GEO 206-01
RESEARCH PROJECT
EURYPTERIDS
ABSTRACT
1.INTRODUCTION
Eurypterids are a large extinct group of arthropods that ranged from 10 cm to 2 m in length. They belonged to the extinct order Eurypterida of the phylum Arthropoda, Subphylum Chelicerata and class Merostomata. According to the fossil record, the first Eurypterids were present in the mid-Ordovician and they thrived in warm shallow water until the late Permian when they went extinct. Thus, they lived for a period of roughly 220 million years between 470 to 248 million years ago and were a widely diverse chelicerate order that lived in the Paleozoic (Dunlop, 2010).
2. HISTORIC OVERVIEW The first Eurypterid fossil was found in 1818, by Dr.S.L Mitchell …show more content…
The front portion is the prosoma where two compound eyes protrude at the sides. There are two smaller ocelli or simple eyes at the top central part. The mouth is underneath the center where the six pairs of appendages are located while the ventral side has shield like plate/plates. Eurpterids like other chelicerates have modified mouth parts called chelicerae which is their first pair of appendages. This is followed by four pairs of appendages which act as walking legs. The walking legs appendages may have spine or may be of a single shape or various sizes and shapes. The final pair of appendages may also be used for walking legs but are usually modified into paddles (Brady and Dunlop, …show more content…
The Eurypterids had great diversity and included various forms of gigantism. Large predatory pterygotids (Eurypterina) became longer in the Siluro-Devonian while sweep feeding Hibbertoperids (Stylonurina) exhibited greater mass from Carboniferous to end Permian (Lamsdell et al, 2010). Various studies were done to determine whether the abiotic environmental factors or the biotic factors such as competition was behind these evolutionary traits. It has been suggested that pterygoids incorporated gigantism to compete with large, swift vertebrate predators in a coevolutionary arms race ( Lamsdell et al, 2010). Romer in 1933 first suggested this hypothesis but was criticized because other paleontologists found his explanation over