The La Brea Tar Pits are full of mysteries. Here are three of the most puzzling

The lake pit in front of the La Brea Tar Pits Museum is left over from asphalt mining that took place in the nineteenth century. (Gina Ferazzi/Los Angeles Times)

Last year we started inviting readers send us their pressing questions about Los Angeles and California.

Every few weeks, we vote on the questions and ask readers to decide which question they want answered in story form.

This question, asked by Ricky Fulton, was included in one of our latest reader surveys: What are the La Brea Tar Pits? Is it a bunch of bubbling tar with dinosaur bones sticking out?

You can vote here in our next reader poll. View previous stories written as part of this project here.

There’s more than meets the eye – and nose – to the La Brea Tar Pits.

For those who don’t know, the La Brea Tar Pits is an internationally recognized geological heritage site, located in the middle of Los Angeles. The site is known for its many fossil quarries (referred to as “pits”), where animals, plants and insects have become trapped over the last 50,000 years and preserved in asphalt.

For scientists, they are an invaluable, unique treasure trove of information that will allow us to better understand what ancient life was like in present-day Los Angeles.

“The kind of science you can do at La Brea Tar Pits is stuff you can’t really do at other paleontological sites in the world just because we have so many fossils and they’re so well preserved,” said Emily Lindsey, associate curator. and director of the excavation site.

Within the fragrant blob – a curiosity for locals, tourists and schoolchildren on excursions – more than 3.5 million fossils have been discovered.

To answer Fulton’s question right away, here’s one thing they didn’t find in the pits: dinosaurs.

That’s right – this is an Ice Age fossil site and experts have not discovered any remains of it T. rexestriceratops or other non-avian dinosaurs.

While the La Brea Tar Pits are short on dinosaur fossils, they are chock-full of fossils of legendary Ice Age animals. The two most common large mammals? Dire wolves (shout out to all “Game of Thronesfans) and saber-toothed cats.

A woman looks at a fossil display at The La Brea Tar Pits in Los Angeles

Columbian mammoths and mastodons were once home to Los Angeles. Today their remains are on display at the La Brea Tar Pits and Museum. (Mel Melcon/Los Angeles Times)

Despite the scientists’ groundbreaking findings, mysteries continue to swirl in the dripping pits.

Sometimes, Lindsey said, the things scientists do not finds in the tar pits are as fascinating as the bones and other objects they discover.

Lindsey described puzzles of the tar pits that have yet to be solved.

Here are three of the most enticing:

Why are the remains of some native species – such as mountain lions – largely missing from the tar pits?

Something strange: scientists have discovered relatively few remains of mountain lions in the tar pits.

P-22’s Hollywood celebrity status As an aside, it might seem odd to worry about the absence of mountain lion fossils when the tar pits have revealed the remains of extinct mammoths, dire wolves, and giant ground sloths.

Still, it’s odd that cougars — which were common in the Los Angeles area during the ice age — make up such a small percentage of the scientists’ findings at the tar pits. The tar pits have remains of at least seven different mountain lions, while the number of saber-toothed cats is somewhere between 2,500 and 3,000.

And it’s not just mountain lions that are missing from the tar pits.

“We have very few mountain lions, very few deer… and only one raccoon,” she said. Aside from coyotes, scientists “have found very few of them [large mammal] ‘survivors of the ice age’, which is interesting.”

Why are mountain lions missing from the tar pits?

The answer could help scientists paint a more detailed picture of what life in prehistoric Los Angeles was like.

Lindsey and her colleagues have a few ideas. Among other possible explanations, it’s possible that—true to their name—mountain lions have always preferred to be in the highlands, not the flatter areas of present-day Los Angeles near the tar pits.

Or maybe mountain lions were afraid to hunt in the same areas as saber-toothed cats. “A mountain lion is like a domestic cat next to a saber-toothed cat – [it’s possible] they wanted to stay away and not be around all those big scary things.

Where is the evidence of human life?

Mountain lions, raccoons and deer aren’t the only mammals missing from the tar pits. There is also a striking lack of human remains.

People were here, but why don’t we find any evidence of them in the La Brea Tar Pits? Lindsey asked. “We have one human skeleton, and then we have a number of artifacts that are probably all from the Holocene (our current geological age), but we have no evidence that humans overlap or interact with the megafauna” via hunting.

This is puzzling, because “many—perhaps even most—scientists believe that the main cause of the megafauna’s extinction was human activity,” Lindsey explains.

As with the mountain lions, Lindsey notes that the absence of ancient humans could indicate their reluctance to hunt nearby saber-toothed cats and other dangerous animals.

A group of adults and children watch a demonstration at the Fossil Lab

People watch a demonstration at the Fossil Lab at the La Brea Tar Pits and Museum. (Kent Nishimura/Los Angeles Times)

“Perhaps the culture that prevailed here was adapted to the coast and they didn’t have to face a pack of wolves to hunt a horse or a camel, for example,” she said. “They could stay close to shore and pick shellfish.”

Why did large mammals begin to disappear – and what does that tell us about our future?

Giant mammals once roamed large areas of the earth.

“There were giant wombats in Australia, there were giant lemurs in Madagascar, there were giant sloths and armadillos in South America,” Lindsey said.

So, Lindsey wonders, why don’t we have saber-toothed cats and mammoths and giant ground sloths wandering Wilshire Boulevard today?

A dramatic change took place. “At the end of the Ice Age, something happened and it wiped out the top of the body size distribution, except in Africa,” she said. “That’s the largest extinction event since the dinosaurs went extinct 66 million years ago.”

Even more chilling is that the loss of the giant mammals is increasingly recognized as “the first impulse in the biodiversity crisis we find ourselves in today,” she said.

Why did this extinction event occur? “Most scientists think that humans must have played quite an important role in this extinction. But the other thing that happened was we came out of the ice age — the last major global warming episode,” she said.

“Understanding the interplay between climate change and human activities, how that affects ecosystems and how those two processes can intersect to cause extinction is incredibly important.”

The La Brea Tar Pits are positioned to help solve the mystery of exactly why the giant mammals went extinct, due to the magnitude and scope of the findings, which can be radiocarbon dated and compared to known shifts that happened simultaneously with humans and climate .

Two people kneel on the ground and carefully dig up fossils

Two volunteers dig up fossils at the La Brea Tar Pits. (Gina Ferazzi/Los Angeles Times)

On the other side of the coin, 90% of the species found in the tar pits are not extinct. “We have tons of rabbits, rodents, lizards, insects and songbirds on file that still live in the LA area,” Lindsey said via email.

“We are a record of survival and resilience,” she said, which raises a few questions. “What made mountain lions successful? What made coyotes so successful? What made oak trees successful?”

As the climate crisis worsens today, the answers to these mysteries may chart a path for the future.

“The next few decades to several centuries will be one of really extreme global changes,” Lindsey said. “How can we use that information to make life work in the future?”

This existential question should give you something to ponder the next time you pass the iconic (and heartbreaking) mammoth statues of the Tar Pits along Wilshire Boulevard.

This story was written directly in response to a reader’s question about the La Brea Tar Pits. Do you have a question about living in Los Angeles or California? Ask us!

This story originally appeared in the Los Angeles Times.

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