Fossils expand menagerie of Jurassic era mammals
For years, scientists believed that the only mammals alive during the Jurassic Period, roughly 145 million to 200 million years ago, were small, shrewlike creatures.
In 2006, that assumption was upset with the discovery of a larger, beaverlike mammal. Now researchers have discovered two fossils that expand the menagerie of Jurassic mammals, collectively known as docodons.
Each seems to have adapted to an environmental niche, researchers reported in two papers in the journal Science. One had skeletal features consistent with tree living, such as incisors for eating tree gum and sap. The other had shortened digits, sprawling limbs, large claws and ribs resembling those of modern digging animals.
“We used to view docodons as a relatively homogeneous group,” said Zhe-Xi Luo, a paleontologist at the University of Chicago and an author of both papers. “Now we’ve found a tree climber with specialized teeth and a super digger that was clearly subterranean.”
The findings help refute the idea that the presence of dinosaurs stunted the evolution of early mammals, he added.
Holes fill in the blanks on sweet-sounding violins
Some of the world’s most prized violins were made in Cremona, Italy, in the 17th and 18th centuries by the Amati, Guarneri and Stradivari families. Researchers at the Massachusetts Institute of Technology wanted to know what accounted for the instruments’ unique acoustical properties.
Using technical drawings, X-rays and CT scans of the instruments, the team compared hundreds of Cremona-era violins, conducting laboratory experiments to see how air flowed through the F-shaped holes on the surface.
The scientists found that the length of the holes, not the width, and the strength of the back plate had the biggest effects on sound quality.
When air escapes a violin, “most of the airflow is coming around the edges” of the holes, said Nicholas Makris, an engineer at MIT and the lead author.
Guarneri violins had the most elongated holes, and hence produce the strongest sound. Makris, whose work was published in Proceedings of the Royal Society A, said he believed the Guarneri construction was not a matter of design, but evolution.
– New York Times