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Data from: An early-diverging procolophonid from the lowermost Triassic of South America and the origins of herbivory in Procolophonoidea

Citation

Pinheiro, Felipe; Silva-Neves, Eduardo; Da-Rosa, Átila (2021), Data from: An early-diverging procolophonid from the lowermost Triassic of South America and the origins of herbivory in Procolophonoidea, Dryad, Dataset, https://doi.org/10.5061/dryad.2z34tmpk8

Abstract

The Procolophonoidea was the only parareptile clade to survive the end-Permian mass extinction, experiencing an important adaptive radiation during the Triassic. The flourishing of procolophonoid lineages in highly stressful post-extinction environments may be, at least in part, a result of their early adaptations to herbivory, which would eventually become the commonest feeding strategy in later representatives of the group. Although procolophonoids are comparatively diverse in the South African Lystrosaurus Assemblage Zone, only the globally widespread taxon Procolophon trigoniceps was thus far reported in South American deposits of similar age. Here we present a new procolophonid genus and species for the Lower Triassic Sanga do Cabral Formation of Brazil. Oryporan insolitus gen. et sp. nov. combines typical adaptations for herbivory with primitive character states that are peculiar to early procolophonoids. Accordingly, our phylogenetic results place the new species as an early-diverging procolophonid, thus far the phylogenetically earliest to develop adaptations for herbivory. Character optimization shows that the bulbous labiolingually expanded molariforms of most procolophonids – interpreted as indicative of high-fibre herbivory – were co-opted from an insectivorous dentition. The new taxon also highlights the diversity of feeding habits displayed by Early Triassic procolophonoids, which was probably crucial for the survivorship of the clade in post-extinction disaster communities.

Methods

X-ray microtomography analysis and 3D-modelling

In order to access relevant characters that were not exposed by mechanical preparation, like the palatal dentition and the marginal dentition in occlusal view, we conducted high-resolution X-ray computed tomography of UFSM 11443 using a SkyScan 1173 tomograph scanner at the Laboratório de Sedimentologia e Petrologia, Pontifícia Universidade Católica do Rio Grande do Sul (PUCRS). The scan was set with 130 kV of X-ray energy, 130 μA of current and 1100 ms of exposure time. The procedure resulted in 1910 tomographic slices containing skull data of the specimen. Virtual preparation and segmentation of skull elements were performed using AVIZO.

Phylogenetic analyses

The phylogenetic relationships of UFSM 11443 were tested through a heuristic analysis using a modified version of the dataset of Cisneros (2008a). Besides the addition of UFSM 11443 as an independent operational taxonomic unit (OTU), the dataset also includes Kitchingnathus untabeni, Phonodus dutoitorum (see Cisneros 2008b; Modesto et al. 2010; MacDougall & Modesto 2011), Lasasaurus beltanae (Falconnet et al. 2012) and Mandaphon nadra (Tsuji 2017). We have also included updated character scores for some of the OTUs, based on MacDougall & Modesto (2011) and MacDougall et al. (2013), as well as an additional character (character 10 from Modesto et al. 2001, following MacDougall & Modesto 2011). The resulting dataset is composed of 28 OTUs and 59 characters. Some characters were treated as additive, according to their original proposal by Cisneros (2008a).  Heuristic searches were conducted using TNT (Tree analysis using New Technology) v.1.5 (Goloboff & Catalano 2016), using the tree bisection reconnection (TBR) algorithm of TNT (100 replications, 100 trees saved per replication, random seed).  

 

Funding

Conselho Nacional de Desenvolvimento Científico e Tecnológico, Award: 407969/2016-0

Fundação de Amparo à Pesquisa do Estado do Rio Grande do Sul, Award: 16/2551-0000271-1

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior, Award: 001

Conselho Nacional de Desenvolvimento Científico e Tecnológico, Award: 305758/2017-9

Conselho Nacional de Desenvolvimento Científico e Tecnológico, Award: 313494/2018-5