Help request! I am putting together a tool for judging rock age based on very crude, whole-rock, hand-sample observations of fossil faunas/floras -- the types of observations a child or beginner could successfully make. I view this as a complement to the very fine, species-level identifications commonly employed as index fossils for individual stages, biozones, etc.
In this initial framework, vibrant orange indicates times in earth history to commonly observe the item of interest; paler orange indicates times in earth history to less commonly observe the item of interest. White indicates very little to no practical probability of observing the item of interest. Please keep in mind that the listed indicators are things like "conspicuous horn corals," purposefully declining to address rare encounters with groups of low preservation potential etc.
Got additions/amendments? Toss them in the comments below! Thank you for your insight and assistance.....