Judging by the number of freaky fossils they uncover, you would think that paleontologists have a penchant for the peculiar. Their day jobs consist of finding strange beasts like the prehistoric snake longer than a school bus, rare ancient saber-toothed squirrels, and the massive “thunder thighs” dinosaur. Sea monsters and giant rabbits may seem weird to you and me, but they are par for the course for anyone who digs up the very distant past.
Dinosaurs were airheads—and not just because they had tiny brains, a new study says.
Three-dimensional scans of the skulls of Tyrannosaurus rex and other dinosaurs reveal the creatures had more empty space inside their heads than previously thought. These air spaces made the skulls light but strong and could have helped dinosaurs breathe, communicate, and hunt.
The extra room may even have paved the way for flight in some species. “Air is a neglected system that is actually an important contributor to what animals do,” said study co-author Lawrence Witmer, a paleontologist at Ohio University in Athens.
TRUTH:
EVIDENCE SUGGESTS THAT TYRANNOSAURUS REX COULD EAT UP TO 500 POUNDS (230 KILOGRAMS) OF MEAT IN ONE BITE.
Witmer and colleague Ryan Ridgely made detailed CT scans of air cavities in the skulls of two predators, T. rex and Majungasaurus; and two ankylosaurs, Panoplosaurus and Euoplocephalus, both plant-eaters with armored bodies and short snouts.
The results mark the first time scientists were able to accurately estimate the weight of a dinosaur’s head. A T. rex head, for example, would have weighed more than 1,100 pounds (about 500 kilograms)—close to the average weight of an adult cow, Witmer and colleagues found.
Until now, paleontologists had to make do with estimates for the weight of dinosaur heads, said Tom Holtz, a paleontologist at the University of Maryland who was not involved in the research. “Larry’s team is able to calculate a volume for the skull, so they can constrain the weight far more securely,” Holtz said. “This is the next best thing to having a fleshy T. rex head to dissect.”
Witmer estimates that T. rex’s head would have been 18 percent heavier if not for the air spaces in its skull. This savings may have allowed T. rex to pack more muscle onto its head, which possibly strengthened its bite and allowed it to tackle bigger prey.
The nasal airways in the ankylosaurs, however, were surprisingly convoluted. It was as if “crazy straws” had been rammed up the creatures’ snouts, Witmer said. These winding airways were often located next to large blood vessels. “Whenever we see that, it raises the possibility that we’re looking at heat transfer,” Witmer said.
This setup would have allowed hot blood circulating through the creatures’ heads to dump excess heat into the airways, helping to cool their brains and the rest of their bodies. The transferred heat also could have warmed up air the dinosaurs breathed, making gas exchange in the lungs easier.
In addition, the twisty nasal passages may have acted as resonating chambers for sounds. The two ankylosaur species examined had slightly different airways, so their voices would have been subtly different, Witmer said.
The research could provide new clues about how dinosaurs achieved flight. Some of the new study’s research subjects were theropods, the group of dinosaurs from which modern birds are descended.
“Very often people have thought that birds have hollow bones because they fly, but it could be the other way around,” Witmer said. “They could have evolved hollow bones for other reasons, and that gave them the lower body mass necessary to take to the air.”
“I’ve been looking at sinuses for a long time, and indeed people would kid me about studying nothing—looking at the empty spaces in the skull. But what’s emerged is that these air spaces have certain properties and functions.”
Lawrence Witmer
Chang Professor of Paleontology, Ohio University College of Osteopathic Medicine
Hans-Dieter Sues is a dinosaur expert at the Smithsonian National Museum of Natural History in Washington, D.C., who did not participate in the research. Witmer “certainly makes a strong case for paranasal sinuses [air-filled spaces within the skull] reducing the weight of the skull in certain dinosaurs,” Sues said. Sues cautioned, however, that “such functional hypotheses are difficult to test even in living species, including our own.” 
Packing what may be the world’s biggest bite, a recently revealed “sea monster” would have given Jaws a run for its money.
A scary new “sea monster” skull went on display in 2011 at the United Kingdom’s Dorset County Museum, showing the world another of the terrifying predators that used to swim in the world’s oceans.
The 7.9-foot-long (2.4-meter-long) skull belonged to a pliosaur, a type of plesiosaur that had a short neck, a huge, crocodile-like head, and razor-sharp teeth. When alive about 155 million years ago, the seagoing creature would have had a strong enough bite to snap a car in half, according to the museum.
Mexican Pliosaur
Two German paleontologists found the 120-million-year-old pliosaur specimen—with a head the size of a car—in Mexico in 2002.
The Dorset County Museum exhibit includes a life-size model of the pliosaur head to show what the animal would have looked like. A digital model of the Dorset pliosaur was also created using data from a high-energy microfocus CT scanner. Scientists from several universities are teaming up for further research from the find, such as searching for fossil plankton that may have been preserved in mud surrounding the fossil pieces.
Amateur collector Kevan Sheehan found the skull in pieces between 2003 and 2008 at the Jurassic Coast World Heritage Site, a 95-mile (152-kilometer) stretch of fossil-rich coastline in England. Sheehan gathered the pieces as they were washed out of a landslide on the coast of Weymouth Bay—the largest segment being more than 176 pounds (80 kilograms). Three pieces were later found by two other collectors, making the skull more than 95 percent complete, according to the museum.
“It is an amazing achievement to have recovered this fossil from an eroding cliff over such a long period of time and without losing any important pieces,” Richard Edmonds, earth science manager for the Jurassic Coast Team, said in a statement. The team is a group of county officials who work to preserve the heritage area.
Arctic Sea Monster
Found in Norway in 2008, one fossilized skull belonged to a 50-foot-long pliosaur that was longer than a humpback whale and had teeth the size of cucumbers.
The Dorset County Council’s museums service purchased the fossil, and later research by University of Southampton scientists suggests that it’s the largest complete pliosaur skull ever found.
Yet Hans-Dieter Sues, a paleontologist at the National Museum of Natural History in Washington, D.C., cautioned in an email that it’s too early to say if the skull is indeed the largest. “Some pliosaurs are gigantic animals, and there is an unfortunate tendency to brand every new find as the largest,” said Sues. “However, no evidence is ever presented to support these claims, which make for good media coverage but are scientifically unwarranted.”
Pliosaurs were successful predators and evolved features to aid in capturing prey. Some pliosaur species developed supersize eyes, fearsome teeth, or extremely long necks. As for the Dorset specimen, further research—including CT scans—may show whether the 52-foot-long (16-meter-long) beast is a new species. Yet Sues noted that “the classification of late Jurassic pliosaurs is still a mess, and, in absence of a reliable, published, modern review of all European specimens, it is hard to sustain any claim of a new species.”
Steamy year-round temperatures may have created the perfect environment for the world’s biggest snakes. Could climate change bring their kind back?
The world’s biggest snake was a massive anaconda-like beast that slithered through steamy tropical rain forests about 60 million years ago, says a new study that describes the ancient giant.
TRUTH:
THE TITANOBOA CERREJONENSIS WAS LONGER THAN A CITY BUS AND HEAVIER THAN A CAR.
Fossils found in northeastern Colombia’s Cerrejon coal mine indicate the reptile, dubbed Titanoboa cerrejonesis, was at least 42 feet (13 meters) long and weighed 2,500 pounds (1,135 kilograms).
“That’s longer than a city bus and … heavier than a car,” said lead study author Jason Head, a fossil-snake expert at the University of Toronto, Mississauga in Canada and a research associate with the Smithsonian Institution. Previously the biggest snake known was Gigantophis garstini, which was 36 to 38 feet (11 to 11.6 meters) long. That snake lived in North Africa about 40 million years ago.
The world’s biggest snake lounges in the tropics in this illustration. (Photo Credit 10.3)
Hans-Dieter Sues, associate director for research and collections at the Smithsonian’s National Museum of Natural History, was not involved with the study but has seen the snake fossils. Sues noted that humans would stand no chance against one of these giants, which killed their prey by slow suffocation.
“Given the sheer size—the sheer cross-section of that snake—it would be probably like one of those devices they use to crush old cars in a junkyard,” Sues said.
In addition, the snake’s heft indicates that it lived when the tropics were much warmer than they are today, a find that holds potential implications for theories of once and future climate change.
Scientists know there’s a link between a snake’s body size, how fast it uses and produces energy, and climate. “We were able to use the snake, if you will, as a giant fossil thermometer,” study author Head said.
His team found that, for Titanoboa to reach its epic proportions, it would mean year-round temperatures would have been about 90 degrees Fahrenheit (32 degrees Celsius)—significantly hotter than today’s tropics.
This supports the idea that tropical temperatures spike as the rest of the world heats up due to global warming, the study authors say. The competing theory is that, during bouts of warming, the tropics stay about the same average temperature as they are today while areas north and south of the Equator heat up.
James Zachos, an expert on ancient climates at the University of California, Santa Cruz, who was not involved in the study, agreed. As the biggest known snake, Titanoboa supports the idea of “much hotter tropics during extreme greenhouse periods,” Zachos said.
Study co-author Jonathan Bloch is a vertebrate paleontologist at the University of Florida’s Museum of Natural History in Gainesville. The same Colombian coal mine that contained the biggest snake also yielded massive turtles and crocodiles, he said.
“You can think about it as an ecosystem dominated by giants, I think, and these are probably giants that got large because of the warmer mean annual temperature,” he said.
The findings paint a picture of what the future might hold if supercharged global warming takes place. According to some models, global temperatures could approach the same levels that gave rise to the biggest snake by the end of this century.
Opposite End of the Spectrum
The world’s smallest snake, the Leptotyphlops carlae, is less than four inches long and was discovered in 2008 on the Caribbean island of Barbados. Due to its tiny size, it can easily be mistaken for an earthworm. L. carlae is a new species of snake that belongs to a group called thread snakes, and it may be on the verge of extinction.
If current greenhouse gas emissions continue apace, there’s a chance snakes the size of Titanoboa could return, Bloch said. “Or maybe snakes would go extinct in the tropics,” he said. “In other words, the warming could happen so rapidly that they wouldn’t have time to adapt.”
Mirror, mirror on the wall. Who is the earliest ancestor of us all? The answer might surprise you.
Microscopic, spongelike African fossils could be the earliest known animals—and possibly our earliest evolutionary ancestors, scientists say. The creature, Otavia antiqua, was found in 760-million-year-old rock in Namibia and was as tiny as it may be important.
TRUTH:
THERE ARE 9,000 SPECIES OF SPONGES, AND THEY OCCUPY VIRTUALLY EVERY AQUATIC HABITAT ON EARTH.
“The fossils are small, about the size of a grain of sand, and we have found many hundreds of them,” said study leader Anthony Prave, a geologist at the University of St. Andrews in the United Kingdom. “In fact, when we look at thin sections of the rocks, certain samples would likely yield thousands of specimens. Thus, it is possible that the organisms were very abundant.”
From these tiny “sponges” sprang very big things, the authors suggest. As possibly the first multicellular animals, Otavia could well be the forerunner of dinosaurs, humans—basically everything we think of as “animal.”
A modern-day stove-pipe sponge (Photo Credit 10.4)
Prior to the new discovery, the previous earliest known “metazoan”—animals with cells differentiated into tissues and organs—was another primitive sponge, dated to about 650 million years ago.
Based on where the new fossils were found, Prave and his colleagues think Otavia lived in calm waters, including lagoons and other shallow environments. The team thinks Otavia fed on algae and bacteria, which the animal drew through pores on its tubelike body into a central space. There the food was digested and absorbed directly into Otavia’s cells. The simple setup seems to have worked.
The fossil record indicates Otavia survived at least two long-term, severe cold snaps known as “snowball Earth” events, when the planet was almost completely covered in ice. Despite such wild environmental swings, “the oldest and youngest Otavia fossils all have the same quasi-ovid form, with large openings leading from the exterior,” Prave said in an email.
In short, the animals didn’t evolve much, he said—suggesting that, at least for its roughly 200 million years of existence, Otavia was built to last.
Fossils of ancient mammals are very rare—mostly because of their small size. But this latest find, a squirrel with very sharp teeth, gives paleontologists new insight into an ancient world.
The fossilized skull and teeth of a fanged, shrewlike mammal have been found in Argentina, a new study says. The new species—dubbed Cronopio dentiacutus for its narrow snout and long fangs—was about 8 to 9 inches (20 to 23 centimeters) long and likely used its pointy teeth to hunt and eat insects.
The Little Guys
C. dentiacutus was very small, like most mammals at the time. “These were the tiny little guys that would squirrel in between the toes of the dinosaurs trying not to get stepped on,” says Guillermo Rougier, a paleobiologist who specializes in these animals. Mammals didn’t grow to be the size of cats and dogs until after the larger dinosaurs became extinct.
The second oldest mammal skull ever recovered from South America, C. dentiacutus existed when dinosaurs still roamed Earth. Paleontologists found the mostly complete skull in 2002 outside a rural village in northern Argentina. At the time, however, the skull was mostly hidden in rock, and its identity remained a mystery.
This is an artist’s rendition of what the saber-toothed squirrel might have looked like. (Photo Credit 10.5)
So in 2005 the scientists sent the skull to a technician, who spent three years removing the rock from around the fossil—finally revealing a saber-toothed, squirrel-like creature.
“When [the movie] Ice Age came out, we thought the squirrel character in it looked ridiculous, but then we found something like it,” said study leader Guillermo Rougier, a paleontologist at the University of Louisville in Kentucky. “This animal looks very peculiar, with long snout and canines, and it highlights that we know so little. Surprises like this are bound to happen.”
Both mammals and dinosaurs appeared near the end of the Triassic period, some 220 million years ago. When dinosaurs disappeared about 65 million years ago, mammals thrived. But ancient-mammal fossils are still exceedingly rare, mostly because of their small sizes.
“Getting on your hands and knees … is how you find small-mammal fossils,” Rougier said. “It is not very glamorous. You basically roll in the dirt all day.” As a result, paleontologists know of roughly one genus of mammal for every million years between 65 million and 220 million years ago—making for a woefully incomplete record. “Imagine trying to reconstruct the history of life with that information,” Rougier said. “We’re certain there were hundreds of [genuses], but for now it’s like trying to reconstruct the brilliance of James Joyce with just ten of his words.”
Don’t make these ancient flightless birds angry. You wouldn’t like them when they’re angry.
A flightless bird with wings like martial arts weapons once thrashed its foes on what’s now Jamaica, a new study says.
Dubbed Xenicibis, the prehistoric bird wielded its unusual wings like nunchucks, or nunchakus, swinging its upper arms so that thick, curved hand bones hinged at the wrist would deliver punishing blows. The weaponlike wings are so unique that study co-author Nicholas Longrich of Yale University at first assumed the odd limbs were evidence of a deformity.
“There are a lot of birds that do have weaponry,” Longrich said. “They just don’t have anything like this.”
“No animal has ever evolved anything quite like this. We don’t know of any other species that uses its body like a flail. It’s the most specialized weaponry of any bird I’ve ever seen.”
Nicholas Longrich
research leader, Yale University
Xenicibis is an extinct member of the ibis family that grew to be the size of a large chicken. Although the ancient animal had been known for years, new analysis of several recently discovered partial skeletons has only now revealed the odd wing bones.
Wings are among the most powerful parts of birds, and some modern species boast specialized wing weapons. Screamer birds, for instance, use daggerlike spurs to fight for mates, while steamer ducks have wrist knobs that can break bones or even kill other birds. Since Xenicibis was flightless, Longrich and colleagues think the ancient bird evolved to have wings that were even more specialized for combat.
Examinations of the skeletons uncovered evidence of past violence—one wing had a fractured hand bone, and another had a centimeter-thick upper-arm bone that had been cleanly snapped in half. The bird’s living ibis relatives are anatomically similar except for the “weapon wings,” so modern ibis behavior may shed light on when and how Xenicibis used its built-in arsenal. Male ibis, for example, regularly battle each other over territories for nesting and feeding.
But Xenicibis may also have needed its powerful wings to fight off other threats. “Most flightless birds, like the dodo, had absolutely no predators around. But Jamaica had many snakes, raptors, and other potential predators,” Longrich said. “So maybe they just needed a bit more defense.”
Boxing Birds
The prehistoric Phorusrhacid, also known as the terror bird, had a hatchet-like skull that was used to kill prey with a succession of punishing blows. The skull was the size of a modern-day horse’s head, and was very strong and rigid when driven straight down into prey. Like the Xenicibis, the terror bird was also flightless, so it most likely evolved to have such a skull in order to survive on land.
Longrich and colleagues are most curious about the ultimate fate of the prehistoric birds. Fossils indicate Xenicibis lived at least as recently as 12,000 years ago. But the record is too sparse at this point to know exactly when they vanished—or if ancient humans might have been involved.
“Did they disappear long before people arrived in Jamaica [several thousand years ago] or last long enough for people to wipe them out?” Longrich said. “They were a convenient size for a family dinner and couldn’t fly. Humans are pretty handy with clubs also, so it might not have been a very fair fight. But at this point we just don’t know.”
Ill-tempered dinosaur used her massive muscular legs to kick away fearsome raptors, expert says.
A newfound dinosaur species that used its “exceptionally powerful” thighs to kick predators likely had a bad temper to boot, one expert says.
The 46-foot-long (14-meter-long) Brontomerus mcintoshi had an immense blade on its hipbones, where strong muscles would have attached, according to a new study. “These things don’t happen by accident—this is something that’s clearly functional,” said study co-author Mathew Wedel.
The team suspects the dinosaur—a type of sauropod, or plant-eating, four-legged lumberer—used its massive legs to either maneuver over hilly ground or deliver “good, hard” kicks to predators, said Wedel, assistant professor of anatomy at Western University of Health Sciences in Pomona, California.
Brontomerus—“thunder thighs” in Greek—may have even attacked like a modern-day chicken, relentlessly kicking and stomping pursuers to death, he added. “I could only imagine how ill-tempered these sauropods would have been,” Wedel said—as are most birds, dinosaurs’ modern-day descendants.
TRUTH:
THE LARGEST DINOSAURS WERE VEGETARIANS.
A “thunder thighs” dinosaur mother protects her offspring in an artist’s conception. (Photo Credit 10.6)
In both cases, “you’ve got a little brain, you’re permanently paranoid about all these meat-eaters around, and you’re trying to protect your young.”
Thunder thighs’ bones were first found in 1994, when scientists rescued two partial skeletons of the then unidentified dinosaur from a fossil quarry that had otherwise been looted in eastern Utah.
When Wedel and colleagues examined the bones in 2007, they realized they’d found a new species—and an “extreme” one at that, Wedel said. For instance, the shapes of the newfound species’ bones showed it had the largest leg muscles of any sauropod yet found.
B. mcintoshi likely needed such extreme defenses to fight off “terrifying” predators such as Deinonychus and Utahraptor, raptors that lived alongside the plant-eater about 110 million years ago in the early Cretaceous period, he said.
The prehistoric animals roamed a landscape that would have resembled Africa’s Serengeti, laced with rivers and mud holes and distinguished by vast, dry upland areas, Wedel noted. Herds of cowlike plant-eaters called Tenontosaurus would have dotted the plains.
“If I could shoot you back in a time machine, it would have been like going on safari, except you’d want something more robust than a Land Rover—maybe a tank,” he said. “The sauropods were probably beautiful animals if you were a long way away with binoculars,” he added.
“But up close, [they were] probably a nightmare.”
Predatory dragonflies the size of modern seagulls ruled the air 300 million years ago, and it’s long been a mystery how these and other bugs grew so huge.
Dragonflies as big as seagulls? Oversized giant cockroaches? Why did these bugs get so big? To avoid oxygen overdose, one study hints.
The leading theory is that ancient bugs got big because they benefited from a surplus of oxygen in Earth’s atmosphere. But a new study suggests it’s possible to get too much of a good thing: Young insects had to grow larger to avoid oxygen poisoning.
“We think it’s not just because oxygen affects the adults but because oxygen has a bigger effect on larvae,” said study co-author Wilco Verberk of Plymouth University in the United Kingdom. “So a larval perspective might lead to a better understanding of why these animals existed in the first place, and maybe why they disappeared.”
Fossils show that giant dragonflies and huge cockroaches were common during the Carboniferous period, which lasted from about 359 to 299 million years ago. During this time, the rise of vast lowland swamp forests led to atmospheric oxygen levels of around 30 percent—close to 50 percent higher than current levels.
According to previous theories about insect gigantism, this rich oxygen environment allowed adult bugs to grow to ever larger sizes while still meeting their energy needs.
For the new study, Verberk and colleague David Bilton instead focused on how varying oxygen levels affect stonefly larvae, which, like dragonflies, live in water before becoming terrestrial adults. Higher concentrations of oxygen in air would have meant higher concentrations dissolved in water.
TRUTH:
SEVENTY-FIVE PERCENT OF ALL ANIMALS ARE INSECTS.
The results showed that juvenile stoneflies are more sensitive to oxygen fluctuations than their adult counterparts living on land. This may be because insect larvae typically absorb oxygen directly through their skin, so they have little or no control over exactly how much of the gas they take in. By contrast, adult insects can regulate their oxygen intake by opening or closing valvelike holes in their bodies called spiracles.
While crucial for life, oxygen can be poisonous in large quantities: Humans exposed to excess oxygen can suffer cell damage leading to vision problems, difficulty breathing, nausea, and convulsions. It’s likely the larvae of many ancient insects also passively absorbed oxygen from water and were not able to regulate their oxygen intake very well—a big danger when oxygen levels were so high.
One way to decrease the risk of oxygen toxicity would have been to grow bigger, since large larvae would absorb lower percentages of the gas, relative to their body sizes, than small larvae. “If you grow larger, your surface area decreases relative to your volume,” Verberk explained.
The new theory could also explain why giant insects continued to exist even after Earth’s atmospheric oxygen levels began decreasing, he said. “If oxygen actively drove increases in body mass to avoid toxicity, lower levels would not be immediately fatal, although in time, they [would] probably diminish performance of the larger insects,” since adults would have evolved to require more oxygen and would get sluggish in air with lower levels, Verberk said.
“Such reduced performance will eventually have made it possible for other species to outcompete the giants.”
Having a bird brain wasn’t such a bad thing 65 million years ago. It was these bigger bird brains that kept them alive while the dinosaurs and their teeny brains went extinct.
Birds survived the global catastrophe that wiped out their dinosaur relatives due to superior brainpower, a 2009 study suggests.
A pair of prehistoric seabirds found in southeast England by Victorianera fossil hunters were examined by researchers from the Natural History Museum in London. The two 55-million-year-old skulls suggest the ancestors of modern birds developed larger, more complex brains than previously thought.
TRUTH:
RESEARCHERS HAVE FOUND THAT PREHISTORIC SEABIRDS’ BRAINS WERE NEARLY THE SAME SIZE AS THOSE IN BIRDS ALIVE TODAY.
This implies that bird ancestors had a mental edge over non-birdlike dinos and flying reptiles, so they were better able to adapt after the so-called K-T mass extinction event around 65 million years ago, said study co-author Angela Milner.
Some ancient groups of birds did go extinct, she noted, so it wasn’t feathers or warm-bloodedness that gave modern birds a leg up. “It had to be something else,” she said, “and it seems to be this bigger brain.”
The study, published in 2009 in the Zoological journal of the Linnean Society, was based on two specimens from the Natural History Museum’s vast fossil collection. Odontopteryx toliapica belonged to an extinct group of giant, bony-toothed seabirds, while Prophaethon shrubsolei was a prehistoric relative of ternlike tropical seabirds.
Milner and colleagues used CT scans of the skulls to make models of the size and shape of the fossil birds’ brains. What they found is that the ancient bird brains were almost the same size as those in birds alive today. The older noggins also showed early growth of a brain region known as the wulst.
“It seems to be the area that’s involved in more complex behavior and cognition, such as being able to learn about your environment and remember it,” Milner said. So after the K-T event, she said, these birds “were just better equipped to deal with challenging physical conditions.”
Fossil bird skulls that have not been flattened out over time are extremely rare, and no examples are known from the time of the K-T event. But Milner says the brain advances seen in the 55-million-year-old birds would probably have begun more than 65 million years ago.
And fossils of the oldest known bird, Archaeopteryx, which lived 147 million years ago, reveal its brain was “nowhere near as well developed as the ones we looked at,” she said.
Julia Clarke, a geoscientist at the University of Texas at Austin who was not involved with the study, says there are various competing theories to explain why birds outlived the dinosaurs. One idea is that the ancestors of all living birds came from the southernmost part of the southern supercontinent Gondwana, where they escaped the worst of the environmental fallout from the K-T event.
Another theory is that modern bird lines evolved in coastal habitats that also were less heavily impacted. As well as providing valuable new evidence for the evolution of birds, she said, the latest study offers an intriguing new theory that will motivate paleontologists to look harder and farther to find more fossils.
“We still desperately need good fossils sampling brain and skeletal features in the species that are very close but outside the [evolutionary tree] of all living birds,” Clarke said. “We can only get so close to understanding the brains of the earliest birds with the sample of known species currently available.”
The prehistoric “ShieldCroc” had a fierce look, but weak jaws. Paleontologists say this “one of a kind” creature was more pelican than pro-wrestler when it hunted.
A new prehistoric croc sporting an odd head “shield” has been found in Morocco, paleontologists say. Dubbed ShieldCroc, the animal’s head appendage was surrounded by blood vessels and covered with a sheath like those seen in frilled dinosaurs, including Triceratops.
At 30 to 35 feet (9 to 11 meters) long, the river-dwelling monster would have preyed on other giant animals of the late Cretaceous, such as 13-foot-long (4-meter-long) coelacanths. But ShieldCroc likely boasted relatively weak jaws, at least compared with those of today’s crocodiles.
“It’s fairly certain that it belonged to a group of crocodyliforms—including the flat-headed crocs—that had really thin, weak jaws and weak chin joints,” said researcher Casey Holliday, a paleontologist at the University of Missouri. Crocodyliforms are part of a group known as the crocodilians, which includes modern-day alligators, caimans, and more.
TRUTH:
SCIENTISTS OFTEN USE THE HEAD SIZE OF AN ANIMAL TO ESTIMATE ITS TOTAL LENGTH.
“So they weren’t wrestling dinosaurs on the water’s edge. They would have been quick, snap feeders waiting for prey to come by and then grabbing it and swallowing it with large, basket-shaped mouths—something like a pelican would do,” Holliday said.
A piece of ShieldCroc’s skull landed in Canada’s Royal Ontario Museum in the early 2000s, but Holliday and colleagues have only recently studied the specimen and its odd headpiece. It’s difficult to determine what purpose the shield served when the animal lived, some 99 million years ago, Holliday noted.
But after rigorous evaluation of the fossil and studies of comparative behaviors with modern crocodilians, scientists suggest the shield may have helped ShieldCroc regulate its temperature and communicate with other ShieldCrocs.
For instance, some crocodyliforms and living crocodilians, such as the Cuban crocodile, have horns on the sides of their heads, which males use to impress females and scare away other males. “We kind of see ShieldCroc having similar behaviors and showing off the roof of its head,” Holliday said.
An illustration of ShieldCroc snatching its prey (Photo Credit 10.7)
Despite these possible similarities with modern crocodilians, the animal appears to have been one of a kind, said Christopher Brochu, a University of Iowa paleontologist, who wasn’t involved in the study. “There’s nothing quite like this among the birds or the crocodilians, which are the two closest living relatives of this thing.”
Five Oddball Prehistoric Crocs
1. RatCroc—rodent-like, with buck teeth for rooting through the ground for tubers and simple animals
2. PancakeCroc—flat-bodied, lying motionless and waiting for prey to swim into its thin, 3-foot-long jaws
3. DuckCroc—used its long, smooth, sensitive nose to poke through vegetation and its hook-shaped teeth to capture frogs and small fish in shallow water
4. DogCroc—a plant-eater with lanky legs, which indicates it was quick enough to run into water if threatened
5. BoarCroc—a 20-foot-long “saber-toothed cat in armor” that preyed on dinosaurs with its three sets of fangs
ShieldCroc’s discovery in Morocco could suggest that modern crocs evolved in what’s now the Mediterranean—a theory that remains hotly debated among crocodilian experts. But there’s no doubt the animal provides evidence of astonishing crocodyliform diversity in the Southern Hemisphere during the late Cretaceous, said Holliday, who described the new species at the 2011 Annual Meeting of the Society of Vertebrate Paleontology in Las Vegas.
“It definitely points to … Africa [as] a melting pot of different crocodyliforms living in the same region at the same time,” Holliday said. “One lineage, including DogCroc, BoarCroc, and others tended to be terrestrial, while another group, including SuperCroc, were big, aquatic, predatory crocs. ShieldCroc represents another group and a more modern flavor of crocs.”
With the discoveries of ShieldCroc and related species, University of Iowa’s Brochu said, “We’re beginning to realize just how diverse and even bizarre the crocodyliforms were in the Southern Hemisphere,” he said. “The group was extremely widespread, and in some places crocodyliforms may have been among the major predators and even herbivores. And in some places they really were simply bizarre.” For instance, “in the southern Mediterranean, including North Africa, we’re seeing these animals that look nothing like any living crocodilian.”
Taking off was no easy task for an enormous bird that lived in the Andes mountains six million years ago. How did this big bird get airborne?
The largest bird that ever flew was an expert glider but was too heavy to fly by flapping its wings, researchers say.
Getting off the ground was a challenge for the 155-pound (70-kilogram) Argentavis magnificens, a condorlike bird that lived in the Andes mountains and the pampas of Argentina about six million years ago. Despite its massive flight muscles and 21-foot (6.4-meter) wingspan, the giant bird probably could not generate enough lift to take off from a level surface, according to a new study.
Fly Like a Bird
NASA engineers have programmed a model airplane to look for rising columns of hot air called thermals and use them to soar like a bird, similar to the way the prehistoric Argentavis magnificens probably flew. This way of flight allows air currents to do most of the work required to gain altitude.
Like human hang gliders, Argentavis probably had to run downhill into a headwind to become airborne, said Sankar Chatterjee of Texas Tech University in Lubbock. “Takeoff capability is the limiting factor for the size of flying birds, and Argentavis almost reached the upper limit,” Chatterjee said. “Heavier birds such as the ostrich had to give up flight.” Once aloft, however, Argentavis was no ostrich. Despite weighing as much as 16 bald eagles, Chatterjee said, “it was an excellent glider, like a sail plane.”
“Mythological versions of giant soaring birds appear in religions all over the world. What we have done is shown that it would have been possible for a so-called monster bird to fly.”
Sankar Chatterjee
curator of paleontology, Texas Tech University
The new understanding of Argentavis flight comes from an unusual collaboration between paleontologists and a retired aeronautical engineer. The researchers took measurements from Argentavis fossils and then conducted their analysis using a computer program designed to study flight performance in helicopters.
“Birds are commonly compared with aircraft, but in reality helicopters are a better analogy,” Chatterjee said. Unlike engine-powered airplanes, he noted, birds rely on their wings for both forward thrust and vertical lift, the two components necessary for flight.
Although Argentavis could not wing skyward on its own, the researchers say, it could have reached high altitudes by riding winds deflected upward over mountains. More commonly, particularly in open terrain, Argentavis probably gained elevation by circling inside rising columns of warm air, known as thermals.
The huge flyer may have traveled hundreds of miles by repeatedly riding thermal “elevators” and then soaring gradually back to earth, Chatterjee said.
Some of the largest flying birds today, such as condors and eagles, pursue a similar strategy. Although capable of powered flight, these species save energy by letting air currents do most of the work required to gain altitude.
In the past, researchers have disagreed as to whether Argentavis was a predator, like most hawks and eagles, or a scavenger. Chatterjee and co-author Kenneth Campbell, of the Natural History Museum of Los Angeles County, say fossil details indicate the species was an active predator.
“[The birds’ skull] was adapted for catching prey and swallowing it whole,” Campbell said. “Its jaw mechanics were not suited for tearing flesh from carcasses, as in vultures, nor for tearing prey animals apart for swallowing, as in eagles and owls.”
TRUTH:
ONE OF THE LARGEST BIRDS TODAY IS THE ANDEAN CONDOR, WHICH HAS A WINGSPAN OF ABOUT 9 FEET AND WEIGHS 25 POUNDS.
But Paul Palmqvist, of the University of Malaga in Spain, has argued that a flying species as large as Argentavis must have been a scavenger. Palmqvist’s argument is based in part on a predictable relationship between body size and foraging area seen in predatory hawks and eagles today.
Given its huge size, Palmqvist says, a predatory Argentavis would not have been able to cover enough ground and locate enough prey to meet its daily needs. “A vulturelike behavior is more reasonable, as vultures have smaller range areas,” Palmqvist said. “Carrion is more available than living flesh.”
The new flight analysis, he said, also tends to support his view. “Given its lack of maneuverability, a predator this size would have a problem landing on its prey,” Palmqvist noted. But Chatterjee and Campbell said the species was certainly a capable enough flyer to attack live prey—probably rabbit-size mammals—from the air.
Found in “bizarre” prehistoric fish, scientists have found a 300-million-year-old brain-the oldest fossil of its kind.
Digital x-ray images of a “bizarre” 300-million-year-old shark relative have revealed the oldest known fossilized brain, researchers announced in 2009.
The unusual discovery raises hopes that scientists will find other ancient brains and use them to study how gray matter has evolved, said John Maisey, a paleontologist at the American Museum of Natural History in New York. “The brain … is remarkably soft tissue—brain tissue is mostly water,” Maisey said. “To preserve anything is quite remarkable.”
TRUTH:
THE BRAIN GROWTH OF MODERN SHARKS, RAYS, AND CHIMAERA FISH SLOWS AS THEY AGE, EVEN THOUGH THE REST OF THEIR BODIES CONTINUE TO EXPAND.
The fossil was found in an iniopterygian, an extinct ancestor of modern ratfishes, also called “ghost sharks” or chimaeras. The fish are also distant relatives of sharks and rays. Maisey said the ancient fish, which swam in an ocean that once covered the midwestern United States, would have fit in the palm of a human hand. Despite their small size, the fish sported a strange appearance: huge eye sockets, rows of sharp sharklike teeth, tails with clubs, large pectoral fins, and spikes on the tips of their fins.
The fossilized brain of this shark ancestor was the size of a pea. (Photo Credit 10.9)
The scans revealed the fish had a pea-size brain much smaller than the braincase itself. This is similar to modern sharks, rays, and chimaera fish, whose brain growth slows as they age, even as the rest of their bodies expand.
The iniopterygian’s brain has a large lobe for vision, and the skull has relatively large eye sockets. This suggests the fish “was using its eyes as a major way to locate prey,” Maisey said. In addition, the hearing-related section of the brain is flattened. This reflects the curious arrangement of the iniopterygian ear, which was optimized for side-to-side movement, but not up and down movement.
“It is really a very puzzling fish as to how it would have moved around and what it could have done,” Maisey said. “They are really, really bizarre.”
A new study claims that Neanderthals were done in by the more successful Homo sapiens. But extinction was not through acts of violence, but acts of love.
Neanderthals may have been victims of love, or at least of interspecies breeding with modern humans, according to a new study.
As the heavy-browed species ventured farther and farther to cope with climate change, they increasingly mated with our own species, giving rise to mixed-species humans, researchers suggest. Over generations of genetic mixing, the Neanderthal genome would have dissolved, absorbed into the Homo sapiens population, which was much larger.
A reconstruction of a Neanderthal female (Photo Credit 10.10)
“If you increase the mobility of the groups in the places where they live, you end up increasing the gene flow between the two different populations, until eventually one population disappears as a clearly defined group,” said study co-author C. Michael Barton, an archaeologist at Arizona State University’s School of Human Evolution and Social Change.
“Normally the first groups who [encounter] a new population are men, hunting parties perhaps. And men, being the way they are—if they meet women from another population, there is bound to be interbreeding.”
Bence Viola
paleoanthropologist, on possible reasons why Neanderthals and humans interbred
Some theories suggest Neanderthals disappeared about 30,000 years ago because the species wasn’t able to adapt to a cooling world as well as Homo sapiens.
Barton tells a different tale, suggesting that Neanderthals reacted to the onset of the Ice Age the same ways modern humans did, by ranging farther for food and other resources. “As glaciation increased, there was likely less diversity in land use, so Neanderthals and modern humans alike focused on a particular survival strategy that we still see today at high latitudes,” Barton said.
“They establish a home base and send out foraging parties to bring back resources. People move farther and have more opportunity to come into contact with other groups at greater distances. The archaeological record suggests that this became more and more common in Eurasia as we move toward full glaciation.”
More frequent contact led to more frequent mating, the theory goes, as the two groups were forced to share the same dwindling resources. “Other things might have happened,” Barton said. “But in science we try to find the simplest explanation for things. This theory doesn’t include massive migrations or invasions—just people doing what they normally do.”
To estimate the effects of the assumed uptick in interspecies mating, Barton’s team conducted a computational modeling study that spanned 1,500 Neanderthal generations. In the end, the model results supported the not entirely new idea that Neanderthals were “genetically swamped” by modern humans.
Though it’s a relative underdog among Neanderthal-demise theories, genetic swamping is a well-known extinction cause among plant and animal species. A smallish group of native, localized trout, for example, may lose their genetic identity after a large influx of a different species with which the native fish are able to breed.
“When endemic populations are specialized, and for some reason there is a change in their interaction with adjacent populations, and that interaction level goes up, they tend to go extinct—especially if one population is much smaller than the other,” Barton explained. “In conservation biology this is called extinction by hybridization.”
TRUTH:
DNA EVIDENCE SUGGESTS THAT NEANDERTHALS MIGRATED AS FAR EAST AS SIBERIA.
Paleoanthropologist Bence Viola said other models have produced different results, and some studies have concluded that relatively little interbreeding occurred. But Viola, of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, is intrigued by Barton’s research.
“From an archaeological and anthropological perspective, this sounds interesting and closer to what I believe—that you can have a lot of interbreeding,” Viola said. “Normally the first groups who [encounter] a new population are men, hunting parties perhaps. And men, being the way they are—if they meet women from another population, there is bound to be interbreeding.”
Barton believes interbreeding caused other distinct human and human-ancestor groups to fade away. “But their genes didn’t disappear,” he added. “And their culture probably didn’t disappear either but was blended into a larger population of hunter-gatherers.”
The Max Planck Institute’s Viola believes interbreeding was a cause—but not the cause. “Neanderthals disappeared around 30,000 years ago, and that was a period when the climate turned colder, and that likely made it physically harder for them to survive,” Viola said. “They also may have been exposed to some type of disease that modern humans brought from Africa and for which they had no immunity.
“Of course these are all things that are very hard to study archaeologically,” Viola added. “So these models are a great tool for investigating ideas.”
Deadly and dog size, the dinosaur Eodromaeus lived in Argentina 230 million years ago, in the time before dinosaurs dominated. What can we learn from the little monster?
The new species is providing fresh insight into the era before dinosaurs overtook other reptiles and ruled the world, a new fossil study says. “This is the most complete picture we have of a predatory dinosaur lineage—what it looked like at the very beginning,” said study co-author Paul Sereno. “It was small but nasty—this animal was fast.”
“It was very cute; you’d want it as a pet. But it might be best as a guard dinosaur, to keep the dogs away.”
Paul Sereno
paleontologist and study author
One of the earliest known dinosaurs, Eodromaeus was only about 4 feet (1.3 meters) long and would have barely reached the knees of an adult human. But this unassuming little dinosaur gave rise to the theropods, including Tyrannosaurus rex and the “terrible claw,” Deinonychus, the new study suggests.
Like those fearsome descendants, Eodromaeus had a long rigid tail, a unique pelvis shape, and air sacs in its neck bones that may have been related to breathing—and which add to evidence that theropod dinosaurs eventually evolved into today’s birds.
Eodromaeus lived alongside—and now appears to have, in a sense, taken the place of—a very similar dinosaur species, Eoraptor, said University of Chicago paleontologist Paul Sereno, also a National Geographic explorer-in-residence. “If you went back 230 million years ago and one of these creatures flitted by, you’d have to wonder which one it was.”
Sereno and his team once thought Eoraptor was an ancestor of meat-eating dinosaurs. But due to recent analysis of Eoraptor fossils, as well as the discovery of Eodromaeus, he now thinks Eoraptor was an ancestor of the giant, long-necked, plant-eating dinosaurs called sauropods.
“That’s the beauty of dinosaur origins,” Sereno said. “Who could predict that these 10- to 15-pound [4.5- to 7-kilogram] creatures—both looking quite similar but eating different things—would end up evolving into things as disparate as Diplodocus and Tyrannosaurus?”
The reclassification of Eoraptor makes sense, agreed Hans-Dieter Sues, a dinosaur expert at the National Museum of Natural History in Washington, D.C., who was not involved in the study. “One thing that everyone noticed when Eoraptor was first discovered was that the back teeth were very odd-looking for a theropod,” said Sues, also a contributing editor to the National Geographic News Watch blog. “It had these little leaf-shaped teeth in the back, and those are teeth you don’t really find in theropods.”
TRUTH:
THE DINOSAUR EODROMAEUS WAS ABOUT 4 FEET LONG AND WEIGHED 10 TO 14 POUNDS.
Nearly all of the bones of Eodromaeus have been accounted for—considered remarkable for such a small creature. Based on its fossils, scientists think Eodromaeus, like its theropod descendants, stood and ran on two legs and had sharp teeth and grasping claws, which the new dinosaur used to snatch the young of other reptiles.
University of Maryland paleontologist Thomas Holtz agreed that Eodromaeus is likely an early theropod ancestor. “I think they’ve got a good case for it here,” said Holtz, who wasn’t part of the new study. “In terms of characteristics, it does seem to be very, very low in the theropod family tree.”
It’s not too surprising that Eodromaeus and Eoraptor looked very similar, he added. Both shared a common ancestor only about ten million years before, which in evolutionary terms is not a very long time. “The closer we get to the common ancestor, the less time they’ve had to diverge, so they look a lot more like each other,” he said. “If you go back far enough, eventually they’re the same creature.”
An Avian Blueprint
The Eodromaeus had air sacs in its neck bones that might have been used for breathing, which adds to evidence that theropod dinosaurs evolved into today’s birds. Modern birds have complex respiratory systems, with two lungs and up to nine air sacs. Such efficient respiratory systems would have boosted meat-eating dinosaurs’ metabolisms and enable them to be active and effective hunters.
The desolate Valley of the Moon in northwestern Argentina, where fossils of Eodromaeus and Eoraptor were found, was filled with lush forests 230 million years ago, according to study co-author Sereno. “It was a gorgeous environment.”
Eodromaeus and Eoraptor shared this Triassic paradise with various other groups of reptiles, including parrot-beaked reptiles that were distantly related to dinosaurs, protomammals, and a number of large crocodile-like creatures. Studying the shared traits between Eodromaeus and Eoraptor could help scientists paint a picture of the unknown last common ancestor of all dinosaurs, University of Maryland’s Holtz said.
That dinosaur Eve, Holtz said, “was probably bipedal, its hands may have already been adapted for grasping … and its diet may not have been strictly meat or plants.” By contrast, “the first dinosaurs may have been omnivores.”
A 125-million-year-old dinosaur had more in his arsenal than just sharp teeth. Researchers believe this guy had venom and shocked its prey like a snake.
Jurassic Park (1993) was packed with pseudo-science, but one of its fictions may have accidentally anticipated a dinosaur discovery announced in 2009—venomous raptors.
Though a far cry from the movie’s venom-spitting Dilophosaurus, the 125-million-year-old Sinornithosaurus may have attacked like today’s rear-fanged snakes, a new study suggests. Rear-fanged snakes don’t inject venom. Instead, the toxin flows down a telltale groove in a fang’s surface and into the bite wound, inducing a state of shock.
In Sinornithosaurus fossils, researchers discovered an intriguing pocket, possibly for a venom gland, connected to the base of a fang by a long groove, which likely housed a venom duct, the study says. Sinornithosaurus fangs also feature snakelike grooves in their surfaces.
“The ductwork leading out of the venom gland gave the venom a way to travel to the base of the teeth, where the venom welled up in the grooves,” said study co-author paleontologist David Burnham of the University of Kansas Natural History Museum and Biodiversity Research Center.
TRUTH:
REAR-FANGED SNAKES DON’T INJECT VENOM—THE TOXIN FLOWS DOWN A GROOVE IN A FANG’S SURFACE AND INTO THE BITE WOUND.
“So when they sank their teeth into tissue of the victim, it allowed the venom, which was really enhanced saliva, to get into the wound.”
Turkey-size Sinornithosaurus, which likely had feathers, lived in the forests of what’s now northeastern China, and was a member of the family Dromaeosauridae. Birdlike Sinornithosaurus probably used its longish fangs to put the bite on prehistoric birds, Burnham said. Like rear-fanged snakes and some lizards, the dinosaur probably had nonfatal venom that could shock its victims into a defenseless stupor—allowing Sinornithosaurus to eat in peace.
Burnham’s research was inspired by the 2000 find of another possibly venomous dinosaur fang and by a recent discovery that today’s top lizard predator, the Komodo dragon, has a venomous bite that weakens victims so they can be eaten later.
Though believed to have descended from dinosaurs like Sinornithosaurus, today’s birds are toothless and so lack a venom delivery system (though some birds do have toxic skin and feathers). But Burnham is more interested in where Sinornithosaurus venom ability came from than how it evolved.
“How primitive is venom really? Does it go all the way back to the archosaurs?” he said, referring to reptiles thought to have predated dinosaurs by 30 million years or more. “These are things people haven’t really tested yet.”
Gotcha! A sculpture of Sinornithosaurus millenii dinosaur on the hunt (Photo Credit 10.11)
The king of the bunnies wasn’t a sleek, supple creature. Paleontologists believe he was a roly-poly beach bum.
The Easter bunny came early in March 2011 for a few scientists working on the Spanish island of Minorca. The team announced the discovery of Earth’s biggest known rabbit species, an oddly unbunny-like giant dubbed Nuralagus rex—“the Minorcan king of the hares.”
The 26-pound (12-kilogram) prehistoric species was about six times bigger than the common European rabbit, found on most continents, according to an analysis of several bones. Study leader Josep Quintana is no stranger to giant Minorcan rabbit fossils, though it took a while before he knew exactly how big a find he’d uncovered.
“When I found the first bone I was 19 years old, I was not aware what this bone represented. I thought it was a bone of the giant Minorcan turtle!” said Quintana, a paleontologist at the Institut Català de Palentologia in Barcelona.
TRUTH:
A 53-MILLION-YEAR-OLD RABBIT’S FOOT WAS UNEARTHED IN INDIA.
The animal, which lived about three to five million years ago, had several “odd” features that have never before been seen in rabbits, living or extinct, according to the study. For one, the giant rabbit’s “short and stiff” vertebral column meant it couldn’t bunny hop. And the relatively small sizes of sense-related areas of its skull suggested that the animal had small eyes and stubby ears—a far cry from modern rabbit ears. “I think that N. rex would be a rather clumsy rabbit walking,” Quintana said. “Imagine a beaver out of water.”
Despite its oddities, N. rex has many skull and teeth features found in rabbits—meaning there’s “no question” it’s a rabbit, according to Brian Kraatz, an expert in rabbit evolution at the Western University of Health Sciences in Pomona, California. “Really this is a rather typical rabbit head [albeit large] stuck on an atypical rabbit body,” said Kraatz, who was not involved in the study.
“When I found the first bone I was 19 years old, I was not aware what this bone represented. I thought it was a bone of the giant Minorcan turtle!”
Josep Quintana
paleontologist and study leader, on his initial thoughts upon discovering the N. rex fossil
The newfound rabbit’s “roly-poly, tank-like” appearance and weird anatomy may have arisen because of its stress-free lifestyle, Kraatz added. That’s because the megarabbit had no predators on Minorca—a luxury that allowed the species to evolve to be bigger and more sedentary, he said. Modern rabbits are small, spry, and have sharp vision to escape predators. “He was probably on an evolutionary vacation,” said Kraatz, like an “islander beach bum.”
Yet, even though the giant rabbit “didn’t have too many cares or worries,” Kraatz said, “he got too comfortable, and eventually went extinct.”
