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Researchers have been hot on the trail of the elusive Denisovans, a type of ancient human known only by their DNA and...
Thousands of scientists in the Russian Academy of Sciences (RAS) are about to lose their jobs as a result of the...
Dyslexia, a learning disability that hinders reading, hasn't been associated with deficits in vision, hearing, or...
Exotic, elusive, and dangerous, snakes have fascinated humankind for millennia. They can be hard to find, yet their...
Researchers have sequenced and analyzed the first two snake genomes, which represent two evolutionary extremes. The...
Snake venoms are remarkably complex mixtures that can stun or kill prey within minutes. But more and more researchers...
At age 30, Dutch biologist Freek Vonk has built up a respectable career as a snake scientist. But in his home country,...
Since arriving on the island of Guam in the 1940s, the brown tree snake ( Boiga irregularis ) has extirpated native...
- 5 December 2013 11:26 am , Vol. 342 , #6163
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Furry Dino Eaters
12 January 2005 (All day)
For 185 million years, dinosaurs evolved into a panoply of predators and prey that fill the record books for size and shapes. Mammals, meanwhile, were nocturnal, shrewlike nobodies that snatched insects and stole the occasional egg. Only after dinosaurs went extinct 65 million years ago could mammals escape from the shadows and begin to thrive. Or so the story goes.
In this week's issue of Nature, Chinese paleontologists describe the largest mammal skeleton--more than a meter long--ever found from the Mesozoic era. And this furry Goliath wasn't content just to eat bugs: A smaller relative was discovered nearby with the bones of a baby dinosaur in its stomach.
The new fossils, each about 130 million years old, come from northeastern China. Paleontologists had already discovered skulls of the smaller animal, called Repenomamus robustus, but could get only a vague estimate of its body size. Now the same team has found a fairly complete specimen of an adult that probably weighed about 4 to 6 kilograms. "It looked something like a Tasmanian devil," says team member Yaoming Hu, a graduate student at the City University of New York. Collaborators include his adviser Jin Meng of the American Museum of Natural History in New York City and colleagues at the Institute of Vertebrate Paleontology and Paleoanthropology in Beijing.
While removing rock from the specimen, preparators made a rare discovery: teeth and bones strewn about inside the ribcage, in the likely position of the animal's stomach. The jumble included the remains of a herbivorous dinosaur hatchling, a 14-centimeter-long Psittacosaurus. One leg appears mostly intact, suggesting that the mammal dismembered and wolfed down its food.
R. robustus wasn't the only mammal that dinosaurs had to worry about. Another skeleton, better preserved, was even larger. Named Repenomamus giganticus, it was 1 meter long and weighed roughly 12 to 14 kg, as much as a modern coyote. "It was probably competing with carnivorous dinosaurs for food and territory," Hu says.
And that raises interesting questions, notes Anne Weil of Duke University in Durham, North Carolina. "What these finds really allow us to do--at least speculatively--is ask how mammals might have influenced dinosaur evolution," she says. In other words, Mesozoic mammals may have cast a shadow of their own.