. Bulletin. Natural history; Natuurlijke historie. 178 PEABODY MUSEUM BULLETIN 42. Fig. 55. Transform coordinates, after the manner of D'Arcy Thompson (1942), of Stylinodon inex- plicatus (6) relative to Stylinodon mirus (a). The figure suggests that S. inexplicatus is a small, neotenous offshoot of S. mirus with differentially stunted growth. Whereas this suggestion may be tantalizing, its investigation is beyond the scope of the present paper. Furthermore, only one incomplete specimen of 5. inexplicatus is known and an ontogenetic series is unknown for its presumed "ancestor," S. m
. Bulletin. Natural history; Natuurlijke historie. 178 PEABODY MUSEUM BULLETIN 42. Fig. 55. Transform coordinates, after the manner of D'Arcy Thompson (1942), of Stylinodon inex- plicatus (6) relative to Stylinodon mirus (a). The figure suggests that S. inexplicatus is a small, neotenous offshoot of S. mirus with differentially stunted growth. Whereas this suggestion may be tantalizing, its investigation is beyond the scope of the present paper. Furthermore, only one incomplete specimen of 5. inexplicatus is known and an ontogenetic series is unknown for its presumed "ancestor," S. mirus (all known specimens of 5'. mirus are adults). Without more, especially the latter, data one can do little more than speculate that perhaps 5. inexplicatus is a broadly paedomorphic form relative to 5'. mirus (cf. Roth 1982 for an interesting case study of paedomorphosis in a lineage of dwarf mammoths based on abundant skeletal material). rence of Wortmania in only the San Juan Basin, New Mexico, and perhaps the Wagonroad or Dragon local faunas, Utah, may be wholly a result of the general rarity of earliest Paleocene deposits, confounded by the fact that Wortmania also appears to have been a particularly rare element of these faunas even when they are well known (, in the San Juan Basin). In contrast, Psittacotherium is a far-ranging genus and this may simply correlate with the fact that there are more and better known Torrejonian-early TifTanian faunas. However, the restriction of the Taeniodonta to western North America does appear to be real. It appears that enough deposits of Paleocene-Eocene age have been sampled in Asia, Europe and South America such that if taeniodonts existed on these continents, it is probable that they would have been found by now. Their restriction to western North America suggests that taeniodonts may have evolved in this area and never emigrated. Kielan-Jaworowska (1980) has suggested that there was a one-way dispersal of mammals from Asia
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