. Bulletin of the Department of Geology. Geology. 110 University of California Publications. [Geology as the lateral teeth of I. planus. The chief distinction rests in the basal thickness of the crown of the tooth, measured from front to back. None of these teeth show a strongly curved crown or a re- entrant angle on the outer margin. There is no median ridge as is seen in Isurus mantelli, a related species from the Cretaceous of Europe. The following notes are on teeth from near Santa Ana: These teeth are very large, the largest teeth being two inches long. The crown is flexuous, curved backw
. Bulletin of the Department of Geology. Geology. 110 University of California Publications. [Geology as the lateral teeth of I. planus. The chief distinction rests in the basal thickness of the crown of the tooth, measured from front to back. None of these teeth show a strongly curved crown or a re- entrant angle on the outer margin. There is no median ridge as is seen in Isurus mantelli, a related species from the Cretaceous of Europe. The following notes are on teeth from near Santa Ana: These teeth are very large, the largest teeth being two inches long. The crown is flexuous, curved backwards in the median teeth, curved forward in the lateral ones. The root is heavy, little. Fig. 11. Isurus tumulus (Agassiz). Miocene of Santa Ana, California. cordate below, its form varying in the different teeth. Some teeth are knife-like, the crown not one-third higher than the breadth at base, the form suggesting that of Isurus planus. Other teeth, supposed to be median, are less flattened, and nearly half higher than broad at base. All are erect or nearly so, with entire edges. Some of the smaller teeth are more curved, and more acuminate. Some of the teeth from near Oil City are still larger, with thicker base, but are otherwise similar. One large tooth with a thick crown and heavy base is curved strongly outward, with a knife-like margin. This is probably an outer tooth of the same species, but no teeth quite like this are found in the living species. 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 University of California, Berkeley. Dept. of Geology. Berkeley : The University Press
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