Who was boss before the dinosaurs?
Who was boss before the dinosaurs? Large hippo-like mammal forerunner ("Placerias") that lived, and died off, during the Triassic. (National Park Service Image)
Who was boss before the dinosaurs?
Lexile: 860L

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The Jurassic witnessed a world populated by dinosaurs. While giant plant-eaters munched their way through ferns and conifer forests, large carnivores chased them down for lunch.
At the height of the Age of Dinosaurs, they were found on every continent. They thrived in the warm environments of the time.
But, dinosaurs were not always so prominent. Fossil evidence shows that they arose about 230 million years ago during the Triassic period. But they remained scarce as other reptiles took center stage. Many mammal forerunners, such as the large plant-eater Placerias, prospered. Huge crocodile-like animals like Smilosuchus were the top predators of the Triassic.
Paleontologists who study the fossil record have discovered that something big happened 200 million years ago. It radically changed life on land and in the sea. And it paved the way for dinosaur diversification and prominence.
What happened was so important that it caused more than half of all life on Earth to go extinct. The large crocodile-like reptiles that had dominated the landscape were eliminated. So were many of the mammal forerunners.
Find out more about the events that opened the door for the Age of Dinosaurs. Join us on Thursday, October 8, 2015, for a "Smithsonian Science How" live webcast on How Fossils Explain the Rise of Dinosaurs. It is airing at 11 a.m. and 2 p.m. EDT on the Q?rius website. Paleontologist Dr. Hans Sues from the National Museum of Natural History will appear live to discuss and answer questions. Get teaching resources to support your webcast experience.

Source URL: https://www.tweentribune.com/article/tween56/who-was-boss-dinosaurs/

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To study dinosaurs, why do scientists rely on fossils instead of photographs?
Write your answers in the comments section below

  • autianae-ste
    9/25/2015 - 01:17 p.m.

    The fossils help the scientists know exactly where in the body the bones were and which part of the dinosaur is studied. I didn't think alligators/crocodiles were that old.

  • ryans-5-ver
    9/25/2015 - 02:30 p.m.

    Wow! What a cool article I wonder if there where any human like mammals before the dinosaurs .

  • lukeh-orv
    9/25/2015 - 03:34 p.m.

    Scientists rely on fossils instead of photographs because photographs didn't exist during the time period that the dinosaurs existed.

  • aidano-1-bar
    9/25/2015 - 04:03 p.m.

    Scientists use fossils over photographs because accurate photos did not exist in the Age of the Dinosaurs."Paleontologists who study the fossil record have discovered that something big happened 200 million years ago" I found this article interesting because I thought that Dinosaurs were the first on the planet.

  • haynesworth,kurtis-cas
    9/26/2015 - 04:09 p.m.

    1. Scientist use fossils instead of photographs because photographs didn't exist then.
    2. This article is interesting to me because I assumed that dinosaurs were the main predators during this time period.

  • marky-ver
    9/28/2015 - 08:50 a.m.

    How can they know how old the fossil it just by looking at it, i am still confused about that. I wonder what the large plant eaters are like do they eat humans too, Now I am scared of crocodiles.

  • amelieb-gra
    9/28/2015 - 10:49 a.m.

    I really liked that article.

  • kates-gra
    9/28/2015 - 10:56 a.m.

    I can't believe a thing like the Placerias lived 230 million years ago!

  • ajm-1-gra
    9/28/2015 - 11:07 a.m.

    I wish that dinosaur weren't excint but that they couldn't harm people

  • ismaelg-hou
    9/28/2015 - 12:39 p.m.

    What elimenated the crocodiles and mammals?

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