10 Fascinating Facts About the La Brea Tar Pits

Courtesy of the Natural History Museum of Los Angeles County
Courtesy of the Natural History Museum of Los Angeles County

There's a gooey time capsule in the heart of Los Angeles, left over from an era when saber-toothed cats, dire wolves, camels, and giant sloths prowled southern California. At the site known today as the La Brea Tar Pits and Museum, natural asphalt has bubbled up from below the ground's surface since the last Ice Age. This murky sludge has trapped and made fossils out of thousands of creatures, as small as bees and as big as mammoths. Here are a few of the amazing discoveries made there.

1. MORE THAN 3.5 MILLION FOSSILS HAVE BEEN DISCOVERED.

The tar pits have yielded one of the biggest collections of Ice Age fossils in the world, and collectively, the statistics are stunning. More than 600 species have been found, from snakes and mollusks to sloths and mountain lions. Of the mammals found at La Brea, around 90 percent are carnivores. (Amazingly, the pits have yielded more 200,000 individual dire wolf specimens alone.) The common explanation is that when big herbivores like mammoths got stuck in the asphalt, they would have looked like an easy meal to predators—who would then become stuck in the tar themselves.

2. PALEONTOLOGISTS STILL DIG THERE 361 DAYS A YEAR.

paleontologists working on bones
Courtesy of the Natural History Museum of Los Angeles County

Why 361? The site is closed July 4, Thanksgiving, Christmas, and New Year's Day. The rest of the time, science is happening. The first excavations at the tar pits began in the early 20th century, and if you visit today, you're still likely to see scientists preserving bones or digging in the asphalt. Still, people often don't realize that it's a place for active scientific research, as the tar pits lie in the middle of Los Angeles, a city synonymous with the entertainment industry. Emily Lindsey, assistant curator at the La Brea Tar Pits and Museum, tells Mental Floss that this has led to some confusion on the part of visitors, who "think sometimes the excavators are actors, or part of an art exhibit, or robots."

3. THE ONLY DINOSAURS FOUND THERE ARE BIRDS.

After the paleontologists at La Brea have convinced you they aren't robots, they'll be quick to clear up another misconception: They don't dig up dinosaurs. (Although, technically, they do. "We have 163 species of birds," Lindsey says. Yes, birds are dinosaurs.) Most of the fossils at La Brea date from 11,000 to 50,000 years ago—about 65 million years after dinosaurs went extinct.

4. THE PRESERVATION OF FOSSILS IS EXCEPTIONAL.

Sticky asphalt is a pain to clean off the bones, but it also keeps them in pristine condition. This means scientists can look at features as subtle as the markings on carnivore teeth. One study in 2014 looked at microscopic patterns on the teeth of five species of big cats found at La Brea. The researchers concluded that the mountain lion was the only one to survive into the present because it wasn't a picky eater, and could survive changes in its food supply.

5. IT'S SO GOOD THAT THE PITS PRESERVE ENTIRE ECOSYSTEMS.

la brea tar pits asphalt
Courtesy of the Natural History Museum of Los Angeles County

The big, extinct megafauna might soak up all the attention at La Brea, but paleontologists at the site have also recovered paper-thin fossils of pollen, bees, plant matter, insects, and other tiny organisms. "This is such a unique site because it's one of the only paleontological sites in the world where you can get an entire ecosystem represented," Lindsey says. "The big animals have pretty broad climate tolerances. Something like an insect has a much more narrow range."

This is important because the presence of smaller organisms can relay more specific information about the ecosystem. And because La Brea has such a long record of fossils, scientists can track how those ecosystems changed—or didn't—over time. For instance, one recent study of beetle fossils in the tar pits suggests that the climate of southern California has been relatively stable over the past 50,000 years. Yes, L.A. has had great weather for a very long time.

6. THE TAR PITS ARE DEATH TRAPS—AND YET ALSO SUPPORT LIFE.

A decade ago, scientists discovered about 200 species of microorganisms living in the asphalt with no water, little to no oxygen, and a heavy dose of toxic chemicals. Some of these microbes represented families of bacterial species that had never been seen before. By studying extremophiles thriving in such hostile environments, scientists may learn more about how life might exist on other planets.

7. ONLY ONE HUMAN SKELETON HAS BEEN FOUND THERE.

In 1914, researchers at the tar pits discovered a 9000-year-old set of human remains of a 20-something-year-old female, dubbed "La Brea Woman." Though some had speculated that she had been trapped in the asphalt or that she was Los Angeles's first homicide case, later studies suggested La Brea woman's remains had been ceremonially reburied in the asphalt, possibly with a domestic dog at her side. No other human remains have been found at La Brea. Historical accounts suggest that local tribes like the Chumash and Tongva used the asphalt from the tar pits as a glue or caulk for their wooden boats, so they must've tread carefully around the tar pits. But most of the fossils from the tar pits date from the period before humans populated the region. Lindsey says a new project will look at what was happening at the tar pits during the Holocene—the period that started after the end of the last Ice Age—which could reveal how the arrival of humans might have contributed to the extinction of big mammals.

8. A POLICE DIVER WORKING A MURDER CASE SURVIVED A PLUNGE INTO A PIT.

In 2013, a police diver willingly went 17 feet under the surface of the sludge to hunt for weapons in a cold case homicide investigation. "I've been under moving ships, in underwater reservoir sheds," LAPD Sergeant David Mascarenas told the Los Angeles Times. "This is by far the craziest thing I've ever done." Despite the bad visibility, Mascarenas was apparently able to make out underwater pinnacles of tar, and he did recover multiple items of interest. He probably also succeeded in sending the LAPD's message that they would "go as far as we can to make it as difficult for a suspect to discard evidence."

9. THERE ARE MORE PITS OUT THERE.

archaeologist digging in the tar pits
Courtesy of the Natural History Museum of Los Angeles County

"There's a couple of sites that have barely been studied but would probably be as rich as the La Brea tar pits," Lindsey says. Venezuela has several tar pits, for instance, but because of the political situation, they haven't been as intensely studied.

10. THE NAME IS REDUNDANT.

"La Brea" in Spanish means "the tar." So when you say "the La Brea tar pits," you're really saying "The the tar tar pits." It's on the long list of tautological place names that also includes Lake Tahoe and the Sahara Desert.

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Amazon/Comfort Spaces
Amazon/Comfort Spaces

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Everlasting Comfort Knee Pillow
Everlasting Comfort/Amazon

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Letsfit White Noise Machine
Letsfit/Amazon

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Eclipse Black Out Curtains
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JALL Wake Up Light Sunrise Alarm Clock
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Philips SmartSleep Wake-Up Light
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Stratus sheets from Slumber Cloud.
Slumber Cloud

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Comfort Spaces Coolmax Sheets
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Coop Eden Pillow
Coop Home Goods/Amazon

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Baloo Weighted Blanket
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Philips SmartSleep Snoring Relief Band
Philips/Amazon

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This Football-Sized Fossil Egg is the First Found in Antarctica, and It May Have Belonged to a Mosasaur

An artist’s interpretation of the birth of a baby mosasaur.
An artist’s interpretation of the birth of a baby mosasaur.
Francisco Hueichaleo, 2020

In 2011, Chilean scientists discovered a football-sized fossil off the coast of Seymour Island, near the northern tip of the Antarctic Peninsula. Though they didn’t know what it was at the time—and simply called it “The Thing”—new research shows that not only is it the first fossil egg ever found in Antarctica, it’s also the largest soft-shelled egg ever found anywhere.

In a study published today in the science journal Nature, researchers from the University of Texas at Austin and the University of Chile dated the nearshore rock formation where the fossil egg was found to be from the Late Cretaceous period—about 68 million years ago—and measured the fossil itself to be roughly 11.4 inches by 7.9 inches (29 centimeters by 20 centimeters). This empty, partially collapsed egg is smaller only than that of the elephant bird, an extinct, flightless species from Madagascar whose eggs averaged about 12 inches by 8 inches.

giant fossil egg from antarctica
A side view of the fossil egg.
Legendre et al. (2020)

But beyond their size, the eggs don’t have much in common; an elephant bird egg is about five times thicker than this fossil egg, and its hard shell has distinct pores and a prismatic layer that the fossil egg lacks. In other words, an elephant bird egg resembles a giant chicken egg. (And giant is no exaggeration—an elephant bird egg could hold the contents of about 150 chicken eggs.)

elephant bird egg next to a chicken egg
An elephant bird egg next to a chicken egg (and a man's head), to put it in perspective.
Oli Scarff/Getty Images

With its soft shell and oblong shape, the new fossil egg, from the new taxon Antarcticoolithus bradyi, is more similar to a lizard or snake egg, which suggests it could’ve been laid by a large reptile. To test that theory, the researchers compared it to the egg traits of 259 species of lepidosaurs—a subclass of reptile that includes snakes and lizards—and surmised that the egg-layer may have been a marine reptile that measured roughly 23 feet (7 meters) or longer.

The researchers believe this mystery mother might have been a mosasaur, a type of large marine lepidosaur whose remains have also been discovered in the area. During the Late Cretaceous period, mosasaurs were among the most fearsome predators in the ocean. They had strong flippers and sharp teeth, and some species grew as long as 50 feet (though that’s still a good 10 feet shorter than the fictional mosasaur depicted in 2015’s Jurassic World). Fossilized contents of their stomachs show they feasted on a variety of wildlife, including fish, seabirds, turtles, plesiosaurs, and more—one mosasaur had even eaten a few other mosasaurs. And although mosasaurs did live in Antarctica, the continent during the Late Cretaceous period looked nothing like its current frigid landscape.

“Antarctica was rich in life,” Dr. Julia Clarke, a professor in UT Austin’s Department of Geological Sciences and co-author of the study, tells Mental Floss. “Temperate forests diverse in plant species covered exposed land. Giant marine reptiles and much smaller coiled ammonites and relatives of living birds hunted in the seas, while on land, mid-sized non-avian dinosaurs ambled.”

mosasaur birth and egg
The egg looks a lot smaller when you compare it to a full-grown mosasaur.
Francisco Hueichaleo, 2020

Since scientists have uncovered the remains of mosasaurs and plesiosaurs of all ages in the rock formation where the fossil egg was found, some think it may have been a popular place for creatures to hatch and raise their young.

“Many authors have hypothesized that this was sort of a nursery site with shallow protected water, a cove environment where the young ones would have had a quiet setting to grow up,” Lucas Legendre, a postdoctoral researcher and the lead author of the study, said in a press release.

If the fossil egg really did belong to a mosasaur, it could alter our understanding of how mosasaurs gave birth. In South Dakota during the 1990s, scientists unearthed the skeleton of a lizard-like mosasaur called a Plioplatecarpus with five unborn offspring preserved in its abdomen. Because they weren’t in eggs, it was generally thought that mosasaurs gave birth to live young. The existence of Antarcticoolithus bradyi, however, suggests the possibility that some mosasaurs laid soft-shelled eggs that hatched immediately after.

According to Clarke, the discovery of the fossil egg is especially exciting because it demonstrates “how much we have yet to learn about the evolution of eggs, from the first egg-layers that moved away from water to the immense diversity of eggs and reproductive strategies we see today.”