petalichthyida
{{Short description|Extinct order of fishes}}
{{Automatic taxobox
| fossil_range = Early Lochkovian - Frasnian
| image = Lunaspis_broili.JPG
| image_caption = Lunaspis
| taxon = Petalichthyida
| authority = Jaeckel, 1911
| subdivision_ranks = Families
| subdivision =
}}
Petalichthyida is an extinct order of small, flattened placoderm fish. They are typified by their splayed pectoral fins, exaggerated lateral spines, flattened bodies, and numerous tubercles that decorated all of the plates and scales of their armor. They reached a peak in diversity during the Early Devonian and were found throughout the world, particularly in Europe (especially in Germany), North America, Asia, South America, and Australia. The petalichthids Lunaspis and Wijdeaspis are among the best known. The earliest and most primitive known petalichthyid is Diandongpetalichthys, which is from earliest Devonian-aged strata of Yunnan. The presence of Diandongpetalichthys, along with other primitive petalichthyids including Neopetalichthys and Quasipetalichthys, and more advanced petalichthyids, suggest that the order may have arisen in China, possibly during the late Silurian.
Because they had compressed body forms, it is speculated they were bottom-dwellers that chased after or ambushed smaller fish. Their diet is not clear, as none of the fossil specimens found have preserved mouthparts.
Taxonomy
According to Zhu's 1991 redescription of Diandongpetalichthys,Zhu, M. "New information on Diandongpetalichthys (Placodermi: Petalichthyida)." Early vertebrates and related problems of evolutionary biology. Science Press, Beijing (1991): 179-192. that genus represents the most basal petalichthyid known, as it has a comparatively elongated head, and shares certain anatomical features with acanthothoracids and primitive arthrodires such as the actinolepids. Quasipetalichthys, in turn, strongly resembles Diandongpetalichthys (aside from having a much more square-looking skull).
In Zhu's redescription, "Quasipetalichthyidae" (comprising Quasipetalichthys, Eurycaraspis, and possibly Neopetalichthys) and "Macropetalichthyidae" (comprising all the other "advanced" petalichthyid genera not including Neopetalichthys, or Diandongpetalichthys) form a dichotomy, with Diandongpetalichthys as a sister taxon.{{cite journal | url=http://www.ivpp.cas.cn/cbw/gjzdwxb/xbwzxz/200812/W020090813369930445831.pdf | title=A NEW MACROPETALICHTHYID FROM CHINA, WITH SPECIAL REFERENCE TO THE ZOOGEOGRAPHY OF THE MACROPETALICHTHYIDAE (PLACODERMI) |author1=Zhu, Min |author2=Wang, Junqing |name-list-style=amp | journal=Vertebrata PalAsiatica |date=October 1996 | volume=34 | issue=4 | pages=253–268}} Neopetalichthys is treated as an incertae sedis within Petalichthyida that may or may not be placed within or near Quasipetalichthyidae.
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
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color:earlydevonian bar:NAM1 from: -416 till: -411.2 text: Diandongpetalichthys
color:earlydevonian bar:NAM2 from: -407 till: -397.5 text: Neopetalichthys
color:earlydevonian bar:NAM3 from: -407 till: -397.5 text: Notopetalichthys
color:earlydevonian bar:NAM4 from: -407 till: -397.5 text: Shearsbyaspis
color:earlydevonian bar:NAM5 from: -407 till: -391.8 text: Wijdeaspis
color:earlydevonian bar:NAM6 from: -400.67 till: -397.5 text: Lunaspis
color:middledevonian bar:NAM8 from: -397.5 till: -391.8 text: Xinanpetalichthys
color:middledevonian bar:NAM9 from: -397.5 till: -385.3 text: Macropetalichthys
color:middledevonian bar:NAM10 from: -387.47 till: -385.3 text: Ellopetalichthys
color:middledevonian bar:NAM11 from: -387.47 till: -385.3 text: Eurycaraspis
color:middledevonian bar:NAM12 from: -387.47 till: -385.3 text: Quasipetalichthys
color:latedevonian bar:NAM13 from: -378.1 till: -374.5 text: Epipetalichthys
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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
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from: -374.5 till: -359.2 color:latedevonian text:Famennian
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from: -416 till: -359.2 color:devonian text:Devonian
References
{{Reflist}}
Sources
- Long, John A. The Rise of Fishes: 500 Million Years of Evolution Baltimore: The Johns Hopkins University Press, 1996. {{ISBN|0-8018-5438-5}}
- {{cite journal
| last = Sepkoski
| first = Jack
| title = A compendium of fossil marine animal genera (Placodermi entry)
| journal = Bulletins of American Paleontology
| volume = 364
|page=560
| year = 2002
| url = http://strata.ummp.lsa.umich.edu/jack/showgenera.php?taxon=564&rank=class
| access-date = 2011-05-20}}
{{Placodermi|Pe.}}
{{Taxonbar|from=Q147585}}
Category:Early Devonian first appearances