''Wiedopterus'' is a genus 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 ...

, an extinct group of aquatic

arthropods 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 ...

. The type and only species of ''Wiedopterus'', ''W. noctua'', is known from deposits of Early

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 ...

age in Germany. The generic name derives from the Wied river, which runs near the site of the initial discovery, and the species name, ''noctua'', derives from

Latin Latin ( or ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...

''noctua'' (

owl Owls are birds from the order Strigiformes (), which includes over 200 species of mostly solitary and nocturnal birds of prey typified by an upright stance, a large, broad head, binocular vision, binaural hearing, sharp talons, and feathers a ...

) which refers to the superficial resemblance 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 ...

(head plate) to an owl. A small eurypterid, the type and only known specimen of ''Wiedopterus'' does not preserve the appendages or the underside of the body, making certain classification of the genus impossible. As such, it is formally classified as

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 ...

incertae sedis or is a term used for a taxonomy (biology), taxonomic group where its broader relationships are unknown or undefined. Alternatively, such groups are frequently referred to as "enigmatic taxa". In the system of open nomenclature, uncertainty ...

'' (indicating uncertain placement within the Eurypterina suborder of eurypterids). Though not yet formally classified as such, ''Wiedopterus'' was suggested to probably belong to the Adelophthalmidae family on account of various features, including its general body outline, the position of its eyes, the first segment after its head being reduced in size as well as there being longitudinal ridges on the posterior segments of its body.

Description

Markus Poschmann, who described ''Wiedopterus'', classified the genus as

'' (indicating uncertain placement within the Eurypterina suborder of eurypterids), but noted that the ''Wiedopterus'' fossils "probably represent adelophthalmoids". ''Wiedopterus'' was a relatively small eurypterid, with the only described fossil specimen, measuring 4.43 centimeters (1.74 in) in length, accounting for a little over half of the animal. If ''Wiedopterus'' was an adelophthalmoid, it would be a medium-sized member of the group, whose members ranged in length from 4 to 32 centimeters (1.6 to 12.6 in). The diagnostic features of the genus, as noted by Poschmann in its description, include the

(head plate) being shaped like a

trapezoid In geometry, a trapezoid () in North American English, or trapezium () in British English, is a quadrilateral that has at least one pair of parallel sides. The parallel sides are called the ''bases'' of the trapezoid. The other two sides are ...

and having a narrow marginal rim, the

compound eyes A compound eye is a visual organ found in arthropods such as insects and crustaceans. It may consist of thousands of ommatidia, which are tiny independent photoreception units that consist of a cornea, lens, and photoreceptor cells which distin ...

being placed close to the center of the carapace, the preabdomen (body segments 1–7) being rounded and wide, with the anteriormost (most forwardly placed)

tergite A ''tergum'' (Latin for "the back"; : ''terga'', associated adjective tergal) is the Anatomical terms of location#Dorsal and ventral, dorsal ('upper') portion of an arthropod segment other than the head. The Anatomical terms of location#Anterior ...

being reduced in size, the

tergites A ''tergum'' (Latin for "the back"; : ''terga'', associated adjective tergal) is the dorsal ('upper') portion of an arthropod segment other than the head. The anterior edge is called the 'base' and posterior edge is called the 'apex' or 'margin'. ...

possessing narrow anterior articulation facets, the

dorsal Dorsal (from Latin ''dorsum'' ‘back’) may refer to: * Dorsal (anatomy), an anatomical term of location referring to the back or upper side of an organism or parts of an organism * Dorsal, positioned on top of an aircraft's fuselage The fus ...

(back) preabdomen not having any prominent ornamentation, and that there is a marked constriction between the preabdomen and the postabdomen (body segments 8–12). The preabdomen of ''Wiedopterus'' was widest at the third or fourth segment, where it measured about 2.05 centimeters (0.81 in) in width.

History of research

''Wiedopterus noctua'' was described by Poschmann in 2015 based on a single specimen recovered in fossil deposits of Early

, probably

Emsian The Emsian is one of three faunal stages in the Early Devonian Epoch. It lasted from 410.62 ±1.95 million years ago to 393.47 ±0.99 million years ago. It was preceded by the Pragian Stage and followed by the Eifelian Stage. It is named after ...

, age. The fossil locality, part of the

Rhenish Massif The Rhenish Massif, Rhine Massif or Rhenish Uplands (, : 'Rhenish Slate Uplands') is a geologic massif in western Germany, eastern Belgium, Luxembourg and northeastern France. It is drained centrally, south to north by the river Rhine and a few ...

, is a wayside outcrop located next to a bus stop, about 500 meters north of the village Bürdenbach and 90 meters northeast of the

confluence In geography, a confluence (also ''conflux'') occurs where two or more watercourses join to form a single channel (geography), channel. A confluence can occur in several configurations: at the point where a tributary joins a larger river (main ...

of the small creek Güllesheimer Bach and the Lahrbach river. The ''Wiedopterus'' type specimen, given the designation PWL2013/5224-LS, preserves the carapace and the first to ninth segment of the opisthosoma, though these are somewhat damaged on the right side. PWL2013/5224-LS was noted by Poschmann to not be the only eurypterid fossil clearly distinguishable from the other eurypterids found at the site, belonging to the genus '' Parahughmilleria'', but it was the only fossil well-preserved enough to be described and formally named. The generic name ''Wiedopterus'' refers to the valley formed by the Wied river, located near the locality where the holotype specimen was found. The epithet , from the Ancient Greek ("wing") is commonly used for eurypterid genera. The species name ''noctua'' is Latin for "owl" and derives from Poschmann finding the carapace and the eyes of ''Wiedopterus'' to be "somewhat reminiscent of an owl".

Classification

''Wiedopterus'' is different from other known Early

eurypterids when it comes to the position of its compound eyes and the shape of its carapace. '' Moselopterus'', '' Alkenopterus'', '' Vinetopterus'' and '' Erieopterus'' are superficially similar, but ''Moselopterus'', ''Alkenopterus'' and ''Vinetopterus'' all have a more horseshoe-shaped carapace, with the carapace of ''Moselopterus'' also has distinct ornamentation, missing in ''Wiedopterus'', and ''Alkenopterus'' and ''Vinetopterus'' have wider and differently shaped, respectively, marginal rims. ''Erieopterus'' has a more rounded carapace, with the eyes positioned more outwardly. The shape and eye position is also similar to the

Silurian The Silurian ( ) is a geologic period and system spanning 23.5 million years from the end of the Ordovician Period, at million years ago ( Mya), to the beginning of the Devonian Period, Mya. The Silurian is the third and shortest period of t ...

Eurypterus ''Eurypterus'' ( ) is an extinct genus of eurypterid, a group of organisms commonly called "sea scorpions". The genus lived during the Silurian period, from around 432 to 418 million years ago. ''Eurypterus'' is by far the most well-studied and ...

'' (though the carapace of ''Eurypterus'' is slightly more quadratic, the eyes are positioned further back and its first opisthosomal tergite is not as small), the Silurian '' Buffalopterus'' and the Silurian–Devonian '' Strobilopterus'' (though ''Buffalopterus'' and ''Strobilopterus'' have a wider carapace and eyes positioned further back). Among the Early Devonian eurypterids, the only species that has a carapace shape similar to ''Wiedopterus'', beyond just superficial similarity, is '' Adelophthalmus sievertsi'', though ''A. sievertsi'' can be distinguished from ''Wiedopterus'' by its carapace and opisthosoma being ornamented by large and small tubercles (rounded projections), and that it had lateral epimera on its preabdominal tergites (spines along the edges). The ''Wiedopterus'' type specimen does not preserve the appendages or its

ventral Standard anatomical terms of location are used to describe unambiguously the anatomy of humans and other animals. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position prov ...

(underside) anatomy, which makes certain classification of the genus impossible. Several features suggest that ''Wiedopterus'' was an adelophthalmid eurypterid, including the general outline of its body, the first tergite being reduced in size, there being morphological differentiation of the body into a pre- and postabdomen, and there being longitudinal ridges on the postabdominal segments, which were subrectangular (vaguely rectangular) in shape. ''Wiedopterus'' possessed a median eye tubercle (a large tubercle between the eyes), a feature present in derived genera within both the

and

Stylonurina Stylonurina is one of two suborders of eurypterids, a group of extinct arthropods commonly known as "sea scorpions". Members of the suborder are collectively and informally known as "stylonurine eurypterids" or "stylonurines". They are known from ...

suborders. The feature is, among other genera, present in ''Adelophthalmus''. Because ''Wiedopterus'' also shares the centrally positioned eyes with ''Adelophthalmus'', it is possible that it was a relatively derived adelophthalmid eurypterid.

Paleoecology

The fossil deposits in which the ''Wiedopterus'' type specimen was found were once a land–sea transitional area, featuring rivers,

deltas A river delta is a landform, wikt:archetype#Noun, archetypically triangular, created by the deposition (geology), deposition of the sediments that are carried by the waters of a river, where the river merges with a body of slow-moving water or ...

and fully marine environments, where the fossils were deposited under rapid environmental changes. Other fossil life known from the same deposits include jawless fish ('' Rhinopteraspis''),

trigonotarbids The order Trigonotarbida is a group of extinct arachnids whose fossil record extends from the late Silurian to the early Permian ( Pridoli to Sakmarian).Dunlop, J. A., Penney, D. & Jekel, D. 2020A summary list of fossil spiders and their relatives ...

('' Spinocharinus'' and '' Archaeomartus''),

scorpion Scorpions are predatory arachnids of the Order (biology), order Scorpiones. They have eight legs and are easily recognized by a pair of Chela (organ), grasping pincers and a narrow, segmented tail, often carried in a characteristic forward cur ...

s ('' Waeringoscorpio''), chasmataspidids,

bivalves Bivalvia () or bivalves, in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class of aquatic molluscs (marine and freshwater) that have laterally compressed soft bodies enclosed by a calcified exoskeleton consis ...

and other eurypterids (''Parahughmilleria''). Also present were early land plants, most prominently Zosterophyllopsida.

References

{{Taxonbar, from=Q48850422 Devonian eurypterids Fossil taxa described in 2015 Fossils of Germany Eurypterids of Europe

Description

History of research

Classification

Paleoecology

See also

References