Pterygotidae
Encyclopedia
Pterygotidae are an extinct family
of eurypterid
s. They were members of the superfamily Pterygotioidea, and were the only eurypterids to have a truly worldwide distribution
, and include the largest arthropod
s to have ever lived.
, (tail) was expanded, or flatter than it was tall. Pterygotidae also had chelicerae (claws in front of the mouth) that were large and long, with strong, well developed teeth on the claws. Their walking legs were small and slender, without spines. They were the largest arthropods to have ever lived; the largest described fragments shows individuals up to 350 cm at the largest length. The pterygotids had good binocular vision
and chelicerae adapted for cutting or crushing, making them some of the most formidable predators of the Paleozoic.
is thought to represent the sister group to the pterygotids. Although the clade Pterygotidae is one of the best supported within the Eurypterida, relationships within the clade have been difficult to resolve.
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
of eurypterid
Eurypterid
Eurypterids are an extinct group of arthropods related to arachnids which include the largest known arthropods that ever lived. They are members of the extinct order Eurypterida ; which is the most diverse Paleozoic chelicerate order in terms of species...
s. They were members of the superfamily Pterygotioidea, and were the only eurypterids to have a truly worldwide distribution
Cosmopolitan distribution
In biogeography, a taxon is said to have a cosmopolitan distribution if its range extends across all or most of the world in appropriate habitats. For instance, the killer whale has a cosmopolitan distribution, extending over most of the world's oceans. Other examples include humans, the lichen...
, and include the largest arthropod
Arthropod
An arthropod is an invertebrate animal having an exoskeleton , a segmented body, and jointed appendages. Arthropods are members of the phylum Arthropoda , and include the insects, arachnids, crustaceans, and others...
s to have ever lived.
Description
Pterygotidae, which lived from the late Early Silurian to the Middle Devonian, were characterized by small to large exoskeletons with semilunar scales. The telsonTelson
The telson is the last division of the body of a crustacean. It is not considered a true segment because it does not arise in the embryo from teloblast areas as do real segments. It never carries any appendages, but a forked "tail" called the caudal furca is often present. Together with the...
, (tail) was expanded, or flatter than it was tall. Pterygotidae also had chelicerae (claws in front of the mouth) that were large and long, with strong, well developed teeth on the claws. Their walking legs were small and slender, without spines. They were the largest arthropods to have ever lived; the largest described fragments shows individuals up to 350 cm at the largest length. The pterygotids had good binocular vision
Binocular vision
Binocular vision is vision in which both eyes are used together. The word binocular comes from two Latin roots, bini for double, and oculus for eye. Having two eyes confers at least four advantages over having one. First, it gives a creature a spare eye in case one is damaged. Second, it gives a...
and chelicerae adapted for cutting or crushing, making them some of the most formidable predators of the Paleozoic.
Genera
- Class MerostomataMerostomataMerostomata is the name given to a grouping of the extinct Eurypterida and the Xiphosura . The term was originally used by James Dwight Dana to refer to Xiphosura only, but was emended by Henry Woodward to cover both groups....
Dana, 1852 - Order Eurypterida Burmeister, 1843
- Suborder Eurypterina Burmeister, 1843
- Superfamily Pterygotioidea Clarke & Ruedemann, 1912
- Family Pterygotidae Clarke & Ruedemann, 1912
- Genus AcutiramusAcutiramusAcutiramus is an extinct genus of eurypterid which lived in the Late Silurian to Early Devonian.Acutiramus was one of the largest eurypterids with pincers 5 cm and length about 2 m...
Ruedemann, 1935 - Genus Ciurcopterus Tetlie & Briggs, 2009
- Genus PterygotusPterygotusPterygotus is the second-largest known eurypterid, or sea scorpion and one of the largest arthropods of all time.-Description:...
Agassiz, 1839 - Genus ErettopterusErettopterusErettopterus is a genus of prehistoric eurypterid. It was related to another large eurypterid, Pterygotus.-Description:Pterygotidae, which lived from the Ordovician to Devonian periods, were characterized by small to large exoskeletons with semilunar scales. The telson, was expanded, or flatter...
Salter in Huxley & Salter, 1859 - Genus Jaekelopterus Waterston, 1964
- Genus Acutiramus
- Family Pterygotidae Clarke & Ruedemann, 1912
Phylogeny
The genus SlimoniaSlimonia
Slimonia is a genus of Silurian eurypterid roughly similar to the genus Pterygotus. Slimonia resembled Pterygotus, save that the former's telson is larger, and that its body was smaller and more slender than the latter. Unlike Pterygotus, which lived in estuaries, Slimonia species lived...
is thought to represent the sister group to the pterygotids. Although the clade Pterygotidae is one of the best supported within the Eurypterida, relationships within the clade have been difficult to resolve.