Megalograptidae
Megalograptidae | |
---|---|
Megalograptus | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Arthropoda |
Subphylum: | Chelicerata |
Order: | †Eurypterida |
Infraorder: | †Diploperculata |
Superfamily: | †Carcinosomatoidea |
Family: | †Megalograptidae Caster & Kjellesvig-Waering, 1955 |
Genera | |
Megalograptidae are a family of
The megalograptids were likely the first major successful group of eurypterids, evidenced by a Late Ordovician radiation. All known members of the Megalograptidea are from the Late Ordovician of Laurentia[1] with the exception of the large Pentecopterus from the Middle Ordovician.
Description
Megalograptids are characterized by large exoskeletons with ovate to triangular scales. The prosoma (head) is subquadrate, with a tonguelike anterior process bearing marginal spines, and compound eyes on the top front of the head. The chelicerae (claws in front of the mouth) are small and short. The first and third pairs of walking legs are short, with diverging or closely spaced spines. The second pair of walking legs is enormously developed, with long paired spines. The fourth pair of walking legs are nearly spineless. The preabdomen, the front portion of the body, is narrow with axial furrows, while the postabdomen is moderately narrow with broad, flat and curved appendages on the last body segment. The telson is short and lanceolate.[2]
Classification
The Megalograptidae are thought to be relatively primitive (between the genus
Genera
Family Megalograptidae Caster & Kjellesvig-Waering, 1955
- Megalograptus Miller, 1874
- Echinognathus Walcott, 1882
- Pentecopterus Lamsdell et al., 2015
See also
- List of eurypterids
References
- ^ PDF) on 2011-07-18.
- ^ Størmer, L 1955. Merostomata. Treatise on Invertebrate Paleontology, Part P Arthropoda 2, Chelicerata, P36.