. Breviora. 1973 CHANARES GO^rP^ Figure 2. Prohelesodon minor, holotype skull in lateral view, X 3/2. expense of the nasal. The secondary palate, as in P. lewisi, extends remarkably far back, exceeding in de\elopment e\en the contemporary Probainognathiis. As in Probainognathus jenseni the postero\entral flanges of the pterygoid are highly developed; also as in that species the posterior end of the lower jaw lies very close to the inner surface of the squamosal, and there was presumably a ligamentous connection, although no development of a '"glenoid" articular surface. As in
. Breviora. 1973 CHANARES GO^rP^ Figure 2. Prohelesodon minor, holotype skull in lateral view, X 3/2. expense of the nasal. The secondary palate, as in P. lewisi, extends remarkably far back, exceeding in de\elopment e\en the contemporary Probainognathiis. As in Probainognathus jenseni the postero\entral flanges of the pterygoid are highly developed; also as in that species the posterior end of the lower jaw lies very close to the inner surface of the squamosal, and there was presumably a ligamentous connection, although no development of a '"glenoid" articular surface. As in P. lewisi there were four premaxillary "incisors," and there are, in the type and MCZ 4100, eight postcanine cheek teeth. As in P. lewisi these teeth are somewhat "hooked" — cur\ed backwards at their tips. Three "incisors" are present in the lower jaw, and seven "cheek" teeth behind the prominent canine. I ha\-e earlier suggested that Prohelesodon lewisi was ancestral to the larger Belesodon of the Brazilian Santa Maria beds. Closely related to the latter w'as the smaller, contemporary, Chiniquodon. Not improbably P. minor may ha\"e been an- cestral to Chiniquodon, a form of similar structure but of considerably larger size. Probaixogxathidae Fam. Nov. The carnivorous cynodonts from the Chanares Formation, Probainognathus and Prohelesodon. are both ob\iously ad\'anced forms, with an elongate secondary palate and other progressi\-e features. Similarly advanced are the Santa Maria forms, Chini- quodon and Belesodon, for which Huene (1944) erected the family Chiniquodontidae. In the past, I ha\e included both. 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 Harvard University. Museum of Comparative Zoology. Cambridge, Mass. , Museum of Comparative Zoology, Harvard
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