. Bulletin. Natural history; Natuurlijke historie. Fig. 8. Comparison of the skulls of Semionotus and Lepidotes. A, Semwnotus after Olsen and McCune (ms); B, Lepidotes after Wenz (1967). Stippled regions are medial to the dermal skull. Note that much of the palate is visible in Semionotus (stippled area), whereas the palate is almost completely covered by extra suborbitals in Lepidotes. Reproduced from Palaeontology (1986), 29(2), p. 213-233, A revision of Senunnotus (Pisces: Semionotidae) from the Triassic and Jurassic of Europe, by A. R. McCune. these as "simple scales" (Fig. 9A) f
. Bulletin. Natural history; Natuurlijke historie. Fig. 8. Comparison of the skulls of Semionotus and Lepidotes. A, Semwnotus after Olsen and McCune (ms); B, Lepidotes after Wenz (1967). Stippled regions are medial to the dermal skull. Note that much of the palate is visible in Semionotus (stippled area), whereas the palate is almost completely covered by extra suborbitals in Lepidotes. Reproduced from Palaeontology (1986), 29(2), p. 213-233, A revision of Senunnotus (Pisces: Semionotidae) from the Triassic and Jurassic of Europe, by A. R. McCune. these as "simple scales" (Fig. 9A) following Olsen and others (1982) and the species that have them as an informal species group, the S. bergeri group. In addition to simple scales, a variety of other forms of dorsal ridge scales are found on Newark semionotids. In Towaco cycle P4, there are six other distinct types. The modified simple-scale type is only a slight variant of the simple-scale type (Fig. 9B). Modified simple scales are distinguished from simple scales by lateral undercutting of the spine so that in dorsal view the spine appears to be supported by a wider scale base. The spine (unstippled in Fig. 9B) is covered by ganoine while the surrounding base is naked bone. Both the distribution of ganoine on the dorsal surface of the scale and the undercutting lateral to the spine occur in varying degrees within some species. In Semionotus minor (McCune 1986), the distribution of ganoine is particularly easy to see by its color and texture relative to bone. In this species, the extremes of variation range from short-spined scales covered completely with ganoine to longer-spined scales with only the central axis of the spine covered by ganoine (Fig. lOA). At least in some Lepidotes toombsi (probably Semionotus; see McCune 1986) and Lepidotes mawsoni, the ganoine does not cover the entire dorsal surface of the bone (Fig. 10). However, for these two species I have not been able to assess the range of intraspecif
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