Geologic time

Color illustration of an ancient bivalve.

Rudist Reefs

About 100 million years ago, during the heyday of the dinosaurs , reefs were built by mollusks called rudist clams . They looked very different from today's coral reefs . Discover more about the...
A rendering of an underwater marine scene depicting life ~145-65 million years ago, when rudist clams were the major reef builders.

Long Before Coral, Mollusks Built the Ocean's Reefs

Rudist clams were major reef builders during the heyday of dinosaurs. Credit: Smithsonian Institution About 100 million years ago , during the heyday of the dinosaurs, reefs were built by mollusks called rudist clams...
Dr. Brian Huber on Building the Sant Ocean Hall

Podcast: Dr. Brian Huber on Building the Sant Ocean Hall

Building the Smithsonian's Sant Ocean Hall --like any major exhibition--was a major undertaking. Over the course of five years, it required hundreds of people with a vast array of skills and backgrounds. Many of...
Offshore Peru, during the Eocene (~56-34 million years ago), showing two archaeocetes (ancient whales): Ocucajea picklingi and Supayacetus muizon.

New Archaeocetes from Peru Are the Oldest Fossil Whales from South America

Offshore Peru, during the Eocene (~56-34 million years ago), showing two archaeocetes (ancient whales): Ocucajea picklingi (above) and Supayacetus muizoni (below). Credit: Carl Buell, http://carlbuell.com The evolution of whales represents one of the great...
An artistic rendering of an ocean landscape as it may have looked during the Archean Eon.

The Ocean Throughout Geologic Time, An Image Gallery

Evidence shows that life probably began in the ocean at least 3.5 billion years ago. Photosynthesis began more than 2.5 billion years ago—the Great Oxidation Event. But it took hundreds of millions of years...
A photo of the cliffs at Mistaken Point, in Newfoundland

Ediacaran Fossils: One Species at a Time

When the cod fishery collapsed in Newfoundland in the early 1990s, the hopes of the local fish harvesters collapsed with it. Hundreds of Newfoundlanders moved away and businesses that depended on the cod fishery...
An illustration of multispecies communities of dugongs from India, Mexico and Florida

The Discovery of Multispecies Communities of Seacows

This reconstruction illustrates multispecies communities of seacows from three different time periods and ocean basins. Each seacow represents a different extinct species of dugong. Credit: Carl Buell/ http://carlbuell.com/ Sirenians , or seacows, are a...
A rendering of an underwater marine scene from the Cambrian Period, featuring an arthropod, annelids, and other animals.

A Collection of Cambrian Fossils

When you're standing in a museum surrounded by fossils, you can almost imagine drifting through time to when long-extinct creatures swam the ocean. Found all over the world, these fossils can be read by...

Top Predators Timeline

What makes a top predator? Razor-sharp teeth? Speed? Strength? Size? Who is the most fearsome hunter? It depends on where and when you look.