Los Angeles County features a number of truly amazing museums, but the La Brea Tar Pits and George C. Page Museum exhibits are extraordinarily unique. The La Brea Tar Pits are world famous and are the only registered National Natural Landmark in Los Angeles County (and one of 39 sites in California). Almost every Angeleno knows about the La Brea Tar Pits, as do many non-Angelenos. The story of this unusual natural feature has stirred scientific interest and imagination for more than a century. In fact, the tar pits were featured in the only fictional film made about Los Angeles of 10,000 years ago – NBC’s La Brea. The 2021 science-fiction television series tells the story of Angelenos falling through a giant sinkhole near the La Brea Tar Pits (hence, La Brea), only to find themselves in prehistoric Los Angeles. We have a lot of questions about that, but we digress.
To be clear: the La Brea Tar Pits are not actually composed of tar at all. They are composed of bitumen or asphalt. The La Brea pits should be more accurately named La Brea Bitumen Pits or La Brea Asphalt Pits. Tar is derived from organic materials such as wood, peat or coal. Bitumen or asphalt is derived from crude oil (or petroleum) seeping to the surface. Nevertheless, we have all long know these as the La Brea “Tar” Pits. So, know that any reference here to “tar” actually means bitumen or asphalt.
Our common imaginations have pictured a hellish deep pool of black tar into which terrified trapped animals slowly sank until they disappeared from sight. The iconic display, alongside Wilshire Boulevard, of a distressed mammoth sinking into a noxious lake in front of its family helps to cement that picture for us. In reality, the pools of asphalt that seeped to the surface were, at most, only a few inches deep. These pools appeared at random locations and likely only when temperatures were hot enough to liquify the asphalt. Yet, even as little as an inch and a half of asphalt could possibly trap a large animal. Scientists believe that animals (especially larger ones) would only occasionally find themselves stuck in the goo to the point that they were unable to free themselves. Yet, over a period of 40,000 years, even just those occasionally unfortunate animals trapped by asphalt left an enormous number of fossilized bones.
Asphalt is not easily removed from fossil remains, as La Brea Tar Pits paleontologists can tell you, but skeletal remains encased in it are kept in pristine condition. Even tiny markings on teeth are preserved. With such amazing preservative, an incredible variety of extinct Ice Age animals have been recovered from the La Brea Tar Pits. More than one million bones have been recovered from the pits, representing more than 231 species of vertebrates. Paleontologists have also identified 159 species of plants and 234 species of invertebrates. At last count, the collection exceeded 3.5 million specimens.
Fossils found in the La Brea Tar Pits only date from the very end of the Pleistocene epoch (also known as the Ice Ages), from 11,700 to 50,000 years ago, which still falls within our current Cenozoic Era. The era of the dinosaurs was significantly earlier, during the Mesozoic Era, from 66 million to 245 million years ago. There are no dinosaur-era fossils found at the La Brea Tar Pits, only those from the late Ice Ages. You may still call them prehistoric, though.
The ratio of carnivores to herbivores found in the La Brea Tar Pits is nine to one. Scientists theorize that trapped herbivores attracted lots of carnivores, even from far away. The carnivores, finding a animal trapped by asphalt and a potential easy meal, also put themselves at risk of becoming trapped. Since the asphalt was not deep, most trapped animals would have likely appeared largely exposed to investigating carnivores. Adding to this, according to research published in 2013, some trapped animals were believed to have lingered alive in the asphalt for as long as 17 to 20 weeks, eventually dying of dehydration, exhaustion, or wounds inflicted by predators and scavengers.
The La Brea Tar Pits are one of the few sites in North America where both Mammoth and Mastodon fossils have been found in the same site. Mastodons were an older species, smaller in size, with shorter and straighter tusks, pointed teeth, and flatter heads. They were believed to dine on crushed leaves, twigs and branches. The larger mammoths were grazers, like modern elephants, with longer and more curved tusks, flat teeth, and a more "domed" head. Most fossils of these two species were found in Pit 9 (including those of 27 individual Columbian Mammoths). The most recent find was in 2006 when a near complete skeleton of an adult mammoth was discovered just next door at a construction project for the new Los Angeles County Museum of Art underground garage. The mammoth was named "Zed."
More than 4,000 individual dire wolves (Canis dirus) have been found in the La Brea Tar Pits. They are the most common mammal found in the tar pits. In fact, one of the most iconic displays at the La Brea Tar Pits Museum is the orange-lit wall of 400 dire wolf skulls. Saber-toothed cats (Smilodon fatalis) come in second place for the number of mammal finds, with more than 2,000 individuals found. Coyotes (Canis latrans) take third place. Dire wolf remains are the oldest fossils found to date, believed to be nearly 44,000 years old. The most commonly found herbivore was the Ancient bison (Bison antiquus), of which 300 individuals have been found.
The La Brea Tar Pits & Museum holds the largest Ice Age fossil collection in the world and the largest collection of Ice Age bird fossils. Bird fossils are rare, because the hollow bones of birds tend not to hold up well as fossils. Bird fossils in asphalt deposits, however, are well-preserved by the asphalt and offer extraordinary detail. The La Brea Tar Pits Museum collection holds about 140 different bird species, most of which still exist today, although 23 species are now long extinct. The largest extinct bird found was Merriam's Teratorn (Teratornis merriami), a large bird-of-prey that stood up to 30 inches tall and had a wing span of 10 to 12 feet.
Many of the animal fossil species found in the La Brea Tar Pits still exist today. Among these are coyotes, dogs, mountain lions, gray foxes, bobcats, rabbits, black bears, raccoons, mice and skunks. There are also grasshoppers, termites, gopher snakes, garter snakes, the western rattlesnake, the western pond turtle, rainbow trout, frogs, freshwater mollusks and many different kinds of birds.
The remains of only one human has ever been found in the La Brea Tar Pits. This was La Brea Woman, a young native woman believed to have lived about 9,000 years ago. We will likely never know for sure, but a fracture in her skull suggests that she might have been L.A.’s earliest known homicide victim.
As mentioned in our feature above about mammoths and mastodons, during the beginning of a nearby construction project in 2006, 16 new fossil deposits were discovered. Paleontologists quickly swooped in to preserve these finds and locate others. Among these was the skeleton of "Zed," noted above. To preserve these finds, 23 large wooden boxes were built around each deposit. The boxes were then moved a short distance to their present location at La Brea Tar Pits to be unboxed and carefully excavated. The project was dubbed "Project 23." It has been ongoing ever since and continues 361 days a year, with only July 4, Thanksgiving, Christmas, and New Year's Day off.
In 2013, as part of a homicide investigation, a Los Angeles Police Department diver actually descended below the surface of the La Brea Tar Pits pond. His purpose was to recover evidence believed to have been discarded there. Apparently, no one had ever done a dive in the pond before. Sergeant David Mascarenas of the LAPD Dive Team spend an hour diving down 17 feet deep in the pond. It was actually once an asphalt mining pit from the late 1800s that had filled with water and, as much of the area, seeping asphalt and methane gas from below ground. Mascarenas described bizarre underwater features such as pinnacle-like tar formations pushed up by methane gas. He had to move through the toxic water and sticky ooze with almost no visibility. He fought to keep his fingers from sticking together, arms from sticking to his suit, and flippers from sticking to the bottom. Upon coming out of the water and feeling light-headed, he had to receive medical attention for methane exposure. "I've been under moving ships, in underwater reservoir sheds ... you name it. This is by far the craziest thing I've ever done," he told the L.A. Times. Nevertheless, the LAPD apparently found the evidence that they were looking for. This wasn't the first time police searched the tar pits. In 1935, police dragged grappling hooks through the pits, searching for the body of missing 19-year-old Mary Alice Bernard. Shortly before going missing, the young woman told her mother that her body would be found "in the bottom of the tar pits." No body was found. Fortunately, the woman was found alive, four months later, as an amnesia patient at a Downtown Los Angeles hospital. In 1938, police again searched the tar pits, after finding a man's discarded clothing and suicide note nearby. As police and firefighters were engaged in searching the tar pits, the man showed up to explain that he had staged the suicide to escape from a girlfriend. He was arrested and, for the hoax, was sentenced to 30 days in jail.
Visit the La Brea Tar Pits & Museum
Experience the Tar Pits, La Brea Tar Pits & Museum
15 Things You Never Knew About the La Brea Tar Pits, by Lindsey Ferrier, Suburban Turmoil
10 Fascinating Facts About the La Brea Tar Pits, by Megan Gannon, Mental Floss
Also see: Prehistoric L.A. Turkey