Pistelähteet

Pistelähteet, known scientifically as Anaspida, are an extinct group of early jawless fish that lived during the Silurian period. They are characterized by their small size, typically only a few centimeters long, and their distinctively segmented armor plates. These plates, which gave them their name ("piste" meaning spot or dot, and "lähde" meaning source or origin, referring to the scattered nature of the armor), covered their heads and bodies, providing protection from predators.

Unlike many other early fish, pistelähteet lacked true paired fins, relying on their tails for propulsion. Their mouths were located on the underside of their heads, suggesting a bottom-dwelling lifestyle where they likely fed on detritus or small invertebrates found in the sediment. Fossil evidence indicates that pistelähteet had a limited sensory system, with small eyes and no evidence of a lateral line system, which is common in other fish for detecting water movement.

The classification of pistelähteet has been a subject of debate among paleontologists. While historically placed within the jawless fish, their exact evolutionary relationships to other early vertebrate groups are still being investigated. Their unique combination of features, particularly their segmented armor, sets them apart from other known fossil fish, making them an important group for understanding early vertebrate evolution. The fossil record of pistelähteet is primarily found in marine sedimentary rocks from the Silurian of Europe and North America.