December 7, 2018

On Dec. 9, 1962, 56 years ago Sunday, the United States Congress established Petrified Forest National Park, an area with one of the greatest and most colorful concentrations of petrified wood in the world. Located in the Painted Desert in northeastern Arizona, the park contains giant logs of agatized wood (wood petrified into agate) and numerous broken sections and petrified fragments. Visitors can view petrified wood and other park features while hiking the park’s many trails. The park also contains dinosaur fossils and Native American petroglyphs (rock carvings).

These petrified logs at Petrified Forest National Park are about 225 million years old. Credit: © George Burba, Dreamstime

The trees of Petrified Forest National Park grew about 225 million years ago during the Triassic Period, when reptiles became the dominant animals on land and in the sea. Reptiles of the Triassic Period included the first dinosaurs and early large marine reptiles. The trees were buried in mud, sand, or volcanic ash, and turned to stone over time. Today, the park is home to a wide variety of plant and animal life. Cactuses, grasses, lichens, and wildflowers live there, as do many types of birds, lizards, rabbits, and other animals.

Click to view larger image
Petrified Forest National Park is located in the Painted Desert in northeastern Arizona. Credit: WORLD BOOK map

People of the Clovis culture first inhabited the area of the park around 13,000 years ago. Fragments of pottery found in the forest show that small groups of farming Indians lived there as early as A.D. 300. Spanish explorers reached the area in the late 1500′s, and American pioneers and homesteaders began settling there in the 1800′s.

Click to view larger image
This map shows the locations of the national parks of the United States, which form part of the country’s National Park System. Credit: WORLD BOOK map

U.S. President Theodore Roosevelt created Petrified Forest National Monument in 1906. After becoming a national park in 1962, the Petrified Forest National Wilderness Area was added within the park in 1970. In 2004, the park expanded from 93,533 acres (37,851 hectares) to 218,533 acres (88,437 hectares). Later additions brought the park’s area to 221,390 acres (89,593 hectares).

July 7, 2017

A new study of ancient cat DNA reveals what many cat owners might long have suspected: your pet is barely domesticated at all. A team of scientists analyzed genetic material from more than 200 ancient cats obtained from Viking graves, Egyptian mummies, and Neolithic (later Stone Age) sites. The study revealed that despite having lived alongside people for thousands of years, cats really began to change only quite recently. The study was published in June in the journal Nature Ecology and Evolution.

A recent study showed that domestic cats like this Maine coon remain genetically quite similar to their wild ancestors. Maine coons, developed in New England in the 1800′s, are the largest domestic cat breed. Credit: © Linn Currie, Shutterstock

Cats have a long association with people. Archaeologists discovered a cat buried alongside a human in a 9,500-year-old grave in Cyprus. Yet cats have not not been fully domesticated the same way that dogs, cattle, pigs, sheep, or goats have been. Those familiar pet and farm animals differ from their wild ancestors in anatomy, behavior, and genetics. Modern house cats, however, remain very similar to their wild ancestors. Pet cats, of course, are much smaller than their wild cousins, but they remain near anatomic mirrors. Behaviorally, watch a panther or a lion in a nature program or in a zoo—then a house cat stalking a bird or simply watching you walk across the room—and you might notice quite similar patterns: sleeping a lot, playing, grooming, investigating, hunting, and even jumping into empty boxes. And genetically speaking, despite thousands of years of human interaction, pet cats did not begin to change until the past few centuries—and then, only a little. The domestication of cats has been neither complete nor easy. In fact, all house cats are descended from just one presumably friendlier-than-the-rest ancestor: the African wildcat.

The wildcat, from which modern house cats descended, still roams Africa, Asia, and Europe. Look familiar? Credit: © Vova Pomortzeff, Shutterstock

The genetic study focused on cat mitochondrial DNA (mtDNA), which is inherited unchanged solely from the mother. This fact makes mtDNA especially useful to trace the ancestry of different animal species. The genetic evidence showed that cat domestication probably began about 9,000 years ago in the Middle East, where farming started. Scholars think that wild cats (wildcats among them) were initially attracted to rodents that infested grain stores of early farmers. With plenty to eat, the cats stuck around the farms but never became fully domesticated. Cats then followed farming peoples as they migrated into Europe more than 6,000 years ago.

The genetic study showed that the familiar tabby markings of modern cats developed during the Middle Ages. Credit: © Shutterstock

The recent study found, however, that most modern pet cats are not directly descended from these first domesticated felines. More than 3,000 years ago, a second episode of cat domestication happened in ancient Egypt. These cats spread out of Egypt to Europe and beyond along Greek and Roman trade routes as far north as Scandinavia and into Asia. Most modern pet cats are descended from this second migration group.

The mtDNA analysis revealed that most domestic cats over the past 9,000 years were striped, like their wild ancestors (witness the tiger). The familiar tabby coats—symmetrically patterned with light stripes and blotches of a dark and light colors—of many house cats today were uncommon until the Middle Ages. It was around that time that people started paying more attention to their cats and started breeding them for different appearances and purposes. The genetic evidence even pinpointed the tabby mutation to western Turkey in the 1300’s. Most cats today carry this tabby gene, but there are now many different breeds from all over the world. The vast majority of cat breeds have been created since the early 1900’s.

Cat shows are popular today, but the very first cat show was much earlier than you might think. According to most accounts, the first show took place in 1598 at St. Giles Fair in Winchester, England. The first modern cat show was held at London’s Crystal Palace in 1871.

April 28, 2017

For decades, dinosaurs have been grouped into two broad categories: long-necked sauropods and meat-eating theropods (along with birds) in one group, and the remaining plant-eaters, such as Stegosaurus, Triceratops, and Iguanodon, in the other. In March, a group led by Matthew G. Baron from the University of Cambridge in the United Kingdom challenged that view. They published their findings in the prestigious scientific journal Nature.

Tyrannosaurus is a fearsome example of a saurischian (reptile-hipped) dinosaur. Credit: © Science Picture Company/SuperStock

To study dinosaur relationships, paleontologists (scientists who study prehistoric life) use a type of analysis called cladistics. In cladistics, researchers evaluate anatomical traits of at least three related species. These evaluations help them construct a cladogram, a kind of family tree illustrating how the species are related to one another. Groups of species that are related to one another are called clades. For dinosaurs, skeletal features are used, such as the absence or presence of a particular bone or a certain feature on a bone.

Click to view larger image
The accepted dinosaur family tree describes two major kinds of dinosaurs: ornithischians and saurischians. Credit: WORLD BOOK illustrations by George Fryer, Bernard Thornton Artists

For 130 years, paleontologists have grouped dinosaurs into two large, confusingly named clades based on the arrangement of their pelvic, or hip, bones. All tetrapods (animals with four limbs) possess three paired sets of hip bones: two ilia (singular: ilium), two ischia (singular: ischium), and two pubes (singular: pubis). In one group of dinosaurs, the pubes run from the hip socket down and away from the center of the animal, close to the ischia. Because these hips looked similar to those of birds, early paleontologists named the group Ornithischia, which means bird-hipped. But ornithischians are not closely related to birds.

Click to view larger image
This illustration shows the difference between bird-hipped ornithischians and reptile-hipped saurischians. Credit: WORLD BOOK illustrations by Alex Ebel

In sauropods and most theropods, the pubic bones project straight down from the hip socket or at a slight forward angle. This is closer to the condition seen in other reptiles, so they were included in the clade Saurischia, which means reptile-hipped. In some small theropods, however, the pubis is “reversed,” angling away from the center of the body at an angle similar to the ischium. Birds evolved (developed over time) from these theropods, making them members of the “reptile-hipped” clade, even though they truly have bird hips.

Baron studied 73 dinosaur species and catalogued 457 skeletal characteristics with them. He coded these characters into a computer program, which returned new controversial results. Theropods were found to be more closely related to ornithischians, with sauropods and some primitive meat-eaters remaining in Saurischia. Despite their different-shaped hips, theropods and ornithischians were found to be united by more than 20 unique characters. To refer to the clade, Baron and company revived the name Ornithoscelida (meaning bird-legged), which had been coined by the famous British zoologist Thomas Henry Huxley in 1870. Fortunately for the sake of clarity, birds would be considered bird-legged dinosaurs under this system!

The new placement would resolve some puzzles about the origins of dinosaurs. The earliest known dinosaur skeletons are about 230 million years old and have been found in South America. But still older reptiles that are regarded as the ancestors to dinosaurs have only been found in northern regions far from South America. To further muddle things, footprints widely attributed to early dinosaurs have been found in eastern Europe and are some 5 million to 9 million years older than the South American skeletons. With the proposed reorganization, those earliest-known skeletal remains would be considered early relatives of sauropods, suggesting that the earliest dinosaurs have yet to be discovered somewhere in the Northern Hemisphere.

While the proposed rearrangement would solve some problems relating to the origin of some dinosaur features, it would create problems relating to the origin of others. For instance, sauropods and theropods both had air sacs connected to their lungs. These air sacs had long chambers that tunneled through their bones, making them lighter. Based on the new family tree, the first dinosaur would have had to possess these air sacs. Why would ornithischians lose a trait that was apparently so useful to sauropods and theropods and remains vital to birds today? Scientists will continue studying them to try to answer this puzzling question.

Though paleontologists commended Baron for the meticulousness of his work, they were quick to point out that more data would be needed to convincingly rearrange the family tree. The Saurischia-Ornithischia division has been upheld for decades by dozens of cladistics analyses, so it will take more than one new analysis to convince paleontologists to overturn 130 years of study. But the bird-legged dinosaur clade will have a leg to stand on if more fossil discoveries and cladistic analyses back up Baron’s findings.

April 13, 2017

For thousands of years, indigenous (native) people of Western Australia knew about giant ancient footprints along the shore of the Indian Ocean. But only recently have scientists learned about, and been able to study, the tracks, which were made by dinosaurs some 100 million years ago. A team of scientists led by Steven W. Salisbury of the University of Queensland studied the collection of fossilized footprints—which includes the largest ever discovered—for five years. Salisbury and his team recently published their findings as a memoir in the Journal of Vertebrate Paleontology.

Richard Hunter, an elder of the Goolarabooloo community, lies alongside a massive sauropod track in the Walmadany area of Dampier Peninsula in Western Australia. Credit: © Steve Salisbury, University of Queensland

A fossil is the mark or remains of an organism that lived thousands or millions of years ago. Most people think of bones or shells when they hear the word fossil. But tracks, trails, and burrows left by ancient organisms are also extremely important in paleontology (the study of prehistoric life). These marks, called trace fossils, give paleontologists a rare glimpse into the lives of prehistoric animals. The scientists can use trace fossils to answer many questions about an animal’s behavior, such as how it moved or how many animals moved together at a time. Scientists cannot usually pair a trace fossil to an exact species (kind) of animal, but they can often determine broadly what type of animal left the mark.

The fossilized tracks in question are on the northern shores of Western Australia. About 130 million years ago, the region was a sandy floodplain covered with braided rivers. Braided rivers have numerous channels separated by small temporary islands. After the tracks were made, floods rapidly covered them in sediment, preserving them from destruction. Thousands of tracks are scattered over several dozen sites in the area, and about 150 are in excellent condition. The findings give scientists a valuable snapshot into life during the early Cretaceous Period in Australia.

Salisbury and his team identified several types of prints coming from ornithopods (plant-eating dinosaurs that could walk on two or four legs), sauropods (large plant-eating dinosaurs with long necks and tails), stegosaurs (relatives of Stegasaurus), and theropods (meat-eating dinosaurs) of different sizes. One of the tracks measures a whopping 5 ½ feet (1.7 meters) long. This print was made by the hind foot of a huge sauropod some 18 feet (5.5 meters) tall at the hip.

The indigenous people of the Western Australia coast had known of the tracks for thousands of years and had incorporated them into their belief system. In one story, the Dreamtime figure Marala, also known as the Emu Man, makes the three-toed footprints that today are believed to have been made by theropods. (The emu is an Australian bird that has three toes on each foot.) The Dreamtime is a fundamental spiritual concept that connects traditional beliefs and practices among the Aboriginal people of Australia.

In 2008, the state government of Western Australia—unaware of the ancient tracks—proposed that a natural gas processing facility be located near the site. Fearing that the tracks would be damaged or destroyed, the Aboriginal people contacted Salisbury to assess the tracks’ scientific importance. As word spread of the natural gas plant and the damage it could cause to the tracks, environmental groups, paleontologists, and local citizens campaigned for the area to be preserved. The company planning to build the processing plant eventually withdrew its application. Now the tracks, with their important connections to prehistory and the Dreamtime will remain protected.

March 10, 2017

Hard gunk stuck in the teeth of fossil Neandertal jaws shows that the prehistoric human beings had a widely varied diet and a sophisticated knowledge of medicinal plants. Scientists analyzing dental calculus (a hard, yellowish substance formed by the buildup of plaque between teeth) from three Neandertal fossils found dramatic differences in diet and evidence that Neandertals likely used some foods as medicine. The scientists’ findings were published in the March 8 issue of the journal Nature.

The teeth of this fossilized Neandertal jaw revealed traces of poplar bark, a source of aspirin. The individual had also consumed Penicillium mold, source of the natural antibiotic penicillin. Credit: © Paleoanthropology Group MNCN-CSIC

Neandertals were prehistoric human beings who lived in Europe and central Asia from about 150,000 to 39,000 years ago. They looked quite different from modern humans. Neandertal skulls were huge compared to ours, with a projecting face; no chin; a low, sloping forehead; and a thick browridge (raised strip of bone across the lower forehead). Because Neandertals had such a brutish appearance, people long assumed the these prehistoric humans possessed only a crude and simple culture. However, new evidence shows they were perhaps smarter than we previously thought.

An international team of scientists examined three fossil Neandertal skulls dating from 42,000 to 50,000 years ago. Two of the skulls were from El Sidrón, a cave in Spain, and one was from Spy Cave in Belgium. The teeth of these fossils were coated with thick layers of hardened dental calculus. The scientists knew that this material preserves DNA from microbes and food debris that pass through an individual’s mouth during their lifetime. The dental calculus of the Spy Neandertal contained traces of meat from wooly rhinoceros and wild sheep, while evidence of plant foods was largely absent. In contrast, the two Spanish Neandertal fossils appeared to have survived on a vegetarian diet of edible moss, mushrooms, tree bark, and pine nuts.

Neandertals lived in Europe and Central Asia from about 150,000 to 39,000 years ago. Credit: © Jay H. Matternes

Other evidence showed that the El Sidrón Neandertals probably also used plants for medicine. The scientists recovered DNA from poplar trees in the dental calculus. While not eaten for food, these trees contain salicylic acid, the pain-relieving ingredient in aspirin. Preserved spores of the Penicillium mold, from which the life-saving antibiotic penicillin is produced, were also recovered. The scientists think the Neandertals ate the plant sources for their medicinal properties. One fossil skull showed evidence of a painful tooth infection, and DNA from a microbe known to cause stomach problems was also recovered from the calculus. Aspirin and penicillin would have helped.

Neandertals died out about 39,000 years ago, when physically modern human beings migrated into Europe. However, Neandertals did not disappear completely. Genetic evidence shows at least some Neandertals interbred with modern-looking populations that settled Europe, Asia, and the Pacific Islands. Neandertals are extinct, but they remain part of the ancestry of some modern peoples today.

January 12, 2017

On Dec. 28, 2016, President Barack Obama created two new large protected areas in the southwestern United States: the Bears Ears National Monument in southeastern Utah and Gold Butte National Monument in southern Nevada. To do so, the president used the executive power provided by the 1906 Antiquities Act. The act, meant to stop looting and destruction at prehistoric American Indian sites, gives the president the power to establish national monuments on federal land. Obama’s December actions protected some 2,500 square miles (6,475 square kilometers) of fragile and important desert landscapes, adding to his legacy of environmental protection.

Bears Ears National Monument in southeastern Utah protects one of the most significant cultural landscapes in the United States, an area with thousands of archaeological sites and other areas of beauty and importance. Credit: Bureau of Land Management

Bears Ears National Monument contains numerous sites considered sacred by Native American groups. The monument protects ancient petroglyphs (rock carvings), cliffside dwellings, and lands traditionally used by Navajo and other native groups to forage for wild plants used for food and herbal remedies. The protected lands will remain open for livestock grazing. The monument is to be administered by the Bureau of Land Management (BLM) and the U.S. Forest Service, in conjunction with an association representing native groups.

Gold Butte National Monument protects a beautiful and culturally significant desert landscape northeast of Las Vegas, Nevada. Credit: Bureau of Land Management

Gold Butte National Monument in southern Nevada contains striking rock formations, forests of Joshua trees, ancient Native American sites, rare fossils, and a number of ecologically sensitive areas. The monument, known to many as “Nevada’s Piece of the Grand Canyon,” will continue to allow such recreational activities as hunting and fishing.

Conservationists, Native American groups, and many others applauded the president’s actions. Opponents of the monument designations included state legislators and county leaders who preferred the lands be used for mineral and fossil fuel exploration.

Theodore Roosevelt was the first president to use the Antiquities Act when he protected Wyoming’s Devils Tower in 1906. In 1908, Roosevelt also set aside 1,250 square miles (3,200 square kilometers) in Arizona’s Grand Canyon, creating a forerunner of the popular national park. Since taking office in 2009, Obama has used the Antiquities Act more than any other president, establishing or expanding more than two dozen new national monuments.

Throughout Obama’s presidency, his administration has taken numerous steps to combat global climate change, promote energy efficiency, and create or extend protections in areas of scenic, historic, and ecological importance.

December 27, 2016

Lida Xing, a paleontologist (scientist who studies fossils) from the China University of Geosciences in Beijing, made a spectacular find just by going to the market. There, he found part of a tiny dinosaur—complete with feathers—perfectly preserved in amber.

A lump of amber has preserved this feathered dinosaur tail (along with ants, a beetle, and bits of foliage) for 99 million years. Credit: © Ryan C. McKellar, Royal Saskatchewan Museum

Amber is a hard, yellowish-brown fossilized resin. It comes chiefly from the resins of pine trees that grew millions of years ago. These resins were gummy materials mixed with oils in the trees. When the oils oxidized (combined with oxygen), hard resins were left. These pine trees were then buried underground or underwater, and the resins slowly changed into lumps of amber. These lumps often contain insects trapped as the resins flowed from the trees. But finding larger animals such as small vertebrates (animals with backbones) is incredibly rare.

Xing found the remarkable fossil at an amber market in the Southeast Asian nation of Myanmar (also called Burma). The seller thought the bushy object in the amber was part of a plant and had polished the piece to be made into jewelry. But it was in fact part of the feathery tail of a small dinosaur. Xing promptly brought the specimen to fellow paleontologist Ryan McKellar of the Royal Saskatchewan Museum in Regina, Canada, where they studied it with other scientists using computed tomography (CT). Computed tomography involves taking many X-ray images of an object from a number of directions. A computer combines the set of X-ray “slices” of the object to create a three-dimensional image called a volumetric model. The scientists recently wrote about what they found in the journal Current Biology.

Paleontologists have discovered feathered dinosaur fossils in the past, but the heavy weight of the sediments and rocks deposited above them had flattened the carcasses during the fossilization process. Because this tail was trapped in amber, however, it was preserved in three dimensions, allowing scientists to see the exact layout of the feathers. Even traces of the pigments that colored the feathers have been preserved, showing that the animal would have been light brown with a whitish underside.

The tail likely belonged to a juvenile (young) bipedal dinosaur related to Tyrannosaurus rex. Despite the specimen’s prominent plumage, paleontologists know that the tail belonged to a nonbird dinosaur (all birds are technically dinosaurs). The fossil dates back 99 million years, some 50 million years after the appearance of early birds such as Archaeopteryx. A tail from Archaeopteryx would have been short and stiff. The tail from this new fossil, however, is long and flexible. It is bent a great deal in the amber, and scientists estimate that only a third of the tail was preserved. Furthermore, the beautifully preserved feathers trapped in amber would have been useless for flight. The feathers possess simple barbs and barbules that would hold strands of the feathers together, but they have much thinner central shafts than modern flight-worthy feathers. These ancient feathers would have been soft and downy, and they probably kept the young animal warm.

The loss of the dinosaur’s tail in amber probably cost it its life. Dinosaurs could not detach their tails the way some lizards can. A dinosaur could likely survive without the tip of its tail, but this fossil is from the mid-section of a dinosaur’s tail. Once the hapless youngster got stuck in resin, it probably either starved to death or became an easy snack for a predator—except for the part stuck in resin, of course.

Lida Xing has a knack for making spectacular finds of amber-entrapped animals. Earlier this year, he announced the discovery of a pair of 100-million-year-old bird wings. His remarkable discoveries are shining a new light on the evolution of feathers in birds and dinosaurs.

December 5, 2016

Imagine going to the zoo and seeing a horselike rhinoceros the size of a small house. It may sound like a fairy tale monster, but Paraceratherium—break it down: para-cera-therium (par uh sehr uh THIHR ee uhm)—was real and it was the largest land mammal that has ever lived. Paraceratherium, which provided inspiration for the gargantuan AT-AT walkers seen in the Star Wars film and entertainment franchise, reached over 16 feet (5 meters) in height. Its skull alone was over 4 feet (1.2 meters) long.

Watch their step: a Paraceratherium herd feeds on a not-so-small leafy tree. Credit: American Museum of Natural History

A prehistoric relative of the modern rhinoceros, Paraceratherium roamed central Asia between 20 and 30 million years ago. It was about 10 feet (3 meters) taller than modern rhinos, and it had no horn. The giant walker had long legs and a long neck to reach leaves in the treetops. Paraceratherium ate vast amounts of plant matter every day to maintain its massive 15-ton (13.6-metric ton) weight. It was so big that even a newborn calf was too much for many large predators to handle, especially with its massive mother lurking protectively nearby. Males had very thick skulls, which they used on each other as clobbering weapons while competing for mating rights with females. The thunderous stomping and skull-crashing during these combats probably warned other creatures to stay far away.

Scientists suspect that Paraceratherium’s cumbersome size led to its demise. Such a gigantic body requires a lot of food fuel and can easily overheat, which is why most modern mammals tend to be small- to medium-sized. Droughts, food shortages, and heat waves would have left Paraceratherium quite vulnerable. Females gave birth to only one calf every few years, so it would have been difficult for these prehistoric giants to keep their population numbers up during tough times.

November 23, 2016

At a recent convention of paleontologists (scientists who study animals and plants that lived in prehistoric times), things got a bit venomous. A group of researchers claimed that a fossil recently identified as an early snake was not a snake at all. Furthermore, they stated that the specimen should not have been studied in the first place. The presentation was the most recent shot fired in the battle over the evolution (a process of change over time) of snakes.

This artist’s impression shows the four-footed tetrapodophis amplectus snatching its prey, an unlucky salamander. Credit: © James Brown, University of Portsmouth

In 2015, Dave Martill and his colleagues at the University of Portsmouth in England reported that they had discovered a new type of primitive snake. They found the ancient animal’s fossilized imprint (which came from Brazil) among the collections of a German museum. The British researchers named their discovery Tetrapodophis amplectus and published their findings in the journal Science. Tetrapodophis means “four-footed snake.” The animal was about 6 inches (15 centimeters) long and possessed four tiny limbs. It lived in an ocean environment some 110 million years ago.

This month, however, at the annual Society of Vertebrate Paleontology conference in Salt Lake City, Utah, Michael Caldwell of the University of Alberta in Edmonton, Canada, gave a presentation refuting Martill’s “four-footed snake” diagnosis. In the creature’s skull, for instance, Caldwell noted “every single character that was identified in the original manuscript as being diagnostic of a snake was either not the case or not observable.” Instead, Caldwell’s group contended that Tetrapodophis is not a snake at all, but rather a member of a group of unrelated marine reptiles.

The fossilized imprint of Tetrapodophis reveals small, specialized feet—or perhaps flippers. Credit: © Dave Martill, University of Portsmouth

This dispute is merely the latest spat among paleontologists on snake origins. Paleontologists agree that snakes likely evolved in the Jurassic Period some 150 million years ago. Some people (like Martill) think that snakes evolved from aquatic reptiles. Over million of years, four-legged reptiles would have spent more and more time in the water, eventually losing their limbs in favor of a long body good for swimming. Later, snakes made their way onto land, with some (sea snakes) remaining in their ancestral habitat. Martill’s group contends that snakes were closely related to mosasaurs, giant marine reptiles that prowled the oceans some 100 million years ago. Most paleontologists, however, think that snakes evolved from burrowing, terrestrial reptiles. As these aimals dug deeper and more complex burrows with their strong heads, their limbs vanished over millions of years. Later, snakes moved into different habitats, including the sea. In this scenario, snakes’ closest relatives would be monitor lizards such as the Komodo dragon. So far, a lack of ancient snake fossils has prevented either hypothesis from being proven.

Further muddying the water, Caldwell—of the “land snake” faction—reported that when he went to study the fossil in the German museum, the fossil was no longer there. Apparently, it had been a loan to the museum from a private collector. The collector had retrieved it from the museum because it had been damaged during an earlier study. Most paleontologists will not study privately owned fossils for this exact reason: an owner may take back the fossil at any time. Science must be repeatable, so a description of a specimen that is no longer available for study is not science at all. Since Tetrapodophis was revealed to be a privately owned specimen, many experts have vowed to ignore it while conducting future studies on snake evolution. We will have to wait for more fossils—in the permanent collections of museums and universities—to determine if snakes started out on land or in the water—with four legs or, perhaps, four flippers.

November 16, 2016

A brief call of nature recently led an Aboriginal man to discover a site preserving some of the oldest known evidence of human settlement in Australia. Clifford Coulthard, an Adnyamathanha elder, stumbled across a rock shelter during a brief bathroom break while surveying in the northern Flinders Range with archaeologist Giles Hamm of La Trobe University in Melbourne. The Adnyamathanha are the Aboriginal people of Australia native to the Flinders Range of South Australia. Subsequent excavations at the rock shelter, called Warratyi, unearthed ancient tools, bones, and other artifacts that are dated to about 49,000 years ago–only about 1,000 years after the first humans arrived in Australia.

The Warratyi rock shelter lies in the desert landscape of South Australia’s Flinders Range. Credit: © Giles Hamm, La Trobe University

Warratyi sits above a desert landscape crossed with deep gorges about 340 miles (550 kilometers) north of Adelaide. In prehistoric times, the rock shelter offered protection from the wind, heat, and cold, as well as a commanding view of the once-stream-filled landscape below. Archaeologists excavated some 4,300 stone artifacts and hundreds of animal bones, emu egg shells, and other materials from layers deep within the site. They estimate that people occupied Warratyi on and off for about 40,000 years, finally abandoning the site about 10,000 years ago when conditions became impossibly dry.

One sharpened bone tool from Warratyi, called a uni point, was used to hunt big game. Archaeologists also excavated bones from a Diprotodon—a prehistoric giant wombat that was the largest marsupial that ever lived. Many archaeologists believe these animals and other Australian megafauna (giant animals) became extinct because of hunting by early humans. Some tools bore tiny bits of feathers as well as red ocher and white gypsum, two common minerals that were used as pigments (coloring materials) by Aboriginal people. Archaeologists believe the tools were decorated and perhaps used for ceremonial purposes.

Archaeologists know that the ancestors of today’s Aboriginal people arrived in Australia at least 50,000 years ago. Scientists believe that these first people came by boat from Southeast Asia, the closest land that was inhabited by human beings at that time. Archaeologists have long thought that the first people to arrive likely lived along the forested and well-watered coast where resources were abundant. Archaeologists believed the dry southern interior of Australia was too inhospitable for these early people. They thought the people of 50,000 years ago could not have survived in regions such as the Flinders Range because they did not yet have the technology to survive the challenging environment. The Warratyi rock shelter, however, proves that Australia’s earliest humans were capable explorers who could quickly adapt even to the harsh conditions of the continent’s arid interior.