ENAMEL HISTOLOGY OF GIRAFFE LOWER MOLARS

CARMEN NACARINO-MENESES; J. MARCOS JANNELLO; ANUSUYA CHINSAMY

Pune

Simposio; 6th International Symposium on Palaeohistology; 2022

Dept of AIHC and Archaeology, Deccan College PGRI Pune

The microscopic structure of dental enamel registers periodic incremental lines. Counting and measuring the lines provide information about the rate and pattern of tooth growth, which in turn allow inferences about key life history traits in extant and extinct species. In low-crowned mammals, similar research has mainly focused on primates and domesticated species, while most wild taxa have remained relatively unexplored. Here, we intend to fill this gap by analyzing the enamel microstructure of first and third lower molars in the extant giraffe Giraffa camelopardalis. Following standard procedures, we prepared longitudinal slides from the anterior (i.e., protoconid, paraconid) and posterior (i.e., hypoconid, metaconid) cusps of two first lower molars and two third lower molars with different degree of wear. The thin sections were studied under polarized light to identify the different enamel incremental markings and to calculate several growth parameters (e.g., daily secretion rate, enamel formation front angle) for each cusp and tooth. All samples show multiple Hunter-Schreger bands that hamper the identification of incremental lines in the cuspal enamel. Thus, incremental markings were mostly recognized in the imbricational enamel, where they appear particularly marked on the buccal side of each cusp. As described in other Artiodactyla, enamel laminations were the most common incremental features in our sample. Additionally, we recognized sub-daily and supra-daily marks. Generally, values of enamel growth parameters were comparable to those reported for closely-related taxa. This preliminary research sets the stage for future histological investigations on the enamel of extinct giraffids.