The oldest snakes in the world belong to a now-extinct species of animal called the "protosnakes". These primitive snakes appeared about 170 million years ago in the late Cretaceous period, which is quite far away. However, our knowledge of these ancient snakes is relatively limited because their fossil record is uncommon.
According to the available fossil evidence, the oldest snakes date back to the Late Cretaceous period, about 120 million years ago. The fossil snake, known as the late chalk snake (Najash rionegrina), was found in Argentina and is believed to be the oldest known snake. While it already possesses some of the characteristics of a snake, such as a long, flexible body, it also retains some characteristics similar to that of a lizard, such as its hind limbs.
Although the late chalk is the oldest known snake species, scientists are still researching and exploring it in order to better understand the evolutionary history of the snake species. Through further discovery and research, more ancient snakes may be discovered and provide us with a deeper understanding of the origin and evolution of snakes.