DOI: 10.5061/dryad.tmpg4f520
title: Data from: Cranial remains of Ramsayia magna from the Late Pleistocene of Australia and the evolution of gigantism in wombats (Vombatidae; Marsupialia)

description: Giant wombats (defined here as body mass ≥ 70 kg) are found in the genera
 Phascolonus, Ramsayia, and perhaps also Sedophascolomys. Of these,
 Ramsayia is the currently the most poorly known, having been described
 from fragmentary mandibular and cranial fragments. Here, we report the
 most complete cranial remains attributable to the genus, identified as the
 species R. magna. The remains provide new important insights into the
 anatomy of the species and the evolutionary adaptations to gigantism in
 Vombatidae. We record parietal sinuses in a vombatid for the first time,
 an adaptation to increased skull size relative to the braincase. The
 presence of a prominent premaxillary spine may indicate the species
 possessed a large, fleshy nose. Both of features are convergent on other
 large-bodied, non-vombatid extinct megaherbivores of Australia such as
 Diprotodon optatum. We use the cranial remains to examine the phylogenetic
 relationships of the giant wombats to other vombatids. Phylogenetic
 analysis using maximum parsimony and Bayesian inference indicates that
 Phascolomys, Ramsayia, and Sedophascolomys form a clade, suggesting a
 single origin of gigantism within Vombatidae. This origin may have been
 related to the exploitation of poor-quality foods by these taxa, and
 preceded the extreme specialisations observed in the incisor and cranial
 anatomy of the giant wombats. U-series and combined U-series and Electron
 Spin Resonance (ESR) dating methods were applied to one fossil tooth. All
 sources of uncertainty considered, age calculations systematically
 correlate the fossil remains to Marine Isotope Stage 5, and an age of
 approximately 80,000 years can be proposed for this specimen. With only a
 single well dated occurrence for this taxon, it is currently impossible to
 determine when and why R. magna became extinct.
description: Supplementary File:
 We critically assess the
 morphological characters used by Tedford (2002) in his phylogenetic
 analysis of Vombatidae, and his character scoring criteria. Character
 numbers follow Tedford (2002; see also Murray, 1998: table
 4).  Data Files: The fossil specimen
 (QMF60370) is from Johansen’s Cave, Mt Etna National Park, Queensland,
 Australia. The specimen is accessioned in the collections of the
 Queensland Museum, Brisbane, Queensland, Australia. The specimen is stored
 in a fibreglass cradle for added protection. The 3D
 models were made using standard turntable photogrammetry. Due to the
 fragile nature of the specimen, two separate models were made of the
 internal and external views, respectively. The specimen was left in the
 fibreglass cradle at the time of photogrammetry. Photos
 were taken with a Nikon D5200 digital SLR camera with F-stop value 22, ISO
 320, and focal length 40 mm. The internal view model was made using 288
 photos and the external view model with 327 photos. Photos were mostly
 taken every ca. 10 degree rotation of the turntable to produce rings of
 images around the specimen. The camera was then elevated by ca. 10 cm and
 a new ring of images taken. This process was repeated two or three times.
 Some additional close-up photos were variously taken of key features of
 the specimen such as teeth. The photos were then
 processed using Agisoft Metashape Professional (version 1.6.1 build 10009
 64 bit) to produce photogrammetry models. Photos were initially aligned at
 the ‘highest’ accuracy with a key point limit of 150,000 and tie point
 limit of 100,000. The dense point cloud was then constructed at ‘ultra
 high’ quality with ‘aggressive’ depth filtering. Subsequently, the mesh
 was made on the basis of depth maps at ‘ultra high’ quality,
 ‘extrapolated’ interpolation, and with a face count of 500,000. Finally,
 the texture (4096 x 4096 pixels) was constructed using a ‘diffuse map’
 with the source data coming from the original photos. Uninformative
 background artefacts (e.g., the benchtop) were removed digitally before
 the models were exported into OBJ format (with associated STL and texture
 files), and 3D PDF, respectively.