The Brief

More than 13,000 years ago, when an abundance of saber-toothed cats roamed the Los Angeles Basin, the giant mammal would hide in tall savanna grasses or behind juniper shrubs and stalk its prey.

“We think they were probably ambush predators,” says Emily Lindsey, associate curator and excavation site director at the La Brea Tar Pits museum and paleontology research site.

When it spotted its target — horses, camels, mammoths or other large animals known as megafauna — it would use its powerful forearms to leap out and pin down its prey.

Then, using its 8-inch-long curved canines — serrated like a steak knife — it would slice through a vein and let the animal bleed out.

“All of that information is based on research here because we have this incredible collection of more than 2,000 saber-toothed cats,” Lindsey says. “It’s really rare that we have the whole record. You don't usually get that in paleontology.”

L.A.'s climate past and future

The La Brea Tar Pits — home to more than 3.5 million Ice Age fossils — is one of the planet’s best-kept records of what it was like in the area we now know as Southern California over the last 60,000 years. It’s also the world’s only active urban fossil dig site.

Fossils found in the asphalt help paint the picture of the life that once flourished here during the Ice Age: saber-tooth cats, giant sloths, dire wolves, grizzly bears, bison as well as juniper and oak trees.

Emily Lindsey, an assistant curator at the LA Brea Tar Pits, places a fossil inside the fossil collection room.

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But it's not just telling the story of the region’s past. This collection of Ice Age fossils also helps scientists understand what led to the most massive extinction of megaspecies on Earth since dinosaurs, when droves of large mammals suddenly died as extreme heat, drought and large-scale wildfires overwhelmed the region.

And as we endure another period of significant environmental change, these fossils also offer a window into the future.

“There was this ‘ah ha’ moment for paleontologists,” Lindsey says. “We said: ‘Oh wait, we have a really unique insight on that story because we can actually look at these different windows of different habitats from different times and see how they respond to climate change in real time.”

It’s part of a growing field called paleoecology, which aims to use the knowledge of prehistoric ecosystems that fossils yield to predict how plants and animals will respond to environmental events now and in the future.

“The fact that we have particular species of plants, or insects, or birds, or rodents can tell us a lot about how hot or cold it was, how wet or dry it was, and how that environment changed through time,” Lindsey says.

This link between the end of the Ice Age and the global warming we’re experiencing now is a focus of the ongoing research at the Tar Pits. Particularly, scientists seek to use fossil data to make decisions about how to preserve biodiversity today.

“You can only get that by looking at the fossil record,” Lindsey says.

The tar pits

About 1,000 feet beneath the metropolis of L.A. sits the Salt Lake Oil Field.
(The Los Angeles Basin is the richest in terms of oil by unit volume on earth). That, paired with the abundance of earthquakes in the region, which create cracks and chasms in the earth, paves the way for the tar pits.

Tar pits — sticky, shallow pools of asphalt that seep up through cracks and fissures in the ground — are essentially naturally occurring preservation deposits. The asphalt is so sticky that when animals stepped into it — even enormous ones like the now extinct pre-Columbian mammoth — they got trapped and couldn't get out.

Inside Tar Pit 91, where research is currently being done.

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The result? Meticulously preserved fossils that have been embalmed in asphalt for tens of thousands of years without exposure to air.

“So we get phenomenal preservation not just of bones, but of leaves and wood, insects and shells,” Lindsey says. “That’s what’s allowed us to build up the richest record of Ice Age life anywhere.”

Researchers examine fossils discovered in the tar pits.

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Using the fossil record to inform conservation decisions

Studies from Tar Pits researchers suggest extreme heat, drought and large-scale wildfires might be at the root of the last major extinction event.

Last year, a study published by researchers there found that large-scale wildfires — possibly started by humans — wiped out many of the large Ice Age mammals. The research broke new ground in an ongoing scientific debate over what triggered the Earth’s last major extinction event.

It adds more evidence to the growing understanding that extreme heat, drought and wildfires can drastically change habitats, leading to species extinction.

“This is just one example of how we can use fossil data to inform conservation and land management decisions today,” Lindsey says.

In an ongoing partnership with the Nature Conservancy, La Brea Tar Pits is now developing a practitioner's guide for land managers, mapping out ways to use fossil data in environmental decision making.

“In other words: How do you use historical and paleontological data to help inform conservation and restoration work in urban areas?” Lindsey says. “This will help address that.”

"When planning for these types of projects, The Nature Conservancy sets goals using information from a variety of sources," says Sophie Parker, director of science for climate and land use at The Nature Conservancy. "Knowing what was present at a site at multiple timepoints in the past, including the more distant past, is useful because it gives us a broader perspective on how to craft our goals."

Asphalt can be observed flowing from the gated tar pits, allowing visitors to witness the phenomenon.

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The Tar Pits also dedicates a small section of the park as the “Pleistocene Garden,” which contains plants that grew at La Brea at different times in history found in the fossil record. With plans for a major re-landscaping of the park currently in the works, there is a focus to significantly expand plants in line with the paleontological science on the grounds.

“It’s a way to viscerally communicate that story but also bring back some of those plants and serve as seed banks and help support urban nature,” Lindsey says.

Sharing the climate story

Beyond the rich scientific research backed by tens of thousands of years of fossil data, Lindsey says the most important part of the work they do at this critical environmental moment is public education.

By presenting current climate research alongside Ice Age fossil data, the hope is that it will drive a deeper understanding of our environmental crisis and emphasize a dire conclusion: then, as now, climate changes and human activities can intersect to drive large scale extinctions.

It's all laid out for the public to see in the La Brea Tar Pits museum and across its grounds.

“To have a place in the third biggest city in North America where people can see an entire scientific process," says Lindsey, "that’s another very powerful thing.”

Remains of mammoths can be seen at the La Brea Tar Pits.

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Zaydee Sanchez

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There is one notable, but perhaps hopeful, difference between then and now, Lindsey says.

The climate change that occurred at the end of the Ice Age 13,000 years ago was purely related to the earth’s orbital cycles.

Today, it’s 100% us.

“Meaning we completely have the ability to stop it if we want to,” Lindsey says. “It’s just a matter of political and societal will. I hope this helps people understand that small human actions could push the ecosystem to a tipping point.”

Eric Swalwell, who had emerged as one of the top candidates in California’s crowded governor’s race, suspended his campaign Sunday evening after a series of women accused him of sexual assault and harassment, including allegations that he raped a former staff member twice.

In the short statement posted on social media, he did not address whether he will remain in Congress.

Swalwell, a married father of three who represents the East Bay, faced swift calls to resign from his House seat and leave the governor’s race after the allegations were published by the San Francisco Chronicle and CNN on April 10. In addition to the political fallout, he’s now facing a criminal inquiry from the Manhattan District Attorney’s Office in New York and possibly Alameda County — where the 2024 and 2019 alleged assaults each took place.

“To my family, staff, friends, and supporters, I am deeply sorry for mistakes in judgment I’ve made in my past,” Swalwell said on X. “I will fight the serious, false allegations that have been made — but that’s my fight, not a campaign’s.

The reports by the Chronicle and CNN included allegations by an unnamed former staffer who said Swalwell sexually assaulted her when she was too intoxicated to consent in both 2019 and 2024. CNN also reported allegations of misconduct from three other women involved in Democratic politics, including one who said Swalwell kissed her without consent and two others who said that he sent them unsolicited nude photos and explicit text messages.

Swalwell flatly denied the allegations of sexual assault in a video he posted on social media Friday, and vowed to fight them. But he seemed to acknowledge at least some infidelity, adding that any mistakes are between him and his wife, and apologizing for “putting her in this position.”

But within hours of the stories publishing, Swalwell was abandoned by nearly all his supporters. Top House Democrats, including Minority Leader Hakeem Jeffries and Speaker Emerita Nancy Pelosi, called for his exit, and he lost 21 endorsements from fellow Democratic members of Congress.

Over the weekend, senior staffers from both his congressional office and campaign resigned, and major labor groups like the California Teachers Association and SEIU California pulled their support. His campaign website no longer contains links to donate or a page listing his donations.

In a joint statement Sunday, 55 of Swalwell’s former staff members called the allegations “serious” and “credible” and urged law enforcement to investigate. They also called on Swalwell to resign from Congress and withdraw from the governor’s race, and apologized to their former colleague “for not knowing what you were enduring.”

“We believe her,” the letter states. “What has been described is not a political attack. It is the account of a young woman who trusted her employer, who was targeted and exploited by someone in a position of power over her, and who has carried this burden for years.”
Swalwell, 45, had a meteoric rise in politics — and a fall that came just as fast. A former Alameda County prosecutor, he first ran for Congress in 2011, as a 30-year old Dublin city councilmember who unseated a 20-term incumbent nearly 50 years his senior.

He rose to national prominence during President Donald Trump’s first term when he was tapped to help investigate Trump during both impeachment inquiries. The roles — as an impeachment manager during the first impeachment, and again as a House manager during the second — led to frequent appearances on cable news and made him one of the Democratic Party’s most high-profile Trump critics.

He briefly ran for president in 2019, but dropped out within months after failing to gain traction. Swalwell announced a run for governor in November, joining a crowded field to replace the termed-out Gov. Gavin Newsom. Other leading Democrats include former Rep. Katie Porter and billionaire Tom Steyer, though the race had remained wide-open and a clear Democratic favorite had yet to emerge.

Over the past five months, Swalwell quickly amassed endorsements from most of his congressional colleagues, state lawmakers and some of California’s largest labor unions. They all abandoned him after the allegations were made public.

Republican Leticia Castillo stunned political observers when she won her Riverside County Assembly seat in the state Legislature two years ago.

The Democratic candidate, Clarissa Cervantes, the sister of the outgoing assemblymember, was favored and had spent more than 10 times as much as her.

This year, Castillo thinks she can do it again.

“I’m accessible to my constituents and they like that,” Castillo said at an evening reception outside a San Diego resort. Republican strategists, legislators and advocates are meeting for the party’s annual convention in downtown San Diego, one month before mail ballots for the June primary appear in mailboxes.

California Republicans are optimistic Castillo and a handful of other GOP legislators can hold onto their seats — but only if they keep President Donald Trump at a distance. It’s emblematic of a tension between leaders who are focused on strategic campaigning and party conservatives’ unabashed embrace of Trump. GOP candidates have been careful not to align themselves too closely with the president, whose affiliation can activate California Democrats to vote against anything from a candidate to a ballot measure.

Inflation and America’s entry into another war have cratered the president’s popularity among voters nationally. And the California party is listening. Officials over the weekend repeatedly downplayed him and his influence in state politics. But between bedazzled sweaters featuring his name and cardboard cut-outs of him, delegates’ support for the president was on full display.

Trump remains deeply unpopular in California. But his support among hard-line conservatives activists has rarely, if ever, wavered since in the last decade. That remains true among California Republican activists, whose devotion has not waned despite Trump’s controversial decision to enter a war with Iran that has caused record-high gas prices.

“I love what he’s doing. I love all the s— he’s saying,” Los Angeles delegate Mary Boston said about Trump and the war in Iran. “The whole establishment — all the Democrats, all the judges — they just hate him because he’s trying to make a difference for you and me.”

Donald who?

However, GOP officials sought to minimize his role.

“I think people here are tired of California. They know that the federal government is doing nothing to harm or help California,” Riverside County sheriff and Republican candidate for governor Chad Bianco said in an interview. Trump last week endorsed his Republican rival Steve Hilton, a former Fox News host, instead of Bianco. “For the last week, people haven’t cared what President Trump is doing,” he said of Trump’s endorsement.

Bianco and Hilton have been reticent to mention Trump. In a state where Democratic voters vastly outnumber Republicans, it’s an imperative.

State party Chair Corrin Rankin said she was surprised to see Trump “weigh in on anything in California,” and refused to comment directly about voters’ discontent with his policies.

Some party leaders are hoping Trump’s toxicity will just blow over come the June 2 primary.

“Just as quickly as the gas prices went up, I think that we’ve all seen in California how quickly gas prices can also come down,” state party Vice Chair John Park said. “Many of the problems that are on the front burner, the ones that people will instinctively tie to President Trump, will subside by then.”

At the convention, the divide between the party establishment and its rank in file was on display. Trump merchandise could be seen all across the convention — at vendor booths, on the walls and on people’s clothes. At some sessions, Trump’s footprint was large. A “Make California Great Again” session was spearheaded by Jo Reitkopp, from Orange County, who founded a group of the same name shortly after Trump was inaugurated in 2016.

Reitkopp and other party activists were advocating for a voter ID ballot initiative that would require voters to show proof of citizenship to vote. The ballot measure is modeled after a voting restriction bill Trump is pushing in Congress.

Running for the Legislature? Stay mum on Trump

Even before voters passed Proposition 50, the ballot measure targeting House Republicans, the California Republican Party was weak and had little relevance. Democrats continue to hold a commanding supermajority in Sacramento, where Republicans are fewer than a third of state lawmakers. No Republican has been elected to a statewide office since 2006.

Things briefly looked different in 2024 after voters shifted to the right in nearly every county as part of the backlash to President Joe Biden. Predominantly Latino and working-class voters in Imperial County backed Trump, the first time they had backed a Republican presidential candidate in decades. Republicans also flipped three seats in the Legislature, a first in 10 years.

Those trends quickly evaporated. Voters in Imperial County and across the state overwhelmingly approved Prop. 50, complicating the narrative that Democrats were losing Latinos in California.

Imperial County GOP Chair Sayrs Morris said candidates’ approach will be to keep mum on Trump because of voters’ frustration with the economy.

“We’re not going out there saying our candidates are MAGA candidates. We’re keeping it focused on them,” said Morris, a Trump supporter. “Right now things are tough. The economy’s not super great. And we’re at war.”

Coachella Republican Assemblymember Jeff Gonzalez will be a test case. He flipped his district two years ago, despite a registration advantage that favors Democrats by 12 percentage points. Among Gonzalez’s challengers are Indio city Councilmember Oscar Ortiz and former El Centro Mayor Tomás Oliva. So far, he’s outraised all of them with $630,000 in his campaign account at the end of last year.

Gonzalez’s campaign spokespeople did not return calls and emails seeking comment.

Republicans are also targeting Castillo’s Riverside Assembly seat and Senate Minority Leader Brian Jones’ San Diego district, where the GOP holds only a slight advantage as voters in north and eastern parts of San Diego County trend leftward. He terms out at the end of this year.

“It’s the one we’re all watching,” GOP activist Justin Schlaefil said.

The debate over who should succeed Jones, a moderate Republican, has been a tension point among Republicans in San Diego.

Jones and U.S. Rep. Darrell Issa have backed San Marcos City Councilmember Ed Musgrove. Meanwhile, Reform California, a multimillion-dollar political organization led by Republican Assemblymember Carl DeMaio, is supporting Kristie Bruce-Lane, a two-time unsuccessful Assembly candidate who is further to the right than Musgrove.

Moderate Republicans fear Lane is too conservative for what will be the most competitive district this year.

Neither candidate gained enough support for an endorsement at a February San Diego County GOP meeting after hours of heated debate.

“We’re spending a lot of money against each other just because of that,” said Schlaefil, a friend of Jones. “It is winnable, but it is very tight.”

Back in Riverside, Castillo has a much larger war chest than two years ago when she narrowly clinched her seat by a few hundred votes against Democratic City Councilmember Clarrissa Cervantes.

Cervantes was initially considered a shoo-in. But she was bogged down by two DUI convictions. Cervantes attributed her loss to poor Democratic turnout. This time, she hopes things will be different.

Castillo is keeping her focus on public safety and parental rights.

“I get people just want to continue to say, ‘Trump, Trump, Trump,” she said. “At the end of the day, we’re in California, and Trump doesn’t rule here.”

Los Angeles Unified reached deals with some of its biggest labor unions on Sunday, ahead of a planned April 14 strike that would shut down the district.

On Sunday morning, LAUSD announced a deal with United Teachers Los Angeles, whose members include 35,000 teachers and counselors. In the evening, district officials announced an agreement with Associated Administrators of Los Angeles, which represents 3,000 principals and other school leaders.

But educators are expected to honor possible picket lines on Tuesday if a deal can't be reached with the remaining union in negotiation, SEIU Local 99. That union represents bus drivers, classroom aides and other staffers.

“Despite [United Teachers Los Angeles] having reached a tentative agreement with the school district, teachers have pledged to stand in solidarity with SEIU Local 99 and join in a sympathy strike," SEIU Local 99 said in a news statement on Sunday.

An LAUSD spokesperson said negotiations are continuing into Sunday evening.

The three unions gave the district an April 14 deadline to reach agreements or else face a walkout. A strike could shut down district schools and disrupt the education of about 400,000 students and the lives of families scrambling for child care.

What are the terms of the UTLA deal?

LAUSD and UTLA announced a tentative two-year agreement. UTLA’s bargaining team had met with the district more than a dozen times since negotiations began in February 2025.

Terms of the new contract include an increase in salary scales by 11.65%, a new-teacher salary of $77,000 per year, four weeks of district-paid parental leave, expanded student mental health supports and a first-ever 20:1 ratio for special education specialist teachers.

“These wins reflect the progress we’ve fought for, enabling educators to stay fully focused on supporting students’ learning and well-being,” said Cecily Myart-Cruz, the union’s president, in a statement.

A district spokesperson told LAist the ongoing cost of the agreement with UTLA is $650 million and also includes “a comprehensive agreement on inclusive practices and staffing,” reduced secondary counseling ratios and smaller ratios for 11th- and 12th-grade academic class sizes.

The union’s members and the LAUSD Board of Education must vote to approve the deal. UTLA said in an Instagram post that its bargaining team "enthusiastically recommends" that union members ratify the new contract.

Learn more about the proposals UTLA made.

What are the terms of the AALA deal?

Major details of the AALA deal weren't immediately available Sunday, other than that it increases members’ salary by 11.65%, only a touch shy of the 12% the union had sought.

A strike would have been a first for the union, which affiliated with the Teamsters in 2024.

The union declared an impasse in February, an assessment the district disagreed with, but it agreed to continue negotiating.

“We don't have the necessary resources to really say we have safe schools, to really say that we're servicing students,” said Maria Nichols, president of AALA, during a pre-strike rally.

What is the staff union negotiating for?

SEIU Local 99 declared an impasse in December. The state appointed a mediator to try to help the two sides reach an agreement. The negotiating teams were scheduled to continue bargaining on Sunday.

The union's 30,000 members include bus drivers, cafeteria workers, classroom and campus aides. The contract expired June 30, 2024.

The union’s proposals include: 

• A 30% wage increase over three years. 
• More hours for workers who don’t have enough to qualify for benefits.

LAUSD’s most recent offer includes: 

• A 13% wage increase over three years.
• A task force that includes SEIU Local 99 members to advise the district on artificial intelligence use.
• Learn more.

SEIU Local 99 reports its members make an average of $35,000 a year.

Maria Avalos is a supervision aide at Fernangeles Elementary School in Sun Valley. Avalos said she’s only assigned four hours of work a day and also cleans houses and sells tamales to support her daughter.

“We need more hours,” Avalos said. “I live in an apartment that has one bedroom for 10 of us.”

What happens if schools close?

If a deal can't be reached with every union and a strike shuts down schools, LAUSD plans to distribute food, tech support and refer families to community organizations for child care. Updates about resources and labor negotiations will be posted to a dedicated website in English and Spanish.

However, during a three-day 2023 strike, families struggled to find care and access their child’s education.

Senior editor for education Ross Brenneman contributed to this story.