Excavations revealed in amazing detail fossils of fish and other animals unable to escape the glassy fragments that plummeted from the sky caused by the thunderous impact that obliterated the dinosaurs.
The deposits also contain water, indicating a mammoth sea surge that the collision created.
University of Kansas paleontologist Robert DePalma and colleagues said the excavation site, called Tanis, offered a momentous peek into events that occurred minutes after the asteroid crashed into the planet.
"This is the first mass death assemblage of large organisms anyone has found associated with (the end of the Cretaceous Period)," said DePalma. "At no other (time) on Earth can you find such a collection consisting of a large number of species representing different ages of organisms and different stages of life, all of which died at the same time, on the same day."