Fig 1.
Localities with Aleodon cromptoni sp. nov.
Map of the main Middle to early Upper Triassic outcrops in the state of Rio Grande do Sul, southern Brazil, highlighting the occurrence of Aleodon (A) and its skeletal reconstruction with available bones (in yellow) based on all known specimens (made by VDPN).
Table 1.
List of specimens referred to Aleodon cromptoni sp. nov. from the Dinodontosaurus Assemblage Zone, state of Rio Grande do Sul, Brazil.
Fig 2.
Chrono- and biostratigraphy of Triassic units with vertebrate Assemblages Zones (AZ) from southern Brazil, and the tetrapod fossil content of the Dinodontosaurus AZ.
The ages of the column follow Gradstein et al. [36].
Table 2.
Measurements (in mm) of Aleodon cromptoni sp. nov. specimens from the Middle-early Late Triassic of southern Brazil.
Measurement parameters were taken from Abdala and Giannini [14]. *Estimated measure.
Fig 3.
Aleodon cromptoni sp. nov. from southern Brazil.
Photographs and accompanying drawings of right maxilla MPDC-501-117 in lateral (A), ventral (B), and medial views (C). Scale bar equals 10mm. Abbreviations: A, main cusp A; C, upper canine; Cr, canine root; fpal, facet for palatine; lpl, lingual platform; max, maxilla; mpm, medial process of maxilla; PC, upper postcanine; pf, paracanine fossa; r, root.
Fig 4.
Aleodon brachyrhamphus and A. cromptoni sp. nov.
Comparison of the left maxilla of A. brachyrhamphus (NHMUK PV R9390) from Tanzania (A), with the right maxilla of the specimen MPDC-501-117 from southern Brazil (B), in ventral view, with accompanying line drawing, and detail of the root through a natural section of the last preserved postcanine tooth in posterior view (C). Scale bar equals 10mm. Abbreviations: A, main cusp A; C, upper canine; Ca, upper canine alveolus; de, dentine; fpal, facet for palatine; gr, groove; in, interlocking; max, maxilla; PC, upper postcanine; ral, resorbed alveoli.
Fig 5.
Aleodon cromptoni sp. nov. from southern Brazil.
Specimen MCN-PV 10338, jaws in lateral (A), medial (B) and dorsal (C) views, with details of left pc10 and pc11 in labial (D) and lingual (E) views, and all the left postcanine tooth row in occlusal view (F). Aleodon brachyrhamphus from Tanzania. Holotype UMZC T906, detail of the left tooth row (canine and postcanines) in occlusal view (G). Scale bar equals 20mm in A-C and 10mm in D-G. Abbreviations: a-b-c-d, lower cusps on crown; ai3, alveolus incisor for i3; c, lower canine; di, diastema; i, lower incisor; lpl, lingual platform; pc, lower postcanine; spl, splenial.
Fig 6.
Aleodon cromptoni sp. nov. from southern Brazil.
Specimen UFRGS-PV-0071-T, anterior half of skull in ventral view (A), detail of the right postcanine row (B), and detail of PC5 in lingual view (C). Scale bar equals 20mm in A. Abbreviations: C, upper canine; eal, empty alveolus; pf, paracanine fossa; I, upper incisor; lpl, lingual platform; max, maxilla; pal, palatine; PC, upper postcanine; pt, pterygoid; v, vomer.
Fig 7.
Aleodon cromptoni sp. nov. from southern Brazil.
Specimen MMACR-PV-018-T, left maxilla in lateral (A) and ventral (B) views. Scale bar equals 20mm. Abbreviations: apc, alveolus for upper postcanine teeth; C, upper canine.
Fig 8.
Aleodon cromptoni sp. nov. from southern Brazil.
Specimen UFRGS-PV-0122-T, skull in dorsal (A), ventral (B) and lateral (C) views, left lower jaw (D) in lateral view, and detail of righ upper tooth row (E) in occlusal view. The arrow (B) indicates the level of the posterior edge of secondary palate. Scale bar equals 50mm. Abbreviations: C, upper canine; lPC, last upper postcanine tooth; PC, postcanine tooth.
Fig 9.
Aleodon cromptoni sp. nov. from southern Brazil.
Specimen UFRGS-PV-0125-T, skull in lateral (A), ventral (B) and dorsal (C) views, with details of the left canine-postcanine tooth row in occlusal view (D) and of left postcanine 3 in distal view. Scale bar equals 50mm in A-C, 10mm in D, and 5mm in E. Abbreviations: a1-4, alveoli for incisors 1 to 4; a1-9, alveoli for postcanines 1 to 9; a8, alveolus for postcanine 8; ac, alveolus for canine; lae, labial edge; lie, lingual edge; pf, paracanine fossa; PC, upper postcanine.
Fig 10.
Aleodon cromptoni sp. nov. from southern Brazil.
Specimen UFRGS-PV-0146-T, skull in lateral view with accompanying line drawing. Scale bar equals 50mm. Light gray indicates most affected areas with breakages. Abbreviations: bs/ps basisphenoid/parasphenoid; C, upper canine; I, upper incisor; ju, jugal; max, maxilla; na, nasal; pa, parietal; PC, upper postcanine; pfr, prefrontal; pm, premaxilla; po, postorbital; pt, pterygoid; sm, septomaxilla; sq, squamosal.
Fig 11.
Aleodon cromptoni sp. nov. from southern Brazil.
Specimen UFRGS-PV-0146-T, skull in dorsal view with accompanying line drawing. Scale bar equals 50mm. Light gray indicates most affected areas with breakages. Abbreviations: fr, frontal; ju, jugal; max, maxilla; na, nasal; pa, parietal; PC, upper postcanine; pfr, prefrontal; pm, premaxilla; po, postorbital; pp, postparietal; sm, septomaxilla sq, squamosal.
Fig 12.
Aleodon cromptoni sp. nov. from southern Brazil.
Specimen UFRGS-PV-0146-T, skull in ventral view with accompanying line drawing. Scale bar equals 50mm. Light gray indicates most affected areas with breakages. Abbreviations: bs/ps basisphenoid/parasphenoid; C, upper canine; co, condyle of exoccipital; I, upper incisor; ju, jugal; max, maxilla; pal, palatine; PC, upper postcanine; pf, paracanine fossa; po, postorbital; pt, pterygoid; sq, squamosal.
Fig 13.
Aleodon cromptoni sp. nov. from southern Brazil.
Specimen UFRGS-PV-0146-T, jaws in lateral view with accompanying line drawing. Scale bar equals 50mm. Abbreviations: c, lower canine; cre, canine reconstruction; d, dentary; pc, lower postcanine; pdc, postdentary bone complex. Dark gray indicates the right jaw and light gray indicates broken bone.
Fig 14.
Aleodon cromptoni sp. nov. from southern Brazil.
Specimen UFRGS-PV-0146-T, detail of left upper postcanine row (A) and left lower postcanine row, with accompanying line drawings. Scale bar equals 10mm. Abbreviations: C, upper canine; Ca, upper canine alveolus; enl, enamel layer; lpl, lingual platform; PC/pc, upper, lower postcanine.
Fig 15.
Aleodon cromptoni from southern Brazil.
Specimen UFRGS-PV-0274-T in dorsal (A) and ventral (B) views, and detail of the snout in ventral view (C) with interpretative drawing of the right postcanine tooth row and detail of left PC6. Scale bar equals 50mm. Abbreviations: aPC, alveolus; PC, upper postcanine.
Fig 16.
Specimen GSN EN-3 from the upper Omingonde Formation, Namibia, tentatively referred to Aleodon cromptoni sp. nov.
Skull in dorsal (A), lateral (B), ventral (C) views, and detail of the right (D) and left (E) upper postcanine tooth rows in occlusal view. Alveoli of the right postcanine tooth row are highlighted in white. Scale bar equals 50mm in A-C and 10mm in D-E. Abbreviations: C, upper canine; PC, upper postcanine.
Fig 17.
Chiniquodon from South America.
Skull of specimen MCP-PV-1600-T (holotype of Probelesodon kitchingi) in lateral view (A). Skull and articulated jaws of specimen UFRGS-PV-1331-T (ex UFRGS-PV-0066-Tg) in lateral (B) and dorsal (C) views, and of specimen PVL 4444 in lateral view (D). Detail of posterior upper left postcanines of PVL 4674 in labial (E) and ventrolingual (F) views. Details of posterior lower left postcanines of PVL 4444 in labial (G) and lingual (H) views. Note the absence of a lingual platform. The arrow points to the mesial side. The dotted lines indicate the shape of the dorsal profile of the skull. Scale bar equals 20mm in A-D and 5mm in E-H.
Fig 18.
Strict consensus tree of 75 most parsimonious trees, showing the phylogenetic position of Aleodon cromptoni sp. nov. within Chiniquodontidae. The numbers at nodes indicate Bremer support and Bootstrap values, respectively.
Fig 19.
Biostratigraphy of selected Gondwanan Triassic units.
Relevant therapsid content considering radiometric data and problematic implications among Gondwanan Triassic units, and accompanying paleomap (modified from Abdala and Smith [13]) during the Middle Triassic with the location of Aleodon cromptoni in southern Brazil and Namibia and A. brachyramphus in Tanzania. Abbreviations: AF, Africa; Ind., Induan; Madag., Madagascar; Ole, Olenekian; SA, South America.
Fig 20.
Selected outcrop of the Dinodontosaurus AZ of the state of Rio Grande do Sul, Brazil (see Fig 1 for geographical location of the outcrops).
A, Vale Verde (in 2016); B, Sanga Menezes in Bom Retiro region (in 2015); C, Sanga Pinheiro (in 1996); D, Cortado Site (in 2013); E, Posto site of Dona Francisca (in 2005); F, Sanga Baum in Chiniquá region (in 2000).
Table 3.
Occurrence of taxa and main localities of the Dinodontosaurus AZ in the state of Rio Grande do Sul, southern Brazil (see Suppl. Info. for references of each occurrence).
Fig 21.
Specimen UFRGS-PV-0265-T of Luangwa sp. (Traversodontidae) from Vale Verde locality, Rio Grande do Sul State, Brazil.
Lower jaws in lateral (A) and dorsal view (B). Scale bar equals 20mm.
Fig 22.
Dendrogram of main localities of the state of Rio Grande do Sul yielding fossil tetrapods of the Dinodontosaurus AZ (see data matrix in S1 File).
Cophenetic correlation coefficient = 0.8474. (W), and (C), and (E) refers to the West, Central, and East portions, respectively, of the state of Rio Grande do Sul.
Fig 23.
Biostratigraphy of the Dinodontosaurus and Santacruzodon AZs.
Tetrapod fossil comparisons and shared taxa with the Chañares Formation of western Argentina. The ages of the column follow Gradstein et al. [36]. The radiometric dating of 236.1, 231.4 and 225.9 Ma on the Ischigualasto-Villa Unión Basin column correspond to the first half of the Chañares Formation [45], the base of the Ischigualasto Formation, and the base of Los Colorados Formation [105], respectively, and the one in the Santacruzodon AZ follows Philipp et al. [43].