Arthrodira


Arthrodira is an order of extinct armoured, jawed fishes of the class Placodermi that flourished in the Devonian period before their sudden extinction, surviving for about 50 million years and penetrating most marine ecological niches.
Greek for "jointed neck", the arthrodires had movable joint between armor surrounding the head and body. Lacking distinct teeth, like all placoderms, they used the sharpened edges of a bony plate as a biting surface. The eye sockets are protected by a bony ring, a feature shared by birds and some ichthyosaurs. Early arthrodires, such as the genus Arctolepis, were well-armoured fishes with flattened bodies. The largest member of this group, Dunkleosteus, was a true superpredator of the latest Devonian period, reaching 1 to as much as 6 m in length. In contrast, the long-nosed Rolfosteus measured just 15 cm.
'' from the Middle Devonian of Estonia
A common misconception is the arthrodires were sluggish bottom-dwellers that were outcompeted by more advanced fish. Leading to this misconception is that the arthrodire body plan remained relatively conserved during the Devonian period, save for increasing in size. However, during their reign, the arthrodires were one of the most diverse and numerically successful, if not the most successful, vertebrate orders of the Devonian, occupying a vast spectrum of roles from apex predator to detritus-nibbling bottom dweller. Despite their success, the arthrodires were one of many groups eliminated by the environmental catastrophes of the Late Devonian extinction, allowing other fish such as sharks to diversify into the vacated ecological niches during the Carboniferous period.

SystematicsFor sources, see Haaramo (2005)

Below is a cladogram from Dupret et al..
ORDER ARTHRODIRA
Arthrodira of unresolved relationships

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color:earlydevonian bar:NAM2 from: -412.8 till: -411.2 text: Eskimaspis
color:earlydevonian bar:NAM3 from: -411.2 till: -409.8 text: Overtonaspis
color:earlydevonian bar:NAM4 from: -411.2 till: -409.8 text: Prescottaspis
color:earlydevonian bar:NAM5 from: -411.2 till: -409.8 text: Wheathillaspis
color:earlydevonian bar:NAM6 from: -411.2 till: -407 text: Kweichowlepis
color:earlydevonian bar:NAM7 from: -411.2 till: -407 text: Murmur
color:earlydevonian bar:NAM8 from: -411.2 till: -407 text: Taunaspis
color:earlydevonian bar:NAM9 from: -408.4 till: -407 text: Tiaraspis
color:earlydevonian bar:NAM10 from: -407 till: -403.83 text: Gemuendenaspis
color:earlydevonian bar:NAM11 from: -407 till: -403.83 text: Stuertzaspis
color:earlydevonian bar:NAM12 from: -407 till: -397.5 text: Arenipiscis
color:earlydevonian bar:NAM13 from: -407 till: -397.5 text: Buchanosteus
color:earlydevonian bar:NAM14 from: -407 till: -397.5 text: Burrinijucosteus
color:earlydevonian bar:NAM15 from: -407 till: -397.5 text: Errolosteus
color:earlydevonian bar:NAM16 from: -407 till: -397.5 text: Goodradigbeeon
color:earlydevonian bar:NAM17 from: -407 till: -397.5 text: Parabuchanosteus
color:earlydevonian bar:NAM18 from: -407 till: -397.5 text: Toombsosteus
color:earlydevonian bar:NAM19 from: -407 till: -397.5 text: Williamsaspis
color:earlydevonian bar:NAM20 from: -407 till: -391.8 text: Laurentaspis
color:earlydevonian bar:NAM21 from: -407 till: -378.1 text: Taemasosteus
color:earlydevonian bar:NAM22 from: -400.67 till: -397.5 text: Atlantidosteus
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color:middledevonian bar:NAM24 from: -397.5 till: -385.3 text: Belemnacanthus
color:middledevonian bar:NAM25 from: -397.5 till: -385.3 text: Grazosteus
color:middledevonian bar:NAM26 from: -397.5 till: -378.1 text: Holonema
color:middledevonian bar:NAM27 from: -397.5 till: -374.5 text: Deirosteus
color:middledevonian bar:NAM28 from: -393.72 till: -391.8 text: Squamatognathus
color:middledevonian bar:NAM29 from: -393.72 till: -369.4 text: Eastmanosteus
color:middledevonian bar:NAM30 from: -387.47 till: -385.3 text: Heterosteus
color:middledevonian bar:NAM31 from: -387.47 till: -385.3 text: Hollardosteus
color:middledevonian bar:NAM32 from: -387.47 till: -385.3 text: Kiangyousteus
color:middledevonian bar:NAM33 from: -387.47 till: -385.3 text: Rhenonema
color:middledevonian bar:NAM34 from: -387.47 till: -385.3 text: Tropidosteus
color:middledevonian bar:NAM35 from: -387.47 till: -385.3 text: Yinosteus
color:middledevonian bar:NAM36 from: -387.47 till: -381.7 text: Rachiosteus
color:middledevonian bar:NAM37 from: -387.47 till: -359.2 text: Dunkleosteus
color:latedevonian bar:NAM38 from: -385.3 till: -381.7 text: Bruntonichthys
color:latedevonian bar:NAM39 from: -385.3 till: -381.7 text: Bullerichthys
color:latedevonian bar:NAM40 from: -385.3 till: -381.7 text: Camuropiscis
color:latedevonian bar:NAM41 from: -385.3 till: -381.7 text: Copanognathus
color:latedevonian bar:NAM42 from: -385.3 till: -381.7 text: Eldenosteus
color:latedevonian bar:NAM43 from: -385.3 till: -381.7 text: Fallacosteus
color:latedevonian bar:NAM44 from: -385.3 till: -381.7 text: Gyroplacosteus
color:latedevonian bar:NAM45 from: -385.3 till: -381.7 text: Harrytoombsia
color:latedevonian bar:NAM46 from: -385.3 till: -381.7 text: Incisoscutum
color:latedevonian bar:NAM47 from: -385.3 till: -381.7 text: Kendrichthys
color:latedevonian bar:NAM48 from: -385.3 till: -381.7 text: Kimberia
color:latedevonian bar:NAM49 from: -385.3 till: -381.7 text: Kimberleyichthyes
color:latedevonian bar:NAM50 from: -385.3 till: -381.7 text: Machaerognathus
color:latedevonian bar:NAM51 from: -385.3 till: -381.7 text: Mcnamaraspis
color:latedevonian bar:NAM52 from: -385.3 till: -381.7 text: Melanosteus
color:latedevonian bar:NAM53 from: -385.3 till: -381.7 text: Panxiosteus
color:latedevonian bar:NAM54 from: -385.3 till: -381.7 text: Plourdosteus
color:latedevonian bar:NAM55 from: -385.3 till: -381.7 text: Torosteus
color:latedevonian bar:NAM56 from: -385.3 till: -381.7 text: Tubonasus
color:latedevonian bar:NAM57 from: -385.3 till: -378.1 text: Dinomylostoma
color:latedevonian bar:NAM58 from: -385.3 till: -374.5 text: Latocamurus
color:latedevonian bar:NAM59 from: -385.3 till: -374.5 text: Malerosteus
color:latedevonian bar:NAM60 from: -385.3 till: -374.5 text: Megaloplax
color:latedevonian bar:NAM61 from: -385.3 till: -374.5 text: Platyaspis
color:latedevonian bar:NAM62 from: -385.3 till: -374.5 text: Rolfosteus
color:latedevonian bar:NAM63 from: -385.3 till: -374.5 text: Timanosteus
color:latedevonian bar:NAM64 from: -385.3 till: -359.2 text: Callognathus
color:latedevonian bar:NAM65 from: -385.3 till: -359.2 text: Cosmacanthus
color:latedevonian bar:NAM66 from: -385.3 till: -359.2 text: Groenlandaspis
color:latedevonian bar:NAM67 from: -385.3 till: -359.2 text: Heintzichthys
color:latedevonian bar:NAM68 from: -381.7 till: -378.1 text: Deveonema
color:latedevonian bar:NAM69 from: -381.7 till: -378.1 text: Dinichthys
color:latedevonian bar:NAM70 from: -381.7 till: -378.1 text: Hadrosteus
color:latedevonian bar:NAM71 from: -381.7 till: -378.1 text: Operchaliosteus
color:latedevonian bar:NAM72 from: -381.7 till: -374.5 text: Brachydeirus
color:latedevonian bar:NAM73 from: -381.7 till: -374.5 text: Oxyosteus
color:latedevonian bar:NAM74 from: -378.1 till: -374.5 text: Belosteus
color:latedevonian bar:NAM75 from: -378.1 till: -374.5 text: Brachyosteus
color:latedevonian bar:NAM76 from: -378.1 till: -374.5 text: Braunosteus
color:latedevonian bar:NAM77 from: -378.1 till: -374.5 text: Cyrtosteus
color:latedevonian bar:NAM78 from: -378.1 till: -374.5 text: Enseosteus
color:latedevonian bar:NAM79 from: -378.1 till: -374.5 text: Erromenosteus
color:latedevonian bar:NAM80 from: -378.1 till: -374.5 text: Leptosteus
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color:latedevonian bar:NAM83 from: -378.1 till: -374.5 text: Parabelosteus
color:latedevonian bar:NAM84 from: -378.1 till: -374.5 text: Pholidosteus
color:latedevonian bar:NAM85 from: -378.1 till: -374.5 text: Rhinosteus
color:latedevonian bar:NAM86 from: -378.1 till: -374.5 text: Synauchenia
color:latedevonian bar:NAM87 from: -378.1 till: -374.5 text: Tapinosteus
color:latedevonian bar:NAM88 from: -378.1 till: -374.5 text: Trematosteus
color:latedevonian bar:NAM89 from: -378.1 till: -359.2 text: Aspidichthys
color:latedevonian bar:NAM90 from: -374.5 till: -369.4 text: Tafilalichthys
color:latedevonian bar:NAM91 from: -374.5 till: -359.2 text: Africanaspis
color:latedevonian bar:NAM92 from: -374.5 till: -359.2 text: Diplognathus
color:latedevonian bar:NAM93 from: -374.5 till: -359.2 text: Selenosteus
color:latedevonian bar:NAM94 from: -374.5 till: -359.2 text: Titanichthys
color:latedevonian bar:NAM95 from: -364.3 till: -359.2 text: Bungartius
color:latedevonian bar:NAM96 from: -364.3 till: -359.2 text: Glyptaspis
color:latedevonian bar:NAM97 from: -364.3 till: -359.2 text: Gorgonichthys
color:latedevonian bar:NAM98 from: -364.3 till: -359.2 text: Gymnotrachelus
color:latedevonian bar:NAM99 from: -364.3 till: -359.2 text: Holdenius
color:latedevonian bar:NAM100 from: -364.3 till: -359.2 text: Hussakofia
color:latedevonian bar:NAM101 from: -364.3 till: -359.2 text: Mylostoma
color:latedevonian bar:NAM102 from: -364.3 till: -359.2 text: Paramylostoma
color:latedevonian bar:NAM103 from: -364.3 till: -359.2 text: Stenosteus
color:latedevonian bar:NAM104 from: -364.3 till: -359.2 text: Trachosteus
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Footnotes