Tiuclaenus minutus Muizon & Marshall, 1987

DIAGNOSIS. — See Muizon & Cifelli (2000).

DESCRIPTION

A maxilla with M1-3 (MHNC 13879) is referred to Tiuclaenus minutus . It bears three almost unworn molars, and has been referred to this species essentially on the basis of its size (Fig. 10A). Tiuclaenus minutus is the smallest “condylarth” species of the Tiupampa fauna and the molars of the new specimen are even slightly smaller than those of MHNC 1240 described by Muizon & Cifelli (2000: fig. 7C). For example, the length of the molar row is 5.86 mm in MHNC 13879, while it is 6.74 mm on MHNC 1240, but such a size difference is likely related to individual variation. The size and proportions of the upper molar of this specimen depart from the other species of Tiuclaenus and from Pucanodus, which are distinctly larger (see Muizon & Cifelli 2000: tables 7-9). However, some slight morphological differences exist between the specimens referred to T. minutus, which differ in the larger size of the para- and metastyles, the para-and metacones more approximated, the more pronounced ectoflexus and labial cingulum. Nevertheless, in spite of these morphological differences we tentatively refer MHNC 13879 to T. minutus, considering that they could regarded as related to individual variation, an interpretation that could be revised when a larger sample of that species will be available.