Dianolepis
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Antiarchi ("opposite anus") is an
order Order, ORDER or Orders may refer to: * Categorization, the process in which ideas and objects are recognized, differentiated, and understood * Heterarchy, a system of organization wherein the elements have the potential to be ranked a number of d ...
of heavily armored placoderms. The antiarchs form the second-most successful group of placoderms after the arthrodires in terms of numbers of species and range of environments. The order's name was coined by
Edward Drinker Cope Edward Drinker Cope (July 28, 1840 – April 12, 1897) was an American zoologist, paleontologist, comparative anatomist, herpetologist, and ichthyologist. Born to a wealthy Quaker family, Cope distinguished himself as a child prodigy interested ...
, who, when examining some fossils that he thought were armored tunicates related to '' Chelysoma'', mistakenly thought that the orbital fenestra (i.e., the hole in the headshield for the eyes, nose and pineal foramen) was the opening for the mouth, or oral siphon, and that the opening for the anal siphon was on the other side of the body, as opposed to having both oral and anal siphons together at one end. The front portions of their bodies were heavily armored, to the point of literally resembling a box with eyes, with the sometimes scaled, sometimes naked rear portions often becoming sinuous, particularly with later forms. The pair of pectoral fins were modified into a pair of caliper-like, or arthropod-like limbs. In primitive forms, such as ''
Yunnanolepis ''Yunnanolepis'' is an extinct genus of primitive antiarch placoderm. The fossils of the various species are found in Early to Middle Devonian strata in Southern China ( Xishancun, Lianhuashan and Xitun Formations). External links ''Yunnanol ...
'', the limbs were thick and short, while in advanced forms, such as '' Bothriolepis'', the limbs were long and had elbow-like joints. The function of the limbs are still not perfectly understood, but, most hypothesize that they helped their owners pull themselves across the substrate, as well as allow their owners to bury themselves into the substrate. Antiarchi, along with Brindabellaspis, form some of the most basal clades of the Placodermi, or Gnathostomata. They are more related to other placoderms and the more derived jawed fish than the Cephalaspidomorphi.


Phylogeny

Below is a cladogram from Jia ''et al.'' (2010):


Timeline of genera

ImageSize = width:1000px height:auto barincrement:15px PlotArea = left:10px bottom:50px top:10px right:10px Period = from:-416 till:-350 TimeAxis = orientation:horizontal ScaleMajor = unit:year increment:5 start:-416 ScaleMinor = unit:year increment:1 start:-416 TimeAxis = orientation:hor AlignBars = justify Colors = #legends id:CAR value:claret id:ANK value:rgb(0.4,0.3,0.196) id:HER value:teal id:HAD value:green id:OMN value:blue id:black value:black id:white value:white id:paleozoic value:rgb(0.6,0.75,0.55) id:cambrian value:rgb(0.49,0.63,0.33) id:ordovician value:rgb(0,0.57,0.44) id:silurian value:rgb(0.70,0.88,0.71) id:devonian value:rgb(0.8,0.55,0.22) id:earlydevonian value:rgb(0.90,0.71,0.43) id:middledevonian value:rgb(0.96,0.81,0.51) id:latedevonian value:rgb(0.96,0.89,0.71) id:carboniferous value:rgb(0.4,0.65,0.6) id:mississippian value:rgb(0.4,0.56,0.4) id:pennsylvanian value:rgb(0.8,0.77,0.53) id:permian value:rgb(0.94,0.25,0.24) id:mesozoic value:rgb(0.38,0.77,0.79) id:triassic value:rgb(0.51,0.17,0.57) id:jurassic value:rgb(0.2,0.7,0.79) id:cretaceous value:rgb(0.5,0.78,0.31) id:cenozoic value:rgb(0.95,0.98,0.11) id:paleogene value:rgb(0.99,0.6,0.32) id:neogene value:rgb(0.999999,0.9,0.1) id:quaternary value:rgb(0.98,0.98,0.50) BarData= bar:eratop bar:space bar:periodtop bar:space bar:NAM1 bar:NAM2 bar:NAM3 bar:NAM4 bar:NAM5 bar:NAM6 bar:NAM7 bar:NAM8 bar:NAM9 bar:NAM10 bar:NAM11 bar:space bar:period bar:space bar:era PlotData= align:center textcolor:black fontsize:M mark:(line,black) width:25 shift:(7,-4) bar:periodtop from: -416 till: -411.2 color:earlydevonian text: Lochkovian from: -411.2 till: -407 color:earlydevonian text:
Pragian The Pragian is one of three faunal stages in the Early Devonian Epoch. It lasted from 410.8 ± 2.8 million years ago to 407.6 ± 2.8 million years ago. It was preceded by the Lochkovian Stage and followed by the Emsian Stage. The most important La ...
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:eratop from: -416 till: -359.2 color:devonian text:
Devonian The Devonian ( ) is a geologic period and system of the Paleozoic era, spanning 60.3 million years from the end of the Silurian, million years ago (Mya), to the beginning of the Carboniferous, Mya. It is named after Devon, England, whe ...
PlotData= align:left fontsize:M mark:(line,white) width:5 anchor:till align:left color:earlydevonian bar:NAM1 from: -416 till: -411.2 text:
Phymolepis ''Phymolepis'' is an extinct genus of yunnanolepidid placoderm from the Early Devonian of China. The type species, ''P. cuifengshanensis'', was named by Zhang Goroui in 1978Chang, K-J. (1978). Symposium on the Devonian System of South China: ...
color:earlydevonian bar:NAM2 from: -416 till: -411.2 text: Chujinolepis color:earlydevonian bar:NAM3 from: -416 till: -411.2 text: Zhanjilepis color:earlydevonian bar:NAM4 from: -416 till: -407 text:
Yunnanolepis ''Yunnanolepis'' is an extinct genus of primitive antiarch placoderm. The fossils of the various species are found in Early to Middle Devonian strata in Southern China ( Xishancun, Lianhuashan and Xitun Formations). External links ''Yunnanol ...
color:earlydevonian bar:NAM5 from: -411.2 till: -407 text: Liujiangolepis color:middledevonian bar:NAM6 from: -391.8 till: -385.3 text: Grossaspis color:latedevonian bar:NAM7 from: -385.3 till: -374.5 text: Taeniolepis color:latedevonian bar:NAM8 from: -378.1 till: -374.5 text: Lepadolepis color:latedevonian bar:NAM9 from: -374.5 till: -359.2 text: Jiangxilepus color:latedevonian bar:NAM10 from: -374.5 till: -359.2 text: Sinolepis color:latedevonian bar:NAM11 from: -374.5 till: -359.2 text: Xichonolepis PlotData= align:center textcolor:black fontsize:M mark:(line,black) width:25 bar:period from: -416 till: -411.2 color:earlydevonian text: Lochkovian from: -411.2 till: -407 color:earlydevonian text:
Pragian The Pragian is one of three faunal stages in the Early Devonian Epoch. It lasted from 410.8 ± 2.8 million years ago to 407.6 ± 2.8 million years ago. It was preceded by the Lochkovian Stage and followed by the Emsian Stage. The most important La ...
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 The Devonian ( ) is a geologic period and system of the Paleozoic era, spanning 60.3 million years from the end of the Silurian, million years ago (Mya), to the beginning of the Carboniferous, Mya. It is named after Devon, England, whe ...


References

*Long, John A. The Rise of Fishes: 500 Million Years of Evolution Baltimore: The Johns Hopkins University Press, 1996. *


External links


Review of Antiarcha at Paleos
{{Taxonbar, from=Q150593 Prehistoric fish orders Articles which contain graphical timelines