Existed 50,000 years ago - the last of the Ice Ages.
Over 42 species of Columbian mammoths, mastodons, giant sloths, saber-toothed cats, long-horn bison, camels, dire wolves, horses, and rodents.
Fossils found in the mud of an ancient ephemeral stream.
Discovered by high school students in the 1960s.
A significant fossil site known as the Costeau Pit includes several thousand fossil cranial and skeletal elements of terrestrial "Ice Age " animals. This site is located and preserved "in situ" beneath Costeau Park at the comer of Alicia Parkway and Costeau Street. Costeau Pit was situated in an old stream channel in which water flowed throughout the year. Today the channel is filled and covered over by Alicia Parkway.
The 1st bones were discovered in 1965 by 2 high school students from La Mirada. The bones were identified as those from a Columbian Mammoth, an ancient elephant. A site study was then conducted under the direction of the Los Angeles County Museum of Natural History. The fossils recovered include remains of:
Giant ground sloths
Extinct horses and camels
The fossil bones are older than 40,000 years and are older than those recovered at the La Brea Tar Pit. Most of the bones and teeth at the pit showed some wear from the stream water. Very few jointed bones were found suggesting that the fossils were carried downstream before being deposited at Costeau Pit.
The largest plant eater found at the Costeau site was the Columbian Mammoth. These mammoths grew as tall as 10 feet at the shoulder and had long ivory tusks up to 15 feet long.
The Ice Age bison found at the site were larger than the bison we know of today. Although they looked the same, they grew as large as 7 feet tall. Two species of bison were found at the pit, the larger, Long Horned Bison and the Antique Bison. More fossil remains of the Long Horned Bison (5 total) were found at the Costeau Pit than have ever been discovered in any other single place in the world. Both types of bison originally migrated from Asia and became extinct around 70,000 years ago.
Extinct Animal Fossils
The horse fossils collected included a complete skull and over 400 teeth. More horse remains were found than any other large animal. Other fossils found from now extinct animals included the giant ground sloth, camel, and dire wolf. The camel remains at Costeau were similar to the modern dromedary camel, however, the Costeau camel was quite large, around 7 feet tall at the back. Dire wolves from the Ice Age have been found over much of the United States, in Mexico, and all over California.
Today, the fossil remains from Costeau Pit are curated at the Los Angeles County Museum of Natural History and have been placed on display by the City at the Laguna Hills Community Center.
Costeau Pit Sign
"This prehistoric giant ground sloth represents the Ice Age animals that flourished here 40,000 years ago. In 1965, sloth bones and teeth were recovered from this site with the fossils of bison, horses, camels, mammoths, dire wolves and saber-tooth cats. These animals lived by a perennial stream, now Alicia Parkway, in grasslands similar to African savannas. Costeau Park was established to preserve the thousands of fossils that remain buried beneath the surface."
Historical Monument: Dedicated July 3, 1999.
Costeau Park is located on Costeau Street off of Alicia Parkway.