A New Small-sized Predatory Pseudosuchian Archosaur from the Middle-Late Triassic of Southern Brazil

Overview

Journal Sci Rep

Specialty Science

Date 2024 Jun 20

PMID 38902259

Authors

Rodrigo T Muller

Affiliations

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Abstract

Before the rise of dinosaurs and pterosaurs, pseudosuchians-reptiles from the crocodilian lineage-dominated the Triassic land ecosystems. This lineage diversified into several less inclusive clades, resulting in a wide ecomorphological diversity during the Middle and Late Triassic. Some giant pseudosuchians occupied the top of the trophic webs, while others developed extensive bony armor as a defense mechanism, which later evolved as a convergence in the avemetatarsalian lineage. On the other hand, there were groups like the Gracilisuchidae, which was composed of carnivorous forms with lightweight build and less than 1 m in length. The fossil record of gracilisuchids is geographically restricted to China and Argentina, with one ambiguous record from Brazil. In the present study, the first unambiguous gracilisuchid from Brazil is described. Parvosuchus aurelioi gen. et sp. nov. comes from the Dinodontosaurus Assemblage Zone of the Santa Maria Formation, which is associated with the Ladinian-Carnian boundary. Composed of a complete cranium, vertebrae, pelvic girdle and hindlimbs, the new species nests with Gracilisuchus stipanicicorum and Maehary bonapartei in a phylogenetic analysis. Its discovery fills a taxonomic gap in Brazilian pseudosuchian fauna and reveals the smallest known member of this clade from the Dinodontosaurus Assemblage Zone, highlighting the diversity of pseudosuchians during the moment that preceded the dawn of dinosaurs.

References

Nesbitt S, Butler R, Ezcurra M, Barrett P, Stocker M, Angielczyk K . The earliest bird-line archosaurs and the assembly of the dinosaur body plan. Nature. 2017; 544(7651):484-487. DOI: 10.1038/nature22037. View

Kellner A, Holgado B, Grillo O, Pretto F, Kerber L, Pinheiro F . Reassessment of , a purported Triassic pterosaur from southern Brazil with the description of a new taxon. PeerJ. 2022; 10:e13276. PMC: 9074864. DOI: 10.7717/peerj.13276. View

Franca M, Ferigolo J, Langer M . Associated skeletons of a new middle Triassic "Rauisuchia" from Brazil. Naturwissenschaften. 2011; 98(5):389-95. DOI: 10.1007/s00114-011-0782-3. View

Foth C, Ezcurra M, Sookias R, Brusatte S, Butler R . Unappreciated diversification of stem archosaurs during the Middle Triassic predated the dominance of dinosaurs. BMC Evol Biol. 2016; 16:188. PMC: 5024528. DOI: 10.1186/s12862-016-0761-6. View

Marsicano C, Irmis R, Mancuso A, Mundil R, Chemale F . The precise temporal calibration of dinosaur origins. Proc Natl Acad Sci U S A. 2015; 113(3):509-13. PMC: 4725541. DOI: 10.1073/pnas.1512541112. View

Muller R, Garcia M . A paraphyletic 'Silesauridae' as an alternative hypothesis for the initial radiation of ornithischian dinosaurs. Biol Lett. 2020; 16(8):20200417. PMC: 7480155. DOI: 10.1098/rsbl.2020.0417. View

Spiekman S, Ezcurra M, Butler R, Fraser N, Maidment S . , a new small-sized coelophysoid theropod from the Late Triassic of Wales. R Soc Open Sci. 2021; 8(10):210915. PMC: 8493203. DOI: 10.1098/rsos.210915. View

de Farias B, Desojo J, Cerda I, Ribeiro A, Ferigolo J, Carlisbino T . Bone histology supports gregarious behavior and an early ontogenetic stage to Decuriasuchus quartacolonia (Pseudosuchia: Loricata) from the Middle-Late Triassic of Brazil. Anat Rec (Hoboken). 2023; 307(4):957-973. DOI: 10.1002/ar.25365. View

Martinelli A, Kammerer C, Melo T, Paes Neto V, Ribeiro A, Da-Rosa A . The African cynodont Aleodon (Cynodontia, Probainognathia) in the Triassic of southern Brazil and its biostratigraphic significance. PLoS One. 2017; 12(6):e0177948. PMC: 5470689. DOI: 10.1371/journal.pone.0177948. View

10.

Paes-Neto V, Lacerda M, Ezcurra M, Raugust T, Trotteyn M, Soares M . New rhadinosuchine proterochampsids from the late Middle-early Late Triassic of southern Brazil enhance the diversity of archosauriforms. Anat Rec (Hoboken). 2023; 307(4):851-889. DOI: 10.1002/ar.25294. View

11.

Butler R, Sullivan C, Ezcurra M, Liu J, Lecuona A, Sookias R . New clade of enigmatic early archosaurs yields insights into early pseudosuchian phylogeny and the biogeography of the archosaur radiation. BMC Evol Biol. 2014; 14:128. PMC: 4061117. DOI: 10.1186/1471-2148-14-128. View

12.

Cisneros J, Damiani R, Schultz C, da Rosa A, Schwanke C, Neto L . A procolophonoid reptile with temporal fenestration from the Middle Triassic of Brazil. Proc Biol Sci. 2004; 271(1547):1541-6. PMC: 1691751. DOI: 10.1098/rspb.2004.2748. View

13.

Muller R, Ezcurra M, Garcia M, Agnolin F, Stocker M, Novas F . New reptile shows dinosaurs and pterosaurs evolved among diverse precursors. Nature. 2023; 620(7974):589-594. DOI: 10.1038/s41586-023-06359-z. View

14.

Ezcurra M, Fiorelli L, Martinelli A, Rocher S, von Baczko M, Ezpeleta M . Deep faunistic turnovers preceded the rise of dinosaurs in southwestern Pangaea. Nat Ecol Evol. 2017; 1(10):1477-1483. DOI: 10.1038/s41559-017-0305-5. View

15.

Desojo J, Rauhut O . Reassessment of the enigmatic "Prestosuchus" loricatus (Archosauria: Pseudosuchia) from the Middle-Late Triassic of southern Brazil. Anat Rec (Hoboken). 2024; 307(4):974-1000. DOI: 10.1002/ar.25401. View

16.

Goloboff P, Catalano S . TNT version 1.5, including a full implementation of phylogenetic morphometrics. Cladistics. 2021; 32(3):221-238. DOI: 10.1111/cla.12160. View

17.

Ezcurra M, Nesbitt S, Bronzati M, Dalla Vecchia F, Agnolin F, Benson R . Enigmatic dinosaur precursors bridge the gap to the origin of Pterosauria. Nature. 2020; 588(7838):445-449. DOI: 10.1038/s41586-020-3011-4. View