A new skull of Stygimoloch spinifer (MPM 8111) from the Upper Cretac eou s Hell Creek Form ation of North Dakota is the most complete specimen discove red to date. It allows much of the skull and braincase of this unusual pachycephalosaurid to be desc ribed for the first time and confirms a suite of diagnostic characters for the species. The skull is long with a vaulted, tran sver sely narrow frontoparietal dome and a robust squamosal forming a prominent posterior shelf. The shelf is ornamented by three to four large, low-angle horn s and mult iple clusters of smaller bony nodes. The orientation of the squamosal is preserved along an unambiguous contact with the frontoparietal suture, allowing definitive determination of the orientation of the squamosal horns . The se cranial features indicate a different mode of agonistic behavior than previously suggested for Stegocera s and Pachycephalosaurus . The high, narr ow dome of S. spinifer is not suited for head-butting, and the orientation of its squamosal horns and ornamental nodes strongly suggest display functions . Several additional specimens are described and referred to S. spinijer. INTRODUCTIONStygimoloch spinifer, an Upper Cretaceous (Maastrichtian) pachycephalosaurid ornithischian from western North America, has a high-domed, transversely narrow skull, distinguished by a unique cluster of well developed horns and bony nodes preserved along the posterodorsal surface of a thickened squamosal shelf. Prior to this report, the published record of Stygimoloch spinijer was limited to two isolated squamosals and one partial cranium. Galton and Sues (1983) named Stygimoloch spinijer from an unusual partial left squamosal ornamented with well-developed horns and robust bony nodes . This specimen (UCMP 119433) was collected from the Hell Creek Formation, McCone County, Montana. Galton and Sues referred an additional squamosal collected by J. B. Hatcher from the Lance Formation, Niobrara County Wyoming (YPM 335) to Stygimoloch spinijer. YPM 335 was first described by Marsh (1896) and refigured by Hatcher et al. (1907) as a dermal ossification of Triceratops. Brown and Schlaikjer (1943) referred this squamosal to Pachycephalosaurus sp . In 1987, Giffin et al. described a tall, narrow. domed pachycephalosaurid skull (MPM 7111) from the Hell Creek Formation of eastern Montana. They noted that it was significantly different from any previously known pachycephalosaurid, and named it a new species, Stenotholus kohleri, primarily on the basis of the markedly different shape of the cranium. Gabriel and Berghaus (1988) formally synonymized Stenotholus kohleri with Stygimoloch spinijer. Their comparison of MPM 7111 and MPM 8111 confirmed that both specimens shared the distinctive frontoparietal dome and cranial features characteristic of S. sp inijer.This study provides, for the first time, an extensive description of the cranial anatomy of Stygimoloch sp inifer and confirms the diagnostic characters for the species. Many aspects of pachycephalosaurid behavioral evolution hav...

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Dinosaurs are recognized as one of the most ubiquitous groups of fossil organisms in the classroom curriculum. There are many resources (books, videotapes, posters, etc.) available to the classroom teacher, but an actual visit to a natural history museum with dinosaur and related paleontological exhibits is out of the reach of the majority of schools unless located near large urban centers or near universities. Advances in distance learning technologies now provide the opportunity to reach audiences unable to visit museums during the course of the school year. These technologies also lend themselves to the evaluation of various pedagogical techniques that bring scientific content to widely dispersed audiences.