The rostral plate is narrower than in suborder Olenellina, bound by rostral and connective sutures.
2.
A single pair of long and slender rostral plate with a narrow and sharp central ridge.
3.
The Cheirurina and Calymenina retain a rostral plate ( an apomorphy ) but in virtually all Phacopina the free cheeks are yoked as a single piece.
4.
R�cklin ( 2011 ) agrees with Denison's synonymizing of " Ottonosteus ", but rejects Denison's synonymization of " Walterosteus ", claiming how " Walterosteus " has a contact between the rostral plate and the pineal plate, which " Enseosteus " does not.
5.
Cephalon : Cranidium subquadrate, glabella cylindrical, slightly contracted at S3, three pairs of glabellar furrows, preglabellar field short or absent, eye ridge wide, long, directed slightly postero-laterally, palpebral lobe cresentic, posterior area of fixigena with fulcrum, free cheeks ( or librigenae ) with long spines; hypostome conterminant, attached to a narrow rostral plate.
6.
""'Pachyosteus bulla " "'is a medium-sized selenosteid arthrodire placoderm known from the Upper Frasnian Kellwasserkalk facies of Late Devonian Bad Wildungen, Germany and from the Famennian portions of the Holy Cross Mountains of Poland . " P . bulla " has a broad skull about 7 to 10 centimeters long, a comparatively long median dorsal plate, and a short rostral plate that meets the pineal plate.
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