zalambdalestes - American Museum of Natural History

24 BULLETIN AMERICAN MUSEUM OF NATURAL HISTORY NO. 281
Fig. 8. Stereophotographs of the upper dentition of Zalambdalestes lechei PSS-MAE 130 in ventral
(A) and left lateral (B) views.
astyle. The protocone is situated lower than
the paracone, directed transversely, with a
slight anterior deviation. The precingulum
and postcingulum are lacking. The surface
between the protocone and paracone [trigon
basin] is hollowed out by wear, retaining a
very characteristic transverse ridge in the
middle, absent from other teeth’’ (Kielan-Jaworowska,
1969a: 188). As was true of the
P3, the P4s in PSS-MAE 108 (figs. 11, 23)
and 129 (fig. 31) are heavily worn and provide
few morphological details. In PSS-MAE
130 (figs. 8, 9, 10A, C), both right and left
P4 are well preserved, with only slight wear
to the crest between the paracone and incipient
metacone, and in most regards follow
the description of Kielan-Jaworowska
(1969a). However, as reported above for the
P3, the crest connecting the paracone and
metastyle in PSS-MAE 130 has an incipient
metacone and two cuspules in the metastylar
region (fig. 10A, C): in the E position (i.e.,
the metastyle) and lingual to it. The three
styles between the parastyle and metastyle
that Kielan-Jaworowska (1969a) described as
‘‘hardly discernible’’ are slightly more pronounced
in PSS-MAE 130 (fig. 10A, C). The
anterior one (stylar cusp B) is separated from
the parastyle by a notch; the posterior two
are immediately posterior to the ectoflexus.
Of these three, the middle (stylar cusp D?) is
the most distinct, although not as prominent