Ptycholepiformes are an extinct order of prehistoric ray-finned fish that existed during the Triassic period and the Early Jurassic epoch.[1] The order includes the genera Acrorhabdus, Ardoreosomus, Boreosomus, Chungkingichthys, Ptycholepis, and Yuchoulepis. Although several families have been proposed, some studies place all these genera in the same family, Ptycholepididae.[2]
Ptycholepiformes had a widespread distribution during the Early Triassic, but were restricted to mainly Europe and North America afterwards. They are known from both marine and freshwater deposits.
Typical features of ptycholepiforms are the fusiform body covered in rhombic ganoid scales, the anterior position of the dorsal fin. In most coeval ray-fins the dorsal fin has a more posterior position), usually situated opposite to the anal fin. Moreover, ptycholepiforms show a series of elongate, horizontal suborbital bones. The skull is usually relatively large.
The scales are typically equipped with distinct longitudinal ridges. In Ptycholepis, the scales are low, whereas in genera, such as Ardoreosomus and Boreosomus, the scales are deeper. Peg-and-socket articulation between scales is present.
Species reached body sizes between 10cm (00inches) and 45cm (18inches).[3]
The evolutionary relationships of Ptycholepiformes are poorly known, but most cladistic analyses place them outside of the Neopterygii.[4] A close relationship between Ptycholepididae and the Carboniferous to Early Triassic Acrolepididae was proposed based on some similarities, but support from phylogenetic analyses is scarce.[5]
Period = from:-251.902 till:-145.0TimeAxis = orientation:horizontalScaleMajor = unit:year increment:10 start:-251.902ScaleMinor = unit:year increment:1 start:-251.902TimeAxis = orientation:horAlignBars = 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:mesozoic value:rgb(0.54,0.54,0.258) id:triassic value:rgb(0.51,0.17,0.57) id:earlytriassic value:rgb(0.6,0.22,0.61) id:middletriassic value:rgb(0.73,0.53,0.71) id:latetriassic value:rgb(0.78,0.65,0.8) id:jurassic value:rgb(0.2,0.7,0.79) id:earlyjurassic value:rgb(0,0.69,0.89) id:middlejurassic value:rgb(0.52,0.81,0.91) id:latejurassic value:rgb(0.74,0.89,0.97) BarData= bar:eratop bar:space bar:periodtop bar:space bar:NAM1 bar:NAM2 bar:NAM3 bar:NAM4 bar:NAM5 bar:NAM6
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: -251.902 till: -247.2 color:earlytriassic text:Early from: -247.2 till: -237 color:middletriassic text:Middle from: -237 till: -201.3 color:latetriassic text:Late from: -201.3 till: -174.1 color:earlyjurassic text:Early from: -174.1 till: -163.5 color:middlejurassic text:Middle from: -163.5 till: -145.0 color:latejurassic text:Late bar:eratop from: -251.902 till: -201.3 color:triassic text:Triassic from: -201.3 till: -145.0 color:jurassic text:Jurassic
PlotData= align:left fontsize:M mark:(line,white) width:5 anchor:till align:left
color:earlytriassic bar:NAM1 from:-251.902 till:-251.2 text:Ardoreosomus color:earlytriassic bar:NAM2 from:-251.2 till:-250 text:Acrorhabdus color:earlytriassic bar:NAM3 from:-251.902 till:-247.2 text:Boreosomus color:earlytriassic bar:NAM4 from:-251.902 till:-247.2 text:Chungkingichthys color:middletriassic bar:NAM5 from:-243 till:-180.53 text:Ptycholepis color:earlytriassic bar:NAM6 from:-251.902 till:-247.2 text:Yuchoulepis
PlotData= align:center textcolor:black fontsize:M mark:(line,black) width:25
bar:period from: -251.902 till: -247.2 color:earlytriassic text:Early from: -247.2 till: -237 color:middletriassic text:Middle from: -237 till: -201.3 color:latetriassic text:Late from: -201.3 till: -174.1 color:earlyjurassic text:Early from: -174.1 till: -163.5 color:middlejurassic text:Middle from: -163.5 till: -145.0 color:latejurassic text:Late bar:era from: -251.902 till: -201.3 color:triassic text:Triassic from: -201.3 till: -145.0 color:jurassic text:Jurassic