The enzymes are believed to have diverged from a common ancestor, preserving the arrangement of the catalytic residues.
The analysis also showed that the big and small eagles diverged from a common ancestor 700,000 to 1.8 million years ago.
Humans and chimpanzees diverged from a common ancestor about 5-7 million years ago.
It is thought that the two species may have begun to diverge from a marine common ancestor following the changes in coastline during the Miocene.
The two species diverged from a common simioid ancestor, and are quite similar, but cannot interbreed.
The two are thought to have diverged from a common ancestor within the past million years.
Protein structures may be similar because proteins have diverged from a common ancestor.
The family diverged from a common ancestor of the Mammutidae, which includes species termed as mastodons.
Asian and African elephants and mammoths diverged from a common ancestor about six million years ago.
All three apparently diverged from a common ancestor some 3 million years ago.