Fig 1.
Location map showing the provenance of the teeth and osteoderms.
Southern South America, with the Cerro Fortaleza type-locality indicated by the star (A). Region between Viedma and Argentino lakes showing the Cerro Fortaleza Formation (red color) outcropping at both sides of La Leona river. The Chorrillo Formation is indicated in green (B). Photography of the site, the red arrow indicates the level with teeth and osteoderms (C). B is based on [2,16].
Table 1.
Cerro Fortaleza theropod and crocodyliform teeth measurements (in mm).
Fig 2.
A-C, Abelisauria indet. (MPM-PV-18805.1), partial tooth in lingual or labial (A) and mesial (B) views; detail of mesial denticles (C). D, partial tooth (MPM-PV-18805.2) of a non-identified archosaur, preserving a patch of enamel showing a highly marked ornamentation. E-F, Titanosauria indet. (MPM-PV-18805.3), partial tooth. G-I, Ankylosaur (MPM-PV-18805.4) partial tooth in labial (G), distal (H) and lingual (I) views. Scale bars = 1 mm (except in A, B = 5mm).
Fig 3.
Ankylosaur interstitial ossicles (osteoderms) in superficial, internal and lateral views.
MPM-PV-18805.14 (A-C), MPM-PV-18805.15 (D-E), MPM-PV-18805.16 (F-H), MPM-PV-18805.17 (I-J), MPM-PV-18805.18 (K-L), MPM-PV-18805.19 (M-P), MPM-PV-18805.20 (Q-S), MPM-PV-18805.21 (T-U), MPM-PV-18805.22 (V-W). Scale bars = 1mm.
Fig 4.
Bone histology of ankylosaur interstitial ossicles.
(A-B) Complete sections of elements MPM-PV-18805.19 (A) and MPM-PV-18805.22 (B). In both images the superficial surface is oriented toward the top of the figure. The deep cortex of MPM-PV-18805.v-w is not preserved. The complex pattern of mineralized structural fiber bundles is clearly observed in the inner core and deep cortex of MPM-PV-18805.m-p. (C-D) Primary bone tissue composed by intercrossed bundles of mineralized structural fibers. White arrows in (C) signal the orientation of the fiber bundles. (E, F) General view (E) and detail (F) of the transition between the inner core (formed by structural fibers) and the external cortex (mostly formed by parallel fibered bone). (G) Detail of the outer cortex at the superficial portion of the ossicles. Note the profuse abundance of mineralized collagenous fibers. (H) Lines of arrested growth in the deep cortex (white arrowheads). (I) Detail of secondary osteons. Pictures have been taken under normal transmitted light (C, E-I), cross-polarized light (B) and cross-polarized light with a lambda filter (A and D). The epoxy resin layer that surrounds the elements in (A) and (B) has been digitally erased to enhance visibility. Abbreviations: lsf, longitudinally sectioned structural fiber bundles; pfb, parallel fibered bone; sf, structural fibers; tsf, transversally sectioned structural fiber bundles; rc, resorption cavity; so, secondary osteons.
Fig 5.
MPM-PV-18805.5 complete crown in lingual (A), mesial (B) and labial (C) views. MPM-PV-18805.6 complete crown in labial (D) and distal (E) views. MPM-PV-18805.7 fragmented crown in mesial (F) and lingual (G) views. MPM-PV-18805.8 almost complete crown in mesial or distal (H), apical (I) and mesial or distal (J) views. MPM-PV-18805.9 fragmented crown in mesial or distal (K) and labial (L) views. MPM-PV-18805.10, fragmented crown in labial (M) and apical (N) views. MPM-PV-18805.11, complete crown in lingual (O) and mesial (P) views. MPM-PV-18805.12, fragmented crown in mesial or distal (Q) and detail of the denticles (R). MPM-PV-18805.13, crown missing the tip in apical (S), lingual (T) and distal (U) views. Scale bars (A-E) = 5 mm; (F-U) = 1 mm.
Fig 6.
Scheme of a peirosaurid skull showing heterodont teeth and the probable location of morphotypes I to IV.
Abbreviations: 1, caniniform tooth; 2, low-crowned conical tooth; 3, spatulate tooth; 4, molariform tooth.
Fig 7.
Paleoambiental reconstruction of Cerro Fortaleza locality (Cerro Fortaleza Formation) showing the coeval dinosaurs and peirosaurid notosuchians described in the present study (and right below is Zamuneria).
Illustration by J. González.