Heterodontosauridae

Heterodontosauridae is a family of theropod dinosaurs that lived during the Late Cretaceous period, approximately 99 to 66 million years ago. They are known for their distinctive heterodont dentition, which means their teeth were of different shapes and sizes. This family includes several genera, with the most well-known being Heterodontosaurus, from which the family name is derived.

Heterodontosaurids were medium-sized theropods, with some species reaching lengths of up to 10 meters. They had a unique combination of features, including a long, low skull, a deep snout, and a relatively short neck. Their teeth were specialized for different functions, with some being sharp and pointed for piercing, others being flat and grinding for crushing, and still others being serrated for slicing.

The exact relationships and classification of Heterodontosauridae within the theropod family tree are still a topic of ongoing research. Some studies suggest that they may be closely related to other heterodontosaurian theropods, such as Allosaurus and Ceratosaurus, while others propose that they are more basal, or primitive, members of the theropod group.

Fossils of Heterodontosauridae have been found in North America, Europe, and Asia, indicating that they had a widespread distribution during the Late Cretaceous. Their remains are typically found in sedimentary rocks, such as sandstone and mudstone, which preserve the bones and teeth of these dinosaurs in excellent condition.