''Pseudopetalichthys problematica'' is a lightly armored pseudopetalichthyid placoderm from the Hunsrückschiefer

Lagerstätte A Lagerstätte (, from ''Lager'' 'storage, lair' '' Stätte'' 'place'; plural ''Lagerstätten'') is a sedimentary deposit that exhibits extraordinary fossils with exceptional preservation—sometimes including preserved soft tissues. These for ...

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 P ...

Germany. The

holotype A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of several ...

and only known specimen is an articulated, but incomplete individual consisting of a large, mostly intact, plate-covered head, the bases of the pectoral fins, and most of the vertebral column, with a total length of . The specimen superficially resembles ''

Stensioella ''Stensioella heintzi'' is an enigmatic placoderm of arcane affinity. It is only known from the Lower Devonian Hunsrück slate of Germany. Anatomy ''Stensioella heintzi'' has an elongated body, a whip-like tail, and long, wing-like pectoral f ...

'', though the structures of the mouth, and

orbits In celestial mechanics, an orbit is the curved trajectory of an object such as the trajectory of a planet around a star, or of a natural satellite around a planet, or of an artificial satellite around an object or position in space such as a p ...

(the orbits being unknown in ''Stensioella''), and placement of the

gill raker Gill rakers in fish are bony or cartilaginous processes that project from the branchial arch (gill arch) and are involved with suspension feeding tiny prey. They are not to be confused with the gill filaments that compose the fleshy part of the ...

s all differ. Some experts suggest that ''P. problematica'' and the related ''

Paraplesiobatis ''Paraplesiobatis heinrichsi'' is a lightly armored Pseudopetalichthyida, pseudopetalichthyid placoderm from the Hunsrück Slate, Hunsrückschiefer Lagerstätte of Early Devonian Germany. The Type specimen, type and only known specimen is an arti ...

'' are the same species, suggesting that the differences between them are merely due to different circumstances of

taphonomy Taphonomy is the study of how organisms decay and become fossilized or preserved in the paleontological record. The term ''taphonomy'' (from Greek , 'burial' and , 'law') was introduced to paleontology in 1940 by Soviet scientist Ivan Efremov t ...

, but this hypothesis can not be tested until more specimens are found. The holotype was originally held in the Schlosspark Museum in

Bad Kreuznach Bad Kreuznach () is a town in the Bad Kreuznach district in Rhineland-Palatinate, Germany. It is a spa town, most well known for its medieval bridge dating from around 1300, the Alte Nahebrücke, which is one of the few remaining bridges in th ...

, but was then lost at an unknown date.

References

External links

''Pseudopetalichthys''
at the

Paleobiology Database The Paleobiology Database is an online resource for information on the distribution and classification of fossil animals, plants, and microorganisms. History The Paleobiology Database (PBDB) originated in the NCEAS-funded Phanerozoic Marine Pale ...

Pseudopetalichthyida Placoderm genera Fossils of Germany {{Devonian-fish-stub Hunsrück Slate fossils