Earth 540 Million Years Ago: The Dawn of the Cambrian

Events of the time

• Ediacara fossils

  555 million years ago · Ediacara Hills, Australia

  Imprints of soft-bodied animals such as Dickinsonia, now known to be an animal from the fats preserved in it.

• Chengjiang fossils

  518 million years ago · Yunnan, China

  Soft-bodied animals preserved in fine mud, including some of the earliest relatives of vertebrates: a snapshot of the Cambrian explosion.

• Burgess Shale

  508 million years ago · British Columbia, Canada

  A Cambrian sea floor with strange animals such as five-eyed Opabinia and the predator Anomalocaris, then near the equator.

Which land was under the sea 540 million years ago?

On the map nearest this age (535 million years ago, Early Cambrian), about 33% of today’s land was under the sea at some point, some 47.0 million km². That makes it number 31 of the 80 maps from 535 to 5 million years ago, which run from 2% to 50%. Each map shows the greatest flooding of its stage, so no single moment had quite this much sea.

• Sauk Sea

  Cambrian to Early Ordovician (approximate) · The centre of North America: the Great Plains, the Midwest and the Great Lakes

  The first great flood over North America’s interior, named after the Sauk sequence of rock layers. Its sandstones and limestones lie under much of the Midwest, and trilobites were its best-known animals.

Was it under the sea? 18 of 42 cities

197 marine fossil sites in the Paleobiology Database are dated closely enough to this map. Of those on today’s land, 99% fall in its shaded sea.

Seas: Ancient seas: PaleoCoastlines v7 (Kocsis & Scotese 2021), CC BY 4.0 · Fossils: Paleobiology Database.