title: Species richness and evidence of random patterns in assemblages of South American Titanosauria during the Late Cretaceous (Campanian-Maastrichtian).
abstract: The Titanosauria were much diversified during the Late Cretaceous, but paleobiological information concerning these sauropods continues to be scarce and no studies have been conducted utilizing modern methods of community analysis to infer possible structural patterns of extinct assemblages. The present study sought to estimate species richness and to investigate the existence of structures in assemblages of the South American Titanosauria during the Late Cretaceous. Estimates of species richness were made utilizing a nonparametric estimator and null models of species co-occurrences and overlapping body sizes were applied to determine the occurrence of structuring in this assemblages. The high estimate of species richness (n = 57) may have been influenced by ecological processes associated with extinction events of sauropod groups and with the structures of the habitats that provided abundant support to the maintenance of large numbers of species. The pseudocommunity analysis did not differ from that expected by chance, indicating the lack of structure in these assemblages. It is possible that these processes originated from phylogenetic inertia, associated with the occurrence of stabilized selection. Additionally, stochastic extinction events and historical factors may also have influenced the formation of the titanosaurian assemblages, in detriment to ecological factors during the Late Cretaceous. However, diagenetic and biostratinomic processes, influenced by the nature of the sedimentary paleoenvironment, could have rendered a random arrangement that would make assemblage structure undetectable.
authors.affiliation: Laboratório de Ecofisiologia Animal, Departamento de Sistemática e Ecologia, Universidade Federal da Paraíba, João Pessoa, PB, Brazil.
authors.forename: Washington Luiz Silva
authors.initials: WL
authors.lastname: Vieira
authors.affiliation: Laboratório de Ecofisiologia Animal, Departamento de Sistemática e Ecologia, Universidade Federal da Paraíba, João Pessoa, PB, Brazil.
authors.forename: Kleber Silva
authors.initials: KS
authors.lastname: Vieira
authors.affiliation: Laboratório de Ecofisiologia Animal, Departamento de Sistemática e Ecologia, Universidade Federal da Paraíba, João Pessoa, PB, Brazil.
authors.forename: Rômulo Pantoja
authors.initials: RP
authors.lastname: Nóbrega
authors.affiliation: Laboratório de Ecofisiologia Animal, Departamento de Sistemática e Ecologia, Universidade Federal da Paraíba, João Pessoa, PB, Brazil.
authors.forename: Paulo Fernandes Guedes Pereira
authors.initials: PF
authors.lastname: Montenegro
authors.affiliation: Museu de Zoologia da Universidade de São Paulo, Ipiranga, São Paulo, SP, Brazil.
authors.forename: Gentil Alves
authors.initials: GA
authors.lastname: Pereira Filho
authors.affiliation: Programa de Pós-Graduação em Ecologia e Conservação (PPGEC)/Departamento de Biologia, Universidade Estadual da Paraíba, Campina Grande, Paraíba, Brazil.
authors.forename: Gindomar Gomes
authors.initials: GG
authors.lastname: Santana
authors.affiliation: Programa de Pós-Graduação em Ecologia e Conservação (PPGEC)/Departamento de Biologia, Universidade Estadual da Paraíba, Campina Grande, Paraíba, Brazil; Departamento de Biologia, Universidade Estadual da Paraíba, Campina Grande, Paraíba, Brazil.
authors.forename: Rômulo Romeu Nóbrega
authors.initials: RR
authors.lastname: Alves
authors.affiliation: Departamento de Química Biológica, Centro de Ciências Biológicas e da Saúde, Universidade Regional do Cariri - URCA, Campus do Pimenta, Crato, CE, Brazil.
authors.forename: Waltécio Oliveira
authors.initials: WO
authors.lastname: Almeida
authors.affiliation: Departamento de Sistemática e Ecologia, Universidade Federal da Paraíba, João Pessoa, PB, Brazil.
authors.forename: Alexandre
authors.initials: A
authors.lastname: Vasconcellos
mesh_terms: D000818:Animals; D058448:Biota; D049628:Body Size; D003163:Competitive Behavior; D016208:Databases, Factual; D025061:Dinosaurs / Q000033:anatomy & histology / Q000145:classification*; D017753:Ecosystem; D019419:Evolution, Planetary; D005580:Fossils; D010802:Phylogeny; D012641:Selection, Genetic; D013020:South America; D013045:Species Specificity; D018709:Statistics, Nonparametric