Here’s one that I didn’t touch on in DISCOVER’s creepy gallery of zombie animals controlled by mind-altering parasites: A parasitic fungus called Ophiocordyceps unilateralis that infects a plain old carpenter ant and takes over its brain, leading the ant to bite into the vein that runs down the center of a leaf on the underside. The ant dies shortly thereafter, but the fungus gains the nutrients it needs to grow this crazy stalk out of the ant’s body and release spores to create the next generation of ant-controlling fungi.
This cryptic cycle has been going on for at least 48 million years.
In a study forthcoming in Biology Letters, Harvard’s David Hughes argues that a fossilized leaf found in a fossil-rich part of Germany’s Rhine Rift Valley bears the scars of the ant’s trademark death bite. The ant bites down hard so the fungus will have a stable position when it grows a stalk out of the ant’s head. But even so, Hughes says, he doubted the mark would turn up in the fossil record—that is, until serendipity reared its random head:
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What 15 million years ago was very bad for Australian marsupials is now very good for paleontologists: Researchers have uncovered a death trap, an underground limestone cave where hundreds of animals stumbled to their demise.
A paper published today in Journal of Vertebrate Paleontology details the resulting fossil menagerie, which includes an extinct wombat-like marsupial known as Nimbadon lavarackorum.
Karen Black of the University of New South Wales led the excavation and says in a press release that her team has already uncovered 26 Nimbadon skulls. The varying ages of the skulls detail the Nimbadon‘s whole life cycle from “suckling pouch” to “elderly adults.”
“This is a fantastic and incredibly rare site,” says Dr. Black [regarding the cave]. “The exceptional preservation of the fossils has allowed us to piece together the growth and development of Nimbadon from baby to adult.” [Society of Vertebrate Paleontology]
See a photo gallery of the excavation and fossil processing below the jump.
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Perhaps you’re one of those people who get their dander up when you hear creationists saying “I’m not descended from some monkey” not only for the obvious reason, but also because you can’t help but blurt out, “No, you mean ‘ape!’ We’re apes, not monkeys.”
Indeed, our superfamily, Hominoidea, split from the group labeled “old world monkeys” millions of years ago—but perhaps not as many million as we thought. In Nature this week, a team of scientists report on a 28-29 million year old fossil that appears to predate the split, meaning the separation would have happened more recently than other studies suggested.
The partial skull of this new creature, which the team dubbed Saadanius hijazensis, turned up in Saudi Arabia in February 2009.
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In the 1980s, fossil record research showed a curious cycle: Every 27 million years, Earth hosted a mass extinction. Some scientists suggested that a dim star dubbed Nemesis was in a deadly dance with our sun, periodically kicking comets out of the distant Oort Cloud to shower our planet with destruction. Morbidly fascinating as it may be, the authors of a new study argue that this “death star” theory doesn’t hold up.
The cyclical extinctions do make a solid pattern, say Adrian Melott of the University of Kansas and Richard Bambach of Smithsonian Institution Museum of Natural History, whose paper is available through arXiv.org. The two have gone back in the record to 500 million years ago, further than any other researchers, and have confirmed the 27 million year cycle at a 99 percent confidence.
According to Bambach, there’s no doubt at all that every 27 million years-odd, huge numbers of species suddenly become extinct. He says this is confirmed by “two modern, greatly improved paleontological datasets of fossil biodiversity” and that “an excess of extinction events are associated with this periodicity at 99% confidence”. This regular mass slaughter has apparently taken place around 18 times, back into the remote past of half a billion years ago. [The Register]
The problem, Nemesis fans, is that the cycle is too precise, the researchers say. If these extinctions result from a dance between our sun and Nemesis, the researchers note, the period of these mass extinctions would change as other stars buffeted the pair and changed the courses of Nemesis’s orbit around the sun.
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Is mulitcellular life like us just the new kid on the biological block, a latecomer to a world dominated by single-celled organisms like bacteria? Perhaps not—multicellular life could be nearly half as old as the Earth itself.
A new study out today in Nature identifies fossils from Gabon in Africa that date back 2.1 billion years. The organic material is long gone, but the scientists say these are the oldest multicellular organisms ever found. That date takes them way back before the Cambrian explosion 500 million years ago that made multiple-celled life widespread on the planet.
“We have these macrofossils turning up in a world that was purely microbial,” says Stefan Bengtson, a palaeozoologist at the Swedish Museum of Natural History in Stockholm and a co-author on the report. “That’s a big deal because when you finally get big organisms, it changes the way the biosphere works, as they interact with microbes and each other” [Nature].
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Twelve million years ago, one sperm whale was king. Between 40 and 60 feet in length the beast scientists named Leviathan melvillei wasn’t any bigger than today’s sperm whales, but look at those teeth!
As described in a paper published in Nature today, Olivier Lambert discovered the whale’s fossils in a Peruvian desert. The creature’s name says it all:
[It] combines the Hebrew word ‘Livyatan’, which refers to large mythological sea monsters, with the name of American novelist Herman Melville, who penned Moby-Dick — “one of my favourite sea books”, says lead author Olivier Lambert of the National Museum of Natural History in Paris. [Nature News]
The prehistoric sperm whale may have eaten baleen whales, and its largest chompers are a foot long and some four inches wide. For all the details, check out Ed Yong’s post on Not Exactly Rocket Science.
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Image: Nature
No offense, Lucy, but at three feet, six inches you were kind of short. Your diminutive, 3.2 million-year-old bones made it difficult to tell whether your species could even walk like us. Fortunately, researchers in Ethiopia have uncovered an older, bigger relative. As described in Proceedings of the National Academy of Sciences, some researchers believe that these new bones show that members of Lucy’s species, Australopithecus afarensis, could walk like modern humans.
The paper’s authors call him Kadanuumuu (kah-dah-nuu-muu)–”big man” in the Afar language. Big Man still isn’t really that big by today’s standard: His 3.6 million-year-old bones show that he stood at around five feet.
The fossilized remains don’t include a head, but Big Man has many of the same bones as Lucy, and also others previously missing: a shoulder blade and a rib cage bits. Lead researcher Yohannes Haile-Selassie argues that Big Man’s skeleton upends previous beliefs about Lucy’s love of tree climbing and more primitive walk.
“This individual was fully bipedal and had the ability to walk almost like modern humans,” said Haile-Selassie. “As a result of this discovery, we can now confidently say that ‘Lucy’ and her relatives were almost as proficient walking on two legs as we are, and that the elongation of our legs came earlier in our evolution that previously thought.” [Cleveland Museum of Natural History]
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The bones of our ancestors do not speak across time with ultimate clarity. The fossils with which scientists reconstruct our family tree are often fragments that offer hints and clues to where we came from. So it comes as no surprise when, as part of the flow of science, researchers offer counter-interpretations to even the most famous of finds.
That’s what happening to Ardi.
Last October Ardipithecus ramidus hit the main stage when, after 17 years of study, a large team led by paleoanthropologist Tim White published its work in the journal Science. The 4.4-million-year-old find shakes up our understanding of our own history, White said—primarily the story of how and when we learned to walk.
Ardi cast doubt on the widely accepted view that our ancestors became bipeds because they left the forest and entered a flatland savanna habitat that demanded it. But Ardi appeared to be a kind of hybrid, comfortable in the trees and on the ground. And, White said, analysis of the site where the fossil was found indicated that Ardi lived in a woodland habitat. If it’s true that early humans walked in the woods, then the “savanna hypothesis” would be swept away.
But not so fast. In today’s edition of Science, two teams of scientists respond (1, 2) with doubts about the story of Ardi.
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Nearly 150 years after scientists discovered the first specimen of the dino-bird archaeopteryx, we get to see what it was made of. Researchers who scanned one of the fossils with x-rays say the specimen contains not just impressions of fossils, but actually the remains of soft tissue with some of the chemical components intact. They published their findings (in press) today in the Proceedings of the National Academy of Sciences.
The team led by Roy Wogelius scanned a 150-million-year-old Archaeopteryx fossil using a synchrotron-type particle accelerator located at the Stanford Synchrotron Radiation Lightsource in California.
The synchrotron excites atoms in target materials to emit X rays at characteristic wavelengths. The scan reveals the distribution of elements throughout the fossil. The green glow of the bones in this false-colour image shows that Archaeopteryx, like modern birds, concentrated zinc in its bones. The red of the rocks comes from calcium in the limestone that had encased the fossil since the animal died [New Scientist].
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Take a good look: according to a new study in PLoS Biology, what you see in this image is a snake about to prey on dinosaur eggs, a 67-million-year-old scene frozen in time and finally discovered. It’s the first time that a snake has been seen eating a dinosaur. The snake is that bit of bones on the left, lead researcher Jeff Wilson says. The egg in the top right contains a tiny titanosaur, one of largest dinosaur groups to ever walk the Earth.
“The snake (Sanajeh indicus) probably lived around the nesting ground and preyed upon hatchlings. They all died instantly when they were covered by a big pulse of sediment from a nearby hill loosened by a storm,” says Wilson [New Scientist]. Wilson guesses that a storm or some other malady might have led the enormous adult dinos to leave the nest, opening the door for the snake to slither in, wait for the baby dinos to hatch, and snack on them. But it never got the chance.
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Dinosaurs and explosives—science stories don’t get much cooler than this.
Researchers in Utah have excavated two complete and two partial skulls of a dino called Abydosaurus mcintoshi, a 105-million-year-old sauropod, which the scientists think might have descended from the brachiosaurus family. “It is amazing. You can hold the skull in your hands and look into the eyes of something that lived a very long time ago” [USA Today], says paleontologist Brooks Britt, co-author of the study that appeared in the journal Naturwissenschaften.
Click through the photo gallery for more pictures from the dig, and for the whole story.
Image: Brigham Young University
Last week, a study found that an early dinosaur had a red mohawk and striped tail, one of the first pieces of solid evidence regarding dinosaur coloration. But a new study forthcoming in Science goes one step further, mapping in full 3D the strange plumage of the earliest-known feathered dinosaur, Anchiornis huxleyi.
Richard O. Prum, leader of the new study, was among the first to document that pigment-giving structures called melanosomes could survive fossilized for millions of years. The shape and arrangement of melanosomes help produce the color of feathers, so the scientists were able to get clues about the color of fossil feathers from their melanosomes alone [The New York Times]. British and Chinese scientists used this technique to release last week’s color study of the 125-million-year-old Sinosauropteryx, and Prum’s team applied it to the 150-million-year-old Anchiornis.
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As much as paleontologists have sorted out about the dinosaurs, one of the main aspects of their appearance—what color they were—has remained mysterious. But in a new Nature study, a team of British and Chinese scientists report that they found a way to unlock the color patters of one of the earliest feathery dinosaurs—it had a red mohawk, they say, with a red and white striped tail.
The dino in question is called Sinosauropteryx, which lived about 125 million years ago. Looking at fossils found in China, the team led by Mike Benton found what they think are the remains of feathers. And they found something inside the feathers that matches modern birds: melanosomes. These structures provide the melanin pigment in bird feathers (and human hair), and what color they are depends on the shape. “A ginger-haired person would have more spherical melanosomes, and a black-haired or grey-haired person would have more of the sausage-shaped structures,” said Professor Benton [BBC News].
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Until or unless we can create a Jurassic Park and build dinosaurs from DNA, the best way to study them may be to build dino models using materials like balsa wood, carbon fiber, and rubber bands.
That’s what a team did for a new study in the Proceedings of the National Academies of Sciences. To figure out how the 120-million-year-old winged dinosaur Microraptor gui took to the skies, the researchers used a well-preserved fossil to build their own. “We went back and forth. We thought, maybe we’ll do 3-D graphics and it’ll look really cool. But it’s more accurate to do the modeling directly from the specimen,” said Dave Burnham, a paleontologist at the University of Kansas [Wired.com].
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Scientists are pushing back the date that the first land-walkers stepped foot on solid ground. Thanks to the discovery of prehistoric footprints from an 8-foot-long animal, scientists now say creatures strolled the Earth 20 million years earlier than previously thought. The prints were made by tetrapods—animals with backbones and four limbs—and could rewrite the history of when, where, and why fish evolved limbs and first walked onto land, the study says [National Geographic News]. The researchers published their results in the journal Nature.
Dozens of the fossilized footprints were found in an abandoned quarry in Poland, and the researchers say that the area was probably a lagoon or an intertidal flat when the tetrapod wandered across it about 395 million years ago. Researchers say the footprints in such old rock was a big surprise: They’re about 10 million years older than body fossils of creatures such as Tiktaalik and Panderichthys, … believed to represent the transition from lobe-finned fish to creatures fully adapted to life on land [Science News].
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