Discussion

Analysis 1: Replacing Tupaia with Ptilocercus in Beard's (1993b) analysis produces only a minor change in tree topology. Whereas Beard's (1993b) analysis supported a Primatomorpha-Chiroptera clade (Figure 2), this analysis instead supports a Primatomorpha-Scandentia clade (Figure 3). This change in tree topology is not particularly surprising because Beard (1993b) stated that support for a Primatomorpha-Chiroptera clade was weak. The change is significant, however, in light of recent molecular results. Beard's (1993b) tree topology did not support the molecular concept of Euarchonta (see Figure 1D and E), but the inclusion of Ptilocercus in the analysis changes the tree topology so that Euarchonta is supported (Figure 3). Hence, when Ptilocercus is included in the analysis, the results are more congruent with those from molecular studies (see Adkins and Honeycutt, 1991, 1993; Allard et al., 1996; Cronin and Sarich, 1980; Honeycutt and Adkins, 1993; Liu and Miyamoto, 1999; Liu et al., 2001; Murphy et al., 2001a,b; Porter et al., 1996; Waddell et al., 1999).

Analysis 2: When additional characters were added to the analysis, Primatomorpha was no longer supported. In fact, in all 21 most parsimonious trees, Volitantia was supported (Figure 4) and bootstrap support for this clade (79%) was relatively strong (Figure 5). That Scandentia was the extant sister taxon to Volitantia is congruent with other recent phylogenetic analyses of cranial, dental, and postcranial data (Bloch et al., 2002; Silcox, 2001a,b, 2002).

It is not surprising that the placement of the three plesiadapiform families was not consistent in the 21 most parsimonious trees, as many of their character states could not be coded due to missing data in these extinct groups (Appendix B). Hence, little can be said about the relationships of plesiadapiforms based on this analysis. In studies of larger data sets that include cranial and dental data in addition to postcranial data, however, plesiadapiforms are consistently found to be the sister taxon to Euprimates, and should therefore be included with Euprimates in the order Primates (Bloch et al., 2002; Silcox, 2001a,b, 2002).

Analysis 3: Support of Volitantia in Analysis 2 is not congruent with molecular results, which exclude bats from Archonta altogether. Chiroptera was, therefore, removed from the analysis as suggested by molecular data, yet Primatomorpha was still not supported (Figure 6). Hence, even when a Dermoptera-Chiroptera clade could not be supported, a Dermoptera-Primates clade was still not supported. In other words, although it was impossible for Volitantia to be supported, there was still no support for Primatomorpha. Alternatively, a Dermoptera-Scandentia clade was supported (Figure 6), and this is congruent with molecular results (Liu and Miyamoto, 1999; Liu et al., 2001; Madsen et al., 2001; Murphy et al., 2001a,b). This is a particularly interesting phylogenetic hypothesis from a biogeographic perspective because both of these taxa are endemic to South and Southeast Asia. If the Dermoptera-Scandentia clade represents a natural grouping, then Volitantia represents an unnatural grouping based on convergences rather than homologies, and dermopterans and chiropterans must have evolved their similarities independently in relation to gliding and flying, respectively (Sargis, 2002d). Insofar as Primatomorpha is concerned, it is not supported whether bats are included in the analysis or not, so there is more evidence for either Volitantia or the Dermoptera-Scandentia clade than there is for Primatomorpha. Hence, Primatomorpha likely represents an unnatural grouping (Sargis, 2002d), and it must be rejected based on these analyses.

In an attempt to further examine potential morphological evidence for a Dermoptera-Scandentia clade, the characters in Appendix A were mapped onto the molecular phylogeny shown in Figure 1D. Possible synapomorphies

Table 4. Possible synapomorphies of Euarchonta and a Dermoptera-Scandentia clade Euarchonta

1. Robust humeral lesser tuberosity with strong medial protrusion (character #2)

2. Spherical capitulum (character #3)

3. Circular and deeply excavated radial central fossa (character #4)

4. Elliptical acetabulum that is elongated craniocaudally (character #13)

5. Cranial expansion of bony buttressing on acetabulum (character #14)

6. Enlarged, flattened, triangular area between greater and lesser trochanters for insertion of quadratus femoris (character #16)

7. Synovial distal tibiofibular joint (character #18)

8. Concave cuboid facet of calcaneus (calcaneocuboid pivot) (character #21)

9. Wide distal facet on the entocuneiform (character #22)

Dermoptera-Scandentia Clade

1. Cuneiform contacts two bones radially (character #9)

2. Deep ungual phalanges that are highly compressed mediolaterally and tall dorsoventrally (character #12)

3. Short, wide, shallow patellar groove (character #17)

4. Craniocaudally wide atlas vertebra (character #23)

5. Short, wide thoracic spinous processes (character #24)

6. Short lumbar spinous processes (character #25)

7. Lumbar transverse processes short and face laterally (character #26)

8. Short, wide scapula (character #27)

9. Small greater trochanter (character #28)

10. Anteroposteriorly shallow femoral condyles (character #29)

11. Short cervical (C3-C7) spinous processes (character #32)

12. Craniocaudally expanded ribs (character #33)

of both Euarchonta and the Dermoptera-Scandentia clade are listed in Table 4. Nine synapomorphies of Euarchonta were found when bats were excluded from the analysis (Table 4). Several of these were considered by Beard (1993b) to be synapomorphies of Primatomorpha, but they are also found in Ptilocercus (Sargis, 2002a,b,d). The Dermoptera-Scandentia clade, on the other hand, is supported by 12 synapomorphies (Table 4). Hence, there appears to be some morphological support for this clade, which previously has been supported only by molecular evidence. Here again, the inclusion of Ptilocercus in the analysis is critical because this morphological support is based on similarities between Cynocephalus and Ptilocercus, not Tupaia.

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