Prehistoric Period

The present-day Blanding's turtle (Emydoidea blandingii) did not exist during the prehistoric period, which is generally thought to have begun at the moment the Earth was formed around 4.6 billion years ago and ended around 11,700 years ago with the end of the Pleistocene epoch. Many species came and departed throughout this enormous time period, as the planet saw major changes in geology and biology, most notably during mass extinctions such as the Permian-Triassic and Cretaceous-Paleogene epochs.

On the other hand, turtles as a class may trace their evolutionary roots back more than 220 million years. Around 220 million years ago, during the Triassic era, the first turtles were discovered. Even though their shells were not completely formed like current turtles', the early turtles Proganochelys and Odontochelys paved the way for the shell structure that is observed in modern turtles.

Various kinds of turtles evolved from a common ancestor during the Jurassic and Cretaceous eras. Around 66 million years ago, at the close of the Cretaceous epoch, turtles' fundamental body plan—including their fully formed shell—had mostly evolved into forms that are familiar today. Some species, such as Blanding's turtle, did not appear until far later.

It is thought that Blanding's turtle evolved during the last few million years, making its origins much more recent. There are gaps in the fossil record that are particular to this species, therefore we don't know when it exactly appeared. Although fossils of other turtle species from more recent times have been discovered, there is no direct evidence of Blanding's turtle from the ancient era.

Hence, while Blanding's turtle is descended from a lengthy line of turtles that goes all the way back to ancient times, the current species Emydoidea blandingii probably arose very late in geological terms, far after the end of the prehistoric period. Its unique origins and evolutionary trajectory mirror the ever-changing nature of biodiversity as a result of diversification and adaptation over millions of years.