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Data from: Australia's prehistoric 'swamp king': revision of the Plio-Pleistocene crocodylian genus Pallimnarchus de Vis, 1886

Citation

Ristevski, Jorgo et al. (2020), Data from: Australia's prehistoric 'swamp king': revision of the Plio-Pleistocene crocodylian genus Pallimnarchus de Vis, 1886, Dryad, Dataset, https://doi.org/10.5061/dryad.8kprr4xkq

Abstract

The crocodylian fossil record from the Cenozoic of Australasia is notable for its rich taxonomic diversity, and is primarily represented by members of the clade Mekosuchinae. Reports of crocodylian fossils from Australia date back to the late nineteenth century. In 1886, Charles Walter de Vis proposed the name Pallimnarchus pollens for crocodylian fossils from southeast Queensland – the first binomen given to an extinct crocodylian taxon from Australia. Pallimnarchus has come to be regarded as a large, broad-snouted crocodylian from Australia’s Plio-Pleistocene, and numerous specimens, few of which are sufficiently complete, have been assigned to it by several authors throughout the twentieth century. In the late 1990s, the genus was expanded to include a second species, Pallimnarchus gracilis. Unfortunately, the original syntype series described as Pallimnarchus pollens is very fragmentary and derives from more than one taxon, while a large part of the subsequently selected lectotype specimen is missing. Because descriptions and illustrations of the complete lectotype do not reveal any autapomorphic features, we propose that Pallimnarchus pollens should be regarded as a nomen dubium. Following this decision, the fossil material previously referred to Pallimnarchus is of uncertain taxonomic placement. A partial skull, formerly assigned to Pallimnarchus pollens and known as ‘Geoff Vincent’s specimen’, possesses many features of diagnostic value and is therefore used as basis to erect a new genus and species – Paludirex vincenti gen. et sp. nov. A comprehensive description is given for the osteology of ‘Geoff Vincent’s specimen’ as well as aspects of its palaeoneurology, the latter being a first for an extinct Australian crocodyliform. The newly named genus is characterized by a unique combination of premaxillary features such as a distinctive arching of the anterior alveolar processes of the premaxillae, a peculiar arrangement of the first two premaxillary alveoli and a large size disparity between the 3rd and 4th premaxillary alveoli. These features presently allow formal recognition of two species within the genus, Paludirex vincenti and Paludirex gracilis comb. nov., with the former having comparatively more robust rostral proportions than the latter. The Paludirex vincenti holotype comes from the Pliocene Chinchilla Sand of the Darling Downs, south-eastern Queensland, whereas the material assigned to Paludirex gracilis is from the Pleistocene of Terrace Site Local Fauna, Riversleigh, northwest Queensland. Phylogenetic analyses recover Paludirex vincenti as a mekosuchine, although further cladistic assessments are needed to better understand the relationships within the clade.

Usage Notes

This dataset serves as supplementary material to the study titled "Australia's prehistoric 'swamp king': revision of the Plio-Pleistocene crocodylian genus Pallimnarchus de Vis, 1886" by Ristevski et al. The dataset is comprised of two main documents (Supplemental Document S1 and Supplemental Document S2, both in PDF formats) as well as an interactive 3D PDF file, and three other files that are related to the phylogenetic analyses conducted in the aforementioned study by Ristevski et al.

Supplemental Document S1 contains information on the phylogenetic dataset that was used by Ristevski et al. The Supplemental Document S2 includes measurement and parameter tables for data relevant to the main study by Ristevski et al. Additionally, high-quality versions of the figures shown in Supplemental Document S1 and Supplemental Document S2 can be found as individual PDF files – these figures are 18 PDF files.

The interactive 3D PDF file (titled "Geoff Vincent's specimen, interactive 3D") contains the digital model of the Paludirex vincenti holotype specimen, which is described in the main study by Ristevski et al. This file can be opened in Adobe Acrobat DC and visualized with the aid of the tools from the 3D toolbar (Rotate, Spin, Pan, Zoom, Walk, Fly). Measurements can also be taken on the 3D models by using the 3D Measurement Tool. Each individual piece of the skull and digitally segmented endocranial element can be viewed in isolation or along with all other (or only some) elements, and even made transparent by using the options in the Model Tree of the PDF document. The background color in the document and the lighting for the 3D models can also be changed, depending on the preference of the viewer.

Lastly, there are three files that are related to the cladistic analyses performed by Ristevski et al. The TXT file (titled "J. Ristevski matrix v1") contains the raw matrix and can be opened in programs for running phylogenetic analyses (e.g. Mesquite, TNT). The other two files, which are in TNT formats (titled "EW results" and "IW (k = 25) results", respectively), contain the results from the performed phylogenetic analyses and can be opened in TNT. In the main study by Ristevski et al. are given the search settings and parameters that were set in order to run the phylogenetic analyses.