. Bulletin of the Museum of Comparative Zoology at Harvard College. Zoology. Oligocene Rodents of Bolivia • Patterson and Wood 501. Figure 31. Sketches of lower deciduous molars (dm4) of selected caviomorphs, not to scale; all drawn as if from the right side. A. Erethizon dorsatum, MCZ no. 51367. Simple pattern. B. Protacaremys prior, AMNH no. 29707. C. P. prior, FMNH no. P 13295. D. P. prior. AMNH no. 29692, reversed. E. Prospaniomys priscus. AMNH no. 29697, reversed. F. Sallamys pascuali. PU no. 20909. G. Cephalomys arcidens. ACM no. 3013. H. Branisamys luribayensis (type of Villarroelomys b
. Bulletin of the Museum of Comparative Zoology at Harvard College. Zoology. Oligocene Rodents of Bolivia • Patterson and Wood 501. Figure 31. Sketches of lower deciduous molars (dm4) of selected caviomorphs, not to scale; all drawn as if from the right side. A. Erethizon dorsatum, MCZ no. 51367. Simple pattern. B. Protacaremys prior, AMNH no. 29707. C. P. prior, FMNH no. P 13295. D. P. prior. AMNH no. 29692, reversed. E. Prospaniomys priscus. AMNH no. 29697, reversed. F. Sallamys pascuali. PU no. 20909. G. Cephalomys arcidens. ACM no. 3013. H. Branisamys luribayensis (type of Villarroelomys bolivianus), GB 014, reversed and restored. I. Erethizon dorsatum, MCZ no. B 7752. Complex pattern. Abbreviations: A—protoconid; B—metaconid; C—hypoconid; D—entoconid. 5H, 31E), as variants in Acarechimys (for validation of this name, see Appendix 2), in Eumysops (Kraglievich, 1965: Fig. 2) and in the Antillean heteropsomvines (Miller, 1929: PL 2, Figs. 3a, 4a; PL 3, Fig. la; PL 4, Fig. 2a). There have been various modifications of this pattern, ranging from relatively simple to highly complex. As examples of simple changes, we may cite: Paradel- phomijs, in which the ver>' marked obliq- uity of the lophids has converted the cir- cular anterofossettid into a slit and has greatly shortened the ectolophid without completely obscuring the primitive pat- tern; and Spaniomys, Stichomys, Cerco- mys, etc., in which an anteroflexid has developed between metaconid and an- terolophid, thus converting the tooth into as good a replica of the molars as the up- per milk tooth usually is. Considerably greater complexity is present in Protacaremys prior, although AMNH nos. 29692 and 29707 and FMNH no. P 13295 are all different in details. Here there are three crests from the pro- toconid to or toward the metaconid (Figs. 5G, 31B-D). The anterior of these is clearly an anterolophid; the nature of the others is more uncertain. However, on the basis of variants seen in Erethizon dorsa
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