Blogs / 80beats

The fossilized pelvis of a Homo erectus woman who lived 1.2 million years ago on the banks of an Ethiopian river has been discovered, and while researchers say it casts new light on human evolution, some of their conclusions are challenging previous theories about these early human ancestors. The pelvis reveals a short, squat woman who wasn’t built for long-distance running, but also a woman with a wide birth canal to accommodate big-brained infants.

Study coauthor Scott Simpson says the pelvis’s wide birth canal indicates that hominds’ increasing brain size was a driving factor in human evolution. Getting through the birth canal is “the most gymnastic thing we ever do,” he says. To accommodate big-brained babies, humans must have developed larger and wider birth canals over time, but with few pelvic fossils, researchers had little idea when these changes began. The Busidima pelvis shows that a wide birth canal was already in place 1.2 million years ago [New Scientist].

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The tiny skull of a juvenile dinosaur with a strange set of chompers has delighted paleontologists, who believe it proves that the species was a transitional phase between carnivorous dinosaurs and herbivores. The Heterodontosaurus has both sharp canine teeth for biting and molars for grinding, suggesting that the species dined on both small reptiles and insects as well as leafy greens.

Says study coauthor Laura Porro: “It’s likely that all dinosaurs evolved from carnivorous ancestors. Since Heterodontosaurs are among the earliest dinosaurs adapted to eating plants, they may represent a transition phase between meat-eating ancestors and more sophisticated, fully herbivorous descendants” [Telegraph]. The omnivorous dino lived 190 million years ago in the Early Jurassic period, Porro says.

Only two other Heterodontosaurus fossils have been found previously, and those both belonged to adults. This newly discovered fossilized skull measures less than 2 inches in length and belonged to a juvenile weighing less than two sticks of butter… [The researchers] studied the juvenile’s skull and determined the individual was probably buried alive in a sandstorm, a mode of death that left its remains in “relatively good condition” [Discovery News].

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Researchers have found a “bizarre” feathered dinosaur with a hodgepodge of characteristics, including four long tail feathers that researchers say may have evolved for display purposes–perhaps to attract a mate or scare off a rival. The well-preserved fossil of the new species, named Epidexipteryx hui, shows that the beast was covered in short, fluffy feathers but lacked the “contour feathers” that help modern birds fly; researchers say Epidexipteryx must have been flightless.

Paleontologist expert Angela Milner commented that the find “shows that feathers were likely being used for ornamentation for many millions of years before they were modified for flight. It provides fascinating evidence of evolutionary experiments with feathers that were going on before small dinosaurs finally took to the air and became birds” [BBC News].

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A new study of a the fossilized remains of the Tiktaalik, the “walking fish” that illuminates how swimming fish evolved into land-dwelling amphibians, shows that there was more to the transition than the switch from fins to limbs. The study shows that the head and braincase were changing, a mobile neck was emerging and a bone associated with underwater feeding and gill respiration was diminishing in size, a beginning of the bone’s adaptation for an eventual role in hearing for land animals [The New York Times].

The creature, dubbed Tiktaalik roseae — or, to be less formal, Fishapod — lived 375 million years ago 600 miles north of the Arctic Circle in a subtropical floodplain that eventually became Ellesmere Island, where it was discovered in 2004 [Wired News]. The fishapod has already earned its reputation as a “missing link” in evolutionary history due to its sturdy, jointed fins and its dual breathing system, with both gills and lungs. But the new study suggests that changes to the animal’s head and the development of the first neck also played a critical role in its evolution.

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The first migration of Homo sapiens, when they left the East African landscapes where they evolved and began a long trek across the Sahara, may have followed a different route than previously believed. A new study shows that prehistoric river channels fed by monsoons once traced a path north through the desert and argues that the modern humans may have followed those channels, going from oasis to oasis until they reached the sea.

The Sahara has had several periods of increased rainfall that made it a wetter and greener place, including one interlude between 130,000 to 170,000 years ago when the researchers believe these river channels flowed with water. Now only visible with satellite radar, the channels flowed intermittently from present-day Libya and Chad to the Mediterranean Sea, says [lead researcher] Anne Osborne…. Up to five kilometres wide, the channels would have provided a lush route from East Africa – where modern humans first evolved – to the Middle East, a likely second stop on Homo sapiens‘ world tour [New Scientist].

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Researchers believe they have found the earliest known animal footprints, left by a centipede-like creature 570 million years ago; if they’re right, the discovery means that animals were walking on the earth 30 million years earlier than previously thought. Researchers say the fossil shows a track of parallel dots, each about two millimeters in diameter, which may have been pressed into the muddy sand by the tiny feet of one of the earliest complex organisms.

But some experts are not convinced by what they’ve seen. Precambrian paleontologist Nick Butterfield said he was “deeply skeptical,” about the conclusions drawn. “From the description—paired rows of dots—it just doesn’t sound like a trackway…. Centipedes and their ilk shuffle along and leave continuous traces in soft (sub-aerially exposed) sediments—they don’t carefully step ahead, lifting each foot out of the mud to place it exactly in a previously made footprint,” he said [National Geographic News].

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A new fossil discovery shows that tiny, shrimp-like invertebrates living 525 million years ago linked up into formations that resemble daisy chains, and researchers say this could be the earliest example yet of animals engaging in group behavior. The fossilized creatures were found in closely interlocked chains of up to 20 individuals, with the tail of one animal inserted into the carapace of the next.

The ancient arthropods, a category of animals that includes insects, crustaceans and spiders, lived in open water rather than remaining on the sea bed. When they died, possibly as a result of moving into water loaded with toxins or short of oxygen, they sank to the seabed, where they were covered in sediment [The Times]. Researchers can’t be certain why the arthropods joined together into chains, but their best guess is that the animals were in the middle of a migration when they perished.

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A 33-foot long, carnivorous dinosaur that lived 85 million years ago had a breathing system similar to that used by modern birds, and researchers say the finding is further evidence of the evolutionary link between dinosaurs and birds. A fossil found in a riverbank in Argentina shows evidence of efficient air sacs that pumped air into the dinosaur’s lungs.

Lead researcher Paul Sereno named the new dinosaur Aerosteon riocoloradensis, which means “air bones from the Rio Colorado.” Instead of lungs that expand and contract, Sereno thinks this beast had air sacs that worked like a bellows, blowing air into the beast’s stiff lungs, much like modern birds…. Most paleontologists believe birds evolved from small, feathered meat-eating dinosaurs, and the earliest known birds were strikingly similar to these dinosaurs [Reuters].

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In the middle of the Australian outback along a mountain chain called the Flinders Ranges, researchers have discovered a 650 million year old reef that was once underwater. Researchers say the tiny fossils they’ve already found in the ancient reef may be the earliest examples of multicellular organisms ever found, and may answer questions about how animal life evolved.

Researcher Malcolm Wallace explains that the oldest-known animal fossils are 570 million years old. The reef in the Flinders Ranges is 80 million years older than that and was, he said, “the right age to capture the precursors to animals” [The Times]. The first fossils discovered in the reef appear to be sponge-like multicellular organisms that resemble tiny cauliflowers, measuring less than an inch in diameter, but Wallace cautions that the creatures haven’t been thoroughly studied yet. The reef’s discovery was announced at a meeting of the Geological Society of Australia this week.

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Paleontologists have dug up the bones of a chicken-sized dinosaur that scampered through the Cretaceous forest 70 million years ago, feasting on termites and other insects. The Albertonykus borealis is believed to have lived like an anteater, using strong claws to rip apart logs for insects as food [Globe and Mail]. The dinosaur, found in fossil-rich Alberta, Canada, is the smallest ever discovered in North America.

The small dinosaur looks like a creature from a Dr. Seuss book, said [researcher Nick] Longrich, who called the findings “pretty cool.” … Most of the bones dug up in North America have been from large animals, he said. “Now that we are finally starting to find some of the smaller ones it is suggesting that our picture of the fauna is skewed. We are primarily picking up the big skeletons. They just preserve better” [CBC].

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About 240 million years ago, a 15-foot amphibian with a nasty bite ruled the Antarctic plains, say paleontologists who have described the creature for the first time. Fossils show that the predator, newly named Kryostega collinsoni, had an extra set of teeth protruding from the roof of its mouth, which helped it shred flesh and hold struggling prey still in its mouth.

The animal, which researchers called Antarctica’s top predator in the Triassic Period, resembled a modern crocodile but was actually a temnospondyl, a prehistoric amphibian that was an early relative of salamanders and frogs. Because of their odd mixture of characteristics, members of this group are sometimes nicknamed “crocamanders” or “frogodiles” [Discovery News]. The new species will be described in the forthcoming issue of the Journal of Vertebrate Paleontology.

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The dinosaurs that held dominion over the Earth in the Jurassic Period didn’t rule the lands because they out-competed every rival, a new study says. Researchers studied fossil evidence from an earlier epoch, the Triassic Period, and say that dinosaurs showed no evidence of being better adapted to their environment than their challengers. “For a long time it was thought that there was something special about the dinosaurs that helped them become more successful during the Triassic, the first 30 million years of their history, but this isn’t true,” said lead author of the study, Steve Brusatte [LiveScience].

Instead they may have just been lucky enough to survive a drastic climate shift when their rivals didn’t. Researchers compared fossils from the 30 million years in the Triassic when dinosaurs coexisted with crurotarsan archosaurs, a group whose only living relative is crocodiles. They found that not only did the groups evolve at the same rate, but the crurotarsans even developed a wider range of body types than dinosaurs, suggesting that the group as a whole was more successful at developing to live in different habitats and ecosystems [Telegraph].

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In a cluster of coal mines in eastern Illinois, researchers have discovered the fossilized remains of ancient rainforests that date from the Carboniferous era, including one forest that stretched for 39 square miles. Researchers say the forests date from both before and after an episode of intense global warming that occurred about 306 million years ago, and may shed light on the ecosystem’s reaction to the drastic climate shift.

Researchers published a report on the first fossilized rainforest last year, but announced this week at the British Association’s Festival of Science that they have since come across five more patches of ancient woods. Says paleontologist Howard Falcon-Lang: “Three of the forests predate global warming and the rest follow it, so we can compare the ecology of those rain forests to see what the effect of global warming was.” During that period the Earth’s climate flipped from being covered with large polar icecaps to a greenhouse state that was completely ice-free, he added [National Geographic News].

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In an arid and lifeless stretch of the Sahara, archaeologists have discovered a massive graveyard and remnants of early settlements that hark back to Stone Age days when the desert was wet, green, and habitable. Researchers say the find is a striking reminder that climates and environments can shift drastically over the geologically short time period of 10,000 years.

In an area of Sahara that’s known to nomads as the “desert within a desert,” researchers found evidence of thriving prehistoric cultures and rich ecosystems on the edge of a lake. There were also hundreds of animal bones. In addition to antelope and giraffe, [lead researcher Paul] Sereno quickly recognized the remains of water-adapted creatures like crocodiles and hippos, then turtles, fish, and clams. “Everywhere you turned, there were bones belonging to animals that don’t live in the desert,” said Sereno. “I realized we were in the Green Sahara” [National Geographic].

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An extinct ancestor of the great white shark had a powerful bite that wouldn’t just put Jaws to shame, according to a new fossil analysis by Australian researchers. The colossal force of Carcharodon megalodon - also known as Big Tooth - made even Tyrannosaurus rex look puny [Telegraph].

In the study, to be published in an upcoming issue of the Journal of Zoology [subscription required], researchers took CT scans of both the skulls of great white sharks and those of the prehistoric megalodon, who swam the oceans about a million and a half years ago. They made computer models of the skulls, and then ran an analysis on the models that engineers use to determine how machinery holds up under stress.

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