Respuesta :
From a thin layer of sediment known as the K-Pg boundary that could be found all over the world, the Cretaceous-Tertiary extinction event is believed to have been caused by a comet or meteor impact.
In your passage, you should be able to find this text:
"A summary of possible causes for the Cretaceous-Tertiary extinction is:
- an asteroid hitting the earth
- volcanism"