Mesoeucrocodylia

Mesoeucrocodylia is an extinct clade of crocodylomorphs that lived during the Mesozoic Era. This group encompasses a wide diversity of forms, ranging from relatively small, gracile animals to large, robust predators. Mesoeucrocodylians appeared in the Late Triassic and persisted through the Cretaceous period, with some lineages potentially surviving into the Paleogene. They are characterized by a suite of anatomical features, including a specific arrangement of skull bones and pelvic girdle structure, that distinguish them from earlier and later crocodylomorphs.

The phylogenetic position of Mesoeucrocodylia is within the larger group Crocodylomorpha, placing them as a sister group to the modern Eusuchia, which includes all living crocodilians. Within Mesoeucrocodylia, there is considerable variation. Some well-known members include the bipedal notosuchians, such as Notosuchus and Pakasuchus, which had unique adaptations for terrestrial life, including short snouts and robust limbs. Other mesoeucrocodylians were more aquatic, with adaptations for semi-aquatic or even fully aquatic lifestyles.

The ecological roles of mesoeucrocodylians varied greatly. Some were likely small insectivores or carnivores, while others were apex predators in their respective ecosystems, preying on fish, dinosaurs, and other vertebrates. Their widespread distribution across Gondwana and Laurasia suggests a significant evolutionary success. The study of Mesoeucrocodylia is crucial for understanding the early evolution and diversification of the crocodylian lineage and the broader crocodylomorph radiation during the Mesozoic.