forerunners

noun

1. 1

   A runner at the front or ahead.

2. 2

   By extension, a non-competitor who leads out the competitors on to the circuit, or who runs/rides the course prior to competitor trials, usually testing or checking the way.

3. 3

   A precursor or harbinger, a warning ahead.

4. 4

   A forebear, an ancestor, a predecessor.

   “Bakelite is a forerunner of today's plastics.”

5. 5

   A postage stamp used in the time before a region or area issues stamps of its own.