Image from page 32 of "Water reptiles of the past and present" (1914) (14769799181)

Identifier: waterreptilesofp1914will
Title: Water reptiles of the past and present
Year: 1914 (1910s)
Authors: Williston, Samuel Wendell, 1851-1918
Subjects: Aquatic reptiles
Publisher: Chicago, Ill., The University of Chicago Press
Contributing Library: Boston Public Library
Digitizing Sponsor: Boston Public Library



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Fig. 4 Fig. s Fig. 4.—Seymouria, a primitive cotylosaurian. Skull, from above: pm, pre-maxilla; n, nasal; /, lacrimal; p, prefrontal; /, frontal; pf, postfrontal; it, inter-temporal; st, supratemporal; sq, squamosal; ds, dermosupraoccipital; t, tabulare;j, jugal; po, postorbital; m, maxilla; s, surangular; ang, angular; pa, parietal. Fig. 5.—-Seymouria, skull from the side. Explanations as in fig. 4. As in other parts of the skeleton, there has been a reductionin the number of parts of the reptile skull from that of the moreprimitive forms, and a better adaptation of those which remainfor the special uses they subserve. This reduction in number hasbeen caused in part by the actual loss of bones, in part by the fusionof contiguous ones. The most primitive reptiles had no less thanseventy-two separate bones in the skull;1 the human skull has 1 Paired maxillae, premaxillae, nasals, prefrontals, lacrimals, frontals, parietals,dermosupraoccipitals, tabularia, supratemporals, intertempo