3D geometric morphometrics analysis of mandibular fragments of Ouranopithecus macedoniensis from the late Miocene deposits of Central Macedonia, Greece

Abstract

Objectives: To explore mandibular shape differences between Ouranopithecus macedoniensis and a comparative sample of extant great apes using three-dimensional (3D) geometrics morphometrics. Other objectives are to assess mandibular shape variation and homogeneity within Ouranopithecus, explore the effects of size on mandibular shape, and explore the degree of mandibular sexual size dimorphism in Ouranopithecus. Materials and methods:The comparative sample comprises digitized mandibles from adult extant great apes. The 3D analysis includes three datasets: one with landmarks registered on the mandibular corpus and symphysis of mandibles preserving both sides, one on hemimandibles only, and one focused on the ramus and gonial area. Multivariate statistical analyses were conducted, such as ordination analyses (PCA), intra-specific Procrustes distances pairs, pairwise male-female centroid size differences, and correlation analyses. Results:The male and female specimens of Ouranopithecus have mandibular shapes that are quite similar, although differences exist. The Procrustes distances results suggest more shape variation in Ouranopithecus than in the extant great apes.

Anatomy of the mandibular corpus of extant cercopithecids : taxonomy and variation

“…The sources of variation in corpus shape, notably sexual dimorphism and ontogeny, were clarified in extant hominoids (Wood et al, 1991; Daegling, 1996; Brown, 1997; Taylor, 2006b; Singh, 2014; Pitirri and Begun, 2020). Such data are of paramount value to interpret the mandibular hominoid fossil record (White and Johanson, 1982; Chamberlain and Wood, 1985; Lockwood et al, 1996; White et al, 2000; Fabbri, 2006; Skinner et al, 2006; Lague et al, 2008; Haile-Selassie et al, 2015, 2022; Ioannidou et al, 2022). Despite a rich fossil record (Freedman, 1957; Delson, 1973; Leakey, 1982; Benefit and Pickford, 1986; De Bonis et al, 1990; Frost and Delson, 2002; Leakey et al, 2003; Hlusko, 2006, 2007; Jablonski and Leakey, 2008; Jablonski et al, 2008a, 2008b; Nakatsukasa et al, 2010; Pallas, 2019; Gommery et al, 2022) and the great taxonomic and functional diversity of its extant representatives (Groves and Kingdon, 2013; Rowe and Jacobs, 2016a), a thorough examination of the corpus shape of extant Old World Monkeys (Cercopithecidae) on a large taxonomic scale is lacking, preventing the extrapolation of any taxonomical and ecomorphological considerations in extant and fossil representatives of this group.…”