Eurypterid (Sea Scorpion) Fossils
ORDOVICIAN to PERMIAN PERIOD: 460 - 248 million years ago
EURYPTERIDS or SEA SCORPIONS were aquatic arthropods that were highly efficient predators predating the most primitive fishes. The largest known arthropods to have ever lived were eurypterids. Eurypterids are believed to have possibly had dual breathing capabilities in order to allow them to live in water and also venture for short periods of time onto dry land. Eurypterids are also scientifically interesting fossils because they are believed to be related to a predatory arthropod found in Cambrian strata dating from demonstrating the first evidence of creatures emerging from water to walk on land.
All eurypterids are extinct and their fossil remains are found in deposits ranging from the Ordovician Period to the Permian Period. Eurypterids are crustacean-like creatures that had a chitinous exoskeleton similar to trilobites. Also similar to trilobites, eurypterids are made up of three fundamental regions - a head (CEPHALON or PROSOMA), a body (ABDOMEN or OPISTHOSOMA) and a tail spike (TELSON or TERMINAL METASOMA). The upper body and head are often combined in terminology to be called a CEPHALOTHORAX and the main body called an ABDOMEN.
Eurypterids have compound eyes and typically had six pairs of appendages found near the head. The first pair were claws (although some varieties lacked claws), followed by four pairs of walking legs and finally, a pair of swimming appendages (also lacking in some varieties). Some types achieved lengths of 2.5 meters but most were between 10 to 12 cm long.
- text copyright Paleo Direct, Inc.