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Acutiramus is a genus of giant predatory eurypterid, an extinct group of aquatic arthropods. Fossils of Acutiramus have been discovered in deposits of Late Silurian to Early Devonian age. Eight species have been described, five from North America (including A. cummingsi , the type species) and two from the Czech Republic (with one of them ...
The chelicerae of Acutiramus likely served as slicing or shearing devices, adding to the evidence that it would have occupied a distinct ecological niche. A significantly less active predator, Acutiramus might have been a scavenger or ambush predator, feeding on soft-bodied animals. [18]
Pterygotus (Curviramus) was later recognized as synonymous with Pterygotus (Pterygotus) by Leif Størmer the same year, [11] and Erettopterus and Acutiramus would be recognized as separate, but closely related, genera (Erettopterus by Erik N. Kjellesvig-Waering in 1961, [11] and Acutiramus by Størmer in 1974). [17]
The coxa is the proximal segment and functional base of the leg. It articulates with the pleuron and associated sclerites of its thoracic segment, and in some species it articulates with the edge of the sternite as well. The homologies of the various basal sclerites are open to debate.
Pterygotioidea (the name deriving from the type genus Pterygotus, meaning "winged one") is a superfamily of eurypterids, an extinct group of aquatic arthropods. Pterygotioids were the most derived members of the infraorder Diploperculata and the sister group of the adelophthalmoid eurypterids.
Only the alimentary canals of a few species of eurypterids, such as Carcinosoma newlini, Acutiramus cummingsi and Eurypterus lacustris, have been described. However, the excellent levels of preservation of the O. augusti fossils have allowed the description of what most likely was the anterior portion of the gut.
Lamsdell and Legg concluded that an inclusive phylogenetic analysis with multiple species of Acutiramus, Pterygotus and Jaekelopterus is required to resolve whether the genera are synonyms of each other. [2] The cladogram below is based on the nine best-known pterygotid species and two outgroup taxa (Slimonia acuminata and Hughmilleria socialis).
Size comparison of six of the largest eurypterids: Pterygotus grandidentatus, Pentecopterus decorahensis, Acutiramus macrophthalmus, A. bohemicus, Carcinosoma punctatum, and Jaekelopterus rhenaniae. Eurypterids were highly variable in size, depending on factors such as lifestyle, living environment and taxonomic affinity.