Comparing surface digitization techniques in palaeontology using visual perceptual metrics and distance computations between 3D meshes

Díaz, Verónica Díez; Mallison, Heinrich; Asbach, Patrick; Schwarz, Daniela; Blanco, Alejandro

doi:10.1111/pala.12518

Cited by 25 publications

(22 citation statements)

References 39 publications

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“…Past analyses showed that surface scans, photogrammetry, and CT scans produced 3D reconstructions with similar quality (Falkingham, 2012; Fau et al, 2016), which is especially true for large specimens at the resolution reached here. Furthermore, Soodmand et al (2018) showed that there was no significant difference between 3D models of a femur digitized with both CT and surface scanner; and Dìez Dìaz et al (2021) showed that, despite the superior visual quality of photogrammetry, the difference in the geometry of 3D meshes generated from photogrammetry and an Artec EVA scanner was even lower than reported in Fau et al (2016) (e.g., <0.01 mm against 0.6 mm). Finally, Waltenberger et al (2021) showed that osteological 3D models obtained from surface scans, photogrammetry, and CT scans could be combined in a single analysis when using 3D GMM.…”

Section: Methodsmentioning

confidence: 99%

Femoral specializations to locomotor habits in early archosauriforms

et al. 2021

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The evolutionary history of archosaurs and their closest relatives is characterized by a wide diversity of locomotor modes, which has even been suggested as a pivotal aspect underlying the evolutionary success of dinosaurs vs. pseudosuchians across the Triassic–Jurassic transition. This locomotor diversity (e.g., more sprawling/erect; crouched/upright; quadrupedal/bipedal) led to several morphofunctional specializations of archosauriform limb bones that have been studied qualitatively as well as quantitatively through various linear morphometric studies. However, differences in locomotor habits have never been studied across the Triassic–Jurassic transition using 3D geometric morphometrics, which can relate how morphological features vary according to biological factors such as locomotor habit and body mass. Herein, we investigate morphological variation across a dataset of 72 femora from 36 different species of archosauriforms. First, we identify femoral head rotation, distal slope of the fourth trochanter, femoral curvature, and the angle between the lateral condyle and crista tibiofibularis as the main features varying between bipedal and quadrupedal taxa, all of these traits having a stronger locomotor signal than the lesser trochanter's proximal extent. We show a significant association between locomotor mode and phylogeny, but with the locomotor signal being stronger than the phylogenetic signal. This enables us to predict locomotor modes of some of the more ambiguous early archosauriforms without relying on the relationships between hindlimb and forelimb linear bone dimensions as in prior studies. Second, we highlight that the most important morphological variation is linked to the increase of body size, which impacts the width of the epiphyses and the roundness and proximodistal position of the fourth trochanter. Furthermore, we show that bipedal and quadrupedal archosauriforms have different allometric trajectories along the morphological variation in relation to body size. Finally, we demonstrate a covariation between locomotor mode and body size, with variations in femoral bowing (anteroposterior curvature) being more distinct among robust femora than gracile ones. We also identify a decoupling in fourth trochanter variation between locomotor mode (symmetrical to semi‐pendant) and body size (sharp to rounded). Our results indicate a similar level of morphological disparity linked to a clear convergence in femoral robusticity between the two clades of archosauriforms (Pseudosuchia and Avemetatarsalia), emphasizing the importance of accounting for body size when studying their evolutionary history, as well as when studying the functional morphology of appendicular features. Determining how early archosauriform skeletal features were impacted by locomotor habits and body size also enables us to discuss the potential homoplasy of some phylogenetic characters used previously in cladistic analyses as well as when bipedalism evolved in the avemetatarsalian lineage. This study illuminates how the evol...

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Section: Methodsmentioning

confidence: 99%

Femoral specializations to locomotor habits in early archosauriforms

et al. 2021

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“…Iterative polygonal modelling is not limited to cross-sectional information, this method can be used in conjunction with muscle surface scan data that can (1) streamline processes in which the user can also collect dissection data at the same time as muscular configurations, and (2) further minimise costs and time commitment for the user because expensive CT-scan data after lengthy staining processes do not need to be collected 1 . However, it is not required to use surface scan-technology that can be expensive and prohibitive itself 85 , 87 ; photogrammetry is an alternative possibility 84 , 86 , in which the user can further minimise total costs by even using a personal smartphone rather than an expensive camera or laser scanning 87 to capture a series of photographs and then subsequently use freeware to build 3D models of each muscle layer (e.g. 1 , 83 ).…”

Section: Methodsmentioning

confidence: 99%

Three-dimensional polygonal muscle modelling and line of action estimation in living and extinct taxa

Demuth

Wiseman

Beesel

et al. 2022

Sci Rep

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Biomechanical models and simulations of musculoskeletal function rely on accurate muscle parameters, such as muscle masses and lines of action, to estimate force production potential and moment arms. These parameters are often obtained through destructive techniques (i.e., dissection) in living taxa, frequently hindering the measurement of other relevant parameters from a single individual, thus making it necessary to combine multiple specimens and/or sources. Estimating these parameters in extinct taxa is even more challenging as soft tissues are rarely preserved in fossil taxa and the skeletal remains contain relatively little information about the size or exact path of a muscle. Here we describe a new protocol that facilitates the estimation of missing muscle parameters (i.e., muscle volume and path) for extant and extinct taxa. We created three-dimensional volumetric reconstructions for the hindlimb muscles of the extant Nile crocodile and extinct stem-archosaur Euparkeria, and the shoulder muscles of an extant gorilla to demonstrate the broad applicability of this methodology across living and extinct animal clades. Additionally, our method can be combined with surface geometry data digitally captured during dissection, thus facilitating downstream analyses. We evaluated the estimated muscle masses against physical measurements to test their accuracy in estimating missing parameters. Our estimated muscle masses generally compare favourably with segmented iodine-stained muscles and almost all fall within or close to the range of observed muscle masses, thus indicating that our estimates are reliable and the resulting lines of action calculated sufficiently accurately. This method has potential for diverse applications in evolutionary morphology and biomechanics.

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“…Digitization (alternatively referred to as "digitalization"; Moya-Costa et al, 2019) initiates 3D digital restoration by converting a fossil into digital form using either penetrative slice-based scanning methods (Cunningham et al, 2014;Sutton et al, 2014;Lautenschlager, 2016a;Lautenschlager, 2016b;Lautenschlager, 2017;Sutton et al, 2017) or light-based surface scanning methods (Díez Díaz et al, 2021). These processes yield digital 3D files of various formats, which are influenced by settings or parameters during scanning.…”

Section: Terminology and Stages Of Digital Restorationmentioning

confidence: 99%

Reproducible Digital Restoration of Fossils Using Blender

et al. 2022

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Digital restoration of fossils based on computed tomographic (CT) imaging and other scanning technologies has become routine in paleontology. Digital restoration includes the retrodeformation and reconstruction of a fossil specimen. The former involves modification of the original 3D model to reverse post-mortem brittle and plastic deformation; and the latter involves the infilling of fractures, addition of missing pieces, and smoothing of the mesh surface. The restoration process often involves digital editing of the specimen in ways that are difficult to document and reproduce. To record all actions taken during the digital restoration of a fossil, we outline a workflow that generates both the restored bone and the sequence of steps involved in its retrodeformation and reconstruction. Our method can also generate an animation showing the transformation of the original digital model into its final form. We applied this method to a dorsal rib and frontal bone of a small-bodied Jurassic-age armored dinosaur from Africa, the digital restoration of which engaged all modalities of deformation (translation, rotation, scaling, distortion) and reconstruction (fracture infilling, adding missing bone, surface smoothing). Each bone was CT-scanned, segmented, and imported into Blender, an open-source 3D-graphics animation program. Blender has an animation tool called an “armature” that allows for precise control over portions of a surface mesh while keeping a record of manipulations. To retrodeform a fossil, an armature is created and then linked, or “rigged,” to the fossil in order to control the displacement and distortion of its fragments. After using the armature to perform retrodeformation, we use Blender to record the movement and distortion of each fragment and also record reconstructive modifications. By ensuring documentation and reproducibility in an open-source program, our workflow and output open a window onto the heretofore largely hidden process of digital restoration in paleontology.

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Comparing surface digitization techniques in palaeontology using visual perceptual metrics and distance computations between 3D meshes

Cited by 25 publications

References 39 publications

Femoral specializations to locomotor habits in early archosauriforms

Femoral specializations to locomotor habits in early archosauriforms

Three-dimensional polygonal muscle modelling and line of action estimation in living and extinct taxa

Reproducible Digital Restoration of Fossils Using Blender

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