Knowra Eurypterid Eurypterid A eurypterid was an extinct aquatic chelicerate arthropod in the order Eurypterida, commonly called a sea scorpion. Eurypterids ranged from small animals to some of the largest known arthropods.
Chelicerata : A subphylum of arthropods that includes arachnids, horseshoe crabs, and sea spiders. Eurypterids belong to this arthropod lineage, whose members lack antennae and bear chelicerae.
Swimming : Movement through water by propelling the body with limbs or body undulations. Paddle-shaped rear limbs helped many eurypterids swim through aquatic habitats.
Silurian : A geological period spanning about 443 to 419 million years ago. Eurypterids diversified greatly during the Silurian, when many iconic forms lived.
Jaekelopterus : An extinct genus of giant eurypterid known from Devonian fossils. Its fossil remains indicate a body length exceeding two meters, among the largest known arthropods.
Arthropod gigantism : The evolution of unusually large body size in arthropods. Eurypterids include some of the largest arthropods known, prompting study of size limits in ancient ecosystems.
Arthropod : An invertebrate animal with a segmented body, jointed appendages, and an external skeleton. Eurypterids shared the defining body plan of arthropods.
Paddle (anatomy) : A broad, flattened limb adapted to push against water during swimming. The enlarged sixth appendage formed a paddle in many swimming eurypterids.
Ordovician : A geological period spanning about 485 to 443 million years ago. The earliest known eurypterids appear in Ordovician rocks.
Pterygotus : An extinct genus of large predatory eurypterids with powerful, claw-like chelicerae. Pterygotus exemplifies the formidable grasping appendages of some large eurypterids.
Paleozoic : The geological era from about 539 to 252 million years ago, marked by major diversification of animal life. Eurypterids flourished across much of this era and vanished before its end.
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