''Bundenbachiellus'' is an extinct genus of

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 ...

described from the Lower

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 ...

Hunsrück Slate The Hunsrück () is a long, triangular, pronounced upland in Rhineland-Palatinate, Germany. It is bounded by the valleys of the Moselle-Saar (north-to-west), the Nahe (south), and the Rhine (east). It is continued by the Taunus mountains, past ...

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 ...

. This genus is known from only one species, ''B. giganteus''. Alongside its possible relative '' Enalikter'' from

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 ...

, it is possible that genus is late-living example of

Megacheira Megacheira ("great hands", also historically great appendage arthropods) is an extinct class of predatory arthropods defined by their possession of spined "great appendages". Their taxonomic position is controversial, with studies either consider ...

, "great-appendage arthropod".

History

''Bundenbachiellus giganteus'' was described in 1929 with the name of ''Megadactylus giganteus'', with incomplete specimen BSPG 1929 II 34, however genus name ''Megadactylus'' was already used for synonym of dinosaur ''

Anchisaurus ''Anchisaurus'' is a genus of basal sauropodomorph dinosaur. It lived during the Early Jurassic Period, and its fossils have been found in the red sandstone of the Upper Portland Formation, Northeastern United States, which was deposited fro ...

'', its genus name was changed into ''Bundenbachiellus'' in 1930. Second species, ''B. minor'' was also described, however that species is later considered as misinterpretation of a

trilobite Trilobites (; meaning "three-lobed entities") are extinction, extinct marine arthropods that form the class (biology), class Trilobita. One of the earliest groups of arthropods to appear in the fossil record, trilobites were among the most succ ...

. Due to

holotype A holotype (Latin: ''holotypus'') is a single physical example (or illustration) of an organism used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of s ...

specimen was incomplete, preserved without anterior section, ''Bundenbachiellus'' was once treated as partial fossil of

cheloniellid Cheloniellida is a taxon (usually referred to as an order) of extinct Paleozoic arthropods. As of 2018,Wendruff, Andrew James, et al. "New cheloniellid arthropod with large raptorial appendages from the Silurian of Wisconsin, USA." BioRxiv (2018) ...

arthropod ''Cheloniellon calmani'', and taxon itself as synonym of ''Cheloniellon''. In 2001, new taxon ''Eschenbachiellus wuttkensis'' was described from complete specimen NM PWL 1997/3-LS, along with other three species of arthropod such as enigmatic ''Wingertshellicus backesi''. However, in 2008 researchers found that ''Eschenbachiellus'' is complete specimen of ''Bundenbachiellus'', and it was completely different from ''Cheloniellon''. Taxon ''Bundenbachiellus giganteus'' was reassessed, and ''Eschenbachiellus'' is considered as junior synonym of ''Bundenbachiellus.''

Morphology

''Bundenbachiellus'' is large arthropod, although complete specimen NM PWL 1997/3-LS is just long, incomplete holotype specimen BSPG 1929 II 34 is estimated to have a length up to . Its

cephalon Cephalon, Inc. was an American biopharmaceutical company co-founded in 1987 by pharmacologist Frank Baldino Jr., Frank Baldino, Jr., neuroscientist Michael Lewis, and organic chemist James C. Kauer—all three former scientists with the DuPont ...

have semicircular head shield, a uniramous and a long

biramous The arthropod leg is a form of jointed appendage of arthropods, usually used for walking. Many of the terms used for arthropod leg segments (called podomeres) are of Latin origin, and may be confused with terms for bones: ''coxa'' (meaning hip, ...

antenna and three pairs of

appendages An appendage (or outgrowth) is an external body part or natural prolongation that protrudes from an organism's body such as an arm or a leg. Protrusions from single-celled bacteria and archaea are known as cell-surface appendages or surface app ...

, and lacked eyes. Trunk have 11 segments with tergites connected by a short ridged area, and each segment have a pair of biramous appendages. On the end of the body, a segment without biramous appendages can be seen and it bears a pair of dorsal spines, and this segment is possibly a

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 ...

. Comparing morphology with its possible relative ''Enalikter'', some characters can be reinterpreted. Biramous antenna and first pair of appendages represent a single triflagellate limb. Other two pairs of appendages on cephalon are probably biramous. Appendages that originally considered to belong to cephalon is possible to be first pair of trunk appendages, making ''Bundenbachiellus'' had 12 pairs of trunk appendages same as these of ''Enalikter''.

Classification

Enalikter_aphson_reconstruction_as_arthropod

Studies in 2001 and 2008 placed ''Bundenbachiellus'' in "Crustaceanomorpha", and possibly a stem

crustacean Crustaceans (from Latin meaning: "those with shells" or "crusted ones") are invertebrate animals that constitute one group of arthropods that are traditionally a part of the subphylum Crustacea (), a large, diverse group of mainly aquatic arthrop ...

as opposed to a stem arachnomorph. However, in 2014, new genus of arthropod, '' Enalikter'' has described from Silurian Herefordshire Lagerstätte, and it shared morphological similarities with ''Bundenbachiellus'' although there are some different characters. That study considered that these taxa fall in a

clade In biology, a clade (), also known as a Monophyly, monophyletic group or natural group, is a group of organisms that is composed of a common ancestor and all of its descendants. Clades are the fundamental unit of cladistics, a modern approach t ...

of short-great-appendage arthropods,

. Alongside ''Enalikter'', ''Bundenbachiellus'' is included in the family Enaliktidae, and probably they are members of the stem clade Leanchoiliida. Its affinity as megacheiran is questioned in subsequent study, still ''Enalikter'' and ''Bundenbachiellus'' should be considered of potential importance to clarify the position of '' Oelandocaris'', taxon with questioned characteristics both for stem-crustaceans and megacheiran.

References

{{taxonbar, from=Q112860948 Fossil taxa described in 1930 Hunsrück Slate fossils Devonian animals of Europe Fossils of Germany Megacheira