Word: fossilizing
(lookup in dictionary)
(lookup stats)
Dates: all
Sort By: most recent first
(reverse)
Excavations at the Nova Scotia site have so far yielded more than 100,000 fossilized bone fragments, all dating from shortly after the mass extinction some 200 million years ago that marked the end of the Triassic period and the beginning of the Jurassic. Because of some rapid change, perhaps a catastrophic event, the fossil record shows, 43% of the animal families whose fossilized remains are found in the older Triassic rock are missing from the Jurassic layers just above it. The sudden mass extinction opened the evolutionary way for the proliferation of the dinosaurs and the emergence...
Last week their remains were still being painstakingly extracted from more than three tons of the fossil-rich rock that were shipped back to laboratories at Harvard and Columbia. Technicians armed with microscopes and carbide needles to pick away at the rock have already discovered some notable specimens: the world's richest collection of fossil bones of tritheledonts, the group of reptiles most closely related to mammals; a large number of sphenodonts, small, lizard-like reptiles whose only living relative is the tuatara of New Zealand; yard-long crocodiles with spindly legs, a whiplike tail and a sleek body that...
Around the time of the mass extinction, the fossil site was apparently in a 300-mile-long rift valley fringed with high mountains. The climate swung between wet and dry spells every 20,000 years or so, leaving telltale alternating layers of lake sediments and sandstone visible on the present-day cliffs. "When it rained," says Olsen, "chunks of rock and mud raced down the mountainsides and buried large swaths of ground." Many of the now fossilized animals escaped the slides, only to be trapped in cracks that opened as the mud flow dried and shrank. Olsen believes the animals...
...fossil find may have implications for the controversial theory proposed by a team headed by Physicist Luis Alvarez and his son Geologist Walter Alvarez, both of the University of California, Berkeley. In their view, at least some of the great extinctions, especially the one that wiped out the dinosaurs 65 million years ago, were caused by the effects of giant comets or asteroids smashing into the earth. The impacts, they suggest, spewed debris into the atmosphere, obscuring the sun, causing temperatures to drop and bringing on a long "winter" that killed much of the life on earth. But, at least...
...Triassic-Jurassic extinction, however, that evidence may exist. Less than 500 miles northwest of the Nova Scotia fossil find is the enormous Manicouagan impact crater, its outermost ring--clearly visible in satellite photographs--measuring more than 90 miles in diameter. Given the margins of error in dating, the age of the crater (about 214 million years) makes it suspect in the 200 million-year-old extinction...