The animals in this story were real. Their skeletons, eggs and nests have been found in the Badlands of Alberta and Montana, close to the Canada-U.S.A. border. They lived there between 75 and 77 million years ago when the climate was warm.

TROÖDON was a two-legged bird-like dinosaur with claws on its feet and hands. It probably ate a variety of things––small animals and insects, as well as plants. A Troödon egg had a shape and size like a large sweet potato. The embryo would have been about 17 cm or 7 inches long, so you could have held the baby in your hand—if it would have let you!

You can figure out the right shape for a Troödon like this:

  • Bend over flat at the waist.

  •  Hold your elbows against your sides.

  •  Let your hands droop.

  • Imagine that you have a long tail.

TROÖDON (TRO-o-don) means “wounding tooth”.

Dr. Jack Horner shows Paula the fossilized mud nest built by Troödon parents 75 million years ago.
Photo Credit: Michael Ellis

HYPACROSAURUS was a four-legged plant-eater with a bill like a duck. It had long back legs, shorter front legs and a crest on its head. These half-circle crests were used to communicate with each other. Baby Hypacrosaurs were found still inside their eggs that were just a bit smaller than a volleyball.

Hypacrosaur eggs in nest found at Devil’s Coulee, Alberta by Dr. Philip Currie and team.
Photo Credit: Mike Todor

When the Hypacrosaur babies first hatched, they would have been about 55 cm or 22 inches long (the size of a medium-sized dog).

 

Reconstruction of Hypacrosaur embryo inside its egg.
Devil’s Coulee Museum, Warner, Alberta. 

Hypacrosaur adults reached a length of almost 26 ft. or 8 m., even bigger than the largest of today’s African elephants.

 

Hypacrosaur skeleton at the Canadian Museum of Nature, Ottawa, Ontario is similar to the kind of Hypacrosaur in Trygg’s story.

 

HYPACROSAURUS (Hi-PACK-row-SORE-us) means “nearly the highest lizard”.

ALBERTOSAURS were the top meat-eaters in the area. They were early cousins of Tyrannosaurus rex (which lived about 10 million years later). Adult Albertosaurs grew to 9 m. or 30 ft. in length. Scientists have discovered these dinosaurs’ skeletons in groups of different ages, so they think that they lived in packs. The theory is that the young Albertosaurs, who were smaller and faster, chased the animals they were hunting toward the larger adults. The big, strong jaws and teeth of the adults finished off the prey so everyone could take part in the meal.

ALBERTOSAUR (al-BERT-o-sore) means “Alberta Lizard”.

See Albertosaurs at the Royal Ontario Museum,Toronto, Ontario and the Royal Tyrrell Museum, Drumheller, Alberta

ALPHADON was a little mammal that was similar to today’s opossum. It carried its babies inside its pouch (like a kangaroo does). The jawbone of the Alphadon that was found in the same spot as the Troödon nests in northern Montana, U.S.A. was about 3 cm or 1¼ inches long. Scientists recently found what they think is a complete Alphadon skeleton. They are working to remove the sediment around the fossil and will know soon what Alphadon actually looked like.

ALPHADON (ALF-a-don) means “First Tooth”

The jaw of an Alphadon mammal found with the Troödon nests in Montana.
Photo credit: Kimberly S. Donau

Opossum today

THE BIG TURTLE who escapes the Albertosaurs in Chapter Twenty was a BASILEMYS VARIOLOSA. It was a land tortoise that ate plants. Turtles have been around for about 150 million years—and they’re still with us.

Turtle fossil BASILEMYS VARIOLOSA at the Royal Tyrrell Museum in Drumheller, Alberta.