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La Brea 4ºA

La Brea Tar Pits, in Los Angeles, California, is a very popular Paleontological Site in the United States. It consists in group of asphalt lakes, where different type of organisms - from unicellular to huge mammals - have being getting trapped during the last 35,000 years.


It is so famous, that it appears in thousands of movies and TV series.



William, our language assistant from the US, gave us a short speech about this place. These are some of the interesting things we asked him and learned about La Brea.

Why are the fossilized remains of so many plants and animals able to be found in the "La Brea" Tar Pits?

Asphalt is good preserving plants and animals. And it is also very sticky. Animals and plants surrounding the pits have a lot of chances of getting trapped and preserved for thousands of years in each pool.

In the case of animals, vegetarian animals occasionally got trapped. Predators tried to capture them, and got trapped too.



How did the "La Brea" Tar Pits form? How long did they take to form?

La Brea Tar Pits began to form just 40000 years ago, towards the end of the Pleistocene Epoch. Crude oil from older previous Epochs seeped out to the surface and started creating these asphalt pools.

Why is "La Brea" such an important place to study the flora and fauna of the Last Ice Age?

Scientists have found in "La Brea" remains of 53 different species of mammals and 135 species of birds; 660 species of plants, insects and mollusks. All individuals have 40000 to 8000 years old.

Each pool has fossils, bones and traces of the animals and plants that lived close to the pools. For this reason, scientists know what ecosystems and landscape looked like in that period and in that place.

For example: some fossils of an ancient elephant were found together with the fossil of a Smilodon californicus (a saber-toothed tiger) and evidences of plants and insects from savannas.

Why large animals that appear in "La Brea" became extinct?

Climate change and weather changes resulted in a drastic shift in the types of plants that grew in "La Brea". The change of plant life had an impact on the herbivores food supply, which had a direct effect on the carnivorous that preyed on them. "La Brea" ecosystems became dryer, and big animals, especially predators, disappeared.

Some theories point that first humans could have also caused changes in the ecosystems that helped the extinction of large animals.

What kind of large animal species are found in "La Brea" as fossils that no longer exis?

There are no alife Mammoths, Mastodons, ancient bisons, Dire wolves, short-faced bear or saber-toothed cats anywhere any longer. There are no tapirs, bobcats, panthers, peccary and llamas living in "La Brea" any longer.  

Why has "La Brea" a Spanish name?

"La Brea" tar pits were discovered by the white men in 1769, the Portola expedition passed through what is now known as Hancock Park. Gasper de Portolá y Rovira was a soldier, governor of Baja and Alta California, explorer and founder of San Diego and Monterey. He served in the Spanish army, and in the Italian and Portuguese army. He died in Spain in 1784. 

To know more about this topic, visit www.tarpits.org


Tar: alquitrán. "Tar pits" se traduciría como pozas de alquitrán, aunque desde el punto de vista geológico se trata de "pozas de asfalto".

Seep out: filtrarse

Saber toothed: "dientes de sable"

Landscape: paisaje

Thanks to: Will, for his presentation. María José, for correcting our English.

Done by: 4ºESO Science students (Alba, Artur, Hannae, Tatiana, Víctor #1, Víctor #2).

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