Mass extinction: Evidence?

Chicxulub: This crater in the Yucatan is mostly underwater, ~ 300 km across, buried deep.
Coincidentally, the dino fossils vanish at ~ the same time (none above Iridium layer, many below).
Global climate changes due to impact could have caused this
OR the correlation could be a coincidence!

Chicxulub: This crater in the Yucatan is mostly underwater, ~ 300 km across, buried deep.