Interactive 3D graph for joint C2-3/C3-4/C4-5/C5-6/C6-7/C7-8 with 3D pose space (points) and alpha shape (translucent shape) for all specimens with that joint in their cervical series. Joint number at the top, specimen list on the right, and preset options for the 3D view of the coordinate system on the top left. Clicking on the preset options “XY”, “YZ”, “XZ”, and “XYZ” positions the graph to visualize the three 2D planes – xy-,yz-, and xz-plane, respectively – as well as an overview of all three axes together (“XYZ”). Scrolling zooms in and out. Left-clicking on the graph and moving the mouse over the window changes the angle of the view. Double clicking on one specimen isolates the path, clicking once removes/adds the path to the graph. Hovering over the points shows the exact coordinates and the associated specimen.

Interactive 3D graph for joint C2-3/C3-4/C4-5/C5-6/C6-7/C7-8 with 3D pose space (points) and alpha shape (translucent shape) for all specimens with that joint in their cervical series. Joint number at the top, specimen list on the right, and preset options for the 3D view of the coordinate system on the top left. Clicking on the preset options “XY”, “YZ”, “XZ”, and “XYZ” positions the graph to visualize the three 2D planes – xy-,yz-, and xz-plane, respectively – as well as an overview of all three axes together (“XYZ”). Scrolling zooms in and out. Left-clicking on the graph and moving the mouse over the window changes the angle of the view. Double clicking on one specimen isolates the path, clicking once removes/adds the path to the graph. Hovering over the points shows the exact coordinates and the associated specimen.

Video showing the workflow to assess the ROM of one vertebral joint in Maya with the MEL scripts mentioned in the main text and freely available for download at „https://bitbucket.org/xromm/xromm_other_mel_scripts/src/main/joint_mobility/)“.

Video showing the workflow to assess the ROM of one vertebral joint in Maya with the MEL scripts mentioned in the main text and freely available for download at „https://bitbucket.org/xromm/xromm_other_mel_scripts/src/main/joint_mobility/)“.

Extinct sloths (Xenarthra, Folivora) are morphologically diverse, despite some similarities among some Pleistocene genera. Cranial and diagnostic postcranial elements (especially limb bones) are taxonomically informative but the axial postcranial skeleton can prove difficult to classify, as in cases with only vertebral remains or when closely related taxa are found together. Here, 24 linear and angular measurements of presacral axial skeletons from eight genera of Pleistocene ground sloths were analysed through multivariate methods for assigning their vertebrae to a genus and to a position along the vertebral column. Both isolated vertebrae and vertebrae associated with partial and complete skeletons of each genus were included. Principal components and linear discriminant analyses show a high percentage (over 90%) of correct taxonomic reclassification. For the position of vertebrae, the accuracy increased significantly when cervical, thoracic and lumbar regions were separately considered instead of the whole column, misclassifying the position of the vertebrae only by a few positions in most cases. Our database is useful for confidently assigning isolated vertebrae of extinct sloths to a specific genus and position, showing that beyond the apparent homogeneity in the axial postcranial skeleton of ground sloths, quantitative studies allow the evaluation of diversity and variation between groups.

Extinct sloths (Xenarthra, Folivora) are morphologically diverse, despite some similarities among some Pleistocene genera. Cranial and diagnostic postcranial elements (especially limb bones) are taxonomically informative but the axial postcranial skeleton can prove difficult to classify, as in cases with only vertebral remains or when closely related taxa are found together. Here, 24 linear and angular measurements of presacral axial skeletons from eight genera of Pleistocene ground sloths were analysed through multivariate methods for assigning their vertebrae to a genus and to a position along the vertebral column. Both isolated vertebrae and vertebrae associated with partial and complete skeletons of each genus were included. Principal components and linear discriminant analyses show a high percentage (over 90%) of correct taxonomic reclassification. For the position of vertebrae, the accuracy increased significantly when cervical, thoracic and lumbar regions were separately considered instead of the whole column, misclassifying the position of the vertebrae only by a few positions in most cases. Our database is useful for confidently assigning isolated vertebrae of extinct sloths to a specific genus and position, showing that beyond the apparent homogeneity in the axial postcranial skeleton of ground sloths, quantitative studies allow the evaluation of diversity and variation between groups.