New Permian fauna from tropical Gondwana

Abstract

Terrestrial vertebrates are first known to colonize high-latitude regions during the middle Permian (Guadalupian) about 270 million years ago, following the Pennsylvanian Gondwanan continental glaciation. However, despite over 150 years of study in these areas, the biogeographic origins of these rich communities of land-dwelling vertebrates remain obscure. Here we report on a new early Permian continental tetrapod fauna from South America in tropical Western Gondwana that sheds new light on patterns of tetrapod distribution. Northeastern Brazil hosted an extensive lacustrine system inhabited by a unique community of temnospondyl amphibians and reptiles that considerably expand the known temporal and geographic ranges of key subgroups. Our findings demonstrate that tetrapod groups common in later Permian and Triassic temperate communities were already present in tropical Gondwana by the early Permian (Cisuralian). This new fauna constitutes a new biogeographic province with North American affinities and clearly demonstrates that tetrapod dispersal into Gondwana was already underway at the beginning of the Permian.

Figure 1. The dvinosaur temnospondyl Timonya anneae gen. et sp. nov. from the Cisuralian of northeastern Brazil.

(a–c) holotype UFPI PV001. (a) dorsal view of skull. (b) CT rendering of posterior portion of palate in ventral view. (c) CT rendering of right jaw, occlusal view. (d–h) articulated skeleton of a juvenile individual in dorsal view, UFPI PV004. (d) general view of the skeleton. (e) details of the right pes. (f) pectoral girdle. (g) pelvic girdle and left limb. (h) counter-slab of UFPI PV004 showing skull roof in ventral view and details of anterior thoracic vertebrae and right forelimb. af, adductor fossa; bo, basioccipital; cb, ceratobranchial; exo, exoccipital; f femur; fib, fibula; h, humerus; i, intercentrum; icl, interclavicle; il, ilium; na, neural arches; paf parasymphysial foramen; pc, pleurocentrum; pgp, postglenoid process of the jaw; psp, parasphenoid; pt, pterygoid; rcl, right clavicle; tib, tibia. Scale bar, 10 mm (a–d) and 5 mm (e–h).

Figure 2. Tetrapods from the Cisuralian of northeastern Brazil.

(a–c) The trimerorhachid Procuhy nazariensis n. g. n. sp. (UFPI PV011), skull roof in ventral view and left hemimandibular ramus partially preserved in lingual view. a.c., anterior coronoid; ang, angular; ar, articular; d, dentary; f, frontal; fr, frontal; g.arc, arcadian groove; h, hamate process; it, intertemporal; j, jugal; l, lacrimal; m.c., middle coronoid; m, maxilla; n, nasal; p, parietal; pa, parietal; part, prearticular; p.c., posterior coronoid; pf, postfrontal; po, postorbital; pp, postparietal; prf, prefrontal; p.ra, retroarticular process; s, splenial; sq, squamosal; st, supratemporal; t, tabular; t, tooth. (d,e) partial skull table of a rhinesuchid (UFPI PV007) in ventral view, (f), right hemimandibular ramus of a rhinesuchid (UFPI PV003). f, frontal; fr, frontal; it, intertemporal; j, jugal; l, lacrimal; m, maxilla; n, nasal; p, parietal; pa, parietal; pf, postfrontal; po, postorbital; pp, postparietal; prf, prefrontal; sq, squamosal; st, supratemporal; t, tabular. (g) Right hemimandibular ramus of Captorhinus aguti, natural mould (UFPI PV014), anterior to the right. (h) Left hemimandibular ramus of Captorhinus aguti, in occlusal view, from Oklahoma, USA (FMNH PR 2107). Scale bar, 50 mm (a–e) 200 mm (f) and 10 mm (g,h).

Figure 3. Location of the new faunal province and phylogenetic relationships of the temnospondyl taxa described herein.

(a) reconstruction of Pangaea during the Cisuralian (278 Myr ago) showing the location of the Parnaíba Basin, and provenance and age of previous rhinesuchid and dvinosaurid temnospondyls: 1, southern USA (Cisuralian); 2, Greenland (Triassic); 3, Russian Platform (Triassic); 4, Paraná Basin (Lopingian); 5, Karoo Basin (Lopingian rhinesuchids and Triassic dvinosaurids); 6, Malawi (Lopingian); 7, Madagascar (Lopingian); 8, India (Lopingian). (b) Cladogram displaying the interrelationships of Rhinesuchidae with Dvinosauria and the position of Timonya and Procuhy within this group; symmetric resampling and decay index values are provided right and left of each node, respectively (symmetric resampling was calculated from 10.000 replicates [p=33] and decay index from 691 trees). Map illustrated by The PLATES Project, Institute for Geophysics, University of Texas at Austin.

Figure 4. Study area in northeastern Brazil.

Location of the collecting sites (represented by white dots) in the Parnaíba Basin, and sedimentological log of the Pedra de Fogo Formation, exposed in a quarry at Timon, type locality of the new dvinosaur temnospondyl Timonya anneae. Sst, sandstone.

Figure 5. Palaeoichthyofauna from the Cisuralian of northeastern Brazil.

(a) UFPI PV016, partial tooth-plate of a sarcopterygian fish (Dipnoi). (b) UFPI PV235, scales of a large sarcopterygian fish (Dipnoi). Both specimens found in Nazária, Piauí State. Scale bars represent 10 mm.

Figure 6. Reconstruction of the Cisuralian lacustrine/wetland community of the Teresina area in northeastern Brazil.

The small dvinosaur Timonya anneae is depicted in the foreground left, the trimerorhachid dvinosaur Procuhy nazariensis is on the right, and the rhinesuchid in the left background. Other species represented are: a dipnoan, primitive actinopterygians, Psaronius tree-ferns, Teresinoxylon trees and small columnar stromatolites.