KT extinction?

Question

What is the evidence to conclude that dinosaurs were living in the era of the layer below the iridium layer(white layers between the two layers)? is that because dinosaurs' fossiles are found in that layer?

What is the evidence to conclude that dinosaurs did not live in the era of the layer above the iridium layer?? Perhaps there are no fossile found?

Thank you

Answer 1

you have pretty much answered your question. yes, the evidence were based on presence of dinosaur and other associated fossils (plants and other animals) below the iridium layer and the absence of most of these fossils (like the dinosaurs, cycads and other organisms were able to survive after the iridium layer).. but then, these are based on stratigraphic study of most rock layers.. one of those theories that are still currently being checked and debated by scientists....

Answer 2

Good question, especially since lizards survived the meteor impact. The truth is that we don't know with 100% certainty what happened at the time of the impact. However as near as we can guess, the impact in Mexico set off a shock wave that created huge tsunami waves and kicked up a layer of dust in a maelstrom of wind. The general thinking is that larger animals could not survive the change in atmospheric conditions if they survived the impact. Lack of sunlight, and increased trapping of heat in the atmosphere killed off most plants and a large percentage of the animals alive at the time.

Fossils do require a few things to be created. Most notably a lifeform and a layer of sedimentary rock. Since no fossils prove that dinosaurs survived past the K/T line, there are three possiblities:
1) That no dinosaurs survived.
2) That dinosaurs did survive, but no fossils were created.
3) That dinosaurs did survive and we have yet to find fossils.

The conventional money is on 1), but you never know what will be discovered.

Answer 3

your analysis is probably the best explanation. maybe you could contact a paleontologist