Table 1.
Specimens or references employed here to score the 14 species added to the taxonomic sample of Reisz et al. [43].
Figure 1.
Phylogenetic relationships of Aenigmastropheus parringtoni and other basal archosauromorphs.
Single most parsimonious tree recovered here with zero length branches collapsed. Abbreviations: Lepidosauro., Lepidosauromorpha; Pr., Proterosuchidae; Prot., Protorosauridae; Rhyn., Rhynchocephalia; Rhyncho., Rhynchosauria; Tanys., Tanystropheidae.
Figure 2.
Bremer support and bootstrap resampling frequencies for the phylogenetic hypothesis presented here.
Numbers below the nodes are Bremer support, absolute bootstrap and GC bootstrap resampling frequencies, respectively, for the single most parsimonious tree recovered here. Numbers above the nodes and with an asterisk are Bremer support values after a posteriori pruning of fragmentary saurian terminals (see text).
Figure 3.
Simplified phylogenetic relationships of Diapsida.
(A) Phylogenetic positions of Sauria (blue box) and several species previously considered as Permo-Triassic lepidosauromorphs (red boxes), based upon the phylogenetic analysis of Bickelmann et al. [70] (illustration simplified) (B) Holotype (AM 3585) of Paliguana whitei, the oldest known lepidosauromorph from the Early Triassic of South Africa, in right lateral view. Scale bar equals 5 mm.
Figure 4.
Protorosaurus speneri, a protorosaurian archosauromorph from the middle Late Permian of Western Europe.
Axial skeleton primarily exposed in right lateral view (BSPG 1995 I 5, cast of WMSN P47361) collected near Münster, Germany. Abbreviations: cav, caudal vertebrae; cvv, cervical vertebrae; dv, dorsal vertebrae; fi, fisch; ga, gastralia; lfl, left forelimb; lsc, left scapula and coracoid; rfl, right forelimb; rhl, right hindlimb; rsc, right scapula and coracoid; sk, skull; sv, sacral vertebrae. Scale bar equals 10 cm.
Figure 5.
Eorasaurus olsoni, a possible early archosauriform from the late Middle–early Late Permian of Russia.
Middle (PIN 156/109: A–G) and posterior (PIN 156/108, holotype: H–L) cervical vertebrae in left lateral (A, H), left ventrolateral (B, C), right lateral (D, I), dorsal (E, F, J), and ventral (G, K, L) views. Abbreviations: acl, accessory lamina; af, anterior articular facet; d, depression; dp, diapophysis; in, intercentrum; lol, longitudinal lamina; ns, neural spine; pa, parapophysis; pcdl, posterior centrodiapophyseal lamina; pdl, paradiapophyseal lamina; poz, postzygapophysis; prdl, prezygodiapophyseal lamina; prz, prezygapophysis; vk, ventral keel. Scale bar equals 1 cm.
Figure 6.
Eorasaurus olsoni, a possible early archosauriform from the late Middle–early Late Permian of Russia.
Anterior dorsal vertebrae and rib in articulation (PIN 156/110: A, B, F), close-up of the anterior dorsal rib (E), and probable long bones (PIN 156/111a, b: C, D) in left lateral (A, E), dorsal (B), and ventral (F) views. Abbreviations: acdl, anterior centrodiapophyseal lamina; ca, capitulum; dp, diapophysis; dr, anterior dorsal rib; la, lamina; pcdl, posterior centrodiapophyseal lamina; prdl, prezygodiapophyseal lamina; poz, postzygapophysis; prz, prezygapophysis; sh, shaft; tp, transverse process; tu, tuberculum. Scale bars equal 1 cm in (A–D, F) and 5 mm in (E).
Table 2.
Measurements of the preserved bones of Eorasaurus olsoni (PIN 156/108, 109, 110) in millimeters.
Figure 7.
Archosaurus rossicus, a proterosuchid archosauriform from the latest Permian of Russia.
Left premaxilla (PIN 1100/55, holotype) in lateral (A), medial (B) and ventral (C) views. Abbreviations: alm, alveolar margin; alv, alveolus; fl, lateral flange; nf, narial fossa; pap, palatal process; ponp, postnarial process; prnp, prenarial process; sya, symphyseal area. Scale bar equals 1 cm.
Table 3.
Measurements of the holotype of Archosaurus rossicus (PIN 1100/55) in millimeters.
Figure 8.
Indeterminate reptiliomorph from the Late Permian–Early Triassic of South Africa.
Cervical vertebra (BP/1/4220) in right lateral (A), left lateral (C), ventral (D, H), anterior (E, F), posterior (G), posterodorsal (I, J) and dorsal (K, L) views. Abbreviations: acp, accessory (interpostzygapophyseal) process; af, anterior facet; be, ventral beveling; cl, median cleft; d, depression; nc, notochordal canal; ns, neural spine; tu, tuberosity; pf, posterior facet; poz, postzygapophysis; posf, postspinal fossa; tp, transverse process. Scale bar equals 1 cm.
Table 4.
Measurements of the preserved bones of BP/1/4220 in millimeters.
Figure 9.
Type locality of Aenigmastropheus parringtoni in the Ruhuhu Basin, southwestern Tanzania, Africa.
Star indicates the approximate geographic and stratigraphic occurrence of Aenigmastropheus parringtoni (locality B35). Abbreviations: Fm, formation; Mb, member; Mt, mountain; Ss, sandstone. Figure modified from Nesbitt et al. [224].
Figure 10.
Aenigmastropheus parringtoni, an early archosauromorph from the middle Late Permian of Tanzania.
Cervical vertebra (vertebra 1 sensu Parrington [9]) (UMZC T836, holotype) in right lateral (A, B), left lateral (C), anterior (D, E), dorsal (F, G), posterior (H, I) and ventral (J, K) views. Abbreviations: af, anterior facet; d, depression; fo, lateral fossa; nc, notochordal canal; ns, neural spine; pa, parapophysis; pcdl, posterior centrodiapophyseal lamina; pdl, paradiapophyseal lamina; pf, posterior facet; posf, postspinal fossa; poz, postzygapophysis; prdl, prezygodiapophyseal lamina; prz, prezygapophysis; prsf, prespinal fossa; scf, subcentral foramen; tp, transverse process. Scale bar equals 1 cm.
Figure 11.
Aenigmastropheus parringtoni, an early archosauromorph from the middle Late Permian of Tanzania.
Cervico-dorsal vertebrae (UMZC T836, holotype) in right lateral (A–D), left lateral (E–H), anterior (I–L), posterior (M–P), dorsal (Q–T) and ventral (U–X) views. Vertebrae 2 (A, E, I, M, Q, U), 3 (C, G, K, O, S, W), 4 (B, F, J, N, R, V) and 5 (D, H, L, P, T, X) sensu Parrington [8]. Scale bar equals 1 cm.
Figure 12.
Aenigmastropheus parringtoni, an early archosauromorph from the middle Late Permian of Tanzania.
Distal half of the right humerus (UMZC T836, holotype) in ventral (A, B), posterior (C), dorsal (D, E), anterior (F), proximal (G) and distal (H) views. Abbreviations: ca, capitellum (radial condyle); d, depression; ecf, ectepicondylar flange; ecg, ectepicondylar groove; ect, ectepicondyle; ent, entepicondyle; pvr, posteroventral ridge; tr, trochlea (ulnar condyle). Scale bar equals 1 cm.
Figure 13.
Aenigmastropheus parringtoni, an early archosauromorph from the middle Late Permian of Tanzania.
Proximal end of the right ulna (UMZC T836, holotype) in anterior (A, B), dorsal (C), posterior (D), ventral (E), proximal (F) and distal (G). Abbreviations: ccb, collapsed cortical bone; d, depression; has, humeral articular surface; li, lip; ol, olecranon; sts, striated surface. Scale bar equals 1 cm.
Figure 14.
Aenigmastropheus parringtoni, an early archosauromorph from the middle Late Permian of Tanzania.
Possible left humeral shaft (A, E, I, M, P, T), possible distal end of radius (B, F, J, N, Q, U) and two indeterminate bones (C, D, G, H, K, L, O, R, S, V) (UMZC T836, holotype) in several views. The dashed line indicates the area sampled for the paleohistological study. Scale bar equals 1 cm.
Figure 15.
Aenigmastropheus parringtoni, an early archosauromorph from the middle Late Permian of Tanzania.
Paleohistological slices of possible left humerus (UMZC T836, holotype). Overview of the bone section in normal light (A) and cross-polarized light with lambda compensator (B); upper left quadrant showing the complete section of the cortex, in which the medullary cavity is to the lower right of the image, in normal (C) and cross-polarized light (D); lower left quadrant showing the complete section of the cortex in cross-polarized light with lambda compensator (E); and close-up of the outer part of the periosteal cortex in cross-polarized light with lambda compensator (F). White arrows in (F) indicate lines of arrested growth (LAGs). Abbreviations: lpo, longitudinal primary osteons; lzb, lamellar-zonal bone; mc, medullary cavity; pfb, parallel-fibred bone; po, primary osteons; pvc, primary vascular canal; rpo, reticular primary osteons; so, secondary osteons; tb, trabecular bone; wb, woven bone.
Figure 16.
Character states supporting the phylogenetic positions of Aenigmastropheus parringtoni and Eorasaurus olsoni.
Anterior and middle dorsal vertebrae of Youngina capensis (BP/1/3859) (A), Tanystropheus longobardicus (SMNS 55341, reversed) (D) and Helveticosaurus (PIMUZ T4352, holotype, reversed) (E) and middle-posterior cervical vertebrae of Aenigmastropheus parringtoni (UMZC T836, vertebra 1, holotype, reversed) (B) and Eorasaurus olsoni (PIN 156/109) (C) in right lateral views. Scale bar equals 5 mm in (A) and 1 cm in (B–E).
Figure 17.
Character states supporting the phylogenetic position of Aenigmastropheus parringtoni.
Humeri of Aenigmastropheus parringtoni (UMZC T836, holotype) (A), Protorosaurus speneri (BSPG 1995 I 5, cast of WMSN P47361, reversed) (B) and Youngina capensis (BP/1/3859) (C) in ventral views; ulna of Aenigmastropheus parringtoni (UMZC T836, holotype) (D) and ulnae and radii of Protorosaurus speneri (BSPG 1995 I 5, cast of WMSN P47361) (E) and Macrocnemus bassanii (PIMUZ T4355) (F) in anterior views. Scale bar equal 1 cm in (A, B, D–F) and 5 mm in (C).
Figure 18.
Character states supporting the phylogenetic positions of Aenigmastropheus parringtoni and Eorasaurus olsoni.
Cervical and dorsal vertebrae of Aenigmastropheus parringtoni (UMZC T836, vertebra 2, holotype) (A), Protorosaurus speneri (ZMR MB R2173) (B) and Tanystropheus longobardicus (SMNS 55341) (C) in posterior views, and cervico-dorsal vertebrae of Eorasaurus olsoni (PIN 156/110) (D), Prolacerta broomi (BP/1/2675) (E) and Proterosuchus fergusi (GHG 363) (F) in dorsal views. Scale bars equal 5 mm in (A, E) and 1 cm in (B, C, D, F).
Table 5.
Measurements of the preserved axial bones of Aenigmastropheus parringtoni nov. gen. et nov. sp. (UMZC T836) in millimeters.
Table 6.
Measurements of the preserved forelimb bones of Aenigmastropheus parringtoni nov. gen. et nov. sp. (UMZC T836) in millimeters.
Figure 19.
Time-calibrated cladogram showing the basal saurian interrelationships recovered here.
Geological timescale after Gradstein et al. [157].
Table 7.
List of specimens/species previously considered as pre-Mesozoic saurians and their age and current taxonomic assignment.
Figure 20.
Paleobiogeographical distribution of Archosauromorpha across Pangea during the late Middle–Late Permian.
Black stars indicate archosauromorph records (paleomap for 260 Ma downloaded from Fossilworks using data from the Paleobiology Database: [206]).
Figure 21.
Late Permian of Tanzania at the time of deposition of the Usili Formation.
Life restoration of Aenigmastropheus parringtoni (foreground), and herd of the dicynodont Endothiodon being pursued by a gorgonopsian. All these vertebrates were found together at the type locality of Aenigmastropheus parringtoni (locality B35). Drawing by Emilio López-Rolandi.