Geological Time Scale

EON ERA PERIOD EPOCH Nautiloids Actinoceratoids Ammonoids Coleoids

P
H
A
N
E
R
O
Z
O
I
C

C
e
n
o
z
o
i
c
Neogene Holocene    
Pleistocene    
Pliocene    
Miocene    
Paleogene Oligocene    
Eocene    
Paleocene    
M
e
s
o
z
o
i
c
Cretaceous      
Jurassic      
Triassic      
P
a
l
e
o
z
o
i
c
Permian      
Pennsylvanian      
Mississippian        
Devonian        
Silurian    
Ordovician    
Cambrian  

Proterozoic

Archaen

Major molluscan groups Back to Molluscs