Pteranodon
Pteranodon (; from Greek πτερόν ( pteron, "wing") and ἀνόδων (anodon, "toothless") is a genus of pterosaur that included some of the largest known flying reptiles, with wingspans over 8 meters (26 feet). They lived during the late Cretaceous geological period of North America in present-day Kansas, Alabama, Nebraska, Wyoming, and South Dakota. More fossil specimens of "Pteranodon" have been found than any other pterosaur, with about 1,200 specimens known to science, many of them well preserved with nearly complete skulls and articulated skeletons. It was an important part of the animal community in the Western Interior Seaway.
Slimonia
"Slimonia" is in many ways similar to the more derived (more "advanced") eurypterids of its superfamily, the Pterygotioidea. In particular, the expanded and flattened telson (the most posterior segment of the body) of "Slimonia" is similar to that of the pterygotid eurypterids and is a feature that "Slimonia" and the pterygotids only share with some derived hibbertopterid eurypterids (where the feature convergently evolved). The pterygotid telson was in general slightly larger than that of "Slimonia" and was more slender. The telson spike of "Slimonia" was much longer than any seen in the Pterygotidae (constituting just over half of the total telson length) however, serrated and ending in a fine point. The largest species of "Slimonia", "S. acuminata", reached a maximum length of 100 cm (39 in) whilst the smallest, "S. dubia", grew to 12 cm (5 in) in length. Though 100 cm is large for a predatory arthropod, "Slimonia" would be exceeded in length by later and more derived (more "advanced") members of the closely related pterygotid family of eurypterids, which would become the largest known arthropods to ever live.