The little-known trout of the headwaters of the Tigris and Euphrates Rivers in eastern Turkey present a fascinating evolutionary puzzle for trout biologists.

Q. Among social scientists, the conventional wisdom has it that you've filled in an important piece of the evolutionary puzzle.

The halls will contain interactive displays and exhibits examining evolutionary puzzles and the mysteries posed by fossil records.

Determining exactly how the members of the Sphenacodontidae-Dimetrodon, Sphenacodon, Ctenospondylus, Cryptovenator, and Secodontosaurus-are related to each other has posed an evolutionary puzzle for paleontologists.

Scientists in Sweden have filled in a piece of an evolutionary puzzle: how the middle ear developed in tetrapods, four-limbed creatures.

If the original crocodilians and other Triassic archosaurs were warm-blooded, this would help to resolve some evolutionary puzzles:

If one little piece of the evolutionary puzzle doesn't fit the whole thing has to go.

Schizophrenia has been considered an evolutionary puzzle due to the combination of high heritability, relatively high prevalence, and reduced reproductive success.

In other mammal chimpanzees and Japanese macaques there is no similar acceleration in the rate of follicular atresia, so this pattern remains an evolutionary puzzle.