Agnolín FL

Introduction The bird-like theropod dinosaur Halszkaraptor escuilliei is a based on an almost complete skeleton from the Upper Cretaceous of Mongolia (Cau et al., 2017). Compared to other theropods, Halszkaraptor shows several unusual features, supporting the institution of a new lineage of Dromaeosauridae, the halszkaraptorines (Cau et al., 2017; Cau & Madzia, 2018; Agnolin et al., 2018), and suggesting a semiaquatic bauplan able to exploit both terrestrial and aquatic resources.

Introduction Although much information has been already gathered about the largest predatory dinosaurs from the Jurassic and Cretaceous Periods, their early evolutionary history is still poorly understood, given the scarcity of fossils. Until now, knowledge concerning the some of the first top predatory dinosaurs mostly relies on herrerasaurids recorded in Carnian strata of South America.

Introduction By the final years of the 20th century, the diversity of dinosauromorphs across Pangea was thought to follow a simple pattern during the Triassic Period.