Mammals are not the only animals to dig burrows. One of the oldest discovered burrows belongs to a type of dinosaur called Oryctodromeus cubicularis.

Illustration by Mark Hallett
  • This family of dinosaurs (a species called Oryctodromeus cubicularis) lived about 95 million years ago in what is today the U.S. state of Montana. Paleontologists discovered the Oryctodromeus fossil family in 2006.

    Oryctodromeus was a burrowing dinosaur. The Montana burrow reached about half-a-meter (1.6 feet) underground, twisting and turning more than 2.1 meters (6.9 feet) along the way.

    1. Dinosaurs, like Oryctodromeus, were terrestrial animals. This means they lived mostly on land. Today, many terrestrial animals dig burrows similar to Oryctodromeus. Can you name some burrowing land animals?

      Answers will vary. Armadillos have burrows very similar to Oryctodromeus. Other burrowing land animals include moles, meerkats, kangaroo rats, gopher tortoises, and puffins.

    2. What are the benefits of having a burrow?

      Answers will vary. Animals usually burrow to find food, escape predators, and survive in extreme environments.

    3. Oryctodromeus wasn't very big. The widest part of its body (its shoulders) was about 26-30 centimeters (10-12 inches). The burrow's tunnel was about 30 centimeters (12 inches) wide. The tunnel was a very tight fit! Why do you think Oryctodromeus dug such a narrow tunnel?

      Answers will vary. A narrow tunnel probably protected Oryctodromeus from larger predators that could not squeeze into it.

    4. A burrow creates a "microclimate." A microclimate is a place where the environmental conditions are different from the surrounding area. Burrow microclimates are usually more moderate than the area outside the burrow. The burrow microclimate helped Oryctodromeus survive in habitats where it probably could not have survived outside. What are some of these extreme habitats?

      Oryctodromeus and other burrowing dinosaurs were able to survive in polar regions, arid and windy deserts, and high mountains.

  • Term Part of Speech Definition Encyclopedic Entry
    arid Adjective


    bipedalism Noun

    form of movement where an animal consistently uses two legs for standing or walking.

    burrow Noun

    small hole or tunnel used for shelter.

    desert Noun

    area of land that receives no more than 25 centimeters (10 inches) of precipitation a year.

    Encyclopedic Entry: desert
    dinosaur Noun

    very large, extinct reptile chiefly from the Mesozoic Era, 251 million to 65 million years ago.

    environment Noun

    conditions that surround and influence an organism or community.

    family Noun

    group of organisms that come from the same ancestors and share similar characteristics. Family is also a classification in chemistry and math.

    Encyclopedic Entry: family
    food Noun

    material, usually of plant or animal origin, that living organisms use to obtain nutrients.

    Encyclopedic Entry: food
    forelimb Noun

    front limb of an animal, such as an arm, leg, wing, or flipper.

    fossil Noun

    remnant, impression, or trace of an ancient organism.

    Encyclopedic Entry: fossil
    habitat Noun

    environment where an organism lives throughout the year or for shorter periods of time.

    Encyclopedic Entry: habitat
    microclimate Noun

    small area where the climate differs within a larger climate region, such as "heat islands" in a city.

    Oryctodromeus Noun

    species of small, burrowing dinosaur.

    paleontologist Noun

    person who studies fossils and life from early geologic periods.

    polar Adjective

    having to do with the North and/or South Pole.

    predator Noun

    animal that hunts other animals for food.

    terrestrial Adjective

    having to do with the Earth or dry land.