That's quite interesting, I wonder what Neil Landman will make of those ammonites? Pity the article does not how a photo of them.
It's quite a rare thing to find fossils at the boundary of the Cretaceous-Tertiary; these must have been some of the very last ammonite species on the planet. Ammonites were in serious decline for a few million years even before their extinction, I think to find them at the point in time marking deaths door is unusual in itself.