The extinction of the dinosaurs

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Any attempt to analyze the events of the extinction of the dinosaurs runs into the fundamental difficulties that hinder the investigation of any of these mass murders of species. (life size animatronic dinosaur)Most fossil bones owe their preservation to quick burial by sediment right after the death of their owner. But generally most spots in the terrestrial biosphere suffer erosion, not deposition. Only in slowly sinking basins, pieces of real estate hundreds of miles across, can we hope to see a long interval of time recorded by the preservation of fossils. If a broad, basin-like valley was near sea level, its rivers and estuaries could blanket the landscape with layers of mud and sand every flood season. (animated dinosaur for sale)The very weight of these blankets of mud and sand tended to push the land surface as if the basin itself were a sagging rubber bowl. If the sinking of the valley’s surface kept up with the rate of buildup in the blankets’ thickness, then the pile of sediment grew thicker and thicker, even though the average height of the land above sea level remained the same. The result, after ten or twenty million years, was a thick sandwich of sediment that might reach a vertical height of five miles.


Sinking basins don’t sink forever.(realistic walking dinosaur costume) If they did, it would be possible to read the entire fossil record of life from bottom to top in one mine shaft sunk into a single valley. Instead, to understand the changing habitats of the end of the Cretaceous, it is necessary to hop from state to state, basin to basin, in order to piece together the disjointed narrative in the sediment, much as silent-movie buffs might try to reconstruct an entire lost feature by splicing fragments of film found in a dozen different studio storage vaults. The fragment of the story recorded at Lance Creek carries us late into the Cretaceous, but not to the very end. In Hell Creek, Montana, and nearby Bug Creek, however, there is a sedimentary section, rich in fossils, that passes right through the last moments of the Cretaceous and continues into the next epoch, the Paleocene. (real dinosaur costume for sale)Even at Bug Creek the strata do not record a year-by-year surveillance of the scene of the crime that would allow us to catch the perpetrator in the very act of extinction. In the best of basins, fossils weren’t preserved every year, or even every hundred years. Big bones, such as those of dinosaurs, required big floods of mud to cover them, and these events didn’t happen except at long intervals, perhaps hundreds or thousands of years apart. Even when buried, bones weren’t necessarily safe.