Fossil

Sticking Around: The La Brea Tar Pits

The following article is from the book Uncle John’s Bathroom Reader Plunges into California.

(Image credit: Jerrye & Roy Klotz, MD)

How much do you know about the Angelenos of the Pleistocene? Yeah, us either. Read on.

FANCY TAR?

Hancock Park, an affluent area of Los Angeles, is well known for its celebrity sightings, million-dollar homes, and the famous Hollywood sign in the distance. But some of the neighborhood’s “residents” are even cooler. World-famous fossils—like the extinct dire wolf, saber-toothed tiger, and Columbia mammoth—are among the millions of specimens that have been excavated from the La Brea tar pits. Located on Wilshire Boulevard in the Miracle Mile, the tar pits contain one of the richest deposits of late Pleistocene era (the last ice age) fossils in North America. The fossils date from 10,000 to 40,000 years ago, and more than three million of them—including plants, mammals, birds, lizards, and insects—have been excavated since paleontologists first began digging there in the early 1900s.

The tar pits on display today were once excavation sites where workers dug for asphalt or scientists dug for fossils. Over the years, humans dug more than 100 pits throughout Hancock Park, but most of them have been refilled with dirt, debris, asphalt, and water. About 13 tar pits remain—the largest, called the Lake Pit, measures 28 square feet and is approximately 14 feet deep.

STICKY, GOOEY DEATH TRAPS

The La Brea tar pits formed thousands of years ago, when gas and oil beneath the ground came under pressure. The molten mixture pushed up through vents in the earth’s crust. Once it reached the surface, the oil pooled in natural depressions aboveground. The lighter part of the pooling oil evaporated—left behind was a heavy, sticky oil. Then rain and underground springs added water, forming ponds and lakes on top of the oil and creating what we now call the tar pits.

The water on the tar pits’ surface was especially attractive to thirsty animals, and during the warm spring and summer, the thick oil underneath was especially sticky. Animals that ventured into to the pits couldn’t escape. Often predators chased their prey into the pits and got stuck too. Paleontologists once found a large bison fossil surrounded by a pack of fossilized wolves. The dead animals eventually sank completely, and their bones and teeth turned brown from the oil. But otherwise, they were almost perfectly preserved for more than 30,000 years.

THOSE STRANGE CATTLE BONES

Hundreds of years ago, local Native Americans used the thick oil at the tar pits as waterproof caulking for their baskets and canoes. When the Spanish arrived in the 18th century, they used it to waterproof their houses. In 1828 the tar pits were part of a Mexican land grant called Rancho de la Brea (brea means “tar” in Spanish). When the United States took over California in 1848, the area was part of the deal, and ultimately, it came into the possession of lawyer and surveyor Henry Hancock…

Oldest microfossils suggest life thrived on Earth about 4 billion years ago

hematite
SIGNS OF LIFE In rocks left over from ancient hydrothermal vents, these microscopic tubes of hematite, an ore of iron, may be remnants of early microbes.

Tiny, iron-rich fossils exhumed from the depths of an ancient ocean could reveal the cradle of life.

These micrometer-scale structures are probably remnants of microorganisms that once lived amidst ancient hydrothermal vents, researchers suggest March 1 in Nature.

“In a nutshell, what we’ve found are the oldest microfossils on Earth,” says study coauthor Matthew Dodd, a biogeochemist at University College London. The rocks that hold the fossils came from Quebec and date to somewhere between 4.28 billion and 3.77 billion years old — when Earth was still a baby. The next oldest microfossils reported are just under 3.5 billion years old, though their validity has been debated (SN: 2/8/14, p.16).

If Dodd’s structures truly are remnants of microbes, “it’s fantastic. I love it,” says astrobiologist Martin Van Kranendonk of the University of New South Wales in Sydney. But he’s not convinced. In fact, he says, “there’s just not definitive proof that any of the textures or the minerals or features they have is unique of life.”

Claims of early life are frequently fraught with controversy. For one, says Dodd, “these are big claims — these are our origins.” And scientists studying early life typically don’t have a lot to work with. It’s not like they’re looking at dinosaur bones. In billions-of-years-old microbes, obvious cellular bits and other familiar flags of life have often been stripped away. And in Earth’s oldest rocks, extreme heat and pressure can cook and squash any remnants of life…

Just Who Inspired ‘She Sells Sea Shells’ Tongue Twister?

In the summer of 1844, King Frederick Augustus II of Saxony and his royal entourage were walking down Broad Street in the coastal town of Lyme Regis when they were drawn to the window of a cottage. Treasures lay on the other side of the glass: Coiled ammonite shells—long since turned to stone—were arranged in an appealing display, and in the center sat the petrified skull of a long-snouted sea reptile with pointed teeth and impossibly huge eyes.

A sign above the door read Anning’s Fossil Depot. The King and his party stepped inside.

There were Jurassic-era fossils throughout the small, unassuming shop, and yet, the single most fascinating thing in the store may well have been its proprietor, Mary Anning. She’d spent a lifetime simultaneously providing for her family and unlocking the secrets of Lyme Regis’s ancient past. Born into poverty in a society famed for its class consciousness, the 45-year-old businesswoman had defied the odds to become one of the world’s most important scientific figures.

Though Anning didn’t receive her due credit from the male naturalists who reaped the benefits of her labors, word of the fossil-hunter’s many achievements still managed to spread far and wide during her lifetime. So it was with complete honesty that this daughter of a poor carpenter casually told the King’s physician, “I am well known throughout the whole of Europe.” And years after her death, her legacy would live on in the English language’s most famous tongue twister: She sells seashells by the seashore.

The seashore where Anning’s shop was located was on the English Channel in southwestern England, in a town called Lyme Regis. With its towering cliffs and tannish-white beaches, Lyme Regis has long been a prime vacation destination. In the late 18th and early 19th centuries, affluent Britons made it their seasonal home away from home. Meanwhile, the poorer citizens who lived in Lyme Regis year-round struggled to make ends meet.

Many supplemented their income by cashing in on the area’s natural history. Around 200 million years ago, the Lyme Regis area lay at the bottom of a Jurassic sea. In Anning’s time—and today—fossilized remains of marine animals from this period can be found protruding from the cliffs and scattered along the beaches that surround the coastal town. Realizing that rich tourists would pay a pretty penny to take home one of these natural curiosities, fossil hunters started selling their finds throughout Lyme Regis.

One of them was Mary’s father, Richard Anning, a carpenter by trade. But even with two revenue streams, he struggled to provide for his family, and their life was marked by tragedy. Richard’s wife, Molly, gave birth to their first child, Mary, in 1794, and a son, Joseph, in 1796. Mary died when she was just 4 after her dress caught on fire; Molly was pregnant with her third child at the time, and when she gave birth six months later, on May 21, 1799, she named the newborn girl Mary. A year later, the second Mary almost died as well when she, her nurse, and two female companions were struck by lightning while walking on the beach. All three women died, but Mary survived.

Of the Annings’ 10 children, only Mary and Joseph reached adulthood. As they grew up, Richard taught them everything he knew about the fossil-collecting business, and he even made Mary a rock hammer so she could excavate small fossils for herself.

Fossil hunting was a perilous job, and over the years, the Annings had many close calls with rockslides and rapidly flooding shorelines. That’s how Richard himself died in 1810. Out on an excursion that winter, he lost his footing and fell off a cliff. Months later, injuries sustained from the accident—coupled with a serious case of tuberculosis—claimed his life. He was 44 years old.

Following his death, Molly took charge of the family fossil shop, which basically consisted of a display table that the Annings would set up in front of their modest cottage near the River Lym. Keeping this business afloat was an economic necessity for Molly and her children—Richard had saddled them with a large debt.

Nobu Tamura via Wikimedia Commons // CC BY-SA 3.0

The family struggled for a year until, in 1811, Joseph—who was working as a part-time upholsterer’s apprentice—discovered the 4-foot-long skull of an ancient marine reptile. Joseph and a hired team excavated the head, but Mary thought more bones might still be found. The following year, she returned to the site and proceeded to expose an entire spinal column, a set of ribs, and other bones.

Thrilled by her discovery, Mary recruited an excavation team of her own. As the creature’s remains were slowly removed from the rock, the group realized that they had a genuine sea monster on their hands: When it was reunited with its skull, the specimen measured an amazing 17 feet long.

The remains belonged to a dolphin-like animal that would later be called Ichthyosaurus, which means “fish-lizard.” Although the Annings did not discover the first known specimen of this genus (as some sources wrongly report), theirs was the most complete skeleton known at the time and therefore became the first to attract interest from Great Britain’s scientists. The fossil was sold to Henry Hoste Henley, the Lord of Colway Manor, for £23. That’s the equivalent of more than £1600 or $2000 in today’s money—enough to purchase six months of food for the Anning family.

The Annings’ ichthyosaur subsequently made its way to the British Museum, where, according to Hugh Torrens, a history of science professor at Keele University, “it aroused great interest as a denizen of the new world that the embryonic science of paleontology was beginning to reveal” [PDF]. When news of the sea dragon spread, the Annings—particularly Mary—became household names in Lyme Regis and beyond.

But fame has never guaranteed fortune. Even after the sale of Mary and Joseph’s ichthyosaur, the family remained in dire economic straits for nearly a decade. Thankfully, an 1820 charity auction thrown in their honor by the wealthy fossil-collector Thomas Birch helped give the Annings some much-needed financial stability.

In 1824, Mary Anning met Lady Harriet Silvester, a rich London widow who was blown away by the self-taught beachcomber’s paleontological expertise. “The extraordinary thing in this young woman,” Sylvester wrote in her diary, “is that she has made herself so thoroughly acquainted with the science that the moment she finds any bones…