by Lamsdell et al. (2015). Tetlie (2007) Lamsdell et al. (2015) Paleobiology The features of Eusarcana indicate that its lifestyle was completely different from many other swimming eurypterids, such as Eurypterus. When walking, Eusarcana would likely have lifted the eye-bearing frontal part of its head above the ground, as indicated by the larger size of the forward walking legs and the placement of the eyes. In contrast, Eurypterus would have kept its head, shovel-shaped and broad, down to the ground while walking. Furthermore, the walking legs of Eusarcana are more powerful than those of Eurypterus in general. The legs decrease in strength the further back they are, indicating that there was an emphasis on lifting the front of the carapace. In Eurypterus the legs are the longest the further back they are, which indicates that it would have had an emphasis on keeping the head down. The swimming legs of Eusarcana were powerfully developed, with paddles both longer and broader than those of Eurypterus, which corresponds to the fact that Eusarcana was a broader and heavier genus of eurypterids. Tail spike In the Pridoli-age Buffalo waterlime fauna where E. scorpionis lived, it represented one of the larger members of the ecosystem, being at least half as long as the larger predatory eurypterids of the genus Pterygotus. With Eusarcana not having large and powerful pincers like the larger pterygotid eurypterids, which not only represented potential competitors but also dangerous predators, the only obvious organ it could use for defense was the pointed and sharp tail spike. The narrowed tail is so long and extended that it exceeds the principal parts of the body, the head and abdomen, in length. The fact that the tail has been preserved as curved in several fossil specimens proves that it would have been flexible in life, with the apparent curvature of the spike on its end making it a dangerous weapon. If curved forwards over the rest of the body, the spike would be positioned with its point turned upwards, effectively acting similar to a scimitar. The similarity between the spike of Eusarcana and that of scorpions opens up the possibility that the tail spike might possibly have possessed poison glands. Though the state in which the specimens have been preserved does not allow determination of either the absence or presence of a poison canal or pores for transferring the venom to potential victims, the