The Smithsonian’s National Museum of Natural History “Sea Monsters Unearthed: Life in Angola’s Ancient Seas" exhibit opens Nov. 9, and it reveals ancient, Cretaceous-era titans that lived off the coast of Angola in the South Atlantic Ocean. See photos.
The exhibition focuses specifically on the marine reptiles that roamed the South Atlantic Ocean basin after it was formed when the African and South American continents drifted apart some 130 million years ago.
An artist’s rendering of a 72-million-year-old ecosystem found off coastal Angola. Click to enlarge. (Karen Carr Studios, Inc.)
More than 130 million years ago, the South Atlantic simply didn’t exist. And new, terrifying life-forms soon colonized the area.
Among the monsters were long-necked plesiosaurs, mosasaurs and even enormous sea turtles.
These are boulders with barnacles and oysters affixed to them that were collected at the top of a cliff as a result of uplift, which is a geologic process causing the Earth’s crust to bulge along Angola’s coast, lifting part of the seafloor out of the water.
(WTOP/Kristi King)
WTOP/Kristi King
These are two examples of creatures making an early entrance into the south Atlantic. An early mosasaur and an early turtle found in Angola.
(WTOP/Kristi King)
WTOP/Kristi King
This is an extinct aquatic lizard that specialized at eating fish.
(WTOP/Kristi King)
WTOP/Kristi King
This creature was specialized to eat hard shelled prey, such as giant oysters.
(WTOP/Kristi King)
WTOP/Kristi King
This is a new species of a turtle of the genus euclastes that was found at the locality. So newly discovered, it hasn’t been named yet. Euclastes is an extinct genus of sea turtle.
(WTOP/Kristi King)
WTOP/Kristi King
The huge monsters that colonized the South Atlantic went extinct in the Late Cretaceous.
(WTOP/Will Vitka)
WTOP/Will Vitka
Ancient oysters along the Angola coast were the size of a human.
(WTOP/Kristi King)
An artist’s rendering of a 72-million-year-old ecosystem found off coastal Angola. If you visited coastal Angola today, you could swim with whales and dolphins. But if you traveled back in time to the Late Cretaceous, you might not have wanted to jump in the water: It was filled with carnivorous reptiles, such as mosasaurs and plesiosaurs. Even some of the sea turtles were enormous.
(Karen Carr Studios, Inc.)
Karen Carr Studios, Inc.
An artist’s rendering of the mosasaur Globidens phosphaticus crunching huge hard-shell oysters on a shallow ocean shelf off Angola’s coast 72 million years ago.
(Karen Carr Studios, Inc.)
Karen Carr Studios, Inc.
An artist’s rendering of what this mosasaur, Angolasaurus bocagei, might have looked like while it was alive.
(Karen Carr Studios, Inc.)
Karen Carr Studios, Inc.
The fossil skull and partial skeleton of mosasaur Angolasaurus bocagei excavated from Angola’s costal cliffs for display in “Sea Monsters Unearthed.”
(Hillsman S. Jackson, Southern Methodist University)
Hillsman S. Jackson, Southern Methodist University
When the South Atlantic Ocean basin was still young, a new deep-water connection between the Southern and Northern Hemispheres allowed giant marine reptiles from the north to move into Angola’s coastal waters.
(Hillsman S. Jackson, Southern Methodist University)
Hillsman S. Jackson, Southern Methodist University
Mosasaurs, drawn by the region’s plentiful food, were among the first reptiles to prowl the Angola waters.
(Hillsman S. Jackson, Southern Methodist University)
Hillsman S. Jackson, Southern Methodist University
These giant lizards once dominated ocean ecosystems around the world, including along Angola’s coast.
(Hillsman S. Jackson, Southern Methodist University)
Hillsman S. Jackson, Southern Methodist University
An artist’s rendering of Prognathodon kianda. Cretaceous seas were particularly savage, with loads of large, carnivorous reptiles prowling the waters with ferocious appetites, like this large mosasaur. Scientists named this species after Kianda, the ruler of the ocean in Angolan mythology.
(Karen Carr Studios, Inc.)
Karen Carr Studios, Inc.
An artist’s rendering of what the ancient sea turtle Angolachelys mbaxi might have looked like when it was alive. Sea turtles have been part of ocean ecosystems for over 150 million years and still swim along Angola’s coast today. This extinct species, Angolachelys mbaxi, is the South Atlantic’s oldest species of sea turtle. Like some modern sea turtles, it used the flat surface of its strong jaws to crush hard-shell prey.
(Karen Carr Studios, Inc.)
Karen Carr Studios, Inc.
A fossil Euclastes sea turtle skull excavated from Angola’s coastal cliffs.
(Hillsman S. Jackson, Southern Methodist University)
Hillsman S. Jackson, Southern Methodist University
Massive reptiles called plesiosaurs hunted fish in Angola’s ancient sea. They weren’t closely related to mosasaurs, but lived in the same ecosystem — and died out in the same mass extinction 66 million years ago. Some plesiosaurs evolved long necks, others had enormous heads, but all had stout bodies, short tails and four large flippers. Nothing in today’s ocean looks like them.
(Karen Carr Studios, Inc.)
Karen Carr Studios, Inc.
Modern cliffs of coastal Angola where Projecto PaleoAngola paleontologists excavate fossils of life that once lived in Angola’s ancient seas.
(Projecto Paleoangola)
Projecto Paleoangola
Sediments covered dead animals that sank to the ocean floor. Over millions of years, these sediment layers turned to rock and the remains fossilized — but they were still underwater.
(Karen Carr Studios, Inc.)
Karen Carr Studios, Inc.
Starting about 45,000 years ago, heat flow within Earth’s mantle caused the crust to bulge in a process called dynamic uplift. Here along Angola’s coast, the bulge lifted the ocean floor hundreds of feet out of the water.
(Karen Carr Studios, Inc.)
Karen Carr Studios, Inc.
Waves pounded the newly surfaced rocks, undercutting them until the overhangs collapsed, leaving towering cliffs. Wind, rain and rivers eroded the exposed rocks, revealing the fossils inside.
(Karen Carr Studios, Inc.)
Karen Carr Studios, Inc.
Moving through water can be difficult, but flippers can help. None of these marine reptiles are closely related — in fact, they all took to the ocean at different times — but each group independently evolved flippers as an efficient way of getting around underwater. This process, where different kinds of animals evolve similar traits in response to similar challenges, is called convergent evolution. Convergent evolution is also the reason why marine reptiles from Angola’s ancient ocean look similar to modern marine mammals — such as whales and dolphins — that live in Angola’s seas today, despite being separated by millions of years of evolution.
(Karen Carr Studios, Inc.)
“It will spark their curiosity, it will answer their questions, it will start them in a pattern of thinking that will change the world,” Jacobs said.
According to Jacobs, there is also a startling similarity between the extinction event at the end of the Cretaceous period and the state of the environment today.
“Only the sea turtles, as marine reptiles, made it through,” Jacobs said. “Now, a similar ecosystem, with different organisms in it, are a source of protein for people — it’s a very large fishery — but it’s in danger also of something that could turn out to be an equally big extinction.”
“The lesson to learn is that when the Earth does an experiment, we can learn from it, and we know that it takes millions of years to recover. Humans can learn from that because they don’t have millions of years to recover from something of the enormous magnitude of driving an ecosystem extinct,” he cautioned.
The exhibit is a cooperative effort between paleontologists and artists working together to determine what ancient animals and their environments looked like based on fossil evidence.
“Fossils tell us about the life that once lived on Earth, and how the environments that came before us evolve over time,” Jacobs said.
“Our planet has been running natural experiments on what shapes environments, and thereby life, for millions of years. If it weren’t for the fossil record, we wouldn’t understand what drives the story of life on our planet,” he explained.
Paleo-artist Karen Carr created multiple murals and reconstructions for the exhibit, which is part of the Projecto PaleoAngola project — a collaboration between Angolan, American, Portuguese and Dutch researchers.
An artist’s rendering of Angola’s Cretaceous seas 72 million years ago, dominated by many species of large, carnivorous marine reptiles. Click to enlarge. (Karen Carr Studios, Inc.)An artist’s representation of life in the ocean ecosystem off Angola’s modern-day coast, dominated by many large marine mammals like whales and dolphins. Click to enlarge. (Karen Carr Studios, Inc.)
Visitors will notice that reconstructions of the mosasaurs bear a significant coloring resemblance to modern whales, despite the fact that whales are mammals and the creatures on display are lizards.
Senior research fellow at SMUMichael Polcyn explains that there’s a very good reason for that.
“I did some research with a colleague of mine in Sweden a few years ago … and we actually got pigment cells out of the skin of mosasaurs, and we were able to demonstrate that these animals are in the dark brown, gray to black sort of range,” Polcyn told WTOP.
“And when you start looking at marine animals generally — be they penguins or whales — you usually see this bicolor patterning where they’re light underneath, dark on top, so when we did the reconstructions with [Karen Carr], you can see from the murals … we chose to reconstruct them with whale-like patterns,” he said.
Yes. As if channeling Jurassic Park (though the likelihood of getting chomped by a dinosaur these days remains mercifully slim), Polcyn and his colleagues were able to extract pigment cells from fossilized mosasaur skin.
“It’s remarkable. We’ve been doing work with Johan Lindgren out of Lund University for a number of years now and we’ve been able to isolate a lot of biomolecules, actually, from mosasaur bones and now, in this case, skin,” Polcyn told WTOP.
It is the first time that these Angolan fossils are on public display, and Polcyn emphasized that citizen or amateur scientists can be a great help to the field.
“An amateur today can make an incredibly valuable contribution just walking the creeks or the deserts, finding things, studying them, bringing them to the attention of scientists,” he said. “You can really make a great contribution as a citizen scientist.”
Some of the most striking fossils are of the mosasaur Angolasaurus bocagei, which was excavated from Angola’s coastal cliffs. The Angolasaurus bocagei grew up to 13 feet long and, with its curved teeth, likely hunted fish along the coast. It is the oldest-known mosasaur from the South Atlantic.
Another mosasaur depicted is the Globidens phosphaticus, which had teeth particularly well adapted to crunch through hard-shell treats such as oysters.
Scientists have determined that the shallow coastal shelf off Angola was once “a giant oyster buffet.”
A third type of mosasaur — the Prognathodon kianda, named for Kianda, the ruler of the ocean in Angolan mythology — is also highlighted in Carr’s artwork for the exhibit.
Sea turtles, of course, survived the mass extinction event at the end of the Cretaceous period (though scientists say humans currently threaten six of the world’s seven sea turtle species) some 66 million years ago. Fossils of one of their now-extinct ancestors, Angolachelys mbaxi, will be on display as well.
William Vitka is a Digital Writer/Editor for WTOP.com. He's been in the news industry for over a decade. Before joining WTOP, he worked for CBS News, Stuff Magazine, The New York Post and wrote a variety of books—about a dozen of them, with more to come.