Scientists have discovered levels of iridium 30 times greater than average in the Cretaceous/Tertiary (KT) boundary, the layer of sedimentary rock laid down at the time of the dinosaur extinction.

One of the ways that we know about this extraordinary event comes from what is known as the Cretaceous-Paleogene (K-Pg) boundary, formerly the Cretaceous-Tertiary (K-T) boundary. This geological ...

Yale graduate student Stephen Chester discovered the last known dinosaur before the catastrophic meteor impact 65 million years ago. Disclaimer: AAAS and EurekAlert! are not responsible for the ...

These occurred at the end of the Ordivician, the Late Devonian, the Permian/Triassic (P/Tr) boundary, the end of the Triassic, and the Cretaceous/Tertiary (K/T) boundary. The fossil record ...