a new genus and species of multituberculate mammal that lived during the Late Cretaceous epoch, has been identified from multi-individual aggregates of .

Not all Cretaceous Period animals were dinosaurs! The pterosaurs continued to diversify, with both the biggest and the smallest-known species appearing during the course of the Cretaceous Period. In the Cretaceous oceans the ichthyosaurs and plesiosaurs were joined by another branch of marine reptile Ч the mosasaurs: fearsome predators that had evolved from lizards.

Fish, sharks, and numerous invertebrates also thrived in the marine environment. With the appearance of flowering plants, and insects such as bees and moths, Earth was becoming ever more familiar. The Cretaceous Ч Paleogene Extinction Event occurred 66 million years ago.

It brought the Cretaceous Period to a close, and led to a new chapter for life on Earth. The mammals of the Cretaceous Period were mostly small and nocturnal Ч a lifestyle forced upon them by the existence of dinosaurs.

They probably led rodent-like lifestyles, but they were not rodents; the modern mammalian orders of today rodents, bats, primates, etc. By the end of the Cretaceous Period the three main mammalian branches Ч monotremes egg laying mammals , metatheria marsupials , and eutherians placental mammals Ч had appeared.

Repenomamus giganticus. Two species have so far been identified: Repenomamus giganticus and Repenomamus robustus. Repenomamus giganticus was one of the largest-known mammals of the Cretaceous period. It weighed about 13kg 28 pounds and was around 1m 3 feet in length.

Fossil evidence suggests that it was carnivorous. A fossilized specimen of the closely-related Repenomamus robustus was found with the remains of a dinosaur in its stomach. This short-legged, stocky mammal lived in China in the Early Cretaceous. Growing to around 50 cm 20 in , it may have resembled the platypus of today.

Steropodon galmani lived around Mya million years ago in the Early Cretaceous. Although most Cretaceous mammals were ground-dwelling, there were exceptions; several groups are thought to have been arboreal tree-dwelling. Volaticotherium is one of a small number of Cretaceous mammals that not only lived in trees, but also developed the ability to glide.

This 20 cm 8 in. The structure of its teeth suggest that it was an insectivore insect-eater. Bees first appeared in the Early Cretaceous, having evolved from wasps.

Wasps appeared during the Jurassic Period. Also evolved from wasps were ants, who, like the bees, made their first appearance in the Early Cretaceous. Although the first termite fossils are from the Cretaceous, it is likely that they appeared earlier in the Mesozoic Era. The wasp family Cynipidae, also known as the gall wasps, first appeared in the Cretaceous.

These insects lay their eggs in trees. Chemicals from either the larvae or the parent induce a growth to appear in the tree. The larva develops inside the growth, which provides it with both protection and food.

Fleas too appeared in the Early Cretaceous, forming a parasitic relationship with both mammals and birds. Insect groups that had appeared before the Cretaceous, such as Coleoptera beetles , Lepidoptera, butterflies and moths and Odonata dragonflies and damselflies continued to evolve and diversify throughout the period. Although dinosaurs were the dominant animals on land, several other reptile groups were present on land and in the air during the Cretaceous Period.

Pterosaurs Ч the first flying vertebrates Ч had first appeared in the Triassic Period. They were abundant during the early and mid-cretaceous, but declined somewhat during the late cretaceous.

This may have been due to the success of the birds. Nemicolopterus fossil. It had a wingspan of just under 25 centimeters 10 in.

It lived in China around million years ago. Pteranodon , a genus of pterosaur with two known species, Pteranodon longiceps and Pteranodon sternbergi , appeared in the Late Cretaceous. More Pteranodon specimens have been discovered than any other type of pterosaur. Pteranodon were among the largest pterosaurs. They lived in North America. It is one of the largest flying animals of all time, with a wingspan that may have reached Quetzalcoatlus was discovered in Texas.

The archosaurs were a group of reptiles that first appeared in the Triassic Period or perhaps even earlier. They quickly split into two groups: Pseudosuchia crocodile-type reptiles , and Avemetatarsalia the dinosaurs and pterosaurs. By the Cretaceous Period the only surviving pseudosuchians were the Crocodyliformes Ч a group of animals that included the ancestors of the crocodilians of today i. Sarcosuchus imperator lived in Africa in the Early Cretaceous. It is one of the largest crocodile-type animals ever to have lived, reaching a length of By comparison, the saltwater crocodile Ч the largest living crocodilian Ч reaches lengths of around 6 m 20 ft.

The squamates the reptile group that includes lizards and snakes had first appeared way back in the Triassic Period. In the Jurassic Period, lizard groups such as geckos and skinks appeared. The Cretaceous Period saw the appearance of the earliest snakes. They had evolved either from monitor lizards or a similar lizard group. Although its body was long and thin like that of a modern snake, it had a small pair of hind legs. In the Cretaceous Period the early birds became more like the birds of today, with some groups losing their ancestral tails and teeth.

By the end of the Cretaceous Period bird groups such as the Palaeognathae ostriches and other flightless birds , Anseriformes waterfowl , Galliformes landfowl and Neoaves all other modern bird types had appeared.

They were to be the only birds to make it through the Cretaceous Ч Paleogene Extinction Event. Art by Velizar Simeonovski. Peteya, Matthew D. Shawkey [ CC BY 4. This pigeon-sized bird still retained features from its dinosaur ancestors, including clawed hands. Its short tail and toothless beak, however, meant that it would have looked much more like a modern bird than a dinosaur.

Cartilaginous fishes such as sharks and rays were also common. Reaching an estimated length of up to 6 m 20 ft. It had a large forked tail and was likely to have been a powerful swimmer. Xiphactinus specimens have been found with the remains of other species, including other Xiphactinus, inside their stomachs. A Xiphactinus specimen found in had a mosasaur flipper in its mouth. It grew to 7 meters 23 ft. Most Cretaceous sharks were smaller than the sharks of today.

Turtles first appeared in the Triassic Period, and both freshwater and marine turtles lived during the Cretaceous Period.

This Late Cretaceous marine species was found in the shallow sea that covered much of Central North America. It reached lengths of up to 4. Two types of plesiosaur roamed the oceans of the Cretaceous Period: the long-necked, small-headed plesiosauroids and the short-necked pliosauroids also known as pliosaurs.

Both types propelled themselves through the water with four powerful flippers. Its neck Ч thought to reach around 7 m 23 ft. It was one of the largest pliosaurs.

Two species are known: Kronosaurus queenslandicus , specimens of which were found in Australia; and Kronosaurus boyacensis , which was discovered in Columbia.

The ichthyosaurs lost their place as top marine predators to the plesiosaurs in the Jurassic Period. They were still present throughout much of the Cretaceous, but became extinct around 95 Mya, before the end of the Late Cretaceous. Its fossilized remains show that it ate turtles and birds, and it is likely to have been an apex predator. Platypterygius specimens have been found all over the world.

Mosasaurs were a group of marine reptiles that appeared in the Early Cretaceous, having evolved from aquatic lizards. At the very end of the Cretaceous Period, mosasaurs became the dominant marine predators after both the ichthyosaurs and the pliosaurs became extinct.

Growing to an estimated length of 17 m 56 ft. It lived right at the end of the Cretaceous Period, and became extinct along with the non-avian dinosaurs in the Cretaceous-Paleogene extinction event. Mosasaurus swam using undulations of its body, aided by its powerful tail.

This fearsome marine predator hunted fish, ammonites, turtles and other marine animals near the surface of the ocean. Crustaceans had appeared millions of years prior to the start Mesozoic Era. Prawns had appeared in the Triassic, and they were joined by crabs and shrimps in the Jurassic.

The Cretaceous saw the appearance of the first true lobsters, and also of many new species of crab. Avitelmessus was a crab that lived in what is now the southeastern United States during the Late Cretaceous. Its shell was around 6 cm 2. This extinct animal would have looked much like the crabs of today. Mollusks were well-established before the Mesozoic Era. Animals such as ammonites, octopuses and nautiluses all swam in the oceans of the Cretaceous Period.

The Cretaceous saw the appearance of the first squid.