Birds got smart by becoming big babes - life - 28 May 2012 Out of the skulls of babes. Modern birds have skulls that look remarkably like those of juvenile dinosaurs, offering an unusual explanation for how birds came to have relatively large brains. As dinosaurs evolved into birds, something arrested their development. The juvenile heads they kept may be responsible for their relatively high intelligence, and their incredible evolutionary success. Birds are living dinosaurs, having evolved from feathered dinosaurs similar to the Velociraptor. They were the only dinosaurs to survive the mass extinction that took place 65 million years ago. Bhart-Anjan Bhullar of Harvard University and colleagues took photos and CT scans of skulls belonging to juvenile and adult dinosaurs, extinct and modern birds, and more distant relatives like crocodiles. They found that compared to their ancestors, birds' faces became flattened, and their brain cases relatively larger. Like bird like human Journal reference: Nature, DOI: 10.1038/nature11146 More from the web
In The Beginning Was the Mudskipper? | The Loom In 1893, the Norwegian zoologist Fridtjof Nansen set off to find the North Pole. He would not use pack dogs to cross the Arctic Ice. Instead, he locked his fate into the ice itself. He sailed his ship The Fram directly into the congealing autumn Arctic, until it became locked in the frozen sea. For two and a half years they drifted with the pack. The Fram meanwhile continued to drift east. Its pilot was a young Swedish engineer named Salamon Andrée. When he got back to Sweden, Andrée discovered that Nansen had actually failed and had returned to Norway. For a week the crew huddled in cramped fog. But in 1897, no one knew where Andrée had gone. They weren’t the bones of Andrée and his crew. Other fossils of these fish had been found elsewhere in late Devonian rocks, but to those who studied that era, Greenland was a revelation. These expeditions were a bit less brutal than Andrée’s and Nansen’s trips. Ichthyostega’s tail was a similar mix of tetrapod and fish. The whole body:
Biological clock began ticking 2.5 billion years ago - life - 16 May 2012 OUR core physiology relies on subtle organic timers: disrupt them, and effects range from jet lag to schizophrenia. Exactly how and when life began keeping time is unclear, but a candidate for the original biological clock may solve the mystery. Biological clocks are ubiquitous in nature, so the first clock should pre-date the evolutionary parting of the ways that led to modern groups of organisms. All the clocks found so far are unique to different groups of organisms, though. Not so the clock discovered by Akhilesh Reddy at the University of Cambridge and colleagues. PRX gets rid of poisonous, highly reactive oxygen (ROS), which is produced by oxygen-based metabolism. Moreover, they found this PRX cycle in mice, fruit flies, a plant, a fungus, an alga, bacteria and even in archaea - the most primitive of all cellular life (Nature, DOI: 10.1038/nature11088). It may even have driven their evolution. New Scientist Not just a website! More From New Scientist More from the web (YouTube)
Amber reveals earliest example of pollinating insects Caroline Morley, online picture researcher (Image: Enrique Peñalver, IGME) Insects and plants have a long, entwined history through pollination. Plants attract insects through their flowers' colour and scent, often providing their visitors with food. For their part, the insects unwittingly carry the pollen from one plant to another thus playing a key role in the plant's sexual reproduction. This photo gives a glimpse to how the relationship began. Below is an image created using synchroton X-ray tomography of one of the insects (identified as Gymnospollisthrips minor). (Image: ESRF) "Thrips might indeed turn out to be one of the first pollinator groups in geological history," said Carmen Soriano of the European Synchrotron Radiation Facility who led the investigation.
Mini-mammoths lived on Crete The carcass of the world's most well-preserved baby mammoth, named Lyuba, who was discovered in Russia's Yamal Peninsula in 2007. Dwarf mammoths in Crete tended to share the physical characteristics of the infant versions of their ancestors. Credit: AFP PARIS: The smallest-ever mammoth roamed Crete up to 3.5 million years ago, measuring some four feet (just over a metre) at the shoulder, the size of a baby elephant today, said a study published Wednesday. Mammuthus creticus weighed in at about 310 kilogrammes (680 pounds) and probably had no woolly coat unlike some of its relatives, study author Victoria Herridge, adding that the animal was “probably quite cute.” “If you were to reconstruct it, I would say OK, make it look a bit like a baby elephant but probably chunkier … with sort of thicker limbs, stockier, and as an adult it would have had curly tusks. “You’d be a bit intimidated” “The nearest image you’re going to get is a baby Asian elephant, but with tusks.”
The False Allure Of Group Selection I am often asked whether I agree with the new group selectionists, and the questioners are always surprised when I say I do not. After all, group selection sounds like a reasonable extension of evolutionary theory and a plausible explanation of the social nature of humans. Also, the group selectionists tend to declare victory, and write as if their theory has already superseded a narrow, reductionist dogma that selection acts only at the level of genes. Why does this matter? The first big problem with group selection is that the term itself sows so much confusion. In this essay I'll concentrate on the sense of "group selection" as a version of natural selection which acts on groups in the same way that it acts on individual organisms, namely, to maximize their inclusive fitness (alternatively, which acts on groups in the same way it acts on genes, namely to increase the number of copies that appear in the next generation; I will treat these formulations as equivalent). 1. 2. 3.
Giant Flea-Like Pest Put the Bite on Dinosaurs Paleo-pests about 10 times bigger than today's fleas may have sneaked up on a huge dinosaur, crawled onto its soft underbelly and taken a bite, likely a painful one, say researchers who have discovered fossils of the flealike organisms. "It would have felt about like a hypodermic needle going in, a flea shot, if not a flu shot," George Poinar Jr., a professor emeritus of zoology at Oregon State University, said in a statement. "We can be thankful our modern fleas are not nearly this big," said Poinar, who wrote a commentary alongside the research article published online April 24 in the journal Current Biology. One possible lifesaver for dinosaurs: These bloodsuckers couldn't jump like today's pesky fleas. The fossils of the two newly identified "flea" species, now called Pseudopulex jurassicus and Pseudopulex magnus, were discovered in Inner Mongolia. More dino fleas?
Triumph of the Titans: How Sauropods Flourished Ever since fossils of the behemoth, long-necked dinosaurs known as sauropods surfaced in England nearly 170 years ago, they have awed and confused scientists. Even when the great English anatomist Sir Richard Owen recognized in 1842 that dinosaurs constituted a group of their own, apart from reptiles, he excluded the gigantic bones later classified as sauropods. Instead he interpreted them as belonging to a type of aquatic crocodile, which he had named Cetiosaurus, or “whale lizard,” for the enormous size of its bones. Nearly 30 years later, in 1871, University of Oxford geologist John Phillips would report the discovery of a Cetiosaurus skeleton sufficiently complete to reveal that, far from being an aquatic crocodile, the animal spent at least some of its time on land. Phillips’s assessment caused considerable consternation among paleontologists for decades—they just could not conceive how such a massive animal could support its weight on land. Select an option below: Customer Sign In
Evolution: This View of Life Magazine Dinosaurs Grew to Outpace Their Young National Geographic Society/Corbis A newborn titanosaur had to get 2,500 times bigger before it reached adulthood. Some dinosaurs grew to gigantic sizes to avoid competition from their own young, rather than to take advantage of abundant oxygen, high temperatures and large territorial ranges, say two studies. But their largeness may also have proved their undoing. Some have argued that dinosaurs were able to grow quickly and fuel large bodies when temperatures were warm, oxygen levels were high, and land masses such as the supercontinent Gondwana provided abundant living space. But although the idea that certain environmental conditions favoured the growth of enormous dinosaurs has been popular among palaeontologists, there is little evidence for it. Friendly environment The team used thigh-bone lengths to work out the body sizes of more than 400 species alive during the Permian, Triassic and Jurassic periods (299 million to 145 million years ago). Bigger and bigger
Worm Discovery Illuminates How Our Brains Might Have Evolved Our earliest invertebrate ancestors did not have brains. Yet, over hundreds of millions of years, we and other vertebrates have developed amazingly complicated mental machinery. "It must have evolutionary roots somewhere, but where?" wrote Henry Gee, an editor at Nature, in an essay published in the journal's March 15 issue. Years of study of common invertebrate lab subjects, such as amphioxus (Branchiostoma lanceolatum) or nematodes, have yielded scant evidence as to the origins of the big, centralized brains we all develop as embryos. These unlovely, simple little worms live most of their brainless lives buried in deep-sea beds. But not everyone in the invertebrate community is convinced that the early antecedent to the vertebrate brain has been discovered. Complexity from simplicity All of our features—from our brains to our bones—emerged from elaboration on the simplest of genetic patterns found in primitive gunk.
Oldest chordate spawned everything with backbones Andy Coghlan, reporter (Image: J.B. Caron) This strange eel-like creature from half a billion years ago is a forerunner of all modern animals with backbones, from fish to reptiles and humans. Some 505 million years old, it is the oldest known chordate. An analysis of 114 fossils of Pikaia gracilens discovered since 1911 shows that it was an evolutionary staging post on the way from worms to vertebrates. "Pikaia is a missing link because of all chordates, it's probably the most primitive," says Simon Conway Morris of the University of Cambridge, UK. Conway Morris says Pikaia probably contributed to the Cambrian explosion, a sudden flourishing of species about 530 million years ago, which produced the first fish within about 40 million years. Although Pikaia didn't have a skull, it did have mouthparts, two small tentacles, and small openings nearby that probably served as gills. The 5-centimetre-long animal also had zig-zag-shaped muscle segments, called myomeres, all along its length.