title: Evaluation of a new method of fossil retrodeformation by algorithmic symmetrization: crania of papionins (Primates, Cercopithecidae) as a test case.
abstract: Diagenetic distortion can be a major obstacle to collecting quantitative shape data on paleontological specimens, especially for three-dimensional geometric morphometric analysis. Here we utilize the recently-published algorithmic symmetrization method of fossil reconstruction and compare it to the more traditional reflection & averaging approach. In order to have an objective test of this method, five casts of a female cranium of Papio hamadryas kindae were manually deformed while the plaster hardened. These were subsequently "retrodeformed" using both algorithmic symmetrization and reflection & averaging and then compared to the original, undeformed specimen. We found that in all cases, algorithmic retrodeformation improved the shape of the deformed cranium and in four out of five cases, the algorithmically symmetrized crania were more similar in shape to the original crania than the reflected & averaged reconstructions. In three out of five cases, the difference between the algorithmically symmetrized crania and the original cranium could be contained within the magnitude of variation among individuals in a single subspecies of Papio. Instances of asymmetric distortion, such as breakage on one side, or bending in the axis of symmetry, were well handled, whereas symmetrical distortion remained uncorrected. This technique was further tested on a naturally deformed and fossilized cranium of Paradolichopithecus arvernensis. Results, based on a principal components analysis and Procrustes distances, showed that the algorithmically symmetrized Paradolichopithecus cranium was more similar to other, less-deformed crania from the same species than was the original. These results illustrate the efficacy of this method of retrodeformation by algorithmic symmetrization for the correction of asymmetrical distortion in fossils. Symmetrical distortion remains a problem for all currently developed methods of retrodeformation.
authors.affiliation: Department of Biomedical Sciences, Grand Valley State University, Allendale, Michigan, United States of America; New York Consortium of Evolutionary Primatology Morphometrics Group, New York Consortium of Evolutionary Primatology, New York, New York, United States of America.
authors.forename: Melissa
authors.initials: M
authors.lastname: Tallman
authors.affiliation: Department of Computer Science, University of California Davis, Davis, California, United States of America.
authors.forename: Nina
authors.initials: N
authors.lastname: Amenta
authors.affiliation: New York Consortium of Evolutionary Primatology Morphometrics Group, New York Consortium of Evolutionary Primatology, New York, New York, United States of America; Department of Anthropology, Lehman College of the City University of New York, Bronx, New York, United States of America; New York Consortium in Evolutionary Primatology, New York, New York, United States of America; PhD Program in Anthropology, City University of New York Graduate Center, New York, New York, United States of America; Department of Vertebrate Paleontology, American Museum of Natural History, New York, New York, United States of America.
authors.forename: Eric
authors.initials: E
authors.lastname: Delson
authors.affiliation: New York Consortium of Evolutionary Primatology Morphometrics Group, New York Consortium of Evolutionary Primatology, New York, New York, United States of America; Department of Anthropology, University of Oregon, Eugene, Oregon, United States of America.
authors.forename: Stephen R
authors.initials: SR
authors.lastname: Frost
authors.affiliation: Department of Computer Science, University of California Davis, Davis, California, United States of America; Stratovan Corporation, Sacramento, California, United States of America.
authors.forename: Deboshmita
authors.initials: D
authors.lastname: Ghosh
authors.affiliation: New York Consortium of Evolutionary Primatology Morphometrics Group, New York Consortium of Evolutionary Primatology, New York, New York, United States of America; New York Consortium in Evolutionary Primatology, New York, New York, United States of America; PhD Program in Anthropology, City University of New York Graduate Center, New York, New York, United States of America.
authors.forename: Zachary S
authors.initials: ZS
authors.lastname: Klukkert
authors.affiliation: Department of Biology, Grand Valley State University, Allendale, Michigan, United States of America.
authors.forename: Andrea
authors.initials: A
authors.lastname: Morrow
authors.affiliation: Department of Anthropology, American Museum of Natural History, New York, New York, United States of America.
authors.forename: Gary J
authors.initials: GJ
authors.lastname: Sawyer
mesh_terms: D000465:Algorithms; D000818:Animals; D002520:Cercopithecidae / Q000033:anatomy & histology*; D005260:Female; D005580:Fossils / Q000033:anatomy & histology*; D010163:Paleontology / Q000379:methods; D010215:Papio / Q000033:anatomy & histology; D025341:Principal Component Analysis; D012886:Skull / Q000033:anatomy & histology*