Obtaining new resolutions in carnivore tooth pit morphological analyses: A methodological update for digital taphonomy

Modern day investigation in fields of archaeology and palaeontology can be greatly characterised by an exponential growth of integrated new technologies, nevertheless, while these advances are of great significance to multiple lines of research, their evaluation and update over time is equally as important. Here we present an application of inter and intra-observer analysis in taphonomy based geometric morphometrics, employing robust non-parametric statistical analyses for the study of experimental carnivore tooth pit morphologies. To fully understand the influence of measurement errors in the collection of this data, our statistical assessment was performed on fully superimposed, partially superimposed and raw landmark coordinates collected from 3D surface scanning. Experimental samples used to assess these errors includes wolf and dog tooth pits used in modern day ecological livestock predation analysis. Results obtained from this study highlight the importance of landmark type in the assessment of error, emphasising the value of semi-landmark models over the use of ambiguous Type III landmarks. In addition to this, data also reveals the importance of observer experience for the collection of data alongside an interesting increase in error when working with fully superimposed landmarks due to the “Pinocchio Effect”. Through this study we are able to redefine the geometric morphometric models used for tooth pit morphological analyses. This final hybrid Type II fixed landmark and semi-landmark model presents a significant reduction in human induced error, generating a more metrically reliable and replicable method that can be used for data pooling in future inter-institutional research. These results can be considered a fundamental step forward for carnivore inspired studies, having an impact on archaeological, palaeontological, modern-day ecological research as well as applications in other forensic sciences.
L.A.C. is supported by the Spanish Ministry of Science, Innovation and Universities with a FPI Predoctoral Grant (Ref. PRE2019-089411) associated to project RTI2018-099850-B-I00 and the University of Salamanca. R.H. is supported by MICINNFEDER PGC2018-093925-B-C32, the AGUAR project number SGR 2017-1040; the Universitat Rovira I Virgili (2014, 2015 and 2016 PFR-URV-B2-147) and CERCA Programme/Generalitat de Catalunya. D.H.R. is supported by the Ministry of Science, Innovation and Universities, under the contract REF: PEJ2019-005420-A as part of the i+D+I Garantía Juvenil. Finally L.A.C., M.Á.M.G and D.G.A. are supported by the General Foundation of the University of Salamanca under the Plan TCUE 2018-2020; Project “WOLF_FOOTPRINT” (PC-TCUE18-20_2013).