. Bulletin. Natural history. A PRIMITIVE DEVONIAN LUNGFISH 35 The great similarity between the skull roofs of D. sussmilchi and D. lehmanni is apparent from Denison's figures, and if this alone were considered there would be no grounds for separating them generically. There are, however, considerable differences in the structure of the palates. These are considered in detail below (see Palate). Uranolophus Denison. This is the most similar to Dipnorhynchus of all the known fossil dipnoans, as is shown by Denison's account (1968a) of the type material from the Lower Devonian of Wyoming (see Fig
. Bulletin. Natural history. A PRIMITIVE DEVONIAN LUNGFISH 35 The great similarity between the skull roofs of D. sussmilchi and D. lehmanni is apparent from Denison's figures, and if this alone were considered there would be no grounds for separating them generically. There are, however, considerable differences in the structure of the palates. These are considered in detail below (see Palate). Uranolophus Denison. This is the most similar to Dipnorhynchus of all the known fossil dipnoans, as is shown by Denison's account (1968a) of the type material from the Lower Devonian of Wyoming (see Fig. 9). The forward position of X and Yj with respect to the "eight bones forming a triangular area in the relatively stable posteromedian part of the skull roof" (Denison, 1968a, p. 360), the junction of the I bones behind B, the multitude of small bones in the snout, the absence of a lateral-line canal between bones X and K, and the extension of the supraorbital canal backwards from "K" to "J" are very distinctive features uniting these two genera. Uranolophus, however, lacks a pineal foramen, and probably for this reason D is a single stable bone; E is also much larger than any possible homologue in Dipnorhynchus and is more like that of Dipterus. The cheek structure of Uranolophus has not been described and this is an un- fortunate gap in our knowledge. However, Denison's figures 3A, 4, and 5 show enough detail to deduce that the cheek must have been a multiplated complex structure. For example, on his figure 4 the shape of Y, and the position of the palatoquadrate (though crushed) show what the shape and position of the oper- culum would have been; the point of emergence of the infraorbital canal from X. A. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Peabody Museum of Nat
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