Pycnodonts were polyphyodont animals

Here, I demonstrate that pycnodonts were polyphyodont animals, through radiographic highlights of dental gems in various states of maturation that are present in both the prearticular and the vomer of at least some Cretaceous genera Neoproscinetes and Phacodus, and for the Eocene genus Pycnodus. I propose the hypothesis that polyphyodonts in pycnodonts involved a differentiated ontogenetic mechanism in young subjects compared to adult ones. In young fish, the growth of the dentition occurred through introdution of new teeth from behind. In adults, only worn teeth were replaced, regardless of their position. The cessation of the ameloblastic activity certainly marked the senescence of the pycnodonts, in which the exhaustion of the ameloblasts prevented dental replacement, making senile subjects edentulous, with bone atrophy and the consequent inability to feed, ultimately leading to the death of the fish.