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Any of various large segmented aquatic arthropods of the order Eurypterida that existed from the Ordovician Period to the Permian Period, having a long tail often with a spinelike appendage at the tip. Also called sea scorpion.

[From New Latin Eurypterida, order name, from Eurypterus, genus name : eury- + Greek pteron, wing; see -pter.]


(Animals) any large extinct scorpion-like aquatic arthropod of the group Eurypterida, of Palaeozoic times, thought to be related to the horseshoe crabs
[C19: from New Latin Eurypterida, from eury- + Greek pteron wing, feather]


(yʊˈrɪp tə rɪd, yə-)

any extinct aquatic arthropod of the Paleozoic order Eurypterida, related to horseshoe crabs.
[1870–75; < New Latin Eurypteridae. See eury-, -pterous, -id2]
ThesaurusAntonymsRelated WordsSynonymsLegend:
Noun1.eurypterid - large extinct scorpion-like arthropod considered related to horseshoe crabs
arthropod - invertebrate having jointed limbs and a segmented body with an exoskeleton made of chitin
Eurypterida, order Eurypterida - extinct aquatic arthropods of the Paleozoic
References in periodicals archive ?
In addition to fish, the aquatic assemblage includes eurypterids (Miller 2007a, 2007b), ostracods (Jones 1889) and gastropods (Whiteaves 1881).
The rare and highly prized fossil remains of eurypterids occur in very few places, and almost always to the exclusion of other kinds of fossils.
Our analysis shows that they could not see as well as other eurypterids and may have lived in dark or cloudy water.
Eurypterids flourished in the Silurian Period (443-416 million years ago), but are not common finds.
Ancestral horseshoe crabs (Class Merostomata, Order Xiphosurida, Suborder Synziphosurina), often found associated with eurypterids in Silurian and Devonian strata, are sporadically represented in the geologic column (Stormer, 1955).
The scorpion body plan is strikingly similar to that of the extinct eurypterids (Chelicerata: Eurypterida), and on this basis, scorpions can be considered reasonable taphonomic analogues for their extinct chelicerate cousins.
Apparently eurypterids were so common and carnivorous that in order for fish to survive among them, they had to have a bony suit of scaled armor.
In Fossil Hall one could also Feel Small in facing immense sandstone slabs with minutely detailed low-relief carbonaceous phantoms of monstrous fishes, sea turtles, palm fronds (much like those outside, soughing by the pool), and huge icky trilobites and eurypterids.
This year, he returns to examine outcrops of ancient tropical seabed deposits on the Grand Rapids Uplands, where extraordinary remains of rare eurypterids ("sea scorpions"), horseshoe crabs, and other odd joint-legged animals have been uncovered.
These previously discovered eurypterids are from the western exposure of the Campbellton Formation and are believed to have inhabited a coastal deltaic setting, along with a rich vertebrate assemblage that included cephalaspids, placoderms, acanthodians, and sharks.
These little-known late Cambrian-mid Devonian marine euchelicerates are characterized by a long postabdomen of nine segments, but share prosomal features with both eurypterids and xiphosurans, rendering their monophyly and affinities uncertain.