Since they were discovered 200 years ago, the plesiosaurs have posed a riddle. Long, brawny, toothy, their skeletal architecture was unsuited to laying eggs and sitting on a nest — and yet, there was no evidence that these reptiles gave birth to live young.

Until now.

In the journal Science tomorrow, a pair of paleontologists will describe a stunning fossil that shows a maturing plesiosaur inside its mother’s abdomen.

The fossil, dating to 78 million years ago, had lain in a museum basement for many years, says first author F. Robin O’Keefe, professor of biological science at Marshall University in Huntington, West Virginia. “Finding a pregnant animal fossil is always really rare, for any group of aquatic reptiles, and finding an undisturbed specimen is very unusual.”

O’Keefe collaborated with Luis Chiappe, director of the Dinosaur Institute at the Natural History Museum of Los Angeles, in studying the fossil, which is part of a new dinosaur-era exhibit at the museum.

Common, but curious

The plesiosaurs were monsters of the deep, says O’Keefe, having lived from roughly 200 million years ago until they went extinct along with the dinosaurs 65 million years ago. “These were apex predators, killer-whale size, and there is a very long, diverse fossil record.”

The specimen in question was complete, except for the head and some neck vertebrae, and was about 4.65 meters long.

Although the fetus was no midget – at 1.5 meters long — it was not ready to be born, O’Keefe says. “It’s really a guesstimate, but we think it is maybe two-thirds developed, definitely not ready for prime time. We have a bit of the back of its skull, and it’s poorly ossified [hardened]. If it was born like that, it would be like having your head made of Play Doh. It had no teeth, tiny flippers, and could not move around.”

The Cretaceous ocean, with its range of giant predators, was “not a place to be that helpless.”

Pride of the plains?

The pregnant plesiosaur was excavated in 1987 by Kansas landowner Charles Bonner. “He knew at the time that this was something interesting, but when it comes out of the ground, it’s inside a plaster jacket,” O’Keefe says. Removing a 15-foot specimen embedded in rock “is a time-intensive and expensive operation.”

But when the natural history museum decided to mount a new paleontology exhibit, the plesiosaur seemed a logical display, and director Luis Chiappe contacted O’Keefe. “He knew it was something interesting, thought it’s maybe a baby,” says O’Keefe. “Would I be interested in working on the specimen?”

A question answers itself

Would any paleontologist not be? And so O’Keefe found himself handling ancient evidence of reptilian motherhood. “My first thought was not some great scientific thought: ‘It’s really cool, you don’t often see fossils that neat.’”

When the rocks spoke, they revealed that this well-known reptile was, finally, in a maternal mood. “So here we have a pregnant plesiosaur, after 200 years of mystery, we have the smoking gun, we now know they gave live birth.”

To prove that, however, the scientists had to discount alternative explanations for finding an embryo inside an adult of the same species:

Does momma care?

We tend to think of reptiles as egg layers, but various flavors of birthing live young have evolved at least 80 times among marine reptiles. “The mother could retain the egg and have it develop inside her, or it could go all the way to a full-blown mammalian pattern, using a placenta to connect to the uterine wall,” O’Keefe says. “Given how big this fetus was, there probably had to be some pretty significant communication between mother and young.”

Paleontology shows structure, not behavior. O’Keefe says the new find suggests that mother plesiosaurs probably cared for their young, a rarity among modern reptiles. If one offspring “has absorbed all your reproductive energy, it makes a lot of sense to take care of it,” he points out.
In raising this possibility, he says, “We climbed out as far out on a limb as we thought we could get.”

And although there is no suggestion that the plesiosaurs nursed their young, live birth would distinguish them from many reptilian relatives and move them closer to modern, maternal marine mammals like whales and dolphins.

– David J. Tenenbaum

We approach the Cave of the Mounds, a landmark (so to speak) in Southwest Wisconsin, along a walkway painted with fossils and markings that start at the Ordovician era (450 million years ago), when the limestone beneath our feet was deposited as a rain of sea shells on an ocean floor. Finally, at the cave’s entry, the asphalt calendar enters the last million years, when the cave started to be excavated by flows of acidic water.

The geological markings under our feet are one indication that the cave-men and -women who operate this site are intent on linking past and present, above- and below-ground.

Cave of the Mounds was discovered in 1939 by workers blasting in a limestone quarry on one of the highest spots in southern Wisconsin. Today, it is a tourist destination with a message — a cool, underground mecca, strategically illuminated, where tour guides leave the nettlesome lectures above ground, and offer easy-to-digest science along the cave’s alleyways.

The above ground section of the site features resurrected prairies and oak savannas, but the main attraction is the stalactites hanging over stalagmites, flowstone, the fossils embedded in ancient limestone, and the rare opportunity to see geology at work as you observe the earth from the inside out.

Aftermath of a flood unparalleled

What caused the huge erosion features, ancient shorelines, and scoured potholes in the “channeled scablands” in Eastern Washington state? In 1923, J. Harlen Bretz coined that ominous moniker and proposed that the features had been created by a gigantic flood.

During this time, geology was ruled by a “uniformitarianism” dogma, which highlighted gradual processes like deposition and erosion, and discounted the power of sudden events like floods (and perhaps even earthquakes, tsunamis and volcanoes).

Skeptics demanded to know the source of all that water in an arid region, and Bretz had a reputation as a kook. Then, geologists gradually realized that the ice-age flood had originated to the east, in glacial Lake Missoula, which had been plugged by the lobe of a glacier emanating from Canada.

In the 1950s, the idea that this huge lake had eaten through an ice dam and then coursed downstream with phenomenal power started gaining acceptance, and in 1979, Bretz, age 96, received the highest award from Geological Society of American for solving this great Earth riddle. Today, scientists believe the floods may have recurred every few years or decades as the ice age was waning, around 14,000 years ago.

The evidence for the floods comes in all sizes. Alternating stacks of coarse gravel and fine sand show gravel left by flood currents under sand left by slower water when the floods receded. A dry river bed called the Grand Coulee, in Eastern Washington, was gouged by the astonishing flow of uncorked glacial melt water. The periodic cascades that shaped Dry Falls, now in Sun Lakes State Park are considered the largest known waterfalls in Earth’s history.

The unbearable whiteness of being

The world’s largest field of gypsum dunes, at White Sands National Monument in south-central New Mexico, could arouse anybody’s inner drywaller, as gypsum is the mineral basis for both drywall and plaster. But here, where 275 square miles of gypsum dunes have built a hot, severe and scorchingly beautiful landscape, there’s not a sheet of drywall in sight.

Set aside as a national monument by President Herbert Hoover in 1933, the dunes trace their origin to vast deposits of hydrated calcium sulfate — gypsum — that were laid down on an ancient lake a quarter-billion years ago. After a geological uplift, they were exposed roughly 10 million years ago, and eventually moved to the present site in a geologic eye-blink — the last 7,000 years.

Mammoth tracks have been seen in the dunes, but they could get buried with time: Some dunes are moving 30 feet a year, as the wind piles them up on the windward side and gravity avalanches them down the lee.

The gypsum dunes are said to be the largest in the world, but what’s most amazing is not the geology, but the evolutionary adaptations life has used to survive these harsh conditions. At least seven species of animals, including three lizards, that are closely related to darker varieties living in the surrounding desert have turned white for camouflage in this bleached world. (The drywalling lizard or the plastering mouse must be here somewhere!)

Visiting the Sands? Ponder a trip to Trinity, the site of the first test of the atomic bomb.

Science museums: Try the trifecta!

The Windy City boasts not just one, but three cool science destinations, all next door to each other on the Museum Campus along the shore of Lake Michigan.

To explore some of the world’s biological and cultural wonders, spend the day at the Field Museum of Natural History, a collision of anthropology, botany, geology, paleontology and zoology. The permanent exhibits include the DNA Discovery Center, a journey through four billion years of earthly life, and Sue, the largest (and most expensive?) complete skeleton of the ferocious T. rex. Among the temporary exhibits was a recent one on the horse and its deep relationship with humans (an exhibit that particularly excited one horse-crazy Why Filer).

If your palate is whetted for a wetter world, walk to the Shedd Aquarium to explore underwater life from the Amazon, the Caribbean and both poles. Green sea turtles, beluga whales, moray eels, piranhas and penguins will be among your hosts.

If otherworldly science is more your thing, visit the Adler Planetarium. Chat about the stars with real space scientists at their Space Visualization Laboratory, or just sit back and watch the star show. Adler’s centerpiece is the Doane Observatory, the largest publicly accessible telescope in the Chicago vicinity. While you can only peer through the lens after dark, this could make for a great conclusion to your trip.

Discover a life aquatic

An Australian freshwater crocodile grows in Baltimore. Seriously. The National Aquarium Baltimore boasts more than 660 species of fish, birds, amphibians, reptiles and mammals, totaling around 16,500 marine creatures.

In addition to its rich marine menagerie, the aquarium has a collection of special exhibits and interactive oceanic enjoyment. See the world through a dolphin’s eyes at Our Ocean Planet, a show that teaches visitors about dolphins and the connections between people and their seafaring friends. Or soak in ocean sensations with a movie at the 4-D Immersion Theater, where you can experience sea life in multiple dimensions, including the smell and feel of (simulated) mist and wind. Or take an expert-led tour, including behind-the-scenes peek of the sharks’ quarters.

The aquarium is also a center for conservation. For example, its Marine Animal Rescue Program tracks the progress of rescued animals after release. Other conservation projects include restoring wetlands and investigating the impacts of mercury on the marine food chain. After all, protecting the life that sustains the ocean ecosystem benefits everyone—not just aquarium visitors.

An excursion exotic to Melville

What’s more breathtaking than seeing the world’s largest animals in the wild? Whale watching puts you up close and personal with these magnificent marine mammals. Since the 1950s, in a 180° turnaround from Herman Melville’s day, people have been flocking by the boatloads to glimpse whales doing what they do rather than to kill them.

Both the U.S. east and west coasts have whales to watch, though you must catch them in the right season during their migration. There’s no guarantee, but on the western seaboard, you could spot orcas and gray whales. The east is home to the right, fin and sei whales. Humpbacks, minkes, and blue whales troll both coastlines.

Several cetaceans (a scientific category including whales, dolphins and porpoises) are endangered, including the North Atlantic right, blue, fin, sei and gray whales. In any case, marine mammals are heavily protected by law, so whale watching should be done with professionals who obey the rules.

Celebrating, protecting southern nature

With more than 500 full-time employees and an annual budget exceeding $30-million, Audubon Nature Institute sounds more like a business than a private, non-profit organization dedicated to explaining and preserving the wonders of nature with a Cajun flavor. The group operates a zoo, aquarium and assorted parks in and around New Orleans. The Aquarium of the Americas focuses on the Caribbean, Amazon, Gulf of Mexico (complete with oil-drilling replica) and Mississippi River.

A primate exhibit in the Audubon Zoo shows dozens of our opposable-thumbed relatives. Its 360 species of animals include a jaguar shown in a replica Amazon jungle. The “Embraceable Zoo” is devoted to full-contact animal admiration, and you can also eyeball, if not pet, a prickly Indian crested porcupine. Audubon maintains two locations that focus on captive breeding and survival of endangered species; these are closed to the public, but we expect to see you at the new insectarium, located in the old Federal customs house, for the beetle races on Sept. 3.

North Carolina: decapitation capitol

Every summer, vacationers flock to North Carolina’s coast for a beach getaway. But beach vacations would have been a hard sell early in the 18th century, as the coast was the stomping grounds of the South’s most feared pirate, Edward Teach, otherwise known as Blackbeard.

Nowadays, the area is proud of its sordid past, attracting pirate-curious tourists and archaeologists alike. In 1996, Blackbeard’s biggest and final ship, Queen Anne’s Revenge, was found off the coast of Beaufort, where it had been hiding for more than 270 years. While the dives did not uncover much treasure, archaeologists estimate the wreckage holds up to 750,000 artifacts, some of which are displayed at Beaufort’s North Carolina Maritime Museum.

Blackbeard is a primary local industry. Ocracoke Island, a favored Blackbeard anchorage, was where he met his fate at the hands of what he mocked as a rabble of “cowardly puppies.” Bath has the legendary ball of light, presumed to be Blackbeard’s ghostly severed head.

So why watch Johnny Depp impersonate a pirate at the multiplex when you can check out the history of this famous scoundrel? Like we said, this old, dead, head-free pirate is a godsend for small business…

Tar is my name. Fossils are my fame

If you’re stuck for a scientific sojourn in Southern California, head for the pits. Since long before there was a Los Angeles, the La Brea Tar Pits have been an oozing, 3-D flypaper for animals, now with that all-too-trendy urban accent. Asphalt, we learn, is not just good for roads, but also for trapping live animals and preserving their fossils. Since their first description in a scientific publication in 1875, the pits have produced prodigious prizes for paleontology. The onsite Page Museum houses more than 650 species of plants and animals, all removed from the black goo, and dating back 11,000 to 50,000 years.

The tar pits were a graveyard for thousands of carnivores, including the dire wolf, coyote and saber-toothed cat, and a smaller number of herbivores, including mammoth and bison. In an effort to transcend the “heroic” era of paleontology and flesh out (if we can put it that way) a comprehensive picture of life in the era of ice, researchers have recently shifted their focus to fossils of plants and smaller animals, including millipedes, 31 species of mollusks, and 25 species of beetles.

Listen hard: Hear the galaxies?

Love big? Dig distant, mysterious and unfathomably old? At the Very Large Array, in western New Mexico, you can gawk at 27 giant antennas used by astronomers to “listen” to radio signals from the universe. When you’re done rubber-necking the hardware, check out exhibits at the visitor center.

Then climb an observation tower to get another view of the world’s premier radio telescope zoo. Notice how every single antenna has silently and inexorably changed its orientation, and is now pointing to another invisible spot in the heavens? You are looking at visual proof of our planet’s normally insensible rotation.

It takes a lot of work, and some hefty equipment, to pry loose the secrets of the universe, and here, the scale of the operation is written across the desert. Since 1980, the VLA has, alone or in tandem with other telescopes, been collecting the astrophysical evidence for the formation and destruction of stars and galaxies. The new “enhanced VLA” can “hear” three times as many radio bandwidths as the VLA and is 10 times more sensitive. How sensitive is that? They say it could hear a cellphone calling from Jupiter…

Go under cover in the capital city

Explore life under cover (and the technology that allows a spy to hide in plain sight) at the International Spy Museum, the only public museum of its kind in the United States. With the largest public collection of international espionage artifacts, the museum provides a unique global perspective of this covert profession — said to be the second oldest — and how it has shaped the past and present.

Before you start your mission, you are challenged to adopt a secret identity. As you snoop about, you’ll discover the Secret History of History, which highlights the influence of spies through the ages; gadgets and stories of espionage during the American Civil War, World War II, and Cold War; and a gallery of spy technology. You can even see if you have what it takes to be an agent in the Operation Spy interactive experience, in which you must find a missing nuclear trigger before it ends up in the wrong hands. Just don’t blow your cover!

Visit the “Boneyard”

Warplanes go to the desert to die, and there, for a fee, you can tour thousands of mothballed fighters, bombers and helicopters at the 309th Aerospace Maintenance and Regeneration Center. Bus tours run from the Pima Air and Space Museum, on the outskirts of Tucson, Ariz. With more than 4,200 planes, the “boneyard” is the ultimate in aerial combat nostalgia.

Some of these planes will be scrapped, others may be sold or salvaged for parts, or pressed back into service during future wars. Seldom celebrated, but perhaps more important from a technological point of view, the site also stores 350,000 tools used to make these machines, including, we presume, the one-of-a-kind tools and dies used to shape jet engines, wings and fuselages.

Ogling killing machines may seem macabre, but then, if you are a U.S. taxpayer, you’ve already paid for this stuff… might as well check it out, and witness how the technology of aerial warfare has changed over the decades!

Edison’s Garden of Invention

In 1887, after he had patented the first practical electric light bulb, mega-inventor Thomas Edison invented an inventor’s playground in West Orange, N.J., just outside Manhattan. Edison stocked the lab with every resource needed to crank out movie cameras and projectors, teletypes, recording and playback devices, batteries and countless other electric gadgets for the fast-modernizing nation.

With labs focusing on chemistry and physics, and with shops devoted to woodworking and metal-working, Edison could concentrate on his strong points: cranking out ideas and masterminding publicity stunts that helped ensure his commercial success. During World War I, 10,000 people cranked out electrical devices for the military at the factories clustered around the lab. Edison worked at the West Orange lab until his death in 1931.

Think of Edison as primarily an inventor? Then you have to wonder how his name wound up on the companies selling electricity to New York and Chicago. God may have made the Garden of Eden, but Thomas Edison made the garden of invention in north Jersey, and it awaits your visit.

– David J. Tenenbaum & Jenny Seifert

Trust Charles Darwin to be his own severest critic. Having expounded a revolutionary evolutionary theory of natural selection, he realized that the past gives birth to the present. Darwin knew about fossils, including the famous, three-section trilobites, that dated to the Cambrian period, now known to have begun about 540 million years ago.

Never one to duck logic, Darwin wrote:

Indeed, according to J. William Schopf, professor and director of the Center for the Study of Evolution and the Origin of Life at UCLA, what came before was totally mysterious when Darwin wrote “Origin of Species” in the 1850s. “Darwin knew about the Cambrian era, and the big extinctions after that were known, but he knew nothing about the earlier fossil record. This was the case for about 100 years.”

And then, starting in 1953, University of Wisconsin-Madison geologist Stanley Tyler noticed ring-like structures in rocks in Minnesota and Ontario’s Gunflint formation.

The rock — a fine-grained quartz relative called chert — was 1.9 billion years old – almost four times as old as the earliest Cambrian fossils.

Tyler, collaborating with Elso Barghorn at Harvard, recognized the circular structures as stromatolites, mushroom-shaped rocks formed by layers of microorganisms called cyanobacteria. In 1965, the two reported that stromatolites were the oldest fossils ever seen.¹

I can see you now!

Why did it take so long for Precambrian life to be recognized? “They had assumed that it would be like younger life, there would be coral, snails and trilobites,” said Schopf, an expert on the oldest life. “The basic problem was that a wrong assumption had been made. Life in the Precambrian turned out to be substantively different in organization and size.”

By exploring the interior of rocks using an increasing array of scientific techniques, Schopf and a growing group of colleagues have found life as early as 3.5 billion years ago.

Not bad for a planet with an estimated age of 4.7 billion years.

Double-not-bad, considering the exceeding scarcity of truly ancient rocks, hidden through the constant tectonic churning of the crust. The oldest rocks yet located are 3.8 billion years old, but any fossils they contain have been distorted by severe heat and pressure.

Still, Schopf said, four lines of evidence show the ancient roots of life on our planet: microfossils, molecular biomarkers, proportions of carbon isotopes and stromatolites. Stromatolites are layered rock formed by layers of microorganisms called cyanobacteria (formerly blue-green algae), which produce oxygen in sunlight.

While some of the fossilized microorganisms found in ancient rock apparently have gone extinct, the cyanobacteria closely resemble living organisms, Schopf told an audience at the University of Wisconsin-Madison on April 26. “Cyanobacteria do the same sort of photosynthesis as a blade of grass today. These are the guys that invented this process, probably 3-plus billion years ago.”

As testimony to nature’s predilection for retaining stuff that works, other fossil microorganisms resemble modern counterparts that require oxygen, cannot tolerate oxygen, or use it when convenient. “We’ve found 12 to 15 major families of cyanobacteria, the same ones that are important today, the same ones that are seen throughout the geological record,” Schopf says.

Tyler did not live to see the publication of his 1965 article, but it revolutionized paleontology, and has been cited by scientists at least six times since 2010.

“Stanley Tyler was a hero for this world,” says Schopf. “As [microbiologist Louis] Pasteur said, chance favors a prepared mind. Here was an economic geologist [concerned with finding minerals and mines] … and yet he saw these scrubbly things, and thought, ‘I bet they are fossils,’ even though they were almost two billion years old. This is the guy who made the discovery.”

– David J. Tenenbaum

For decades, one name has dominated discussion of the ancient New World: Clovis. Tools representing the characteristic Clovis technology, first found in Clovis, New Mexico, in 1929, have long been considered the product of the first inhabitants of the Americas. With a tool style that’s been found across much of North America, Clovis was the best-selling brand in “the first Americans” competition.

Clovis technology is apparently a home-grown phenomenon, as it’s never been found in Northeast Asia, the source of migrants into the New World.

The oldest solid date for Clovis people is 13,100 years ago, says Michael Waters, an archeologist at Texas A&M University. Now, in an article in Science on March 25, Waters and colleagues argue that tools have been found near Austin, Texas, that date to 15,500 years ago.

The researchers found 15,528 artifacts at a site called Buttermilk Creek. Most of their finds were flakes busted off while making stone tools, but the site also yielded 56 stone choppers, points and scrapers.

Using a technique that calculated when an object was last in direct sunlight, “We took the most conservative route to estimate the age,” says Waters, who directs the Center for the Study of the First Americans at A&M. The stone tools and flakes were probably made by a band of hunter-gatherers who paused at the creekside site.

Looking for a date

Because no organic remains were available for carbon-dating, the scientists relied for dating on optically stimulated luminescence, or OSL. “OSL has been around for a long time, has been employed in geology for 30-plus years” for dating windblown sand and silt, says Waters. “It’s been compared to radiocarbon dates, toe-to-toe, and in all cases, OSL ages have been determined to be comparable.”

The OSL dating, which essentially figures how long something has been buried, took place at the University of Illinois, in Chicago, under the direction of Steven Forman.

The find at Buttermilk Creek is the latest — and one of the better documented — archeological sites to break the Clovis barrier. Others pre-Clovis finds have been made in Oregon, Wisconsin, Pennsylvania and even Chile.

The news got WhyFilers wondering:

How convincing?

To get the skinny on the Texas discovery, we phoned Steve Shackley, a professor of anthropology at the University of California at Berkeley. “Proof does not exist in science,” he told us, “but Mike [Waters] has made good, defensible arguments.”

Much of the discussion about the Buttermilk Creek site concerns the vertical position — the stratigraphy — of stone artifacts, and the Waters team went to great lengths to show that older material was under younger stuff, as expected in an undisturbed site. Undetected dislocations can confuse archeologists, who tend to think deeper is older and shallower is younger.

Buttermilk Creek actually offers a three-fer: Clovis artifacts are sandwiched above those now identified as pre-Clovis, but below artifacts are in a more modern style. “This site has all these time periods, superimposed, in the correct order,” says Shackley. Because Waters is “one of the foremost” experts in analyzing the geology of archeological sites, “I think it’s going to be difficult to defeat his stratigraphic work. He’s been very careful about it.”

Douglas Bamforth, an archeologist at the University of Colorado, says the Waters team has avoided three errors that often destabilize ancient archeological claims:

“They have absolutely dated the site, they absolutely have artifacts, and the article talks in great detail about how intact the sediment was, they have really addressed whether the artifacts are in place,” says Bamforth. “They have refitted the [stone] flakes to the tools; I am totally convinced they have an intact site” and solid dates.

But that does not prove, to Bamforth, that the artifacts are pre-Clovis — they may be early Clovis. “The deep levels at the site are certainly older than the oldest carbon-14 date on Clovis-style projectile points, which Waters very emphatically argues is the beginning of the Clovis period. But the first problem with seeing the deep levels as different from Clovis is that there seems to be exactly nothing in those levels that differs from Clovis [as the site does not contain arrow- or spear-points that would prove or disprove the case]. … So I do not see why the site is not just early Clovis.”

Not so fast!

Aware that the latest find may be seen as final vindication for the “Clovis was not first” viewpoint, we phoned Thomas Dillehay, professor of anthropology at Vanderbilt University and the University of Southern Chile, who fought for decades to have Chile’s Monte Verde site recognized as pre-Clovis. Now that Monte Verde is finally accepted as one of the best-confirmed pre-Clovis sites, we figured the experience would make Dillehay receptive to the new find.

We were wrong. “I have a mixed opinion,” Dillehay told us, proceeding to list some shortcomings in the study. “It would be most convincing if there was standard radiocarbon dating, and even better if those dates were taken from features like hearths and food stains. OSL dating has become more reliable, but it’s still not as reliable as carbon-14, although the sequences do line up very nicely with sediment dating.”

Dillehay has questions about the three-layer sandwich of pre-Clovis, Clovis and post-Clovis material. “I’m not saying the materials are mixed. Geologists, to identify the strata, applied these excellent, meticulous sediment and particle analyses, but there was no clear visible stratigraphy to distinguish Clovis from pre-Clovis, and again this does not meet standard archeological criteria.”

Dillehay also points to the lack of “diagnostic, complete projectile points in either the Clovis and pre-Clovis material. In a discipline that has placed incredibly heavy emphasis on formal projectile points as the primary criteria for acceptance of a site, along with C-14 [radioactive carbon] dating, and geologic stratigraphy, I find this sort of acceptance, which seems to be uncritical, to be a major shift in the discipline.”

Still, Dillehay says “the interdisciplinary work is first rate, and I admire the multidisciplinary approach. But had there been C-14 dating and diagnostic projectile points, all this extraneous analysis would probably not be needed.”

It certainly would be nice to find arrow- or spear-points, says Waters, but “You can’t dictate what you will find. You have to roll with the punches.” Further excavation may or may not reveal a “smoking gun projectile point,” Waters adds. “We don’t know what kind of weaponry they used. In Siberia and Alaska, people were using a lot of bone, ivory and antler weaponry, and it might be that early folks in North America were using this as well.”

But due to heat and humidity, such organic material would not be preserved in the Texas site, he says.

Migration routes

The timing of human occupation of North America bears heavily on their migration route from Northeast Asia, which is accepted, for geographic and genetic reasons, as the source of the first Americans. The melting of the last ice age during the Clovis period, starting roughly 11,000 years ago, producing an ice-free corridor through Northwest Canada that would have allowed transit into the North American interior.

But the region was clogged with glaciers a few thousand years earlier, meaning that any early immigrants would have moved along the coast, either on foot, or via short hops in boats.

The possibility of coastal movement got a boost in a study¹ published March 4, which reported the discovery of stone tools dating from 11,400 to 12,200 years ago on the Channel Islands west of Los Angeles.

According to study leader Jon Erlandson, an archeologist at the University of Oregon, the ancient residents of these offshore islands made delicate stone tools to hunt in the ocean. “The points we are finding are extraordinary, the workmanship amazing. They are ultra thin, serrated and have incredible barbs on them. It’s a very sophisticated chipped-stone technology.”

The stone artifacts are quite different from the fluted points left throughout North America by Clovis and the later Folsom peoples, who hunted big game on land, said Erlandson. “This is among the earliest evidence of seafaring and maritime adaptations in the Americas, and another extension of the diversity of Paleoindian economies.”

The find is yet another reason to doubt that Clovis was first, says Shackley. “When you get dates to 11,000 or 12,000 years ago, out on islands, that makes it tough for the Clovis-firsters, who reject maritime entry. On the Channel Islands, they had get out there by boat,” and if they were already using boats, that means they could also have boated down the West Coast, he adds. “A lot of people accept that now.”

But even if people did move south along the coast rather than inland, Dillehay says they probably needed a long time to reach Chile. “There are hundreds if not thousands of rivers that descend the western slope of the mountain chain from Alaska to Tierra del Fuego, and every river, whether major or secondary, is a temptation to head upriver,” slowing the overall southward movement.

Photo: University of Oregon Northern Great Basin Field School

In Paisley caves in south-central Oregon, researchers uncovered pre-Clovis artifacts and the oldest human DNA discovered in the Americas. Radiocarbon dates show that people lived in the caves between 12,000 and 14,340 years ago.

And if Monte Verde was occupied by 14,500 years ago, this logic suggests that people reached North America much earlier than even the 15,500 pre-Clovis date in Texas.

Should we trademark the “pre-pre-Clovis” brand?

At any rate, the increasing number of solid pre-Clovis finds answers a riddle: How did Clovis artifacts appear in so many places at roughly the same time? According to the Waters report, “These data are evidence that by 15.5 ka [thousand years ago], human populations occupied the continental United States… . The sites of Cactus Hill, Virginia, and Miles Point, Maryland, hint that these [pre-Clovis] technologies may have been present a few millennia earlier. This early occupation of North America provides ample time for people to settle into the environments of North America, colonize South America by at least about 14.1 to 14.6 ka (Monte Verde, Chile), develop the Clovis tool kit, and create a base population through which Clovis technology could spread.” ²

When science gets ossified

Although we’ve covered the Texas discovery as a bit of gee-whiz archeology, it’s more accurate to say that the discipline proceeds by stacking study atop study, says Sissel Schroeder, a professor of anthropology at the University of Wisconsin-Madison and expert on ancient peoples of the Americas. Although most of the signs left by people who lived in North America will never be found, if they even still exist, “We work with the best information we have. The very small samples of data can make some of our interpretations less robust. Archeology is a cumulative science, so future finds can potentially add confirmatory evidence, or can disconfirm earlier conclusions; you just have to be open to recognizing that your interpretations could change.”

But scientists, like other people, can get stuck, she adds. “It seems easy for certain interpretive frameworks to become quite entrenched, and repeated over and over again. Into the 1920s, it was hugely debated that there were even people in the Americas” at the end of the last ice age. “There were a number of very provocative finds that led scholars to suggest that people had been here at the end of the Pleistocene [about 12,000 years ago], but wasn’t until the find at Folsom, New Mexico [in 1926] that scholarly acceptance began to develop.”

The Folsom find, soon followed by the discovery of those distinctive fluted points near Clovis, New Mexico, sparked “a transformative intellectual step for archeologists,” says Schroeder. “This was a radical shift in thinking.”

“You build a reputation based on a particular perspective,” says Bamforth, “and it’s hard to see evidence that is in opposition; we all believe we are really good at what we do.” Those who gain fame for overturning the conventional wisdom can wind up in the opposite corner, defending their own views long after contradictory evidence arises.

Some early claims for pre-Clovis sites were based on faulty excavation or inaccurate dating, which left a tradition of doubt, Bamforth says. For example, erroneous radiocarbon dates arose after dig sites were contaminated with groundwater. And European-style artifacts unearthed in the Hudson River valley, once interpreted as evidence for ancient European immigration, actually came from ship’s ballast that was dumped into the river, Bamforth told us.

Once archeologists got used to refuting claims, that skeptical attitude itself became entrenched, says Bamforth. “Because people were making such poor claims, very powerful people in the field clamped down on any claims for antiquity, and often the rejected claims turned out to be correct. People at the Smithsonian famously had nothing to do with Folsom until finally the evidence carried the day. There’s a famous photo showing a Folsom spearpoint between the ribs of an extinct bison. That’s proof you can’t argue with.”

Clovis-first is dead, at long last!

After 40 years of assault, Clovis-first seems dead at last. The Texas find “anchors the fact that people were here in the 14,000 or 15,000 year range, there is no longer an argument with that,” says Bamforth.

As the technology of archeology improves, Waters expects some of the most interesting finds to emerge from South America. “We have this North American bias. I’ve heard a lot about early sites in South America of the same age [as the Texas site] or older that nobody hears about. If you think about the immensity of South America, there is no way Clovis was first. There are going to be some amazing finds in the next 10 years, given the South American evidence, the work with genetics and DNA. The story of the first Americans is going to stay exciting.”

– David J. Tenenbaum

Historians tell us the Spanish introduced pressurized water systems to the New World. But a new study indicates that the Maya were building pressurized pipes between about 450 and 750 AD, in Palenque, a major Mayan city in modern-day Mexico.

The Maya built a large number of cities in the Yucatan, Guatemala and Belize, before their cities were suddenly and mysteriously abandoned around 800. The Maya, whose descendants still live in the region, wrote with hieroglyphs, had extensive knowledge of astronomy, and their economy was strong enough to support cities such as Palenque, Chichen Itza and Cobal.

Until now, nobody had found evidence for pre-Spanish pressurized water in the New World, say the two authors of the new study.

The evidence takes the form of a narrow constriction in the underground Piedras Bolas aqueduct that routed water from a spring into Palenque. Unlike many Mayan cities, Palenque was built in low mountains, with only about 2,200 hectares of reasonably flat land. Untamed streams would gobble valuable real estate, so the Maya built limestone conduits to rout water through the city.

In some cases, the Maya plastered the inside of conduits with stucco to prevent leaks. And like modern builders, they Maya covered the conduits with stones that paved city streets and plazas.

Streaming, but not video

The suggestive constriction was six meters below the spring that supplied the stone pipe, and that height differential put the water under pressure, says co-author Christopher Duffy, a professor of civil and environmental engineering at Penn State University. The system is “analogous to a modern water distribution system. The water tower produces a ‘hydraulic head,’ or water pressure. The pipes go underground, and back up into the home, where water flows under pressure.”

The small opening at the bottom allowed the Maya to close off the conduit, so it would stay full of water. Air in the system will neutralize the hydraulic head, Duffy says.

Unfortunately, the Palenque site has been disturbed, and tantalizing questions remain, Duffy says. “We don’t know how they distributed the water from this point, but we can’t see any other purpose, other than as a control point in the buried conduit.”

Paving paradise to put up a … fountain — or a toilet?

Archaeologists already know that the Maya had an extensive irrigation system, fed by nine streams that ran through Palenque to the fields below.

The constricted conduit, one of nine, had a capacity of about 68,000 liters, and it alone could have stored enough water to supply scanty rations for several thousand people for a week during the dry season.

The pressurized pipe could have supplied a fountain where people could dip jars to collect drinking water. But the putative fountain was “probably beautiful,” says co-author Kirk French, a lecturer in anthropology at Penn State. “Everything the Maya did at Palenque was over the top, grandiose, in art and architecture.”

Fountains also serve a social purpose, says French. “They are in a central part of the city, where people can fill jugs and socialize. It’s funny, we refer to ‘water-cooler conversations,’ but it seems this has been going on for a very long time.”

Did the Maya’s pressurized plumbing have a more, er, “sanitary” function? “We don’t know the exact application,” admits Duffy, who specializes in hydrology, “although we were recently told, after the paper came out, that there are sweat baths, and perhaps toilets, in the palace at Palenque.”

In fact, the palace has “four toilet-like features,” French says, “They are in a line, at the right height, and share the same drain, but it’s hard to prove that they are toilets.”

The sanity of sanitation

Toilets or not, the newly discovered plumbing shows that the Maya “are better engineers than they ever got credit for,” Duffy says. Although the Maya may have never seen pressurized water flow in nature, people are inventive, especially when it comes to something as important as water.

“We think this is the first example in the New World, but a lot more will probably be discovered,” says Duffy. “The Maya built like the Romans. They were practical. They would build, if it failed, they would build again. It’s a standard engineering strategy. Do something, fail, learn, and do it again.”

– David J. Tenenbaum

All in all, the period since the ice age abated about 15,000 years ago has been pretty interesting. Melting ice raised the oceans, flooding the Bering Strait land bridge across which the Americas were populated. Temperatures rose around the globe, leading to the invention of cities, armies, writing and bacon.

Here’s an enduring question. Why were the giant mammals that made the Americas more zoologically diverse than Africa all exterminated within a few thousand years after the big melt-down? Bye-bye beavers as big as black bears, giant sloths, saber-toothed cats, and the elephant-like mastodon.

[svgallery name="mastadon"]

As Australian paleontologist Christopher Johnson wrote in Science this week, all 10 species of mammals weighing more than a ton had gone extinct in North America by 10,000 years ago.

Why?

Many theories are proposed for the sudden disappearance: An impact of a comet or asteroid around 12,900 years ago. Rapid ecological changes that accompanied the warming. Widespread wildfires. And hunting – the “overkill” hypothesis. Although similar disappearances roughly coincided with the arrival of people in Europe, Eurasia and Australia, and hunger is certainly the ultimate motivation, did people actually lay waste to entire groups of large mammals?

The debate may seem academic, and it has been one of the most brutal and tenacious debates in academia.

Reading the dung calendar

Now we get some solid evidence that the extinction of the mastodon and other large herbivores closely followed the arrival of humans in North America, and that it preceded a pervasive change in type and prevalence of trees.

The new evidence, contained in research by Jacquelyn Gill and Jack Williams of the University of Wisconsin-Madison, and colleagues, was published in Science this week, and although it does not prove the overkill hypothesis, it does usher a new type of evidence into the debate: spores of fungi that grow in herbivore dung.

Between 14,800 and approximately 13,700 years ago, fungal spores of the genus Sporormiella declined by up to 98 percent in sediments found in lakes in Indiana and New York State.

Mastodons eat black ash trees as the last ice age begins to abate. Image courtesy Barry Roal Carlsen, University of Wisconsin-Madison.

For decades, students of ancient ecology have been poking through pollen in sediments to see what plants were alive when the sediment was deposited. Pollen are durable structures, but it turns out that Sporormeilla spores are equally tough, and if you have the patience (Why Filers immediately excuse ourselves at this point!) counting spores provides a good gauge of the number of herbivores.

Because the same sample also contains pollen and charcoal, it’s also possible to document the co-existing plant community, and get an idea of the extent of wildfires.

Fungi are a new addition to the paleoecologist’s toolkit, says Gill, first author of the paper, and a graduate student in Williams’s lab. “Only recently have fungal spores been getting any attention; we used to basically ignore them if we counted them at all, but now we realize they are a good source of information about early conditions.”

Being skeptics, we asked whether the decline could simply represent a change in conditions that was less conducive to preservation, but Gill says not. “If so, you would expect other proxies to show similar transitions. Since the same sediment that contains the spores also contains pollen, we’d expect to see pollen disappear, but we don’t.”

The dating game

Having a firm date for the decline of mastodons and other large herbivores is mainly helpful for eliminating some possible explanations, says Gill. The decline started almost 2,000 years before the putative impact of a comet or asteroid. And a change in climate apparently did not cause a broad habitat loss, Gill adds. “The extinction started before the habitat changed; the vegetation is relatively stable until after the extinctions began. We do have evidence of warming taking place, but if climate change is causing the extinctions, it’s not through a loss of food.”

A major ecological change did follow the elimination of large mammals, however, as documented by pollen representing a new assembly of trees, including ash and ironwood, which had probably been held in check by hungry herbivores, growing along with less nutritious conifers like spruce and larch. Once the grazers left, these trees began to dominate the landscape — and then became fuel for wildfires that burdened younger sediment with charcoal.

Graduate student Jacquelyn Gill holds a sediment jar with a scrap of charcoal being prepared for carbon dating. Photo: The Why Files

Although the sexy “overhunting” hypothesis is sure to get a boost from the Science paper, Gill says one study hardly proves the case. And as Johnson notes in his commentary in Science, the Clovis people who spread across much of North America arrived more than 1,000 years after the decline began. Evidence for earlier North American populations is sketchy and scarce, but it is arising, Johnson added.

A second focus of the Gill paper may be equally important: the effect, rather than the cause, of the extinctions. “What happens when half of the species larger than a German shepherd go extinct in North America?” Gill asks. “Elephants eat 300 pounds of food a day, and when animals like the mastodon are rapidly taken out, you would think the landscape would notice, but that has been absent from the discussion. People were underestimating the power of these fungal spores to tell about the local presence of animals and vegetation.”

– David J. Tenenbaum