The La Brea Tar Pits are full of mysteries. Here are three of the most puzzling
Last year we started inviting readers to send us their pressing questions for Los Angeles and California.
Every few weeks we ask the questions votingasking readers to decide which question they would like answered in the form of a story.
This question, asked by Ricky Fulton, was included in one of our recent reader polls: What are the La Brea Tar Pits? Is it a pile of bubbling tar from protruding dinosaur bones?
There’s more than meets the eye—and the nose—at the La Brea Tar Pits.
For those who don’t know, La Brea Tar Pits is internationally recognized geological heritage site, located in downtown Los Angeles. The site is known for its numerous fossil quarries (called ‘pits’) where animals, plants and insects have been trapped and preserved in the asphalt for the past 50,000 years.
For scientists, they are an invaluable, unique treasure trove of information that allows us to better understand what ancient life was like in present-day Los Angeles.
“The type of science you can do at the La Brea Tar Pits is something you can’t really do at any other paleontological site in the world, just because we have so many fossils and they’re so well preserved,” said Emily Lindsey, associate curator and Director of Excavations.
More than 3.5 million fossils have been found in the smelly slime – a curiosity for locals, tourists and students on field trips.
To answer Fulton’s question right away, here’s one thing they didn’t find in the pits: dinosaurs.
That’s right – it’s an Ice Age fossil site, and experts haven’t found any remains of T. rexestriceratops or other non-avian dinosaurs.
While the La Brea Tar Pits have no dinosaur fossils, they are full of fossils of legendary Ice Age animals. The two most common large mammals? Dire Wolves (shout out to all “Game of Thrones” fans) and saber-toothed cats.
Despite the scientists groundbreaking discoveriesmysteries continue to swirl in the leaking pits.
Sometimes, Lindsey said, the things you learn do not found in the tar pits are as fascinating as the bones and other objects they uncover.
Lindsey described the puzzles posed by the tar pits that remain to be solved.
Here are three of the most tempting:
Why are the remains of some native species—such as mountain lions—largely absent from tar pits?
Something strange: Scientists have found relatively few remains of mountain lions in the tar pits.
P-22’s Hollywood celebrity status aside, it may seem odd to worry about the lack of some 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 mountain lions — which existed in the Los Angeles area during the Ice Age — make up such a small percentage of scientists’ discoveries in the tar pits. The tar pits have the remains of at least seven different mountain lions, while the saber-toothed cats number somewhere between 2,500 and 3,000.
And it’s not just mountain lions missing from the tar pits.
“We have very few mountain lions, very few deer … and only one raccoon,” she said. Aside from coyotesscientists have found “very few of them [large mammal] ‘survivors of the ice age’, which is an interesting thing.’
Why might mountain lions be missing from tar pits?
The answer could help scientists paint a more detailed picture of what life was like in prehistoric Los Angeles.
Lindsey and her colleagues have a few ideas. Among other potential explanations, it’s possible that—true to their name—mountain lions have always preferred to be in the mountains rather than the flatter areas of present-day Los Angeles near the tar pits.
Or perhaps mountain lions were afraid to hunt in the same areas as saber-toothed cats. “The mountain lion looks like a domestic cat next to a saber-toothed cat – [it’s possible] they wanted to stay away and not be around all these 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 conspicuous lack of human remains.
“People were here, but why don’t we find any evidence of them in the La Brea Tar Pits?” asked Lindsay. “We have one human skeleton and then we have some artifacts that are probably from the Holocene (our current geologic epoch), but we have no evidence of human overlap or interaction with the megafauna” through hunting.
This is puzzling because “many—perhaps even most—scientists believe that the primary cause of megafauna extinction is human activity,” Lindsay explains.
Like mountain lions, Lindsey notes that the absence of ancient humans may point to their reticence when hunting nearby saber-toothed cats and other dangerous animals.
“It’s possible that the culture that was here was adapted to the coast and didn’t need to fight, say, a pack of dire wolves to go hunting for a horse or a camel,” she said. “They could have stayed close to shore and I’m picking clams.”
Why did large mammals start to disappear – and what does this tell us about our future?
Once upon a time there were giant mammals roaming vast swathes of land.
“There were giant wombats in Australia, there were giant lemurs in Madagascar, there were giant sloths and armadillos in South America,” Lindsey said.
So, asks Lindsay, why don’t we have saber-toothed cats, mammoths and giant ground sloths roaming Wilshire Boulevard today?
A dramatic change has occurred. “At the end of the Ice Age, something happened and it wiped out the upper end of the body size distribution everywhere except Africa,” she said. “This is the largest extinction event since the dinosaur extinction event 66 million years ago.”
More chillingly, the loss of the giant mammals is beginning to be recognized as “the first impulse in the biodiversity crisis we find ourselves in today,” she said.
Why did this extinction event occur? “Most scientists believe that humans must have had a fairly significant role in this extinction. But the other thing that was happening was that we were coming out of the Ice Age – the last big episode of global warming,” she said.
“Understanding a type of interaction between climate change and human activities, how this affects ecosystems and how these two processes can intersect to lead to extinction is extremely important.
The La Brea Tar Pits are positioned to help solve the mystery of exactly why the giant mammals died out, due to the size and scope of their findings, which can be radiocarbon dated and matched to known changes that occurred at the same time as humans and the climate.
On the other side of the coin, 90% of the species found in the tar pits have not gone extinct. “We have tons of rabbits, rodents, lizards, insects and songbirds in our archive that are still living in the Los Angeles area today,” Lindsey said via email.
“We’re a record holder for survival and resilience,” she said, which raises several questions. “What made mountain lions successful? What made coyotes so successful? What made the oaks successful?’
Like the climate crisis is worsening today, the answers to these mysteries could pave the way for the future.
“The next few decades to several centuries are going to be some really extreme global changes,” Lindsey said. “How can we use this information to help life succeed going forward?”
This existential question should give you something to think about the next time you pass the iconic (and heartbreaking) Tars mammoth statues off Wilshire Blvd.
This story was written in direct response to a reader’s question about the La Brea tar pits. Have a question about living in Los Angeles or California? Ask us!
This story originally appeared on Los Angeles Times.