Retrodeformation of fossil specimens based on 3D bilateral semi-landmarks: Implementation in the R package “Morpho”

Abstract

Many fossil specimens exhibit deformations caused by taphonomic processes. Due to these deformations, even important specimens have to be excluded from morphometric analyses, impoverishing an already poor paleontological record. Techniques to retrodeform and virtually restore damaged (i.e. deformed) specimens are available, but these methods genenerally imply the use of a sparse set of bilateral landmarks, ignoring the fact that the distribution and amount of control points directly affects the result of the retrodeformation. We propose a method developed in the R environment and available in the R-package “Morpho” that, in addition to the landmark configurations, also allows using a set of semi-landmarks homogeneously distributed along curves and on surfaces. We evaluated the outcome of the retrodeformation, regarding the number of semi-landmarks used and its robustness against asymmetric noise, based on simulations using a virtually deformed gorilla cranium. Finally, we applied the method to a well-known Neanderthal cranium that exhibits signs of taphonomically induced asymmetry.

Dynamic Musculoskeletal Functional Morphology: Integrating diceCT and XROMM

“…This finding prompted the development of an alternative method of generating a transformation matrix. Because the middle hyoid marker was either within (Monkey J) or immediately adjacent (Monkey K) to the hyoid bone, new rigid body transformation matrices were generated using the rotonto function of the Morpho package in R (v2.5.1, Schlager, ) that generated zero error for the middle hyoid marker and minimized error for the other two markers. The alternative reconstruction resolved the abnormal rotation about the anteroposterior axis.…”

A New Tool for Digital Alignment in Virtual Anthropology

“…Fossil remains often appear badly deformed by biostratinomic and taphonomic processes (Hughes and Jell, ; Arbour and Currie, ; Schlager et al, ) which usually result in major cracks, missing portions, or alteration of the biological symmetry (Ogihara et al, ; Arbour and Brown, ; Di Vincenzo et al, ). This lack of information can now be recovered by applying virtual reconstruction procedures, which take advantage of software implementations to perform the restoration of the digital versions of fossil remains.…”

“…DTA performs at least as well as manual alignments. Yet, as compared to manual procedures, it is faster, requires no prior anatomical knowledge and expertise and allows indefinite manipulation of the fossil items.Fossil remains often appear badly deformed by biostratinomic and taphonomic processes (Hughes and Jell, 1992;Arbour and Currie, 2012;Schlager et al, 2018) which usually result in major cracks, missing portions, or alteration of the biological symmetry (Ogihara et al, 2006;Arbour and Brown, 2013;Di Vincenzo et al, 2017). This lack of information can Additional Supporting Information may be found in the online version of this article.Abbreviations: AM = aligned model; DM = disarticulate model; DTA = Digital Alignment Tool; GPA = generalized Procrustes analysis; RM = reference model; SM = starting model…”

“…Fossil remains often appear badly deformed by biostratinomic and taphonomic processes (Hughes and Jell, 1992;Arbour and Currie, 2012;Schlager et al, 2018) which usually result in major cracks, missing portions, or alteration of the biological symmetry (Ogihara et al, 2006;Arbour and Brown, 2013;Di Vincenzo et al, 2017). This lack of information can Additional Supporting Information may be found in the online version of this article.…”

“…Several case-studies are reported in the literature (Zollikofer et al, 2005;Benazzi et al, 2014;Amano et al, 2015;Di Vincenzo et al, 2017), and the use of virtual reconstructions is now becoming commonplace. Unfortunately, the efficiency of the virtual reconstruction is rarely quantified (e.g., Ogihara et al, 2006;Tallman et al, 2014;Schlager et al, 2018).…”