Rancho La Brea – a time machine in asphalt

Ever since I was a kid, I have dreamed of travelling back in time — a couple of million years, to walk among prehistoric animals. While this may sound like every kid’s fantasy and evoke a picture of –yawn!– dinosaurs, I’m really not talking of that far back.

Time was when giant mammals walked the earth. We are not sure why they disappeared, or evolved into forms extant today. The George C Page Museum of Tar Pit Discoveries in Los Angeles, California helps us understand that there were some giant and unique mammals that lived in the Pleistocene (2,588,000 to 11,700 years ago). They were found preserved in sticky black oozing asphalt and excavations began in 1900. Although asphalt is not the same as tar, people have been calling this area the tar pits for a long time. Ergo, the name Rancho La Brea (brea is Spanish for tar) stuck.

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Is that Diego from Ice Age?

About a hundred thousand years ago, through fissures in the ground, asphalt seeped up and formed pools in some low-lying areas. Animals that died in or near these pools, or got trapped in these pools by accident and eventually died, were covered by sediments and asphalt over time. In the asphalt pits they were preserved almost wholly intact, without yielding to the usual process of decomposition that would have left few traces of their form and structure. As a result, we have today these fossilized remains of prehistoric mammals at Rancho La Brea. These remains were unearthed by human activity.

As I entered the grounds of the Museum, I immediately caught the smell of asphalt that is common when new roads are being laid. While I stood near one of the biggest pools of asphalt in the compound, I could see large bubbles escaping the surface of the sticky goo. This was trapped odourless methane, caused by a chemical reaction set off by bacteria in the asphalt.

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This is not a representation of a Columbian mammoth drowning. And that is not water!

I was amazed by the exhibits I saw inside the museum. I had only read or seen on TV about saber-tooth tigers and giant sloths. Now, I was actually seeing their fossils.

Harlan's Ground Soth
Harlan’s Ground Sloth

This sloth, based on its skeletal structure, could have been around three meters in length and weighed upward of a thousand kilos. A giant, by current sloth standards.

Smilodon - Maybe they came up with the name coz of the teeth showing grin
Smilodon – Maybe they came up with the name because it always looked like it was grinning due to the canines?

The Smilodon is one of the best known of the Saber-Toothed Cats or Saber-Tooth Tigers as they are popularly called today. Hollywood brought this feline to life in the Ice Age series. These animals were characterised by a powerful, heavy body and may not have been very good at pursuing prey at speeds. Like anybody else, I was and still am fascinated by the enormity of the canine teeth. At La Brea, they say that the cat might have been able to open its mouth to over 90 degrees and that it had large jaw muscles to enable this feat. However, I am not completely convinced. Another thing that makes me wonder is the impact the canines would have had to endure while the cat tackled large prey as has been inferred. A lot of questions and a lot of possible answers… anyway I’m no expert.

Large canines and the large angle of the jaws
Large canines and the large opening of the jaws

Two species of bison have been discovered at La Brea – the Long-horned Bison and the Ancient Bison. The Ancient Bison is, however, the more numerous species at La Brea comprising of over 300 unique individual fossils. These bison were larger than the American Bison extant today.

The Ancient Bison
The Ancient Bison

Then there were the Mastodons, prehistoric relatives of modern-day elephants. American Mastodons were smaller is size than Woolly Mammoths but resembled them in general structure.

Mastadon
Fossils of adult American Mastodon and calf

Next up was a mammoth of a fossil! Or, the fossil of a mammoth. Either way is correct. This fossil of the Columbian Mammoth – the picture below is just the size of the creature with its fossilized bones. Imagine the size of the actual animal taking into account muscle tissue, hide and hair! The tusks are spectacular. The remains of over 35 individuals have been excavated from Rancho La Brea, most of them from a single excavation pit.

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Columbian Mammoth

Next up was the fossil of a feline that would give the Saber Tooth a run for its money – the Naegele’s Giant Jaguar. Although named  a Jaguar, this animal is supposed to have been more closely related to the now extinct Cave Lion of Europe and Asia. The Giant Jaguar is also known as the American Lion. The remains of over 80 individuals have been excavated from Rancho La Brea.

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Naegele’s Giant Jaguar or American Lion

The only extinct member of the dog family (Canidae) found at Rancho La Brea is the the Dire Wolf. I had heard this name in the fantasy drama television series, The Game of Thrones. At that time I did not know that the dire wolf was in fact an animal that actually existed previously. The representation of the dire wolf in the series was almost accurate, I must say. The dire wolf was similar in size as the existing gray wolf but more heavily built.

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Dire Wolf

The interesting thing about the dire wolf fossils at Rancho La Brea is the sheer number – more than 200,000 specimens have been excavated!

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Display of a large number of dire wolf skulls at the Page Museum

In addition to the Western Camel and the Large-headed Llama, which were not very common (numbering around 36 and 7 specimens), the pits also had the fossils of the Short-faced Bear (30 specimens). The Short-faced Bear was the largest predator of the late Pleistocene era in North America, estimated to have weighed around 680 to 800 kilos and standing around 1.5 meters at the shoulder!

The tar pits were not just home to mammal fossils. There were also fossils of birds that were trapped in the asphalt. Some of these were giants too, like the Merriam’s Giant Condor.

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Merriam’s giant condor

There was a section in the museum that showcased the interior work area where scientists and volunteers cleaned and documented fossils excavated from the pits outside. Here visitors could watch the work in progress.

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In the background – the room where the work-in-progress can be observed

As it was nearing closing hours at the museum, I rushed to one of the excavation sites, Pit 91, to take a look. Unfortunately, I do not have a photograph of the pit. However, I can share this photograph of an infographic showing the number of fossils that have been excavated from the pit all the way from 1915 till date. Look at the numbers – 73 Saber-tooths and 56 Dire wolfs from just one pit!

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Count of the mammals that were excavated from pit 91

The snapshot below gives you an idea of what the tar pits actually are. The extreme left section shows Rancho La Brea in 1914 when the place was pretty much full of oil derricks that were pumping oil from natural underground reservoirs that supply asphalt to the tar pits.

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Did you know?

The last thing that many a Pleistocene mammal would have seen might have been a pair of sabers closing in on it. Makes me think twice about that wish of going back in time!

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Imagine if these canines were the last things you saw!

This painting from the Jesse Earl Hyde Collection (courtesy of Wikimedia Commons) offers an artist’s imagination of life as it existed in the tar pit

Rancho la Brea Tar Pool. Restoration by Charles. R. Knight/Wikimedia Commons

Rancho la Brea Tar Pool. Restoration by Charles. R. Knight for Amer. Mus. (N.Y.) mural decorations 9′ by 12′ in hall of the Age of Man. One sloth (Mylodon, now Paramylodon) trapped, two guarding against Sabre Tooth (Smilodon). Condors (unidentified further, likely Teratornis) waiting on McNabb’s cypress. In the rear of pool which has yielded much elephant (Columbian mammoth) material. San Gabriel range with Mt. Lowe center and Mt. Wilson at right of erect sloth. Old Baldy at right. Credit: Charles R. Knight/The Jesse Earl Hyde Collection, Case Western Reserve University (CWRU) Department of Geological Sciences/Wikimedia Commons

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