Jaekelopterus rhenaniae

Jaekelopterus is a genus of predatory eurypterid, a group of extinct aquatic arthropods. Fossils of Jaekelopterus have been discovered in deposits of Early Devonian age, from the Pragian and Emsian stages. There are two known species: the type species J. rhenaniae from brackish to fresh water strata in the Rhineland, and J. howelli from estuarine strata in Wyoming. The generic name combines the name of German paleontologist Otto Jaekel, who described the type species, and the Greek word πτερόν meaning "wing".

Named after Otto Jeakel,‭ ‬Jaekelopterus is currently the largest known eurypterid,‭ ‬even bigger than the more famous Pterygotus.‭ ‬Again this demonstrates how the arthropods grew to giant proportions which continue to remain unknown in today‭’‬s living arthropods.‭ ‬Jaekelopterus itself it thought to have been a freshwater species that possibly hunted other arthropods and possibly fish.

The upper size estimate of Jaekelopterus was extrapolated by comparing the size of the chelicerae to other more complete specimens and then scaling up the size of the compared specimens to reveal the size.‭ ‬The problem with this method is that it is only as reliable as the similarity between the compared specimens,‭ ‬and caution needs to be exercised when using it.‭ ‬This caution was also reflected by the authors of the discovery,‭ ‬Simon Braddy and Markus Poschmann,‭ ‬who estimated the length of Jaekelopterus at‭ ‬2.5‭ ‬meters,‭ ‬even though comparison scaled it closer to‭ ‬2.6‭ ‬meters in length.