1. of, relating to, or denoting the second period of the Mesozoic Era, lasting from approximately 201 to 145 million years ago, characterized by the dominance of dinosaurs and the first appearance of birds
Usage: geological term; often capitalized when referring to the geological period

1. the Jurassic Period or the rocks and fossils formed during this time
Usage: geological term; often capitalized

Examples

• The Jurassic Period saw the rise of large sauropod dinosaurs.
• Archaeopteryx, one of the earliest known birds, lived during the Jurassic.
• Jurassic rocks in this region contain many well-preserved fossils.
• The climate during the Jurassic was generally warmer than today.
• Many of the dinosaurs featured in popular movies lived in the Jurassic Period.
• Geologists study Jurassic deposits to understand ancient ecosystems.