Waeringopteroid
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Waeringopteridae is a family of
eurypterid Eurypterids, often informally called sea scorpions, are a group of extinct marine arthropods that form the Order (biology), order Eurypterida. The earliest known eurypterids date to the Darriwilian stage of the Ordovician period, 467.3 Myr, mil ...
s, an extinct group of aquatic
arthropod Arthropods ( ) are invertebrates in the phylum Arthropoda. They possess an arthropod exoskeleton, exoskeleton with a cuticle made of chitin, often Mineralization (biology), mineralised with calcium carbonate, a body with differentiated (Metam ...
s. The Waeringopteridae is the only family classified as part of the superfamily Waeringopteroidea, which in turn is classified within the infraorder
Diploperculata Diploperculata is an infraorder of eurypterids, an extinct group of aquatic arthropods commonly known as "sea scorpions". The name, derived from Greek διπλόω ("double") and ''operculum'', refers to the distinguishing feature that unites the ...
in the suborder
Eurypterina Eurypterina is one of two suborders of eurypterids, an extinct group of chelicerate arthropods commonly known as "sea scorpions". Eurypterine eurypterids are sometimes informally known as "swimming eurypterids". They are known from fossil depos ...
. The earliest known member of the group, ''
Orcanopterus ''Orcanopterus'' is a genus of a eurypterid classified as part of the family Waeringopteridae. The genus contains one species, ''O. manitoulinensis'', from the Ordovician of Manitoulin District, Manitoulin, Canada. Morphology Limbs ''Orca ...
'', has been recovered from deposits of
Katian The Katian is the second stage of the Upper Ordovician. It is preceded by the Sandbian and succeeded by the Hirnantian Stage. The Katian began million years ago and lasted for about 7.6 million years until the beginning of the Hirnantian mill ...
(
Late Ordovician The Late Ordovician is the third and final epoch of the Ordovician period, lasting million years and spanning from around 458.2 to 443.1 million years ago. The rocks associated with this epoch are referred to as the Upper Ordovician Series. At ...
) age and the latest known surviving member, ''
Grossopterus ''Grossopterus'' is a genus of prehistoric eurypterid classified as part of the family Waeringopteridae. The genus contains two species, ''G. inexpectans'' from Gilboa, United States and ''G. overathi'' from Overath, Germany.Dunlop, J. A., Penn ...
'', has been recovered from deposits of
Siegenian The Siegenian was an epoch of the Devonian The Devonian ( ) is a period (geology), geologic period and system (stratigraphy), system of the Paleozoic era (geology), era during the Phanerozoic eon (geology), eon, spanning 60.3 million years ...
(
Early Devonian The Early Devonian is the first of three Epoch (geology), epochs comprising the Devonian period, corresponding to the Lower Devonian Series (stratigraphy), series. It lasted from and began with the Lochkovian Stage , which was followed by the Pr ...
) age. The name Waeringopteridae is derived from the type genus '' Waeringopterus'', which is named in honor of eurypterid researcher Erik N. Kjellesvig-Waering. Waeringopterid fossils are very rare and the family only contains five known species classified in three different genera (''Waeringopterus'', ''Orcanopterus'' and ''Grossopterus''). Four of these species are from the ancient continent of
Laurentia Laurentia or the North American craton is a large continental craton that forms the Geology of North America, ancient geological core of North America. Many times in its past, Laurentia has been a separate continent, as it is now in the form of ...
, with the only species known from outside of it being a Devonian species recovered from
Germany Germany, officially the Federal Republic of Germany, is a country in Central Europe. It lies between the Baltic Sea and the North Sea to the north and the Alps to the south. Its sixteen States of Germany, constituent states have a total popu ...
. It is thus considered likely that the group originated in Laurentia before spreading to Germany during the Devonian. As the fossil record of the group is extremely poor, little is known of the morphology of the taxa within the group. Although confirmed by phylogenetic analyses as monophyletic, and routinely used within eurypterid taxonomy,Dunlop, J. A., Penney, D. & Jekel, D. 2015. A summary list of fossil spiders and their relatives. In World Spider Catalog. Natural History Museum Bern, online at http://wsc.nmbe.ch , version 16.0 http://www.wsc.nmbe.ch/resources/fossils/Fossils16.0.pdf (PDF). "Waeringopteroidea" and "Waeringopteridae" are as of yet not formally published clades, the names instead deriving from a 2004 thesis by O. Erik Tetlie. Some researchers refer to the group more formally as the "waeringopteroid clade" rather than as the superfamily "Waeringopteroidea", pending a formal publication.


Description

Although waeringopterid fossils remain rare and in most cases fragmentary and very little concrete information on the group can confidently be established due to the poor fossil record, the waeringopterid eurypterids are joined by a handful of known features shared by all genera within the group. Like all other
chelicerates The subphylum Chelicerata (from Neo-Latin, , ) constitutes one of the major subdivisions of the phylum Arthropoda. Chelicerates include the sea spiders, horseshoe crabs, and arachnids (including harvestmen, scorpions, spiders, solifuges, tic ...
, and other arthropods in general, waeringopterid eurypterids possessed segmented bodies and jointed appendages (limbs) covered in a
cuticle A cuticle (), or cuticula, is any of a variety of tough but flexible, non-mineral outer coverings of an organism, or parts of an organism, that provide protection. Various types of "cuticle" are non- homologous, differing in their origin, structu ...
composed of
protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residue (biochemistry), residues. Proteins perform a vast array of functions within organisms, including Enzyme catalysis, catalysing metab ...
s and
chitin Chitin (carbon, C8hydrogen, H13oxygen, O5nitrogen, N)n ( ) is a long-chain polymer of N-Acetylglucosamine, ''N''-acetylglucosamine, an amide derivative of glucose. Chitin is the second most abundant polysaccharide in nature (behind only cell ...
. The chelicerate body is divided into two tagmata (sections); the frontal
prosoma The cephalothorax, also called prosoma in some groups, is a tagma of various arthropods, comprising the head and the thorax fused together, as distinct from the abdomen behind. (The terms ''prosoma'' and ''opisthosoma'' are equivalent to ''cepha ...
(head) and posterior
opisthosoma The opisthosoma is the posterior part of the body in some arthropods, behind the prosoma ( cephalothorax). It is a distinctive feature of the subphylum Chelicerata (arachnids, horseshoe crabs and others). Although it is similar in most respects ...
(abdomen). In the waeringopterids, the fifth pair of appendages were spiniferous. The
telson The telson () is the hindmost division of the body of an arthropod. Depending on the definition, the telson is either considered to be the final segment (biology), segment of the arthropod body, or an additional division that is not a true segm ...
(the posteriormost segment of the body) was xiphous (long and pointed). The eyes of waeringopterid eurypterids were located close to the marginal rim of the
carapace A carapace is a dorsal (upper) section of the exoskeleton or shell in a number of animal groups, including arthropods, such as crustaceans and arachnids, as well as vertebrates, such as turtles and tortoises. In turtles and tortoises, the unde ...
(the "head" plate). The waeringopterids were almost all small eurypterids. ''Waeringopterus cumberlandicus'' reached in length, while ''Grossopterus overathi'' reached . ''Orcanopterus manitoulinensis'' reached in length. Though this is relatively long in comparison to modern arthropods, other members of Diploperculata, such as the
pterygotid Pterygotidae (the name deriving from the type genus ''Pterygotus'', meaning "winged one") is a family of eurypterids, an extinct group of aquatic arthropods. They were members of the superfamily Pterygotioidea. Pterygotids were the largest known ...
s or the
carcinosomatid Carcinosomatidae (the name deriving from the type genus ''Carcinosoma'', meaning "crab body")Meaning osomaat ''www.dictionary.com''. Retrieved 7 September 2018. is a family of eurypterids, an extinct group of aquatic arthropods. They were members ...
s, reached much larger sizes, surpassing two meters.


Classification

The Waeringopteridae is the only family within the superfamily Waeringopteroidea and contains the genera ''
Grossopterus ''Grossopterus'' is a genus of prehistoric eurypterid classified as part of the family Waeringopteridae. The genus contains two species, ''G. inexpectans'' from Gilboa, United States and ''G. overathi'' from Overath, Germany.Dunlop, J. A., Penn ...
'', ''
Orcanopterus ''Orcanopterus'' is a genus of a eurypterid classified as part of the family Waeringopteridae. The genus contains one species, ''O. manitoulinensis'', from the Ordovician of Manitoulin District, Manitoulin, Canada. Morphology Limbs ''Orca ...
'' and '' Waeringopterus''. The cladogram below presents the inferred phylogenetic positions of most of the genera included in the three most derived superfamilies of the
Eurypterina Eurypterina is one of two suborders of eurypterids, an extinct group of chelicerate arthropods commonly known as "sea scorpions". Eurypterine eurypterids are sometimes informally known as "swimming eurypterids". They are known from fossil depos ...
suborder of eurypterids (
Adelophthalmoidea Adelophthalmidae (the name deriving from the type genus ''Adelophthalmus'', meaning "no obvious Compound eyes, eyes") is a Family (biology), family of eurypterids, an extinct group of aquatic arthropods. Adelophthalmidae is the only family class ...
,
Pterygotioidea Pterygotioidea (the name deriving from the type genus ''Pterygotus'', meaning "winged one") is a superfamily (taxonomy), superfamily of eurypterids, an extinct group of aquatic arthropods. Pterygotioids were the most Derived trait, derived membe ...
and the waeringopteroids), as inferred by O. Erik Tetlie and Markus Poschmann in 2008, based on the results of a 2008 analysis specifically pertaining to the Adelophthalmoidea and a preceding 2004 analysis. "Waeringopteridae" and the superfamily that includes it, "Waeringopteroidea" (named after eurypterid researcher Erik N. Kjellesvig-Waering), are not formally published clades. The names derive from a 2004 thesis by O. Erik Tetlie and are as such not actually technically valid names. Nevertheless, as phylogenetic analyses confirms the grouping as monophyletic and the names supply an easy way to refer to the group, they remain routinely used within studies centered around eurypterid taxonomy. In these studies, the names are usually within quotation marks and/or are noted to not be properly valid names that derive from a thesis. The group is also sometimes referred to as the "waeringopteroid clade" rather than as the "Waeringopteroidea" within studies to differentiate it from the properly described superfamilies, pending the formal publication of Waeringopteroidea.


Distribution and paleobiogeography

Out of the five known waeringopterid species, four are from the fossil deposits in areas that were part of the ancient continent of
Laurentia Laurentia or the North American craton is a large continental craton that forms the Geology of North America, ancient geological core of North America. Many times in its past, Laurentia has been a separate continent, as it is now in the form of ...
. Only the last known surviving species, '' Grossopterus overathi'', from the
Devonian The Devonian ( ) is a period (geology), geologic period and system (stratigraphy), system of the Paleozoic era (geology), era during the Phanerozoic eon (geology), eon, spanning 60.3 million years from the end of the preceding Silurian per ...
of
Germany Germany, officially the Federal Republic of Germany, is a country in Central Europe. It lies between the Baltic Sea and the North Sea to the north and the Alps to the south. Its sixteen States of Germany, constituent states have a total popu ...
, is known from outside of Laurentia and it is thus assumed that the group originated in Laurentia before they spread to modern-day Germany in the Devonian. Further fossil finds are required to properly study the distribution and evolutionary history of the group. The temporal range of the group extends from the
Late Ordovician The Late Ordovician is the third and final epoch of the Ordovician period, lasting million years and spanning from around 458.2 to 443.1 million years ago. The rocks associated with this epoch are referred to as the Upper Ordovician Series. At ...
(''
Orcanopterus ''Orcanopterus'' is a genus of a eurypterid classified as part of the family Waeringopteridae. The genus contains one species, ''O. manitoulinensis'', from the Ordovician of Manitoulin District, Manitoulin, Canada. Morphology Limbs ''Orca ...
'') to the
Early Devonian The Early Devonian is the first of three Epoch (geology), epochs comprising the Devonian period, corresponding to the Lower Devonian Series (stratigraphy), series. It lasted from and began with the Lochkovian Stage , which was followed by the Pr ...
(''
Grossopterus ''Grossopterus'' is a genus of prehistoric eurypterid classified as part of the family Waeringopteridae. The genus contains two species, ''G. inexpectans'' from Gilboa, United States and ''G. overathi'' from Overath, Germany.Dunlop, J. A., Penn ...
'').


See also

*
List of eurypterid genera This list of eurypterid genera is a comprehensive listing of all genera that have ever been included in the order Eurypterida, excluding purely vernacular terms. The list includes all commonly accepted genera, but also genera that are now consider ...


References

{{Taxonbar, from=Q21588877 Diploperculata Silurian first appearances Devonian extinctions Prehistoric arthropod families