Osteohistology and growth dynamics of the Brazilian noasauridVespersaurus paranaensisLanger et al., 2019 (Theropoda: Abelisauroidea)

Abstract

Although the knowledge of bone histology of non-avian theropods has advanced considerably in recent decades, data about the bone tissue patterns, growth dynamics and ontogeny of some taxa such as abelisauroids are still limited. Here we describe the bone microstructure and growth dynamics of the Brazilian noasaurine Vespersaurus paranaensis using five femora and six tibiae and quantify the annual growth marks through retrocalculation of missing ones to estimate ontogenetic ages. The femoral series comprises four femoral histological classes (FHC I-IV), varying from two annuli or LAGs to seven LAGs. Femora show that sexual maturity was achieved around the seventh to tenth year of life, whereas the tibiae suggest it was earlier (around three to five years old). Tibiae represent three histological classes (THC I-III) displaying from three to nine LAGs. Two tibiae (THC III) exhibit an external fundamental system indicating that these specimens reached full skeletal size. The heterogeneous maturity observed in Vespersaurus hind limb bones could result from differential allometry scaling between femora and tibiae length with the body length. The predominant parallel-fibered bone matrix suggests that Vespersaurus grew more slowly than most theropods, including other abelisauroids, in a pattern shared with the noasaurines Masiakasaurus knopfleri from Madagascar and CPPLIP 1490 from Brazil. This deviation from the typical theropod growth pattern may be mainly correlated with small body size, but also may related to resource limitation imposed by the arid climate prevailing in southwestern Gondwana during Cretaceous. Moreover, given the ecological and phylogenetic similarities among these taxa, such features would probably be apomorphic within Noasauridae.

Bone histology supports gregarious behavior and an early ontogenetic stage to Decuriasuchus quartacolonia (Pseudosuchia: Loricata) from the Middle‐Late Triassic of Brazil

“…This indicates that ulna and fibula would grow circumferentially slower than the other bones. Indeed, the growth trajectory may change between different bones because of different factors, such as injury, illness, feeding, biomechanical stresses, and evolutionary allometry scaling (Padian et al, 2016; Souza et al, 2020). Until now, histovariability in “Rauisuchia” is known only between appendicular bones, ribs, and osteoderms.…”

“…At present, several groups of archosauromorphs have been the subject of paleohistological studies, but most of them focused on the understanding of growth patterns in Avemetarsalia (e.g., pterosaurs, non-avian dinosaurs, and birds). Some of these studies had the privilege of having a sample with an ontogenetic series (e.g., Araújo et al, 2023;Chinsamy, 1993;Horner et al, 1999Horner et al, , 2000Horner et al, , 2001Souza et al, 2020;Wosik & Evans, 2022), an essential condition to access the complete life history of a taxon. In contrast, non-archosaurian archosauromorphs and archosauriforms, as well pseudosuchian archosaurs, despite having an upcoming interest in their paleobiological aspects accessed by bone microstructure analysis, are known for studies mostly based on incomplete samples (but see exceptions, e.g., Mukherjee, 2015).…”

Contexto Litoestratigráfico E Consideracões Sobre a Formação Do Jazigo Fossilífero Do Município De Cruzeiro Do Oeste-Pr

“…Langer et al (2019) eSouza, et al (2020) demonstrou que o Vespersaurus cresceu mais lentamente que a maioria dos terópodes, estando associado com o tamanho pequeno do corpo ou mesmo as restrições de recursos imposta pelo ambiente local durante o Cretáceo. Estudos realizados em fósseis de pterossauros também indicam que esses se tratavam de indivíduos juvenis tardios ou subadultos no momento do soterramento(Kelner, et al 2019), favorecendo a interpretação das condições restritivas de ocupação pela fauna, bem como das condições hidrodinâmicas e geodinâmicas ativas no momento da formação do jazigo fossilífero, muito condizente com a interpretação de fluxos sazonais de cheias, que levavam a destruição dos habitats da fauna local.A despeito da dificuldade de estabelecimento de relações entre a fauna de pterossauros e dinossauros, a presença de répteis voadores distintos no mesmo local, evidencia condições simpátricas na fauna Pterosauria, conforme apontado porKellner et al (2019).A fauna representada por indivíduos de pequeno porte, embora representante de espécimes jovens, pode indicar restrições de ocupação do espaço, que poderia ser constituído de oásis, cujos fluxos hídricos relâmpagos e sazonais levaria a destruição dos habitats, constituído por substrato arenoso e móvel, facilmente mobilizado pelas águas.CONCLUSÃOAs sequências arenosas que compõem as formações Rio Paraná e Goio-Êre se dispõem na parte noroeste do estado do Paraná, formando um relevo de colinas baixas em contato irregular com coberturas sedimentares quaternárias, e cujas drenagens dissecam vales fazendo aflorar na base rochas ígneas básicas da Formação Serra Geral.…”