News Briefs II
Utah Facts Are Filling in Gaps In Dinosaur KnowledgeThe Washington Post
Fossil hunters digging in the forbidding rockscape of central Utah have unearthed a bony bonanza: scores of specimens from a period around 100 million years ago that has been virtually unknown to scientists. Among the finds are perhaps the oldest tyrannosaurus in North America, the first of the duck-billed dinosaurs, the last of the long-necked, herbivorous sauropods, and dozens of animal species never before identified.
The discoveries provide strong support for two long-standing theories. One is that many North American dinosaur types from the period were in fact Asian immigrants whose ancestors crossed a temporary land bridge that formed between what are now Siberia and Alaska. Another is that the rise of low-growing flowering plants in that era might have helped put the enormous sauropods (such as brontosaurus) out of business.
Debate on both notions has suffered because fossil evidence from the era has been "exceedingly sparse," the researchers write in Tuesday's issue of the Proceedings of the National Academy of Sciences.
"In terms of the age of dinosaurs, we've got a pretty good record from the very end," around 65 million years ago during the last of the Cretaceous period, said Richard L. Cifelli of the University of Oklahoma. "And we've got a lot from very long ago, in the age of the stegosaurus and brontosaurus," both of which arose during the Jurassic period that lasted from 190 million to 136 million years ago.
"Then in between," he said, "there's about a 70 million-year gap."
Or there was until Cifelli and colleagues began excavating what are now the arid scarps of a geological region called the Cedar Mountain Formation. About 100 million years ago, it was a lush and marshy flood plain where "a really big slow-moving river system" flowed from west to east, carrying plenty of sediment in its waters. The skeletal remains of animals that died in the locale were entombed in shale and sandstone far beneath the surface. It was subsequently covered by a vast inland sea. Later upheavals exposed sections of the formation, prompting the curiosity of scientists.
Chernobyl's Legacy Starts to ShowThe Washington Post
Eleven years after the world's worst nuclear accident, the long-term effects of the Chernobyl incident remain unclear. Now, a new study of birds near the Ukrainian nuclear plant suggests that radiation caused lasting genetic damage to at least some wildlife.
Swedish and French scientists found that a high proportion of barn swallows captured in contaminated areas have partial albinism, a condition that appears as splotches of white feathers completely lacking in pigment. Albinism occurred two to 10 times more frequently among birds near the plant than among birds from uncontaminated areas. Besides having spots, birds with albinism are generally weaker and less likely to survive to breeding age.
Although genetic damage has been detected in humans and other creatures directly exposed to radiation from the accident, the evidence has been mixed on whether the defects would be passed to offspring.