The titan of sea scorpions, Pterygotus grew up to more than three meters long, the size of some modern crocodiles. Unlike actual scorpions, Pterygotus did not have a true stinger, its tail bearing little more than a superficial resemblance to its namesake. Instead, Pterygotus used it as a paddle for swimming in the water; more usually, however, Pterygotus crawled along the sea bottom or was just lying in ambush - it was too heavy to swim too far for too long. It was capable of relatively fast bursts of speed, though.
Despite its' fame, Pterygotus was only the second largest of the sea scorpions; the Jaekelopterus was larger though not by much. Pterygotus remains are mostly found in the Upper Silurian (418 MYA) in Europe, but it has been found also in the Lower Devonian strata of North America, as well as other places around the world belonging to the Silurian-Devonian time period.
In Walking with Monsters, Pterygotus is depicted as an ambush hunter, lying in wait for the sea-bed for unsuspecting prey to arrive. Although some animals, like Cephalaspis, were able to detect and evade Pterygotus, others like Brontoscorpio were not so lucky. It was also shown to care for its young.
In the series
A mother Pterygotus was hiding under the sea bed, attacked and killed an unsuspecting Brontoscorpio. She then fed the remains to her young. Several others are seen swimming past some orthocones.