The Ocean Through Time

Life began in the ocean around 3.5 billion years ago and as evolution progressed, many species went extinct -- and some left behind fossils -- as others appeared. And even now, the ocean hasn't stopped changing as evolution continues and humans leave their mark.

EDUCATOR RESOURCES

LATEST TODAY'S CATCH

Elevator Rudists

May 1, 2013 - 9:48AMThese "elevator" rudists, an ancient bivalve, used one long heavy valve to anchor themselves in the sediment. They used their tentacles (shown here in pink) to filter food from the sea water. Discover more about the ancient...

Teeth and Jaw of an Ancient Shark
Mar 21, 2013 - 9:20AM
This well-preserved fossil is the only intact partial skull ever found of a...

Megalodon Teeth
Feb 26, 2013 - 10:35AM
Two fossilized teeth from a megalodon (Carcharodon megalodon) dating back...
Arm Bone Fossil of an Ancient Toothed Whale
May 11 2012 - 11:46am
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. This is the second specimen found at this locality on the remote western side of Vancouver Island. Nick used a rock saw to...
Dispatches from the Field: Treacherous stream crossings and a new fossil find
May 11 2012 - 9:58am
Editor's note: Read Nick's first blog post about "toothed" baleen whales to see what their team is excavating on Vancouver Island.  
Really Small Fry Shifting Baselines in Marine Fish Stocks
Really Small Fry: Shifting Baselines in Marine Fish Stocks
Dec 4 2009 - 1:06pm
A public service announcement uses a dramatic example to emphasize that ocean fish aren’t as big as they used to be. Find out more about the decline in the ocean's top -- and often large -- predators in a recorded talk by marine ecologist and National Geographic explorer Enric Sala.
Ammonite
Jan 26 2010 - 11:45am
Like the modern nautilus, this relative of modern squid hunted from inside the safe haven of a protective shell. Ammonites went extinct around the same time as the dinosaurs—65 million years ago.  Find more about ocean predators in our interactive timeline Who's on Top?
Bones and Teeth of South America's Oldest Fossil Whales
Sep 12 2011 - 2:55pm
These are fossil remains of archaeocetes, ancient whales, from the Paracas Formation of Peru's Pisco Basin. Smithsonian paleobiologist Nicholas D.
Cretaceous-Paleogene Boundary (65 Million Years Ago)
Sep 21 2011 - 9:53am
This rendering shows life at the end of the Cretaceous Period, before the impact of a 6.2 mi (10 km) asteroid triggered mass extinctions on land and sea. Dinosaurs are the most famous victims of the extinction at the end of the Cretaceous, 65 million years ago. But they weren't alone. Nearly half...
So You Think You're Smarter Than a Cephalopod?
May 5 2011 - 4:41pm
The blanket octopus can rip a poisonous tentacle from a Portuguese man-o-war and wield it like a sword to ward off enemies as it soars through the ocean trailing its webbed cloak behind it.
Ediacaran Community, Proterozoic Eon (2,500 - 542 Million Years Ago)
Sep 20 2011 - 3:42pm
Earth’s first animals had soft bodies. This illustration shows a community of soft-bodied Ediacaran (edi-A-karan) animals. Some species resemble living ocean creatures. Others are unlike any known organisms and cannot be classified. Scientists have found fossils of these fauna in sedimentary rocks...
Recliner Rudists
Aug 9 2012 - 10:27am
Where ocean currents were strong, ancient rudist “recliners” lay unattached on the seabed. Notice the pink tentacles, which were used to filter feed. Learn more about ocean life throughout deep time in our Ocean Over Time interactive or an image gallery. 
Early Whale with Webbed Feet
Aug 21 2012 - 8:51am
This early whale was well suited to life at sea. But it also lived on land. An ancestor of the right whale, Maiacetus lived 49-40 million years ago. It had flipper-like limbs and webbed feet, like modern seals. But it also had ankle bones - clues that although Maiacetus swam, its...
Fossils Get a CT Scan
May 22 2012 - 4:33pm
When paleontologists, like the Smithsonian National Museum of Natural History's own Nick Pyenson, curator of marine mammal fossils, dig up fossils in the field, they can't just toss them in their backpacks and carry them home because the fossils are too fragile. One method they use to protect the...
Expedition to Excavate a Fossil Whale
Jun 17 2011 - 11:03am
My graduate student Jorge and I are departing today for Panama, to excavate a fossil whale that was discovered by an undergraduate student working with Smithsonian Tropical Research Institute researcher Aaron O'Dea.
The Discovery of Multispecies Communities of Seacows
Jan 26 2012 - 11:26am
Sirenians, or seacows, are a group of marine mammals that include manatees and dugongs. In the modern ocean, only one species of seacow is found in each world region, however, the fossil record tells a different story. According to the fossil record of these marine mammals, which dates back 50...
An Ancient Whale Skeleton, Unexcavated
May 7 2012 - 3:54pm
Nick Pyenson, the curator of fossil marine mammals at the Smithsonian's National Museum of Natural History, points to the skull and skeleton of a fossil "toothed" mysticete (baleen whale) on the West Coast Trail of Vancouver Island in 2009. The skeleton, which is being excavated this spring 2012 by...
Shark Ancestors
Dec 17 2009 - 6:55pm
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.
Excavating an Extinct Toothed Whale
Excavating an Extinct Toothed Whale
Jun 23 2011 - 11:20am
A time-lapse video shows researchers from the Smithsonian's National Museum of Natural History and Smithsonian's Tropical Research Institute racing to excavate the fossil of an extinct toothed whale on a beach in Piña, Panama. The fossil is from the Squalodontidae group, commonly known as "shark-...