Growing with dinosaurs: a review of dinosaur reproduction and ontogeny.

Since the start of the twenty-first century, there has been a notable increase in annual publications focusing on dinosaur reproduction and ontogeny with researchers using these data to address a range of macroevolutionary questions about dinosaurs. Ontogeny, which is closely tied to osteological morphological variation, impacts several key research areas, such as taxonomic diversity, population dynamics, palaeoecology, macroevolution, as well as the physiological and reproductive factors driving ecological success. While these broad studies have significantly advanced our understanding of dinosaur evolution, they have also revealed important challenges and areas needing further investigation. In this review, we aim to outline some of these challenges in major research areas linked to dinosaur ontogeny, namely reproductive biology, osteohistological growth strategies, morphological osteological variation and the link between ontogeny and macroevolution. We also offer some recommendations for best practices and promising future research directions. These recommendations include increasing sample sizes through fieldwork and exhaustive use of pre-existing fossil collections, using micro-computed tomography (μCT) scanning methods to increase dataset sizes in a non-destructive manner, methodical collection and reposition of μCT scan data, assessing ontogenetic maturity, establishing consistency in terminology and methods and building comprehensive extant comparative datasets.