Successional structure in continental tetrapod faunas from Argentina along the Cretaceous

SEBASTIÁN APESTEGUÍA

Sao Pedro, Brasil

Simposio; 6º Simpósio sobre o Cretáceo do Brasil / 2º Simposio sobre el Cretácico de América del Sur.; 2002

Universidad de Río Claro

Three main evolutive stages can be recognised in the faunas of Cretaceous continental tetrapods, specially dinosaurs, that lived in Argentina. The first (Neocomian to Early Aptian) involves relics of widespread global Jurassic faunas. The second (Late Aptian to Early Campanian) or Gondwanan (Early Gondwanan + South American + Greatergondwanan), includes faunas relatively isolated, evolving separately and with the rise of several endemisms at family level. The third and last stage involves the stablishment of several land connections around different Gondwanan and Laurasian territories, producing thus several mixed faunas all around the world. Five faunistic dominance patterns are recognised as follows: ‘Basal Neosauropod-Basal Tetanuran-Stegosaur Global Dinosaur Domain’ (Neocomian-Early Aptian); ‘Carcharodontosaurid-Basal Titanosauriform-Diplodocimorph Early Gondwanan Dinosaur Domain’ (Late Aptian-Mid Cenomanian); ‘Coelurosaur-Titanosaurid-Basal Euiguanodontian South American Endemic Dinosaur Domain’ (Late Cenomanian-Coniacian); ‘Abelisauroid-Saltasaurine Greatergondwanan Endemic Dinosaur Domain’ (Santonian-Early Campanian) and ‘Allochthonous Ornithischian Dinosaur Domain’ (Late Campanian-Maastrichtian). Some events like the extinction (or loss of dominance) of basal titanosauriforms, diplodocimorph and carcharodontosaurids seem to be linked with the diversification of titanosaurids and large coelurosaurs. Rising of saltasaurine sauropods seems to fit with exctinction of large coelurosaurs (although remained in Salta) and diversification of abelisauroids. Arriving of allochthonous ornithischians disrupted mainly coastal environment ecology. Crocodiles, turtles and mammals were in concordance with dinosaur domains. Frogs are not properly known yet. Birds were not considered because of its vagility but a continuously increasing diversity is enviewed.