00:00A Cretaceous scene of mass death in North Dakota shows that the asteroid that ended
00:12the reign of the dinosaurs struck when it was springtime in the Northern Hemisphere.
00:17The site is called Tanis, and abundant fish fossils reveal that a river once flowed there.
00:23But 66 million years ago, just minutes after a massive asteroid crashed near the Gulf of
00:27Mexico, a wave swept upstream and buried dozens of animals alive, turning the site into a death pit.
00:36Scientists recently analyzed fish fossils from Tanis, looking for clues about the impact.
00:41They found tiny glass balls, called spherules, embedded in the fish's gills.
00:46The spheres fused from ultra-hot sediments when the asteroid ejected towering plumes of dirt
00:51from the impact crater.
00:53Other researchers had previously calculated that impact spherules would have fallen from
00:57the sky between 15 and 30 minutes after the asteroid crashed into Earth.
01:02Because the spheres were in the fish's gills, but hadn't been swallowed, the fish were likely
01:07buried alive just after inhaling the glassy beads, within 30 minutes after the impact.
01:13The scientists then used powerful X-ray scans to examine the fish's bones.
01:18They mapped patterns and growth cycles over time, finding that bone growth peaked by the end
01:23of the summer, and then declined over the winter.
01:26When the fish died, they were just entering a time of significant bone growth, which coincided
01:31with spring.
01:34Analysis of carbon isotopes in the bones revealed a similar pattern in the plankton that the
01:38fish were eating.
01:40Plankton are most numerous in summer.
01:43Carbon traces in the fish bones showed that plankton numbers were growing, but hadn't reached
01:47peak abundance yet.
01:49This told the scientists that the fish died when it was still springtime.
01:53TANIS offers a remarkable 3D snapshot of the immediate aftermath of the Earth-shaking asteroid
01:59impact, and researchers suspect that there are other such sites that have yet to be discovered.
02:19And that's a great food for us.
02:23This is the problem.
02:25This has been a beautiful trip for us.
02:28This is my first time on the road to a solitary crawling location.
02:33This is my first time on the road to a poczÄ…t of the earth.
02:38This has been a full place for us and now on the road to a condition.
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