Explanation

Yes I'll try my best! E is weakening the theory about an asteroid by saying that fossils of dinosaurs were found below the layer of dust that settled from the asteroid which shows that the dinosaurs were already dying due to reasons besides the asteroid. The second part of E is showing that more fossils, or teeth in this case, above the dust level show that more dinosaurs died after the asteroid impact. So E is showing that there was something prior to the asteroid which was having an impact on the dinosaurs and an asteroid wasn't necessarily the only reason they became extinct. Hope this helps a bit!

Endorsing this!