Data collection (3D acquisition)
We virtually reconstructed 101 crania of adult individuals ofDasyurus hallucatus – including males and females from four mainland populations (Pilbara, Kimberley, Northern Territory and Queensland) and other island populations (Groote Eylandt and other small islands). Adult status was determined through incisor wear (Oakwood, 2000) and P3 eruption (Woolley et al., 2013). We 3D-scanned most of the specimens from museum collections (Queensland Museum, Australian Museum, Western Australian Museum, Australian National Wildlife Collection and American Museum of Natural History) with a GoMeasure 3D HDI109 blue light surface scanner (LMI Technologies Inc., Vancouver, Canada). Each cranium was placed in 3 different orientations on a motored rotary table that turned every 45 degrees (8 rotations per round). The 24 resulting 3D images (8 rotations x 3 orientations) were then meshed together with the scanner’s software (FlexScan3D 3.3) to export a complete 3D image of each skull. This file was then treated in for hole filling (so as to not affect the biological shape of the structure), mesh decimation (to facilitate computation) and mesh reformatting (as “.ply” files need to be in binary format for subsequent importations of the mesh in R). Several photos of each specimen were also taken to help identify landmarks by discriminating biological structures from 3D artefacts in the landmarking process. Seven fully fleshed specimens from the Groote Eylandt population were CT-scanned at the Centre for Advanced Imaging at The University of Queensland in a micro CT-scanner. In order to obtain the 3D model, segmentation of the DICOM grayscale images provided by the micro CT-scan was performed with Mimics Research version 20.0. All 3D models can be accessed through MorphoSource. The University of Queensland animal ethics committee (permit number SBS/009/16/ARC) and the Northern Territory Parks and Wildlife Commission (permit number 58566) approved the research methods and the collection of the Groote Eylandt specimens.