Don’t let their fierce looks fool you: Some male carnivorous dinosaurs were actually devoted dads, researchers say. A new study examined the bones of three species of dinosaurs found sitting on fossilized egg clutches and declared that in these species, it was the males who sat on the nests and cared for the young. The three types of dinosaurs, Troodon, Oviraptor and Citipati, lived roughly 75 million years ago and were theropods — the primarily meat-eating group that also includes monstrous beasts like Tyrannosaurus rex and Giganotosaurus [Reuters].
The new findings upend some notions of dinosaur family life, and also suggest that birds, which are believed to have evolved from small, feathered dinosaurs, may have inherited this behavioral trait. Study coauthor Frankie Jackson says the study “sheds light on the origins of parental care systems in birds.” … Males protect or support offspring in more than 90 percent of bird species — a distinctly rare attribute in the animal world. In mammals, males provide parental care in 5 percent of species, and it’s even rarer in reptiles [Washington Post].
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Three prehistoric turtle fossils dating from 220 million years ago have provided new evidence to fuel the debate over how the turtle’s remarkable shell evolved. The fossils, which were found in southwestern China, show turtles with fully developed shells on their bellies, but nothing above on their backs. Says researcher Xiao-chun Wu: “Since the 1800s, there have been many hypotheses about the origin of the turtle shell. Now we have these fossils of the earliest known turtle. They support the theory that the shell would have formed from below as extensions of the backbone and ribs, rather than as bony plates from the skin as others have theorised” [Telegraph].
Researchers write in their paper in Nature [subscription required] that they named the new species Odontochelys semistestacea, which means toothed, half-shelled turtle. Wu and his coauthor Chun Li say the fossils support the theory that the lower shell, called the plastron, evolved first, and that the upper shell, called the carapace, formed later. This process corresponds with the shell formation seen in turtle embryos and hatchlings [Telegraph].
The new research contradicts the other main theory regarding the evolution of the turtle shell, which holds that the shell evolved from bony plates on the skin that broadened and fused together to form the turtle’s armor. The entire structure would then fuse to the underlying ribs and backbone. (Modern reptiles, such as crocodiles, have these bony plates, as did some dinosaurs, such as ankylosaurs.) The newly studied Odontochelys specimens, however, showed no signs of bony skin plates [LiveScience].
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On the seafloor near the Bahamas, researchers have discovered a single-celled organism about the size of a grape, and they say the unusual organism raises interesting questions about the evolution of complex, multicellular animals. The oversized protists were found at the end of long, linear tracks that appear to have been made by the slowly rolling amoebas; lead researcher Mikhail Matz says the tracks resemble fossilized impressions from over 1 billion years ago, which scientists had assumed were made by multicellular worms. “We were looking for pretty animals that have eyes, are coloured, or glow in the dark; instead, the most interesting find was the organism that was blind, brainless, and completely covered in mud,” he said [BBC News].
The origin of multicellular life has been shrouded in mystery, because few animals fossils have been found that predate the beginning of the Cambrian Period around 542 million years ago. Some researchers point to rare Precambrian “trace fossils” – such as slither prints left in ancient sea bottoms – as evidence for complex animal life predating the Cambrian. The oldest of these trace fossils yet found are 1.8 billion years old, about three times older than any animal in the fossil record [The Scientist]. However, the new tracks raise another possibility: that the ancient traces were created by large single-celled organisms.
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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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