Dinosaur Death Pit
January 19, 2010—Two predatory dinosaurs known as Guanlong wucaii struggle in a muddy pit in a painting of China's Xinjiang region during the late Jurassic period, about 160 million years ago. Guanlong, which means "crested dragon," was a small theropod, a group of bipedal raptors from the lineage that includes Tyrannosaurus rex.
The painting depicts one of China's mysterious dinosaur "death pits"—3.5- to 6.5-foot-deep (1- to 2-meter-deep) depressions filled with the largely complete skeletons of several small theropod species. Now a new study has pinpointed a possible origin of the traps: They may be the mud-filled footprints of the 20-ton sauropod dinosaur Mamenchisaurus.
—Reporting by Brian Handwerk