title: Diversification events and the effects of mass extinctions on Crocodyliformes evolutionary history.
abstract: The rich fossil record of Crocodyliformes shows a much greater diversity in the past than today in terms of morphological disparity and occupation of niches. We conducted topology-based analyses seeking diversification shifts along the evolutionary history of the group. Our results support previous studies, indicating an initial radiation of the group following the Triassic/Jurassic mass extinction, here assumed to be related to the diversification of terrestrial protosuchians, marine thalattosuchians and semi-aquatic lineages within Neosuchia. During the Cretaceous, notosuchians embodied a second diversification event in terrestrial habitats and eusuchian lineages started diversifying before the end of the Mesozoic. Our results also support previous arguments for a minor impact of the Cretaceous/Palaeogene mass extinction on the evolutionary history of the group. This argument is not only based on the information from the fossil record, which shows basal groups surviving the mass extinction and the decline of other Mesozoic lineages before the event, but also by the diversification event encompassing only the alligatoroids in the earliest period after the extinction. Our results also indicate that, instead of a continuous process through time, Crocodyliformes diversification was patchy, with events restricted to specific subgroups in particular environments and time intervals.
authors.affiliation: Bayerische Staatssammlung für Paläontologie und Geologie , Richard-Wagner-Strasse 10 , Munich 80333, Germany ; Ludwig-Maximilians Universität , Munich, Germany ; Faculdade de Filosofia Ciências e Letras de Ribeirão Preto , University of Sao Paulo, Avenida Bandeirantes 3900, 14040-901 Ribeirão Preto , São Paulo, Brazil.
authors.forename: Mario
authors.initials: M
authors.lastname: Bronzati
authors.affiliation: Departamento de Biologia e Zootecnia , Faculdade de Engenharia de Ilha Solteira, UNESP, Rua Monção 226, 15385-000 Ilha Solteira , São Paulo, Brazil.
authors.forename: Felipe C
authors.initials: FC
authors.lastname: Montefeltro
authors.affiliation: Faculdade de Filosofia Ciências e Letras de Ribeirão Preto , University of Sao Paulo, Avenida Bandeirantes 3900, 14040-901 Ribeirão Preto , São Paulo, Brazil.
authors.forename: Max C
authors.initials: MC
authors.lastname: Langer
keywords: Crocodyliformes; diversification; mass extinction; phylogeny; topology-based methods