Paleohistology and life history of Procervulus and Eotragus (Ruminantia, Artiodactyla) from the Middle Miocene site of els Casots (NE Iberian Peninsula)

The Miocene Climatic Optimum (MCO) event (ca. 16.9–14.7 Ma) was a period of increased warmth spanning more than 2 Myr that offers valuable insights into climate-driven ecological changes. The early Middle Miocene site of els Casots (MN5, ~15.9 Ma), in the Vallès-Penedès Basin (NE Iberian Peninsula), is of extraordinary importance due to the abundant vertebrate remains and its coincidence with the midpoint of the MCO. Procervulus (Cervidae) and Eotragus (Bovidae) are of particular interest among the recorded taxa due to their basal phylogenetic position within their respective clades and their (apparently) similar ecology. Dental histology can provide valuable information about an organism’s life history (LH) through the analysis of its tissues, as their incremental development records growth rates and periods of physiological stress. To investigate possible LH differences between the two clades, we analyzed the enamel histology of their molars with a focus on their enamel daily secretion rate (DSR). Our results indicate that both species exhibited a particularly high DSR, which agrees with a fast LH strategy. The similarity in DSR between Procervulus and Eotragus further strengthens the similarity between cervids and bovids during their early evolutionary stages. Furthermore, Procervulus from els Casots shows no significant differences compared with Procervulus from Artesilla in central Iberia, where likely drier and more open habitats prevailed. However, the likely presence of open woodlands in the surroundings of the more forested environment of els Casots suggests that the two Procervulus spp. inhabited similar environments and might partially explain their ecological similarities.