It is an old paper (1999), but I'm not convinced that there is any ongoing controversy about the iridium layer. In other words I'm pretty sure that it is attributed to an impact as described above, and it just happens that before it are dinosaurs. After it, no dinosaurs.
It is my recollection and understanding (no references at hand) that the dinosaurs were already in severe decline prior to the impact event, and that there was some minor post impact dinosaur survival. Still, the impact certainly seemed (weasel word alert) to pretty much put a period at the end of the dinosaur sentence.
I wonder about (but am far too lazy to research) the the pre-impact environmental changes?
Moose
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