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. 2020 Apr 8;15(4):e0230890.
doi: 10.1371/journal.pone.0230890. eCollection 2020.

A new archosauromorph from South America provides insights on the early diversification of tanystropheids

Tiane M De-Oliveira  1   2 , Felipe L Pinheiro  2 , Átila Augusto Stock Da-Rosa  1   3 , Sérgio Dias-Da-Silva  1   3 , Leonardo Kerber  1   4   5
Affiliations

A new archosauromorph from South America provides insights on the early diversification of tanystropheids

Tiane M De-Oliveira et al. PLoS One. .

Erratum in

Abstract

After the Permo-Triassic mass extinction, the archosauromorph fossil record is comparatively abundant and ecologically diverse. Among early archosauromorphs, tanystropheids gained considerable attention due to the presence of extreme skeletal adaptations in response to sometimes overspecialized lifestyles. The origin and early radiation of Tanystropheidae, however, remains elusive. Here, a new Early Triassic archosauromorph is described and phylogenetically recovered as the sister-taxon of Tanystropheidae. The new specimen, considered a new genus and species, comprises a complete posterior limb articulated with pelvic elements. It was recovered from the Sanga do Cabral Formation (Sanga do Cabral Supersequence, Lower Triassic of the Paraná Basin, Southern Brazil), which has already yielded a typical Early Triassic vertebrate assemblage of temnospondyls, procolophonoids, and scarce archosauromorph remains. This new taxon provides insights on the early diversification of tanystropheids and represents further evidence for a premature wide geographical distribution of this clade. The morphology of the new specimen is consistent with a terrestrial lifestyle, suggesting that this condition was plesiomorphic for Tanystropheidae.

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Conflict of interest statement

The authors have declared that no competing interests exist.

Figures

Fig 1
Fig 1. Type locality of Elessaurus gondwanoccidens (UFSM 11471).
A. Geographic map evidencing the type-locality of Elessaurus gondwanoccidens, (São Francisco de Assis, Brazil); B. Simplified stratigraphic profile of the outcrop, showing the level where UFSM 11471 was found. Map was modified from Zerfass et al. [27] and stratigraphic profile modified from Da-Rosa et al. [22] and Pinheiro et al. [23]; silhouette adapted from Rieppel [15], showing bones preserved of UFSM 11471 in dark gray color. Reprinted from Da-Rosa et al. [22] under a CC BY license, with permission from Átila Stock Da-Rosa, original copyright 2009.
Fig 2
Fig 2. Elessaurus gondwanoccidens (UFSM 11471) from the Sanga do Cabral Formation (Lower Triassic), Brazil.
Photograph and explanatory drawing respectively. Abbreviations: fe, femur; ti, tibia; gr, groove; fi, fibula; il, ilium; sv, sacral vertebra; cv, caudal vertebrae.
Fig 3
Fig 3. Sacral and caudal vertebrae of Elessaurus gondwanoccidens (UFSM 11471) in dorsal view.
Photograph and explanatory drawing respectively. Abbreviations: sv2, second sacral vertebra; cv, caudal vertebrae 1–3.
Fig 4
Fig 4
Plantar (A) and posteroplantar (B) views of the pes of Elessaurus gondwanoccidens (UFSM 11471) from the Sanga do Cabral Formation (Lower Triassic), Brazil. Photographs and explanatory drawings respectively. Abbreviations (A): ca, calcaneum; dt 4, distal tarsal 4; mt. metatarsal 1–5; d3—d4, digits; ph, phalange. (B) ti, tibia; fi, fíbula; ca, calcaneum; as. astragalus; tu, calcaneal tuber; mt, metatarsal 5; dt 1, distal tarsal 1; ce, centrale; dt 3, distal tarsal 3; dt 4, distal tarsal 4.
Fig 5
Fig 5
A- Archosauromorph phylogeny showing the recovered position of Elessaurus gondwanoccidens (UFSM 11471), from the matrix of Pritchard et al. [6] and the geographic distribution maps for Tanystropheidae through time (green circles) and the Brazilian fossil record (red star) (data from the Paleobiology Database, https://paleobiodb.org/#/) (B, Early Triassic; C, Middle Triassic; D, Late Triassic).
Fig 6
Fig 6. Life restoration of Elessaurus gondwanoccidens, from the Sanga do Cabral Formation (Lower Triassic), Brazil.
Artwork by Márcio L. Castro.
See this image and copyright information in PMC

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