Introduction
Defining the Problem
Procyonid Origins
The major carnivore radiations took place about 40 million years before present (MYBP) in the late Eocene and early Oligocene (Ewer, 1973:363; Wayne et al., 1989). Between 30 and 40 MYBP, a progenitor split into the ursid and procyonid lineages, which evolved into present-day bears, pandas, and raccoons (Wayne et al., 1989). The taxonomic relatedness of pandas to bears and raccoons has been tested extensively and a number of authors have summarized current thinking on the problem (Martin, 1989; Wayne et al., 1989; Wozencraft, 1989a, 1989b; Decker and Wozencraft, 1991). Davis (1964:322-327) and others (Leone and Wiens, 1956; Todd and Pressman, 1968; Sarich, 1976; O'Brien et al., 1985) place the giant panda, Ailuropoda melanoleuca, with the ursids. The taxonomic status of the red panda, Ailurus fulgens, appears to be less certain. Some current investigations align the red panda with bears (Segall, 1943; Todd and Pressman, 1968; Hunt, 1974; Ginsburg, 1982; Wozencraft, 1984:56-110; 1989a), whereas others place them intermediate to procyonids and bears (Wurster and Benirschke, 1968; Sarich, 1976; O'Brien et al., 1985), or in close relationship to the giant panda (Tagle et al., 1986).
The procyonid radiation took place in North America and produced forms that were mostly arboreal and omnivorous (Eisenberg, 1981:122; Martin, 1989). The center of this diversification occurred in Middle America (Baskin, 1982; Webb, 1985b) during the Miocene (Darlington, 1963:367; Webb, 1985b). Fossil procyonids from the late Miocene are represented in Florida, California, Texas, Nebraska, Kansas, and South Dakota (Baskin, 1982; Martin, 1989) and include such genera as Bassariscus, Arctonasua, Cyonasua, Paranasua, Nasua, and Procyon (Baskin, 1982; Webb, 1985b). During the Miocene procyonids underwent a modest radiation within tropical and subtropical climates of North America's central and middle latitudes. Cyonasua, which has close affinities to Arctonasua (Baskin, 1982), appears in tropical South America in the late Miocene and immigrated there either by rafting across the Bolivar Trough or by island-hopping through the Antilles archipelagoes (Marshall et al., 1982; Marshall, 1988). Thus, procyonids were found on both continents prior to formation of the Panamanian land bridge (Darlington, 1963:367, 395; Marshall et al., 1982; Marshall, 1988). Origins of Bassaricyon and Potos are obscure but probably occurred in tropical rainforests of Middle America (Baskin, 1982; Webb, 1985b). A subsequent Pleistocene dispersal carried several modern genera ([Table 1]) across the Panamanian land bridge into South America (Webb, 1985b). Bassariscus and Bassaricyon represent the most primitive genera in Procyoninae and Potosinae subfamilies, respectively ([Table 1]; Wozencraft, 1989a; Decker and Wozencraft, 1991).
In the early Tertiary, mid-latitudes of North America were much warmer than they are now, but not fully tropical, and temperate deciduous forests, associated with strongly seasonal climates, occurred only in the far north (Barghoorn, 1953; Colbert, 1953; Darlington, 1963:589, 590). Major climatic deteriorations, with their attendant cooling of northern continents, occurred during the Eo-Oligocene transition, in the middle Miocene, at the end of the Miocene, and at about 3 MYBP (late Pliocene). This last deterioration corresponds with closure of the Panamanian isthmus (Berggren, 1982; Webb, 1985a). Climatic deterioration went on at an accelerating rate during the late Tertiary, with glacial conditions developing at the poles by the mid-Pliocene (Barghoorn, 1953). Therefore, throughout the Tertiary, as continents cooled, northern climate zones moved toward the tropics (Barghoorn, 1953; Colbert, 1953; Darlington, 1963:589, 590, 594, 595; Webb, 1985a).
Table 1.—Classification of recent Procyonidae after Wozencraft (1989a) and Decker and Wozencraft (1991). Information in parenthesis indicates general geographic distribution (modified from Kortlucke and Ramirez-Pulido (1982) and Poglayen-Neuwall (1975)): S.A. = South America; C.A. = Central America; M. = Mexico; U.S. = United States; C. = Canada. Lower case letters preceding geographic areas signify north (n), south (s), and west (w).
Order Carnivora Bowdich, 1821
Suborder Caniformia Kretzoi, 1945
Family Procyonidae Gray, 1825
Subfamily Potosinae Trouessart, 1904
Genus Potos E. Geoffroy and G. Cuvier, 1795
P. flavus (S.A., C.A., M.)
Genus Bassaricyon Allen, 1876
B. alleni[A] (S.A.)
B. beddardi[A] (S.A.)
B. gabbii[A] (nS.A., C.A.)
B. lasius[A] (C.A.)
B. pauli[A] (C.A.)
Subfamily Procyoninae Gray, 1825
Genus Bassariscus Coues, 1887
B. astutus (M., wU.S.)
B. sumichrasti (C.A., M.)
Genus Nasua Storr, 1780
N. narica[B] (nS.A., C.A., M., swU.S.)
N. nasua[B] (S.A., sC.A.)
Genus Nasuella Hollister, 1915
N. olivacea (S.A.)
Genus Procyon Storr, 1780
P. cancrivorus (S.A., sC.A.)
P. gloveralleni[C] (Barbados)
P. insularis[C] (Maria Madre Is., Maria Magdalene Is.)
P. lotor[C] (C.A., M., U.S., sC.)
P. maynardi[C] (Bahamas, New Providence Is.)
P. minor[C] (Guadeloupe Is.)
P. pygmaeus[C] (M., Quintana Roo, Cozumel Is.)
[A] The several named forms of Bassaricyon are a single species, Bassaricyon gabbii (Wozencraft, 1989a).
[B] These are considered conspecific in some current taxonomies (Kortlucke and Ramirez-Pulido, 1982); however, the scheme followed here maintains them as separate species (Decker, 1991).
[C] Several named forms of Procyon are a single species, Procyon lotor (Wozencraft, 1989a).