Ancient Seas

The water and sea basins we know today have been on Earth for much longer than the first humans. Clues from the ocean (in the form of seafloor or ice cores, and fossils) can help us learn about how the oceans reached their current state.

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A rendering of an underwater marine scene from the Cambrian Period, featuring an arthropod, annelids, and other animals.

DIVE DEEPER

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...
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...
Photograph of the model of a Giant Megatooth Shark, taken from the front..

Shark Ancestors

Long before great white sharks appeared, much larger ancestors roamed the ocean. This giant ancient shark -- the Giant Megatooth ( Carcharodon megalodon ) -- was probably big enough to eat a whale.
Smithsonian scientists race the tide the excavate an ancient whale fossil entombed in rock

Fossil Whale Found, Excavated, Jacketed, and Returned to STRI!

A time-lapse video of the excavation of an extinct toothed whale on a Panamanian beach. Jorge and I packed up the night we arrived in Panama with Aaron O'Dea and his team from STRI...

Submersible Collects Deep-Sea Corals

Come along as scientist Dr. Brendan Roark narrates a submersible dive to collect and study deep-sea corals. Roark studies deep-sea corals to understand the history of the ocean and past ocean climates. Learn more...
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...
An illustration of a recently discovered species of Monodontid, Bohaskaia monodontoides, and its beluga and narwhale relatives

Smithsonian Scientists Describe a 'New' Fossil Whale

A reconstruction of a new fossil beluga relative, Bohaskaia monodontoides , described by Smithsonian scientists, is pictured in the foreground. Its living relatives, the beluga and narwhal, are illustrated left to right in the...
Nick Pyenson points to a skull and skeleton of a fossil whale.

Excavating a "toothed" baleen whale from Vancouver Island

Nick Pyenson, the Smithsonian's curator of fossil marine mammals, points to the skull and skeleton of a 23-25 million year old fossil "toothed" mysticete whale. Credit: NDP and J. A. Goldbogen/SI The whales that...
A researcher holds an arm bone from a "toothed" mysticete whale from Vancouver Island.

Dispatches from the Field: Treacherous stream crossings and a new fossil find

Nick Pyenson, curator of fossil marine mammals at the Smithsonian's National Museum of Natural History, holds an arm bone from a "toothed" mysticete from Vancouver Island. Credit: J. A. Goldbogen Editor's note: Read Nick's...
A Hawaiian petrel in flight

4,000 Years of Marine History through the Eyes of a Seabird

A Hawaiian petrel flies over part of its North Pacific feeding grounds. Credit: Photo courtesy of Jim Denny Most people have never heard of the Hawaiian petrel , an endangered, crow-sized seabird that spends...
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...
Fossil Whale Digsite at Cerro Ballena, Chile

The Whale Graveyard Whodunit

Chilean and Smithsonian paleontologists study several fossil whale skeletons at Cerro Ballena, next to the Pan-American Highway in Atacama Region, Chile, in 2011. Credit: Adam Metallo / Smithsonian Institution One of the ocean's tiniest...
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When Did Today’s Whales Get So Big?

More recently than you might think, say scientists who scoured the fossil record Two skulls belonging to extinct marine mammal herbivores used in the new study, both from the Smithsonian’s collections. Credit: A. Boersma...

Did Whale Evolution Go Backwards?

Whales swim, but their ancestors walked. Whales are mammals (like us) whose ancestors lived on land. Life probably began in the ocean and then evolved to colonize the land. Yet the whale’s ancestors gradually...

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.