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.

中文翻译：

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巴西诺亚龙类 Vespersaurus paranaensis Langer 等人的骨组织学和生长动态，2019 年（兽脚亚目：Abelisauroidea）

尽管近几十年来非鸟类兽脚亚目动物的骨组织学知识有了长足的进步，但有关骨组织模式、生长动力学和某些分类群（如阿贝力龙类）的个体发育的数据仍然有限。在这里，我们使用五个股骨和六个胫骨描述了巴西 noasaurine Vespersaurus paranaensis 的骨骼微观结构和生长动态，并通过对缺失的回溯计算来估计个体发育年龄来量化年度生长标记。股骨系列包括四个股骨组织学类别 (FHC I-IV)，从两个瓣环或 LAG 到七个 LAG。股骨显示性成熟是在生命的七到十岁左右实现的，而胫骨表明它更早（大约三到五岁）。胫骨代表三个组织学类别 (THC I-III)，显示三到九个 LAG。两个胫骨 (THC III) 表现出外部基本系统，表明这些标本达到了完整的骨骼尺寸。在 Vespersaurus 后肢骨骼中观察到的异质成熟度可能是由于股骨和胫骨长度与身体长度之间的异速生长缩放导致的。主要的平行纤维骨基质表明，晚龙的生长速度比大多数兽脚亚目恐龙（包括其他阿贝力龙科）慢，其生长模式与马达加斯加的诺亚卡龙 Knopfleri 和巴西的 CPPLIP 1490 共享。这种与典型兽脚亚目动物生长模式的偏差可能主要与体型较小有关，但也可能与白垩纪冈瓦纳西南部盛行的干旱气候造成的资源限制有关。此外，考虑到这些分类群之间的生态和系统发育相似性，这些特征可能在 Noasauridae 内是异形的。