Megalograptus is a genus of eurypterid, an extinct group of aquatic arthropods commonly referred to as sea scorpions which lived throughout the worlds oceans during the katian stage of the late Ordovician period some 453 to 445 million years ago. The first fossils of megalograptus were recovered by L. B. Welch near Liberty Ohio, in rocks of the Elkhorn Formation in 1874. Welch then presented his findings to be described by Samuel Almond Miller in 1874. Miller mistakenly believed the fossil material, consisting of a postabdominal tergite and two fragments of an appendage, was the integument of a graptolite (a member of Graptolithina, an extinct group of colonial pterobranchs), and gave it the name Megalograptus, meaning "great writing" in greek. With the species name M. welchi being in honor of L.B. himself. The status of Megalograptus as a graptolite was first questioned in 1908 by Rudolf Ruedemann, who was researching Ordovician graptolites. Ruedemann instead recognized the remains of M. welchi as eurypterid fossils, this idea would be confirmed by August Foerste and Edward Oscar Ulrich later that same year. In the time since several additional more complete specimens have been recovered throughout both the USA and Canada representing at least 5 species: M. welchi, M. alveolatus, M. ohioensis, M. shideleri, and M. williamsae. Megalograptus varied considerably in size with the smallest species reaching a mere 3.9 inches (10cms) in length while the largest reached 2.7 feet (78cms) in length. Megalograptus is easily distinguishable from other eurypterids for sporting 6 sets of appendages with the third being particularly massive spined and forward-facing, as well as a unique sharp spike-shaped telson which has cercal blades capable of grasping. The carapace of Megalograptus was vaguely quadratic in shape and flattened, lacking a marginal rim, sporting large kidney shaped compound eyes and six small downward-facing spikes. Certain fossils of megalograptus are so well-preserved that researchers know that megalograptus would have been a mix of brown and black in coloration. In life Megalograptus lived in near-shore marine environments feeding upon prey such as trilobites, mollusks, other invertebrates, conodonts and early fish. Megalograptus was inturn preyed upon by large orthocones such as Cameroceras and larger eurpyterids including other megalograptus individuals.
Art used belongs to the following creators:
Megalograptus: Masato Hattori https://www.pinterest.es/pin/802063014874206839/
Megalograptus: Jack Mayer Wood https://twitter.com/thewoodparable/status/1172231601545252870?s=12
Megalograptus and Astraspis: Paleoguy
The Ordovician Seas: James Kuether https://www.facebook.com/585329611633916/photos/a.605954959571381/1665858696914330/?type=3