It is mid-November, and beads of sweat form on my forehead. Coalescence is inevitable. And it happens quickly; small beads merged into one humongous droplet, and it begins to meander its way down my nose, and there it dangles, stubbornly defying gravity.
I am in Los Angeles, walking back in time. Although it is taking me a while to get there. Time travel isn’t quick. I walk out of my motel onto Crenshaw Boulevard, and start walking. On my map, the distance from motel to end point looks pretty short. It turns out I have chosen to walk along the longest road ever built by humans. The air is hot and dry. I feel the warm wind from the heat of the cars drafts against me as they drive past. The sidewalks are practically empty. No one, it appears, walks in Los Angeles.
An hour and fifteen minutes later, I am at the actual end of Crenshaw Boulevard (a street name that will stay with me always). I reach Wilshire Boulevard, one of the main arteries running east west across the city. Here, there is a different feel altogether. Where Crenshaw was lined with motels, fast food restaurants, and small, one story houses, Wilshire has large two story houses fronted by lawns and large drives, and there are tall, glass office buildings home to international businesses. My legs aching, I carry on. I am nearly there. Witshire has more people on the pavements. I pass smartly dressed business men and women darting in and out of doors on their mobiles. Women in Yoga pants appear to effortlessly float past, while the hipster beard makes an appearance more than once. I feel a little out of place, with my dusty, tired sandals, my chequered shirt clinging to my back, and myself looking a little like I have walked across a desert. But I am close. I am not here for the yoga pants. Or the hipster beards. I am here for the sabretooth cats. And the giant sloths.
On Witshire Boulevard, you can take a few paces away from the tall white, shiny, clean buildings, and step back in time. Here, in the middle of the 21st century hustle and bustle, you enter a different era: a time when giant American mastodons stomped. You have reached Rancho La Brea.
The Tar Pits at La Brea are world famous. Hundreds of thousands of fossils of Late Pleistocene animals and plants have been recovered at this one site. Animals and plants have become trapped in thick, sticky tar pits, and perished, showing us what life was like from around 50,000 years ago to just a few hundred years ago. What makes this site unique is the vast number of carnivores found here: around 70% of the fossil animals are carnivores. (Simply, an herbivore ended up trapped in the sticky tar, and was feasted upon by carnivores, which then themselves ended up getting stuck too.) It is the large carnivores that have captured the imagination of the media, like the enormous sabretooth cat Smilodon fatalis: which is in fact the state fossil for California. I have come here to find out more.
I meet with the Collections Manager at La Brea Tar Pits and Museum, Aisling Farrell. Her naturally warm welcoming smile and soft Irish accent immediately calms me, and removes any worries I had about being a tiny bit late. She laughs as I explain I walked here: “No one walks in LA!” she exclaims. I guess it is true then.
We walk outside of the George C. Page Museum, towards a fenced off area. Here there are life-sized models of mammoths and an American mastodon dramatically posed as if they were alive 20,000 years ago. I comment on the wonderfully elaborate models. Aisling looks at me, and smiles. “This is an old mine that has filled up with ground water,” she says turning back to look at the mammoth family. “The water table here is really high, so when it rains, this old mine traps a lot of water. It is nice, but it doesn’t show how the animals really got stuck in the tar.” I was about to probe a little more, when an enormous bubble of methane gas loudly came to the surface, and we spoke about the old mines.
Asphalt has been mined at Rancho La Brea for centuries. Although the site was privately owned in the mid-1800s, locals were allowed to mine asphalt for their own personal use (fuel, buildings, and roads). Bones were noted in the deposits, but they were thought to belong to domesticated animals, and it wasn’t until 1875 that the bones were recognised as fossils. The surveyor, developer, and highly respected citizen, Major Henry Hancock, acquired the land and began commercially mining the asphalt. Palaeontologist, William Denton, from Massachusetts, soon after visited the site and noticed sabretooth cat fossils, along with fossil deer and horse. Even so, it wasn’t until in early 1900 that palaeontologists seriously began studying the bones here.
Today, well over 3.5 million fossils have been recovered from the site. And over 600 species have been identified. This is an incredibly rich site.
With the sun beating down overhead, we walk across the grass. Aisling wants to show me something. We pass a few more small fenced off areas. “There are some spots here where the tar still reaches the surface,” she says, noticing my inquisitive look. “Even today small birds and animals do get stuck here.”
The grass is a vibrant green. A school group is being led by one of the several tour guides at La Brea. A young family is enjoying a picnic. The park is free for anyone to come and enjoy. “The land was left to the city by the Hancock family,” Aisling says as we make our way past a dog walker, with four dogs. “They owned a lot of land in LA. Unusually, they were also very interested in the fossils found here. They could have sold the land, but instead, left it to the people of Los Angeles to preserve the fossil site.”
We come to a small wooden building. Inside is a large window, overlooking a pile of dirt. Looking closer, it isn’t dirt, it is dried tar. And there are bones in it! Aisling is holding a bunch of keys as she spots the excitement on my face at seeing the bones exposed for the first time in millennia. She unlocks a door to the side, and we step through. We are leaning over the pit, on the other side of the glass. A curious father and daughter watches us from inside the wooden building. This is Pit 91, she explains. Fossils are being carefully excavated by staff and volunteers, and visitors to the park can watch them in action. The main deposit is not huge, just about three meters by two meters in the centre. The bones, darkened by the asphalt are easy to spot.
The commitment to the Page Museum to show the public the work that goes on here is inspirational. Large panels are scattered across the park, clearly and visually letting the visitors learn about the heritage of the site and the creatures that were once home here. In this park visitors are able to watch real palaeontologists excavate bones of extinct animals in front of them. I wondered how many children (and parents) watch these excavations and want to change their path to become a scientist.
Every single individual bone is carefully excavated and recorded. Today the information with each individual specimen is much more detailed than it was 100 years ago. Even the sediment is sampled for microfossils and some is sent off for pollen analysis providing more information about the climate and a detailed picture of the surrounding flora. Pit 91 has actually added over 320 new species to the fauna and flora of Rancho La Brea, including spiders, fish, amphibians, and insects. With new fossils being excavated daily, and the uncountable microfossils, a number of ‘three and a half million specimens’ at the museum is a very conservative estimate.
We talk about museum work, numbering, and the databasing, as Aisling leads us to one of the store rooms. Drawers upon drawers fill racks running the length of the store room. The sense of awe silences you as you walk in. Here, are thousands upon thousands of animals that lived not very long ago. You know you have stepped back in time. Passionately, Aisling talks about the animals that once lived here, while opening drawers: dire wolves, sabretooth cats, horses, camels, and more. So many creatures once walked on this very spot.
The skeletons on display in the museum are not from individuals, but composites: elements taken from several individuals and put together. I ask why it is not easy to find individuals in the excavations. “The general view of animals getting stuck and sinking into the tar is wrong,” she says. “An entire animal is rarely preserved. Think of it like fly paper. When a fly gets stuck on fly paper, the feet sink into the viscous stickiness. This is like how it was for the animals: the feet would get stuck. The body above the tar could have been eaten by predators, or even moved by the water, or weathered away. Anything below would be preserved. We rarely find full skeletons, perhaps because only a fraction of the animal got buried.”
I had always assumed the tar pits were a little like quick sand. Apparently this is a common misunderstanding. And it is why Aisling is not too fond of the flooded mine we saw earlier with the mammoth family. Fly paper. Not quicksand. The sticky tar seeps up from folded rocks deep below the surface. Some animals get trapped, and then sediment or water covers the tar. More tar seeps up, more animals get trapped, and more sediment covers it. It is often not as simple as that: sometimes the water can mix up bones and sediment.
The list of animals recovered from the site is spectacular. Along with reptiles, insects, fish and amphibians, are some glorious Late Pleistocene North American beasts: dire wolves, mastodons, mammoths, ground sloths, horses, camels, bison, monster birds, short faced bears, American lions, and sabretooth cats (in fact two species of sabretooth cat: Smilodon fatalis and Homotherium serum). Aisling watches me as my eyes widen, and my voice goes slightly high pitched in the excitement of slowly pulling open each drawer. “Although there are lots of species, there is a bias with the fossils.” Carefully placing back a Smilodon fossil, I listen as she explains. It is also extremely likely that there will be gaps in time. “The tar is less sticky in cold weather. We see it here in winter.” Aisling never looses the passion in her voice, even as she talks about animals that are not here. The fossil deposits do not represent one continuous time period. There will be gaps. The gaps may be a couple of decades, or a couple of centuries long.
The biggest project Aisling and her colleagues are working on at the minute, is to produce a detailed time line of the site. They want to use the large fossils along with the microfossils to discover how the environment has changed over this time, and how species responded to these changes.
It is an enormous project. Aisling, like her colleagues I met on my visit, know how big this is. They also know how important it is. If a detailed record going back 45,000 years can be created, it will show how animals and plants have adapted to environmental changes. And this can be used to see how animals and plants may respond to the dramatic climate changes happening now.
In the middle of Los Angeles is a world far away from the one we live in today. One without mobiles, or tablets. A world where the worries of modern life do not exist. A world where enormous lions stalked, and monster birds glided ahead. This was a world not that long ago. The fossils recovered from Rancho La Brea show us what an incredible landscape LA once was. What is truly magnificent is how visitors can see the work the staff and volunteers do to excavate, preserve and research the specimens. Today, over a hundred years after the first fossils were written about, Aisling and colleagues are still discovering new fact about the past, and using them to help protect our future.
Written by Jan Freedman (@JanFreedman)
An enormous thank you to Aisling Farrell, for sharing her endless enthusiasm and knowledge about the collections. Please do follow Aisling on Twitter (@AislingLaBrea)
My visit was made possible due to funding through the Jonathan Ruffer Curatorial Grants, overseen by the Arts Council (UK).
Campbell, K. E. & Tonni, E. P, (1983), ‘Size and locomotion in teratorns’, Auk. 100(2).pp.390-403. [Full article]
Feranec, R. S. (2004), ‘Isotopic evidence of saber-tooth development, growth rate, and diet from the adult canine of Smilodon fatalis from Rancho La Brea’, Palaeogeography, Palaeoclimatology, Palaeoecology, 206 (3-4), 303-10. [Full article]
Figueirido, B., J. A. Perez-Claros, V. Torregrosa, A. Martin-Serra, and P. Palmqvist. “Demythologizing Arctodus Simus, the ‘Short-Faced’ Long-Legged and Predaceous Bear That Never Was.” Journal of Vertebrate Paleontology 30, no. 1 (2010): 262-75.[Full Text]
Heintzman, P. D., G. D. Zazula, J. A. Cahill, A. V. Reyes, R. D. E. MacPhee, and B. Shapiro. “Genomic Data from Extinct North American Camelops Reveise Camel Evolutionary History.” Molecular Biology and Evolution in press (June 2 2015).[Abstract]
Howard, H, (1947), ‘A preliminary survey of trends in avian evolution from Pleistocene to recent time’, Condor. 49(1). pp.10-13. [Full article]
Martin, P. S. (2007), Twilight of the Mammoths. University of California Press. [Book]
Martin, L. D., and B. M. Gilbert. “An American Lion, Panthera Atrox, from Natural Trap Cave, North Central Wyoming.” Contribs. to Geology, Univ. Wyoming 16, no. 2 (1978): 95-101.[Abstract]
McMenamin, M.A.S.; et al. (1982). “Amino acid geochemistry of fossil bones from the Rancho La Brea Asphalt Deposit, California”. Quaternary Research. 18 (2): 174–83. [Abstract only]
Merriam, J. C., and C. Stock. The Felidae of Rancho La Brea. Carnegie Institute of Washington Publications, 1932.[Book]
Miller, L. H, (1909), ‘Teratornis, a new avian genus from Rancho La Brea’, University of California Publications, Bulletin of the Department of Geology. 5. pp.305-317.
Stock, C., 1930. ‘Rancho La Brea. A record of Pleistocene life in California,’ Science Series. No 37. Natural History Museum of Los Angeles.
Tejada-Flores, A. E. and Shaw, C. A. (1984), ‘Tooth replacement and skull growth in Smilodon from Rancho la Brea’, Journal of Vertebrate Paleontology, 4 (1), 114-21. [Abstract only]
van Valkenburgh, B. and Hertel, F. (1993), ‘Tough Times at La Brea: Tooth Breakage in Large Carnivores of the Late Pleistocene’, Science, 261, 456-59. [Full article]