Martin Jenkins on Dinosaurs, Fossils and the T-Rex

Martin Jenkins spent years as a conservation biologist before writing more than fifty nonfiction books for young readers. The Story of Life on Earth, a YouTube series made in homage to his work, follows the fossil record from Earth’s earliest life to the age of dinosaurs. Episode 8, How Dinosaurs Took Over After Earth’s Worst Extinction, is where the dinosaurs take center stage, and it ends by pointing ahead to the T-Rex.

How dinosaurs went from sideshow to rulers

Dinosaurs were not the obvious winners. About 231 million years ago, in the Ischigualasto Formation of northwestern Argentina, early dinosaurs like Eoraptor, Herrerasaurus and Eodromaeus were living side by side. Most were small, and many walked on two legs. Eoraptor was about the size of a dog. Larger, crocodile-like reptiles held more of the territory.

A 2008 University of Bristol study compared Triassic dinosaurs with their crocodile-line cousins across nearly 500 skeletal features and found the crocodile relatives had the wider range of body plans. The researchers’ explanation for why dinosaurs won anyway was luck. Dinosaurs survived two mass extinctions that their rivals did not.

The first was the Great Dying at the end of the Permian. The second came about 201 million years ago, when huge volcanic eruptions along the rift between what would become North America and Africa brought rapid warming and ocean acidification. Many of the large crocodile-line reptiles disappeared. The dinosaurs came through.

The age of giants, and the T-Rex still to come

In the Jurassic, dinosaurs spread and grew. Sauropods like Brachiosaurus and Diplodocus, from about 150 to 154 million years ago, became the largest animals ever to walk on land. Their fossils, along with those of Stegosaurus and the predator Allosaurus, come from the Morrison Formation of the western United States.

The episode ends by looking ahead to the next part of the dinosaur story, including Tyrannosaurus rex, which would not appear for more than 80 million years.

Dinosaurs, fossils and the T-Rex in pictures

Scenes from The Story of Life on Earth, from the armored fish of the Devonian to the T-Rex and the small mammals that outlived it.

  • AI illustration of a Tyrannosaurus rex skull fossil partly exposed in sandstone at a dig site, with brushes and a trowel, for a page on dinosaurs and fossils in the work of children’s author Martin Jenkins
    A T-Rex skull fossil at a dig site
  • Fossil jaws of the armored fish Dunkleosteus beside a living reconstruction, from The Story of Life on Earth, an independent series inspired by Martin Jenkins’s books
    Armored fish and their fossil jaws, Episode 5
  • AI illustration of a coiled ammonite fossil in layered rock beside a brass hand lens, for a page on dinosaurs and fossils in the work of children’s author Martin Jenkins
    Ammonite fossils in layered rock
  • Illustration of the end-Permian mass extinction with erupting volcanoes and a reptile on cracked lava, from The Story of Life on Earth, an independent series inspired by Martin Jenkins’s books
    The Great Dying, Episode 7
  • Illustration of a long-necked sauropod and a predatory dinosaur on a Jurassic landscape, from The Story of Life on Earth, an independent series inspired by Martin Jenkins’s books
    Jurassic giants, Episode 8
  • AI illustration of a paleontologist’s field table with fossil dinosaur teeth and notebooks under a canvas shade in the badlands, for a page on dinosaurs and fossils in the work of children’s author Martin Jenkins
    A fossil hunter’s field table in the badlands
  • Illustration of Tyrannosaurus rex facing a Triceratops, from The Story of Life on Earth, an independent series inspired by Martin Jenkins’s books
    How the T-Rex hunted, Episode 9
  • AI illustration of a Tyrannosaurus rex with a sparse feathery ruff at the edge of a Late Cretaceous forest at dusk, for a page on dinosaurs and fossils in the work of children’s author Martin Jenkins
    A T-Rex at the edge of a Late Cretaceous forest
  • Illustration of a small early mammal on a mossy log near a dinosaur skeleton after the extinction, from The Story of Life on Earth, an independent series inspired by Martin Jenkins’s books
    What survived the dinosaurs, Episode 10

Dinosaurs and fossils in Martin Jenkins’s books

The series follows Martin Jenkins’s 2019 book Life: The First Four Billion Years, illustrated by Grahame Baker-Smith, which traces Earth’s story from the Big Bang through the fossil record and the age of dinosaurs to the first humans. The dinosaur blog Dino Dad Reviews recommended it and singled out its attention to the animals that came before the dinosaurs.

Every episode so far

Episode 1, Before Life · Episode 2, The First Spark · Episode 3, The 2.5 Billion Year Secret · Episode 4, Before We Had Eyes · Episode 5, How the Ocean’s Top Predators Came to Be · Episode 6, How Simple Mosses Built Our Modern World · Episode 7, The Great Dying · Episode 8, How Dinosaurs Took Over (this page)

Watch Episode 8 on YouTube or see the full series on the YouTube Series page.