Scelidotherium bravardi ( Lydekker, 1886 )

Scelidotherium bravardi ( Lydekker, 1886)

Referred material: Cranial fragment, hemimandible, five ribs, one cervical vertebra, fragment of vertebral apophysis, right femur and foot, left scapula, femoral head, tibia, and pelvic fragment: PIMUZ A/ V 506 ( Figs. 6 View Fig , 11 View Fig ); incomplete maxilla bearing the right Cf1 and almost complete right mandible with complete dentition: PIMUZ A/ V 507; caniniform, mf1, and mf2: PIMUZ A/ V 519; left mf2: PIMUZ A/ V 520; five caudal vertebrae and several bones of the foot: PIMUZ A/ V 528 ( Fig. 7 View Fig ); incomplete right mandible: PIMUZ A/ V 4093.

Comment: Te specimens reassigned here to S. bravardi all appear to be adult and relatively smaller in size than those previously treated for S. leptocephalum . Te only exception is represented by PIMUZ A/V 507, a young specimen in which the predental spout is oriented more dorsally than in S. leptocephalum , a diagnostic feature of S. bravardi ( Miño-Boilini et al., 2014) . In addition, the posterior lobe of the mf3 is straight, without the characteristic C-shaped cross-section of S. leptocephalum ( Miño-Boilini et al., 2014) . PIMUZ A/V 506 shows the same characteristics in the mandible. Te mf3 of PIMUZ A/V 506 and PIMUZ A/V 4093 also exhibits the same shape of PIMUZ A/V 507 in occlusal view. I therefore propose a reassignment to S. bravardi for these three specimens. PIMUZ A/V 519 and PIMUZ A/V 520 have the tooth pattern proposed by Corona et al. (2013) for Scelidotherium but with a strong trilobulation and an elliptical caniniform in cross-section (PIMUZ A/V 519) which suggests a reassignment to S. bravardi ( Miño-Boilini et al., 2014) . Only one specimen can be identified based on postcranial material: PIMUZ A/V 528. Among multiple foot bones, PIMUZ A/V 528 has a well-preserved calcaneum for which the sustentacular facet is slightly continuous with the cuboid facet in proximal view, a feature favoring a reattribution to S. bravardi ( Miño-Boilini et al., 2014) . Te presence of S. leptocephalum and S. bravardi in the Pampean Region offers the opportunity to relate the evolution of the clade with the drastic paleoenvironmental variations of the region during the Pleistocene, especially since S. leptocephalum is considered a species particularly well adapted to arid environments (see below). Te high abundance of both species in the Roth collection at PIMUZ will allow to generate comparisons on intraspecific variation between the two species. Tese occurrences reveal the evolutionary success of the clade in the Pleistocene Pampean Region with a much higher abundance of S. leptocephalum than S. bravardi .