cambrian

Everyday

1. (science) The Cambrian was a period of Earth's history about 540 to 485 million years ago, when many kinds of animals with hard shells first appeared in the sea. tree →
2. Cambrian means to do with Wales, as in the Cambrian Mountains, from Cambria, the Latin name for Wales. tree →

In the lessons

In science lessons about fossils and evolution, the Cambrian explosion was when many animal groups appeared quickly; trilobites are famous Cambrian fossils. The period was named after rocks studied in Wales. In geography, the Cambrian Mountains run through mid-Wales, and the Cambrian Line is a railway.

Examples

• Trilobites lived in Cambrian seas. tree →
• Many animal groups appeared in the Cambrian explosion. tree →
• There were no animals on land in the Cambrian. tree →
• The Cambrian period is named after Wales. tree →
• We hiked in the Cambrian Mountains. tree →
• Cambrian rocks contain early fossils. tree →

Note

Capital C. Said KAM-bree-un. Before the Cambrian came the Precambrian; after it came the Ordovician. No dinosaurs lived then; they came hundreds of millions of years later.