The giant asteroid’s impact into shallow waters in the Gulf of Mexico 66 million years ago was bad enough. But then an amalgam of additional disasters ensued: Rocks fell from the sky, wildfires ignited and tsunamis inundated distant shorelines.

It was the beginning of the end of the Mesozoic Era when dinosaurs ruled the world.

Scientists released a new record of this day of chaos in Proceedings of the National Academy of Sciences on Monday. Their timeline of the first day of the Cenozoic Era was developed using high-resolution photography, microscopy, computed tomography imaging and magnetic measurements of hundreds of feet of sedimentary rock recently recovered from Chicxulub, one of the largest impact craters on Earth.

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In 2016, researchers drilled deep in waters off the Yucatán Peninsula for the first time into Chicxulub’s peak ring, a circle of mountains within the crater.

This new study, led by Sean P. S. Gulick, a marine geophysicist at the University of Texas at Austin, focuses on a subset of these cores, which are effectively a 430-foot-long sedimentary rock record of the first day after the asteroid impact.