Four sixteenth notes

¼ of a beat,
¼ of a beat,
¼ of a beat,
¼ of a beat 

Division by four is an evolution of binary rhythm.
It has appeared during the last millennium.
For a long time, the master figure, containing all the elements, was the only one used.
The other possibilities, derived from it, have appeared one by one.

The new notes, those introduced by the division by four, have a lesser rhythmical weight than the old ones.
This is normal since they are placed on the ¼ and ¾ of the beat.

This grid combines with the two we've already seen:

The result is this suite of sixteen values that repeats for each bar.

Approximative grid of rhythmical weights

Sixteen combinations or rhythmic possibilities can be achieved using the division by four.
However, they were not all used before 1975-85.
A sudden evolution occurred during this period and the population of the whole world started feeling the rhythm like never before.
Previously, music based on the division by four only contained twelve figures, at least in popular culture.
This revolution has permitted some kind of parity of the sixteen figures.

A: Count 1, 2, 3, 4, 1, 2, 3, 4, aloud, making sure you space the numbers equally, be curt and precise.

B: Beat your foot on number 1 only.

C: Say Ta, Ta, Ta, Ta, instead of 1, 2, 3, 4.