So Volcanoes Created the Dinosaurs? A Quantitative Characterization of the Early Evolution of Terrestrial Pan-Aves

The early Mesozoic is marked by several global-scale environmental events, including the emplacement of large igneous provinces, such as Siberian Traps, Wrangellia, and Central Atlantic Magmatic Province (CAMP). These have been hypothesised drivers successful diversification Pan-Aves, lineage archosaurs closer to birds than crocodiles. We characterize here body size evolution terrestrial pan-avians (excluding pterosaurs) along Triassic Early Jurassic, using phylogenetic- occurrence-based approaches, in an attempt test influence drivers. As diversity metrics, we quantified raw species richness phylogenetic (using time-calibrated trees), net rates were estimated with PyRate episodic fossilized-birth-death model. also characterised through-time patterns (femoral length) evolutionary rates. Our results indicate that macroevolutionary shifts from occurrence data are placed more recently time those phylogenetic-based shown higher increase, rates, disparity Pan-Aves Carnian. This consistent hypotheses suggesting Carnian Pluvial Episode (CPE) was crucial for radiation group. Yet, phylogeny-based show diversity/diversification Ladinian Norian, a minor effect (CPE). found no meaningful diversity, diversification, or size-related metrics across Triassic-Jurassic boundary. Even if end-Triassic mass extinction possibly emptied ecospace, allowing dinosaur increase during our suggest this expansion did not occur fast homogeneously entire In fact, sustained reduction sub-zero seen after extinction, but should be interpreted care towards end they may biased “edge effect.” Overall, few consistently identified all results, nuanced complex anticipated.