You don't think an asteroid caused the Chicxulub crater? There's an awful lot of evidence in support of it. How else do you explain a 180 km crater, the iridium layer, the shocked stone, the ejecta spherules, etc?

There are several relevant asteroid theories. Since you say "negate", I assume you mean the theory that the asteroid was the sole cause of the K-Pg extinction event?

Shrug. Okay. Perhaps there were multiple causes; volcanism, marine regression, and extraterrestrial impact. https://en.wikipedia.org/wiki/Cretaceous%E2%80%93Paleogene_e... . I don't think anyone would be severely upset should this prove true.

That's still an asteroid theory.