1034
Journal of Paleontology 91(5):1025–1046
Figure 5. Birgeria sp. (NMMNH P-77117) from the Smithian of the Winecup Ranch, Elko County, Nevada, USA. (1) Part a (above) and counterpart b (below); (2) schematic drawing of 5.1 with interpretations of skeletal features; black arrows point to macroscopic teeth on the jaw bones (except prearticular); anterior is left. Scale bar = 50mm (total).
ventral internal laminae of the dentary are well visible, delimiting the space occupied by Meckel’s cartilage. A fragment of the den- tigerous upper margin of the prearticular is preserved. Dentition.—Teeth are preserved on several jaw bones
(Fig. 5). The basal portions of close-set lingual teeth are pre- served in the posterior segment of the dentary. One tooth of the maxilla and one of the dentary is each visible in transverse section on part b of the fossil. In addition, longitudinal rows of close-set, macroscopic teeth are present on the dermopalatine and the ectopterygoid in the upper jaw, and on the prearticular in the lower jaw. At least one row of large teeth is observed on both the dermopalatine and the ectopterygoid. These teeth are smaller than the lingual teeth of the maxilla. The medial surface of the dermopalatine and ectopterygoid is covered with minute teeth, cross sections of which are seen along the oral margins of these bones. At minimum one row of teeth lines the dorsal margin of the prearticular. These teeth are smaller than the larger teeth of the dermopalatine and the ectopterygoid. Macroscopic teeth are not developed on the surangular. Preoperculum, operculogular series, and suborbitals.—The
fragmentarily preserved preoperculum is composed of two shanks—an anterior and a posteroventral one (Fig. 5). Mainly the dorsal and posterior bone margins are visible. The dorsal border is straight and subvertical, whereas its caudal confine- ment is convex. At the level of the knee of the preoperculum, a weak notch is discernible. A section of the preopercular sensory canal traverses the posteroventral shank centrally in anterodorsal direction, then continues rostrad near the straight dorsal margin of the bone. The most anterior part of the canal is not preserved. The operculum is situated dorsal to the anterior shank and has an elongate, ovoid shape. The rostral end of this bone is pointed. Nine submandibular branchiostegal rays are preserved ventral to the dentary. The anterior rays are
rostrocaudally broader than the posterior ones. The anterolateral corner of each ray protrudes rostrally. One or two suborbitals are possibly seen near the anterior end of the fossil.
Remarks.—The overall anatomy ofNMMNHP-66225 supports its referral to Birgeria Stensiö, 1919. However, attribution at the species level is not possible due to the absence of diagnostic characters. Based on comparison with B. groenlandica Stensiö, 1932 (cf. Nielsen, 1949), a total length of ~145–165cm is esti- mated for P-77117.
Family Saurichthyidae Owen, 1860, emend. Stensiö, 1925 Genus Saurichthys Agassiz, 1834
Type species.—Saurichthys apicalis Agassiz, 1834 from the Ladinian (Middle Triassic) of Bayreuth, Germany, by original designation.
Occurrence.—From the latest Permian of China to the Late Triassic of Europe and possibly China.
Saurichthys sp. Figure 6
Occurrence.—Bed PLR 35 (Jattiot et al., in press), latest Smithian Pseudosageceras augustum Zone, Thaynes Formation (Fig. 2), Palomino Ridge, Section 2 (Jattiot et al., in press), southern Elko County, Nevada, USA (Fig. 1).
Description.—PIMUZ A/I 4397 (Fig. 6) is a three-dimensional skull fragment preserved in a limestone slab. The posterior part of the specimen, as well as the maxilla, preoperculum, lower jaw, and operculogular series are missing. The superficial layer of the
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