Re: what came before dinosaurs?

[Scott <HORTON@BCRSSU.AGR.CA>]

>>What came before dinos, et. al.?

>Most of Earth history.  That task is a little big for a dino FAQ, although
>we might suggest some good books on general paleontology and historical
>geology.

I think it would be instructive to newcomers to give them a VERY brief outline
of the evolution of life on earth, to put the dinosaur age in perspective. It
should include names of some genera found in popular books. I am not the person
qualified to do this very well without my references at hand, but I could out-
line it something like this for others to correct and/or enhance:

4500-3500mya}PreCambrian: no life
3500-500mya }           : microscopic organisms
500-225mya   Cambrian et al: fish, trilobites, lungfish, amphibians, et al
225-?mya     Triassic ("Early Dinosaur Age"): primitive dinosaurs (Herrera-
             saurus, et al), mammal-like reptiles, Dimetrodon
?-?mya       Jurassic ("Middle Dinosaur Age"): Apatosaurus, Allosaurus, 
                         Stegosaurus, first pterosaurs? & birds? plesiosaurs,
                                                      mosasaurs, ichthyosaurs
?-65mya      Cretaceous ("Late Dinosaur Age"): Tyrannosaurus, Triceratops, et al
65-2mya      ("Age of Mammals"): mammoths, sabre-tooth tigers, whales, et al
2-0mya                         : modern mammals (man, et al)

The correct dates need to be filled in, along with a more complete list of
popularly-recognizable dinosaur genera and groups of animals.