Osteological traits of the swimming: (A-C) Scapteromys aquaticus (ILPLA 052, CNP 711). (A) Cranial view of the atlas showing the neural process very high and laterally compressed and (B) oval shape of the radial head in proximal view. (C) Dorsal view of calcaneus, exhibiting a long calcaneus tuber. caf, calcaneoastragalar facet; crf, cranial facet; d, dens; np, neural process; rh, radial head; suf, sustentacular facet; tc, tuber calcaneus; tp, trochlear process; trp, transverse process. Scale bars: 5 mm.