Why is a plesiosaur not a dinosaur?

When dinosaurs ruled on land, these reptiles prowled the seas. Plesiosaurs inhabited the seas from around 200 million to 65 million years ago. They were not dinosaurs, despite living at the same time as dinos. It is thought that plesiosaurs fed mainly on fish, breathed air and laid their eggs on beaches.

Why are plesiosaurs not classified as dinosaurs?

Plesiosaurs also went extinct at the end of the Cretaceous epoch. … Their extinction may simply have been caused by excessive competition with other marine reptiles. Another creature commonly mistaken for a dinosaur is Dimetrodon, with its distinctive “sail” back and sprawling reptilian stance.

Is a plesiosaur a dinosaur?

Marine reptiles, such as ichthyosaurs, plesiosaurs and mosasaurs are not dinosaurs. Nor is Dimetrodon or other reptiles in the same group (previously called ‘mammal-like reptiles’ and now called synapsids). … It was a different kind of extinct reptile and lived even longer ago than dinosaurs.

What qualifies as a dinosaur?

Reptiles, such as crocodiles and lizards, have legs that sprawl out to the side. Their thigh bones are almost parallel to the ground. They walk and run with a side-to-side motion. Dinosaurs, on the other hand, stand with their legs positioned directly under their bodies.

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Are sharks dinosaurs?

Today’s sharks are descended from relatives that swam alongside dinosaurs in prehistoric times. … It lived just after the dinosaurs, 23 million years ago, and only went extinct 2.6 million years ago.

Are ichthyosaurs Diapsids?

Ichthyosaurs are superficially dolphin-like reptiles that were important marine predators from the Triassic Period through the middle of the Cretaceous Period. … For now, paleontologists think that ichthyosaurs are diapsids, but exactly where they fit in the diapsid tree is not yet known.

Are any dinosaurs alive today?

Other than birds, however, there is no scientific evidence that any dinosaurs, such as Tyrannosaurus, Velociraptor, Apatosaurus, Stegosaurus, or Triceratops, are still alive. These, and all other non-avian dinosaurs became extinct at least 65 million years ago at the end of the Cretaceous Period.

Do sea dinosaurs still exist?

500 million years old—Nautilus

Originally, there were 10,000 different species—today, only a few survive in the western Pacific Ocean and coast of the Indian Ocean.

Were there any marine dinosaurs?

Question #14: Were there any swimming dinosaurs? Answer: No dinosaurs were adapted to an entirely aquatic life, although some may have gone into the water to get prey. … There were many aquatic reptiles that lived during the time of the dinosaurs, including plesiosaurs, nothosaurs, and mosasaurs.

What was before dinosaurs?

The age immediately prior to the dinosaurs was called the Permian. Although there were amphibious reptiles, early versions of the dinosaurs, the dominant life form was the trilobite, visually somewhere between a wood louse and an armadillo. In their heyday there were 15,000 kinds of trilobite.

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Are Dinosaurs Real?

Dinosaurs are a group of reptiles that have lived on Earth for about 245 million years. In 1842, the English naturalist Sir Richard Owen coined the term Dinosauria, derived from the Greek deinos, meaning “fearfully great,” and sauros, meaning “lizard.” Dinosaur fossils have been found on all seven continents.

Is a chicken a dinosaur?

So, are chickens dinosaurs? No – the birds are a distinct group of animals, but they did descend from the dinosaurs, and it’s not too much of a twist of facts to call them modern dinosaurs. There are many similarities between the two types of animal, largely to do with bone structure.

Are Sharks older than dinosaurs?

As a group, sharks have been around for at least 420 million years, meaning they have survived four of the “big five” mass extinctions. That makes them older than humanity, older than Mount Everest, older than dinosaurs, older even than trees. It is possible that sharks just got lucky in the lottery of life.

What killed the Megalodon?

Extinction of a mega shark

The cooling of the planet may have contributed to the extinction of the megalodon in a number of ways. As the adult sharks were dependent on tropical waters, the drop in ocean temperatures likely resulted in a significant loss of habitat.

What is the closest thing to a dinosaur today?

10 Living Descendants and Relatives of Dinosaurs

  • Sea Turtles. …
  • Ostriches. …
  • Snakes. …
  • Sharks. …
  • Crustaceans. …
  • Bees. …
  • Duck-Billed Platypuses. …
  • Tuatara Lizards. All lizards and reptiles are closely related to dinosaurs, but none more so than tuatara lizards.
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21.10.2020

Archeology with a shovel