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Categories: Geoscience: Geomagnetic Storms, Paleontology: Early Mammals and Birds
Published A jaw-dropping conundrum: Why do mammals have a stiff lower jaw?
(via sciencedaily.com) Original source The lower jaws of lizards, birds, fish and even dinosaurs are comprised of multiple bones per side. Yet mammals diverged from all other vertebrates and settled on just one bone, repurposing the extra bones into a more elaborate inner ear, perhaps the better to hear. The single bone per side, fused in primates into one jawbone, makes the jaw more rigid. A paleontologist asks, Did the stiffer, rigid jaw make mammals more successful?
Published Humans' ancestors survived the asteroid impact that killed the dinosaurs
(via sciencedaily.com) Original source A Cretaceous origin for placental mammals, the group that includes humans, dogs and bats, has been revealed by in-depth analysis of the fossil record, showing they co-existed with dinosaurs for a short time before the dinosaurs went extinct.
Published Megalodon was no cold-blooded killer
(via sciencedaily.com) Original source How the megalodon, a shark that went extinct 3.6 million years ago, stayed warm was a matter of speculation among scientists. Using an analysis of tooth fossils from the megalodon and other sharks of the same period, a study suggests the animal was able to maintain a body temperature well above the temperature of the water in which it lived. The finding could help explain why the megalodon went extinct during the Pliocene Epoch.
Published Extinct warbler's genome sequenced from museum specimens
(via sciencedaily.com) Original source The Bachman's warbler, a songbird that was last seen in North America nearly 40 years ago, was a distinct species and not a hybrid of its two living sister species, according a new study in which the full genomes of seven museum specimens of the bird were sequenced.
Published Lost giants: New study reveals the abundance decline of African megafauna
(via sciencedaily.com) Original source A groundbreaking new paper focuses on the size and abundance of living and fossil African large mammals, shedding light on the ecological dynamics behind the decline of these iconic creatures. The findings challenge previous assumptions about the causes of megafaunal extinctions in Africa and provide new insights into the restructuring of ecosystems over millions of years.
Published Dinosaurs were the first to take the perspectives of others
(via sciencedaily.com) Original source Understanding that others hold different viewpoints from your own is essential for human sociality. Adopting another person's visual perspective is a complex skill that emerges around the age of two. A new study suggests that this ability first arose in dinosaurs, at least 60 million years before it appeared in mammals. These findings challenge the idea that mammals were the originators of novel and superior forms of intelligence in the wake of the dinosaur extinction.
Published Fossils of a saber-toothed top predator reveal a scramble for dominance leading up to 'the Great Dying'
(via sciencedaily.com) Original source A tiger-sized saber-toothed creature called Inostrancevia has previously only been found in Russia. But scientists have discovered its fossils in South Africa, suggesting that it migrated 7,000 miles across the supercontinent Pangaea during the world's worst mass extinction 252 million years ago. Heading to South Africa allowed it to fill a gap in a faraway ecosystem that had lost its top predators.
Published Researcher uses mammal DNA to zoom into the human genome with unprecedented resolution
(via sciencedaily.com) Original source Scientists have precisely identified base pairs of the human genome that remained consistent over millions of years of mammalian evolution, and which play a crucial role in human disease. The team analyzed the genomes of 240 mammals, including humans and identified base pairs that were 'constrained' -- meaning they remained generally consistent -- across mammal species over the course of evolution. The most constrained base pairs in mammals were over seven times more likely to be causal for human disease and complex trait, and over 11 times more likely when researchers looked at the most constrained base pairs in primates alone.
Published New tusk-analysis techniques reveal surging testosterone in male woolly mammoths
(via sciencedaily.com) Original source Traces of sex hormones extracted from a woolly mammoth's tusk provide the first direct evidence that adult males experienced musth, a testosterone-driven episode of heightened aggression against rival males, according to a new study.
Published New research redefines mammalian tree of life
(via sciencedaily.com) Original source Scientists from around the globe are using the largest mammalian genomic dataset in history to determine the evolutionary history of the human genome in the context of mammalian evolutionary history. Their ultimate goal is to better identify the genetic basis for traits and diseases in people and other species.
Published Information 'deleted' from the human genome may be what made us human
(via sciencedaily.com) Original source What the human genome is lacking compared with the genomes of other primates might have been as crucial to the development of humankind as what has been added during our evolutionary history, according to a new study led by researchers at Yale and the Broad Institute of MIT and Harvard. The new findings, published April 28 in the journal Science, fill an important gap in what is known about historical changes to the human genome.
Published Mammalian evolution provides hints for understanding the origins of human disease
(via sciencedaily.com) Original source Even though it is important to know where these variations are located in the genome, it's also useful to know how or why these genetic variations happened in the first place.
Published X-ray analysis sheds new light on prehistoric predator's last meal
(via sciencedaily.com) Original source We now know more about the diet of a prehistoric creature that grew up to two and a half meters long and lived in Australian waters during the time of the dinosaurs, thanks to the power of x-rays. Researchers used micro-CT scans to peer inside the fossilized stomach remains of a small marine reptile -- a plesiosaur nicknamed 'Eric' after a song from the comedy group Monty Python -- to determine what the creature ate in the lead up to its death.
Published Fossils reveal the long-term relationship between feathered dinosaurs and feather-feeding beetles
(via sciencedaily.com) Original source New fossils in amber have revealed that beetles fed on the feathers of dinosaurs about 105 million years ago, showing a symbiotic relationship of one-sided or mutual benefit.
Published Apes may have evolved upright stature for leaves, not fruit, in open woodland habitats
(via sciencedaily.com) Original source Anthropologists have long thought that our ape ancestors evolved an upright torso in order to pick fruit in forests, but new research from the University of Michigan suggests a life in open woodlands and a diet that included leaves drove apes' upright stature.
Published Starting small and simple -- key to success for evolution of mammals
(via sciencedaily.com) Original source The ancestors of modern mammals managed to evolve into one of the most successful animal lineages -- the key was to start out small and simple, a new study reveals.
Published Woolly mammoths evolved smaller ears and woolier coats over the 700,000 years that they roamed the Siberian steppes
(via sciencedaily.com) Original source A team of researchers compared the genomes of woolly mammoths with modern day elephants to find out what made woolly mammoths unique, both as individuals and as a species. The investigators report that many of the woolly mammoth's trademark features -- including their woolly coats and large fat deposits -- were already genetically encoded in the earliest woolly mammoths, but these and other traits became more defined over the species' 700,000+ year existence. They also identified a gene with several mutations that may have been responsible for the woolly mammoth's miniscule ears.
Published Analysis of dinosaur eggshells: Bird-like Troodon laid 4 to 6 eggs in a communal nest
(via sciencedaily.com) An international research team has determined that Troodon, a dinosaur very close to modern birds, was a warm-blooded animal (an endotherm), but had a reproductive system similar to that of modern reptiles. The scientists applied a new method which allowed for accurate determination of the temperature when the egg's carbonate shell was formed. Furthermore, the researchers showed that Troodon laid 4 to 6 eggs per clutch. As nests with up to 24 Troodon eggs had been found, the scientists conclude that several Troodon females laid their eggs in communal nests.
Published Predatory dinosaurs such as T. rex sported lizard-like lips
(via sciencedaily.com) A new study suggests that predatory dinosaurs, such as Tyrannosaurus rex, did not have permanently exposed teeth as depicted in films such as Jurassic Park, but instead had scaly, lizard-like lips covering and sealing their mouths.
Published How the 'marsupial sabertooth' thylacosmilus saw its world
(via sciencedaily.com) A new study investigates how an extinct, carnivorous marsupial relative with canines so large they extended across the top of its skull could hunt effectively despite having wide-set eyes, like a cow or a horse. The skulls of carnivores typically have forward-facing eye sockets, or orbits, which helps enable stereoscopic (3D) vision, a useful adaptation for judging the position of prey before pouncing. Scientists studied whether the 'marsupial sabertooth' Thylacosmilus atrox could see in 3D at all.