Geologic Time Scales: Characteristic Organisms Flashcards
1
Q
Precambrian
A
all life forms lacked hard shells or skeletons, so preservation is unlikely
2
Q
Archaean
A
Stromatolites, showing signs of cyanobacteria
3
Q
Mid-Hadean
A
RNA
4
Q
Phanerozoic Eon
A
shelled invertebrates
5
Q
Paleozoic Era
A
marine invertebrates
6
Q
Mesozoic Era
A
reptiles
7
Q
Cenozoic Era
A
mammals
