Answer: Required order would be
Tertiary > Silurian > Triassic > Jurassic
Step-by-step explanation:
Since we have given that
Period Number of years ago
Jurassic 
Silurian 
Tertiary 
Triassic 
We need to write in the order from oldest to youngest.
Since according to age, we get that Tertiary is the oldest and Jurassic is the youngest among them.
So, Required order would be
Tertiary > Silurian > Triassic > Jurassic