All major, COELUROSAURIAN BIOGEOGRAPHIC HYPOTHESES

Pittman, Michael & Xu, Xing, 2020, Pennaraptoran Theropod Dinosaurs Past Progress And New Frontiers, Bulletin of the American Museum of Natural History 2020 (440), pp. 1-353 : 125

MAJOR COELUROSAURIAN BIOGEOGRAPHIC HYPOTHESES

Besides the clade-level biogeographic hypotheses summarized above (see Geographic and Temporal Distribution of Coelurosaurians), analyses of dinosaurian biogeography as a whole, including coelurosaurians, have given varying emphasis to particular biogeographic processes, namely vicariance events, regional extinction events, and dispersal events.

Many authors attach particular importance to vicariance events because of the global continental fragmentation that occurred during the late Mesozoic (Sereno, 1999b; Upchurch et al., 2002; Choiniere et al., 2012). The Middle Jurassic occurrences of tyrannosauroids (e.g., Kileskus and Proceratosaurus ) and Late Jurassic avialans (e.g., Archaeopteryx and possible avialan Anchiornis [also proposed as a troodontid]), are consistent with the idea that major coelurosaurian lineages were established at least before the Late Jurassic (Rauhut et al., 2010; Choiniere et al., 2012). Together with several early-diverging coelurosaurian Gondwanan occurrences (e.g., Bicentenaria from South America and Nqwebasaurus from Africa), a geographically widespread distribution of coelurosaurian lineages before the breakup of Pangaea has been inferred, which makes vicariance possible upon separation of the continents ( Choiniere et al., 2012). Proposed continental scale vicariance events include the Laurasia-Gondwana separation during the Late Jurassic (as shown in fig. 1: Hypothesis 1) and the final disconnection of South America and Africa during the Early Cretaceous (as shown in fig. 2: Hypothesis 2) (Sereno, 1999b). Possible vicariance-induced phylogenetic patterns have been identified in the distributions of maniraptoran lineages (Makovicky et al., 2005) and Ornithomimosauria (De Klerk et al., 2000) . However, other workers have seen continental-scale vicariance as a rare occurrence, and argue that regional extinctions were primarily responsible for late Meso-