NEW YORK-Scientists have found an extraordinary snapshot of the fallout from the asteroid impact that wiped out the dinosaurs 66 million years ago.

Excavations in North Dakota reveal fossils of fish and trees that were sprayed with rocky, glassy fragments that fell from the sky. The deposits show evidence also of having been swamped with water - the consequence of the colossal sea surge that was generated by the impact. The detail is reported in PNAS journal.

Robert DePalma, from the University of Kansas, and colleagues say the dig site, at a place called Tanis, gives an amazing glimpse into events that probably occurred perhaps only tens of minutes to a couple of hours after the giant asteroid hit the Earth.

When this 12km-wide object slammed into what is now the Gulf of Mexico, it would have hurled billions of tonnes of molten and vaporised rock into the sky in all directions - and across thousands of kilometres.

And at Tanis, the fossils record the moment this bead-sized material fell back down and strafed everything in its path. Fish are found with the impact-induced debris embedded in their gills. They would have breathed in the fragments that filled the water around them. There are also particles caught in amber, which is the preserved remnant of tree resin. It is even possible to discern the wake left by these tiny, glassy tektites, to use the technical term, as they entered the resin. Geochemists have managed to link the fallout material directly to the so-called Chicxulub impact site in the Gulf. They have also dated the debris to 65.76 million years ago, which is in very good agreement with the timing for the event worked out from evidence at other sites around the world. From the way the Tanis deposits are arranged, the scientists can see that the area was hit by a massive surge of water. Although the impact is understood to have generated a huge tsunami, it would have taken many hours for this wave to travel the 3,000km from the Gulf to North Dakota, despite the likely presence back then of a seaway cutting directly across the American landmass.