. Early Devonian fishes from Utah : Arthrodira . Fig. 90. Aethaspis utahensis, cranial roof, type, PF 1405 (X 3/2) common arthrodire in the Water Canyon Formation and shows a certain amount of variation in size, there is only a single specimen that can be determined with certainty as belonging to a juvenile individual. This is an incomplete median dorsal (PF 563, fig. 92, B), whose total length is estimated to be 36 mm. Its median region is missing, but its outer parts are ornamented with moderate-sized tubercles showing a tendency, anteriorly at least, to unite at their bases into ridges. Thi
. Early Devonian fishes from Utah : Arthrodira . Fig. 90. Aethaspis utahensis, cranial roof, type, PF 1405 (X 3/2) common arthrodire in the Water Canyon Formation and shows a certain amount of variation in size, there is only a single specimen that can be determined with certainty as belonging to a juvenile individual. This is an incomplete median dorsal (PF 563, fig. 92, B), whose total length is estimated to be 36 mm. Its median region is missing, but its outer parts are ornamented with moderate-sized tubercles showing a tendency, anteriorly at least, to unite at their bases into ridges. This ornament is distinctly of the A. major type. Among the known specimens of A. utahensis there is not one that can be proved to belong to a fully adult individual, and it is probable that the cranial roof of the type specimen is not fully grown, since its sutures are quite distinct. However, the median dorsal referred here (PF 964, fig. 94, A) is considerably larger than that of the juvenile
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Keywords: ., bookcentury1900, bookcollectionbiodiver, booksubjectfishesfossil
