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Mission Jurassic: The Dinos

Mission Jurassic: The Dinos

Welcome to the Jurassic Period!

The Jurassic Period is one of three periods that occurred during the Mesozoic Era—the age of reptiles—when dinosaurs roamed the earth.

  • Triassic Period—252-201 million years ago
  • Jurassic Period—201-145 million years ago
  • Cretaceous Period—146-66 million years ago

The dinosaurs currently on display in DinosphereⓇ, including Tyrannosaurus rex, are from the Cretaceous Period. The fossils we are recovering from the Jurassic Mile are from the Jurassic Period—a period when dinosaurs exploded in diversity of size and shape. Some would become truly massive, including the legendary “long neck” dinosaurs, like the specimens found at The Jurassic Mile.

Dinosaur Fossils we might find in the Morrison Formation

The Morrison Formation is a huge packet of rocks that runs from Montana to New Mexico. Dinosaurs of all shapes and sizes from the Late Jurassic Period are found in these rocks.

At the Jurassic Mile we are currently excavating Theropods, predatory, carnivorous dinosaurs who typically stood on two feet, and Sauropods, long-necked, long-tailed four-legged herbivorous dinosaurs that were giants in size. Besides the massive bones, we have also found evidence of inchnofossils—footprints, burrows, nests, and even dung!

Allosaurus (Theropod)

Pronunciation: “Al-oh-sore-us”
Meaning: Different lizard
Teeth: Huge jaws opened extremely wide, revealing dozens of long, sharp teeth
Interesting facts:

  • One of the biggest predators of its time in North America
  • Fast runner
  • Three-fingered forearms

Brachiosaurus (Sauropod)

Pronunciation: “BRAK-ee-oh-sore-us”
Meaning: Arm lizard
Teeth: Shaped like pointed ice cream scoops
Interesting facts:

  • Long forelimbs mean shoulders were high above its hips
  • Belongs to a group of sauropods called macronians, which means “big noses”
  • Seymour, the adult brachiosaur sculpture that looks into the Welcome Center at The Children’s Museum, is a life-sized Brachiosaurus

Diplodocus (Sauropod)

Pronunciation: “DIP-low-DOE-cus”
Meaning: Double beam
Teeth: Rows of peg-shaped teeth at the front of its jaws
Interesting facts:

  • Swallowed small stones to help grind the unchewed plants in its stomach because it had no back teeth
  • Fossil footprints tell us that Diplodocus lived in herds
  • Some Diplodocus specimens are longer than two Tyrannosaurus rex specimens placed end to end!

Marine Fossils we might find in the Sundance Sea

The Sundance Formation consists of rocks that are slightly older than the Morrison Formation and were deposited in an inland sea called the Sundance Sea. During the Late Jurassic Period the seas teemed with a huge variety of life. Marine reptiles often grew to the size of large dinosaurs. These were some of the biggest and most fearsome creatures to have ever lived, including the bizarre Liopleurodon—which grew up to 33 feet long and lived in the seas off the coast of what is now the U.K.


Pronunciation: “op-thal-mo-sore-us”
Teeth: Rounded, cone-like
Interesting facts:

  • Name means “Eye lizard”
  • Had huge eyes (up to 9 inches in diameter), used to hunt fish and squid in low light
  • Only known ichthyosaur from the Sundance Sea


Pronunciation: “gry-fee-ah”
Interesting facts:

  • Commonly called “devil’s toenails”
  • Mesozoic oysters
  • Lived in large colonies in shallow waters


Pronunciation: “pack-e-tooth-is”
Interesting facts:

  • Name means “heavy squid”
  • Unlike squids, had an internal skeleton
  • Probably the favored food of many marine reptiles, including Opthalmosaurus.
Mission Jurassic: The Dinos Mission Jurassic: The Exhibit Mission Jurassic: The Site Mission Jurassic: The Team