This post is an addendum to my previous entry Careful With That Time Machine! Please read that post for more context.
Lateral Time measures the distance between timelines. The lateral distance between two timelines is equal to the length of Linear Time that has elapsed since the two timelines diverged.
Therefore, any timeline that saw me win the lottery in 2006 is currently 10 (lateral) years distant from this one, whereas any timeline where dinosaurs still rule the Earth is currently millions of years distant.
To avoid encounters with surprise dinosaurs, the time traveller will need to be able to measure and navigate both Linear and Lateral Time.
The adverse effects on time travel caused by the Law of Exclusivity when travelling within one's native time period can be avoided or at least greatly lessened by travelling a lateral distance equal to or in excess of one's respective age in years.