Combined paleohistological and isotopic inferences of thermometabolism in extinct Neosuchia, using <i>Goniopholis</i> and <i>Dyrosaurus</i> (Pseudosuchia: Crocodylomorpha) as case studies

Abstract The evolution of thermometabolism in pseudosuchians (Late Triassic to the present) remains a partly unsolved issue: extant taxa (crocodilians) are ectothermic, but clade was inferred ancestrally endothermic. Here we thermometabolic regime two neosuchian groups, Goniopholididae (Early Jurassic Late Cretaceous) and Dyrosauridae (middle Cretaceous late Eocene), close relatives crocodilians, order elucidate evolutionary pattern across Metasuchia present), comprising Neosuchia Notosuchia (Middle until Miocene). We propose new integrative approach combining geochemical analyses infer body temperature from stable oxygen isotope composition tooth phosphate paleohistology phylogenetic comparative methods resting metabolic rates red blood cell dimensions. † Dyrosaurus Goniopholis share with crocodilians similar lifestyles, forms, bone tissue organization, temperatures, rates, Consistently, ectothermy for parsimonious implication neosuchians metasuchians being primitively ectothermic.