At a site dubbed Tanis in North Dakota’s Hell Creek Formation, paleontologists have unearthed an assemblage of exquisitely-preserved fossilized organisms — fish stacked one atop another and mixed in with burned tree trunks, conifer branches, mammals, mosasaur bones, insects, the partial carcass of a Triceratops, marine microorganisms called dinoflagellates and snail-like marine cephalopods called ammonites — that were killed suddenly...
