:Pseudopetalichthyida
{{Automatic Taxobox
| fossil_range = Emsian
| image = Pseudopetalichthyida.JPG
| image_caption = Artist's reconstructions
| parent_authority = Denison 1975
| taxon = Paraplesiobatidae
| authority = Berg 1940
| subdivision_ranks = Species
| subdivision =
- Pseudopetalichthys problematica†
- Paraplesiobatis heinrichsi †
- Nessariostoma granulosa †
}}
Pseudopetalichthyida is an order of lightly armored placoderms known only from rare fossils in Lower Devonian strata in Hunsrück, Germany. Like Stensioella heintzi, and the Rhenanida, the Pseudopetalichthids had armor made up of a mosaic of tubercles. Like Stensioella heintzi, the Pseudopetalichthids' placement within Placodermi is suspect. However, due to a gross lack of whole, uncrushed, articulated specimens, there are no other groups that the Pseudopetalichthids could be, for a lack of a better word, pigeonholed into.
On the other hand, according to anatomical studies done on the crushed specimens that have been found, those experts who do regard the Pseudopetalichthyida as placoderms consider them to be a group more advanced than the Ptyctodonts. And as such, pro-placoderm experts consider Pseudopetalichthyida to be the sister group of the Arthrodires + Phyllolepida + Antiarchi trichotomy and the Acanthothoraci + Rhenanida dichotomy.
The best known species is the type species Pseudopetalicthys problematica. Some experts have suggested that Paraplesiobatis heinrichsi is the same species as P. problematica, but, due to the specimens of the latter species being crushed in a different position than the specimen of the former species, the anatomies of the two forms appear different (Moy-Thomas & Miles). However, this problem will be resolved only with more specimens. The anatomy of the specimens of Nessariostoma granulosum are sufficiently different from the other two pseudopetalichthyids to be recognized as a separate species. N. granulosum bears a superficial resemblance to Stensioella heintzi, and it was this resemblance that originally led to the pseudopetalichthyids' grouping within Stensioellidae.
Timeline of genera
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from: -416 till: -411.2 color:earlydevonian text:Lochkovian
from: -411.2 till: -407 color:earlydevonian text:Pragian
from: -407 till: -397.5 color:earlydevonian text:Emsian
from: -397.5 till: -391.8 color:middledevonian text:Eifelian
from: -391.8 till: -385.3 color:middledevonian text:Givetian
from: -385.3 till: -374.5 color:latedevonian text:Frasnian
from: -374.5 till: -359.2 color:latedevonian text:Famennian
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from: -416 till: -359.2 color:devonian text:Devonian
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color:earlydevonian bar:NAM2 from: -407 till: -403.83 text: Paraplesiobatis
color:earlydevonian bar:NAM3 from: -407 till: -403.83 text: Pseudopetalichthys
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from: -416 till: -411.2 color:earlydevonian text:Lochkovian
from: -411.2 till: -407 color:earlydevonian text:Pragian
from: -407 till: -397.5 color:earlydevonian text:Emsian
from: -397.5 till: -391.8 color:middledevonian text:Eifelian
from: -391.8 till: -385.3 color:middledevonian text:Givetian
from: -385.3 till: -374.5 color:latedevonian text:Frasnian
from: -374.5 till: -359.2 color:latedevonian text:Famennian
bar:era
from: -416 till: -359.2 color:devonian text:Devonian
References
- Long, John A. The Rise of Fishes: 500 Million Years of Evolution Baltimore: The Johns Hopkins University Press, 1996. {{ISBN|0-8018-5438-5}}
- Moy-Thomas, J. A. & Miles, R. S. Paleozoic Fishes (2nd ed)Chapman and Hall, London, 1971.
External links
- [https://web.archive.org/web/20080113051549/http://www.fmnh.helsinki.fi/users/haaramo/Metazoa/Deuterostoma/Chordata/Placodermi/Placodermi.htm Mikko's Phylogeny Archive]
{{Placodermi}}
{{Taxonbar|from=Q3924915}}