Ptycholepiformes

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 and . ==Systematics==

Ardoreosomus fossil Boreosomus fossil Ptycholepis fossil Yuchoulepis fossil The evolutionary relationships of Ptycholepiformes are poorly known, but most cladistic analyses place them outside of the Neopterygii. 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. • Order †Ptycholepidiformes Andrews et al. 1967 • Family incertae sedis • Genus †Ardoreosomus Romano et al., 2019 • †Ardoreosomus occidentalis Romano et al., 2019 (type species) • Family †Boreosomidae Gardiner 1967 • Genus †Acrorhabdus Stensiö,1921 • †Acrorhabdus asplundi Stensiö, 1921 • †Acrorhabdus bertili Stensiö, 1921 (type species) • †Acrorhabdus latistriatus Stensiö, 1921 • Genus †Boreosomus Stensiö 1921 [Diaphorognathus Brough 1933] • †Boreosomus arcticus (Woodward, 1912) [Acrolepis arctica Woodward 1912] (type species) • †Boreosomus gillioti (Priem, 1924) [Diaphorognathus gillioti (Priem 1924); Gyrolepis gillioti Priem 1924] • †Boreosomus merlei Beltan, 1957 • †Boreosomus piveteaui Stensiö, 1921 • †Boreosomus reuterskioeldi Stensiö, 1921 • †Boreosomus scaber Stensiö, 1921 • Family †Chungkingichthyidae Su 1974 • Genus †Chungkingichthys Su, 1974 • †Chungkingichthys tachuensis Su, 1974 (type species) • Family †Ptycholepididae Brough, 1939 corrig. • Genus †Ptycholepis Agassiz, 1832 non Gray 1842 ex Richardson, 1843 • †Ptycholepis barboi Bassani, 1886 • †Ptycholepis bollensis Agassiz, 1833 (type species) • †Ptycholepis calloviensis Kaznyshkin, 1990 • †Ptycholepis curta Egerton, 1854 • †Ptycholepis gracilis Davis, 1884 • †Ptycholepis magna Bürgin, 1992 • †Ptycholepis marshii Newberry, 1878 • †Ptycholepis monilifer Woodward, 1895 • †Ptycholepis prisca Bürgin, 1992 • †Ptycholepis schaefferi Bürgin, 1992 • Genus †Yuchoulepis Su, 1974 • †Yuchoulepis gansuensis Su, 1993 • †Yuchoulepis szechuanensis Su, 1974 (type species) ==Timeline of genera==

ImageSize = width:1000px height:auto barincrement:15px PlotArea = left:10px bottom:50px top:10px right:10px Period = from:-251.902 till:-145.0 TimeAxis = orientation:horizontal ScaleMajor = unit:year increment:10 start:-251.902 ScaleMinor = unit:year increment:1 start:-251.902 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: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 ==References==