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首页> 外文期刊>Journal of Systematic Palaeontology >New material of the Late Cretaceous marine turtle Ctenochelys acris Zangerl, 1953 and a phylogenetic reassessment of the 'toxochelyid'-grade taxa
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New material of the Late Cretaceous marine turtle Ctenochelys acris Zangerl, 1953 and a phylogenetic reassessment of the 'toxochelyid'-grade taxa

机译：白垩纪晚期海龟Ctenochelys acri Zangerl的新材料，1953年和“弓形虫”级分类群的系统发育重新评估

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Late Cretaceous marine turtles formerly referred to the family Toxochelyidae represent perhaps the earliest members of the clade including extant marine species of cryptodire (Chelonioidea). Though more pelagically specialized marine taxa such as Protostegidae (i.e. Archelon, Desmatochelys) predate the first occurrence of any known 'toxochelyid' species, phylogenetic analyses of modern and fossil Testudines have shown that the protostegids may be a separate radiation of stem cryptodires only distantly related to modern marine turtles. This hypothesis has since been supported by ancillary evidence from the stratigraphic record and has been argued from a perspective of rampant homoplasy. This information brings into question our understanding of chelonioid evolution with regard to their previously assumed monophyly, and supports the placement of 'toxochelyids' as perhaps the earliest definitive members of total group Chelonioidea (Pan-Chelonioidea). However, many 'toxochelyids' are known from partial holotypes, preventing accurate species diagnosis and precluding these species from character-based phylogenetic analyses. A poorly known member of this clade, Ctenochelys acris, is herein redescribed based on several nearly complete specimens from the early Campanian Mooreville Chalk of Alabama. Ctenochelys acris is characterized by large, dorsolaterally oriented orbits, significant contributions of the palatines to the secondary palate, a broad maxillary triturating surface, and almost equilaterally pentagonal posterior peripherals. This redescription not only identifies previously unknown apomorphies of Ctenochelys spp. but also provides an opportunity to examine the 'toxochelyids' within a global phylogenetic context. A constraint tree reflecting the recognized molecular topology for extant Testudines is used as a backbone and the resulting phytogeny is then placed within a chronostratigraphic framework in an effort to present a scenario that reconciles anatomical, temporal and phylogenomic patterns for marine turtles. This analysis supports the placement of protostegids outside of Chelonioidea as marine eucryptodirans and establishes Ctenochelys spp. as perhaps some of the earliest representatives of Pan-Cheloniidae.
机译：晚白垩纪的海龟以前被称为弓形虫科，可能代表了进化枝的最早成员，其中包括现存的隐孢子虫（Chelonioidea）。尽管诸如Protostegidae（即Archelon，Desmatochelys）等更具远洋专业性的海洋生物群在任何已知的“弓形虫”物种首次出现之前，但对现代和化石睾丸类的系统发育分析表明，该原生动物可能是仅与远缘相关的茎隐藻的单独辐射到现代海龟。此假说此后得到了地层记录的辅助证据的支持，并从猖homo的同质性角度进行了论证。这些信息使我们对先前关于类mono虫类的类oni虫进化的理解成为疑问，并支持将“类毒素”作为总类Che虫（Pan-Chelonioidea）中最早的确定成员。然而，许多“毒卵石”是从部分全基因型中已知的，这妨碍了准确的物种诊断，并且无法从基于特征的系统发育分析中排除这些物种。本文根据阿拉巴马州Campanian Mooreville Chalk早期的几份几乎完整的标本重新描述了该分支的一个鲜为人知的物种Ctenochelys acris。 Ctenochelys acris的特征是，背外侧定向的轨道较大，the对次级pa的显着贡献，上颌磨碎面较宽以及后方的等边五边形。此重新描述不仅标识了C蛇科的奇异型。而且还提供了在全球系统发育背景下检查“弓形虫”的机会。反映现存睾丸激素公认的分子拓扑结构的约束树被用作骨干，然后将所得到的植物遗传学置于年代地层学框架内，以努力提出一种与海龟的解剖学，时间学和植物学模式相协调的方案。该分析支持将原种动物放置在海螯鱼体内，并将其作为C鱼属。作为泛Pan科的最早代表。

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