It's incorrect to say that prokaryotes are not monophyletic. Prokaryotes are actually considered a paraphyletic group. Here's why:

* Monophyletic: A monophyletic group includes an ancestor and all of its descendants.

* Paraphyletic: A paraphyletic group includes an ancestor and some, but not all, of its descendants.

Prokaryotes are a paraphyletic group because they include the common ancestor of all life, but they exclude the descendants that evolved into eukaryotes.

Here's a breakdown:

1. Early life: The first life forms on Earth were prokaryotes.

2. Evolution of eukaryotes: Eukaryotes evolved from prokaryotes, specifically through a process called endosymbiosis.

3. Prokaryote diversity: After the divergence of eukaryotes, prokaryotes continued to diversify into bacteria and archaea.

Since eukaryotes are descendants of the same ancestor as bacteria and archaea, the group "prokaryotes" is not monophyletic because it excludes eukaryotes.

Therefore, it's not accurate to say that prokaryotes are not monophyletic. Instead, they are considered a paraphyletic group.