Monday, April 28, 2008
Art Chadwick's Dino Dig Site
The mass mortality event is preserved within a normally graded bed in a poorly consolidated claystone or mudstone with large limb bones at the base, grading upward to vertebrae and toe bones at all query sites. The bones universally exhibit little evidence of weathering; abrasion and other transport degredation are also conspicuously absent. The claystone is conformably overlain by fine-grained, well-sorted immature sandstone showing evidence of rapid accumulation. We propose that a large population of ornithopods...was catastrophically decimated and initially accumulated in a nearshore freshwater environment. Subsequently, the disarticulating remains were remobilized and transported basinward to a deeper water setting as a graded bone bed.
I had listened to his talk at the BSG conference a while back, but did not remember hearing that the bones were sorted by bone size. Anyway, there's lots of interesting information in there.