The fossil record shows that for many plant and animal groups, the time between speciation events
A) is usually about 50,000 years.
B) varies greatly, but averages 6.5 million years.
C) is usually greater than 40 million years.
D) is equivalent to the length of 100 generations of a species.

Question

Quizplus · Accepted Answer

The fossil record shows that the time between speciation events varies greatly across different plant and animal groups, but on average it is about 6.5 million years. This is based on the observation of the emergence of new species in the fossil record and the time gaps between the appearance of new lineages. While there are some examples of rapid speciation events or long periods of stasis, the 6.5 million-year average provides a general estimate of the tempo of evolution over geological time scales.

The Fossil Record Shows That for Many Plant and Animal