. Advances in the study of mammalian behavior. Mammals. 132 Spec. Publ. Amer. Soc. Mamm. 7. Body weight or volume (kg or liters) Fig. 9. Divergence of archaic mammals (shaded area) from the reptilian base. See Jerison, 1973, 1976, for additional information. (Modified from Jerison, 1973.) The first increase in encephalization in mammals above the basal grade probably occurred in early Cenozoic primates—Paleocene Plesiadapis, Eocene and Oligocene omomyids, and Eocene adapids. I reviewed these data recently (Jerison, 19796) and sum- marize them in Fig. lOA; the diagonal line is Eq. 6, and the po
. Advances in the study of mammalian behavior. Mammals. 132 Spec. Publ. Amer. Soc. Mamm. 7. Body weight or volume (kg or liters) Fig. 9. Divergence of archaic mammals (shaded area) from the reptilian base. See Jerison, 1973, 1976, for additional information. (Modified from Jerison, 1973.) The first increase in encephalization in mammals above the basal grade probably occurred in early Cenozoic primates—Paleocene Plesiadapis, Eocene and Oligocene omomyids, and Eocene adapids. I reviewed these data recently (Jerison, 19796) and sum- marize them in Fig. lOA; the diagonal line is Eq. 6, and the polygon is that for living and subfossil prosimians. The seven fossils rep- resent the beginnings of the adaptive radiation of primates w^ith respect to encephalization. This includes Aegyptopithecus, the ear- liest anthropoid primate about which we have information. From Fig. lOA, it appears that the Eocene adapids, Smilodectes and Adapts, were below the grade of encephalization of living pro- simians. The Eocene omomyids, Tetonius and Necrolemur, were at that grade, and the Oligocene omomyid, Rooneyia, was above that grade and approached the grade of the living tarsier. If we treat the adapids as having been in the ancestry of the majority of living prosimians and the omomyids as having been in the ancestry of living tarsiers, the picture is that of increasing encephalization dur- ing the Eocene and Oligocene, a 20 million year interval. This is a difTerent picture from the stasis suggested by the evidence of the earliest mammals. The earliest of the mammals that we know was already at a grade that occurs in living mammals. The earliest of. 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 Eisenberg, John Frederick; Kleiman, Devra G; American Society of Mammalogists. [Shippensburg, Pa?] : American Society of
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Keywords: ., bookcentury1900, bookcollectionbiodiversity, booksubjectmammals
