Dental development and age at death of the holotype of Anapithecus hernyaki (RUD 9) using synchrotron virtual histology

Abstract

The chronology of dental development and life history of primitive catarrhines provides a crucial comparative framework for understanding the evolution of hominoids and Old World monkeys. Among the extinct groups of catarrhines are the pliopithecoids, with no known descendants. Anapithecus hernyaki is a medium-size stem catarrhine known from Austria, Hungary and Germany around 10 Ma, and represents a terminal lineage of a clade predating the divergence of hominoids and cercopithecoids, probably more than 30 Ma. In a previous study, Anapithecus was characterized as having fast dental development. Here, we used non-destructive propagation phase contrast synchrotron micro-tomography to image several dental microstructural features in the mixed mandibular dentition of RUD 9, the holotype of A. hernyaki. We estimate its age at death to be 1.9 years and describe the pattern, sequence and timing of tooth mineralization. Our results do not support any simplistic correlation between body mass and striae periodicity, since RUD 9 has a 3-day periodicity, which was previously thought unlikely based on body mass estimates in Anapithecus. We demonstrate that the teeth in RUD 9 grew even faster and initiated even earlier in development than suggested previously. Permanent first molars and the canine initiated 49 and 38 days prenatally, respectively. These results contribute to a better understanding of dental development in Anapithecus and may provide a window into the dental development of the last common ancestor of hominoids and cercopithecoids.

An infant burial from Arma Veirana in northwestern Italy provides insights into funerary practices and female personhood in early Mesolithic Europe

“…Histomorphometry of dental enamel allows the collection of parameters such as the Daily Secretion Rate (DSR, i.e. the speed at which the ameloblast—the enamel forming cells—moves towards the outer surface of the tooth) and, for still growing crowns, the age-at-death as the time spent from the NL to the end of enamel formation 16 , 51 , 52 .…”

Accessory cusp expression at the enamel-dentine junction of hominin mandibular molars

“…Fossil hominin tooth samples are often very small, meaning that it is rarely practical to include only unworn or lightly worn teeth. Using X-ray, synchrotron and neutron microtomography, however, it is possible to image, in three dimensions, the internal dental structures of many fossil specimens ( Davies et al, 2020 ; Le Cabec, Dean & Begun, 2017 ; Martinón-Torres et al, 2019 ; Skinner et al, 2016 ; Skinner et al, 2008 ; Xing, Martinón-Torres & De Castro, 2018 ; Zanolli et al, 2020 ). Accessory cusps are ‘primary-definitive’ traits (sensu Nager, 1960 ), a term that refers to dental features that are present at the unworn OES, but derive from the enamel-dentine junction (EDJ).…”

Those who died very young—Inferences from δ15N and δ13C in bone collagen and the absence of a neonatal line in enamel related to the possible onset of breastfeeding

“…This incremental marking can be analyzed retrospectively in tooth sections by light and scanning electron microscopy (SEM; Birch & Dean, 2014;Hillson, 2014;Hurnanen, Visnapuu, Sillanpaa, Loyttyniemi, & Rautava, 2017;Kurek et al, 2016;Sabel et al, 2008;Sebald, Stenzel, Gruenewald, & Grupe, 2018;Witzel, 2014b). Nondestructive techniques will potentially replace destructive approaches based on sectioned teeth in the future (Le Cabec, Dean, & Begun, 2017;Nava et al, 2017;Tafforeau & Smith, 2008). The NNL marks the division between the enamel secreted prenatally and postnatally.…”