. Early Devonian fishes from Utah : Heteroostraci . Mm Fig. 66. Cardipeltis wallacii, PF 804; dorsal shield (X H)- been considered to represent the dorsal shield of a heterostracian. However, since Brotzen (1936, p. 10, footnote 2) expressed doubt that this belonged to an ostracoderm and compared it with the median-dorsal plate of an arthrodire, it is necessary first to establish the class and order to which the shield belongs. This is done most conclusively by its histological structure, which is preserved moder- ately well in specimens from the Water Canyon Formation, but generally very poor
. Early Devonian fishes from Utah : Heteroostraci . Mm Fig. 66. Cardipeltis wallacii, PF 804; dorsal shield (X H)- been considered to represent the dorsal shield of a heterostracian. However, since Brotzen (1936, p. 10, footnote 2) expressed doubt that this belonged to an ostracoderm and compared it with the median-dorsal plate of an arthrodire, it is necessary first to establish the class and order to which the shield belongs. This is done most conclusively by its histological structure, which is preserved moder- ately well in specimens from the Water Canyon Formation, but generally very poorly in those from Beartooth Butte. Histology: In section (fig. 71, A) the shield may be divided into three layers. Superficially, there is a layer formed by the ridges.
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Keywords: ., bookcentury1900, bookcollectionbiodiver, booksubjectfishesfossil
