Abstract Fragments of turtle shell are known from several Upper Cretaceous formations in Mexico, including Corral de Enmedio and Packard Shale, Sonora; Aguja and Cerro del Pueblo, Coahuila; San Carlos, Chihuahua; El Gallo, Baja California; and Ocozocoautla, Chiapas. Turtles are important members of Upper Cretaceous vertebrate assemblages throughout North America and are considered a useful tool to define biogeographic patterns. The Upper Cretaceous sedimentary rocks exposed in the Aguja Formation record the final transgressive/regressive sequence of the Western Interior Cretaceous Seaway and the subsequent transition from a marine to terrestrial environment. The total area of outcrops is small compared to correlative exposures of these strata elsewhere in North America, in spite of this, numerous invertebrate and vertebrate fossils have been collected. The Aguja Formation in Texas preserves one of the southernmost well-studied Upper Cretaceous (Campanian) terrestrial vertebrate faunas in North America; contrary to what happens with the outcrops in northern Chihuahua, where the record of terrestrial vertebrates is scarce and especially those related to Testudines. Non-marine strata of the Aguja Formation do not appear to be present farther south in Mexico, and this is the reason why the Aguja fauna is relevant to documenting latitudinal variation in Campanian continental faunal associations. In this paper, the richness of Upper Cretaceous turtles collected from three localities within the Aguja Formation in Chihuahua is reviewed. Six taxa are recognized based on shell fragments with distinctive sculpture patterns: stem cryptodires, including cf. Baenidae, c.f. Denazinemys nodosa and cf. Compsemys victa, and crown group cryptodires including trionychians (trionchids and Basilemys sp.) and a kinosternoid (cf. Yelmochelys rosarioae). With the recognition of these taxa, new records are reported for the Aguja Formation (e.g. cf. Yelmochelys rosarioae) and Mexico (e.g. c.f. Denazinemys nodosa). The knowledge of Cretaceous turtle richness of the Aguja Formation and Mexico is increased and confirms the proposal of the variability richness along the North American localities. This latitudinal variability suggests that at any time turtles would have had a climatically controlled northern limit of distribution, and the richness of turtles would have decreased as this limit was reached.

中文翻译：

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来自墨西哥奇瓦瓦阿古贾地层（晚白垩世，坎帕阶）的非海龟

摘要 在墨西哥的几个上白垩统地层中已知有龟壳碎片，包括 Corral de Enmedio 和 Packard Shale，Sonora；Aguja 和 Cerro del Pueblo，科阿韦拉；奇瓦瓦州圣卡洛斯；下加利福尼亚州埃尔加洛；和恰帕斯州的奥科佐科奥特拉。海龟是整个北美上白垩纪脊椎动物群落的重要成员，被认为是定义生物地理模式的有用工具。出露于 Aguja 组的上白垩统沉积岩记录了白垩纪西部内陆海道的最终海进/海退序列以及随后从海洋环境到陆地环境的转变。尽管如此，与北美其他地方这些地层的相关暴露相比，露头的总面积很小，收集了大量的无脊椎动物和脊椎动物化石。德克萨斯州的 Aguja 地层保存了北美最南端的上白垩纪（坎帕阶）陆生脊椎动物群之一；与奇瓦瓦北部露头的情况相反，那里的陆生脊椎动物记录很少，尤其是与 Testudines 相关的记录。Aguja 组的非海相地层似乎并不存在于墨西哥的更南部，这就是为什么 Aguja 动物群与记录坎帕尼亚大陆动物群落的纬度变化相关的原因。本文综述了从奇瓦瓦州 Aguja 组内三个地点采集的上白垩统龟类的丰富性。根据具有独特雕刻图案的贝壳碎片识别出六个分类群：茎隐虫，包括参见 Baenidae，cf Denazinemys nodosa 和 cf. Compsemys victa 和冠组隐翅目，包括trionychians（trionchids 和Basilemys sp.）和类动甾体（cf. Yelmochelys rosarioae）。随着对这些分类群的认可，Aguja 组（例如，参见 Yelmochelys rosarioae）和墨西哥（例如，Denazinemys nodosa）有了新的记录。增加了对 Aguja 组和墨西哥的白垩纪海龟丰富度的了解，并证实了沿北美地区变化丰富度的提议。这种纬度变化表明，在任何时候，海龟都会有一个受气候控制的北部分布限制，当达到这个限制时，海龟的丰富度会下降。和冠组cryptodires，包括trionychians (trionchids and Basilemys sp.) 和kinosternoid (cf. Yelmochelys rosarioae)。随着对这些分类群的认可，Aguja 组（例如，参见 Yelmochelys rosarioae）和墨西哥（例如，参见 Denazinemys nodosa）有了新的记录。增加了对 Aguja 组和墨西哥的白垩纪海龟丰富度的了解，并证实了沿北美地区变化丰富度的提议。这种纬度变化表明，在任何时候，海龟都会有一个受气候控制的北部分布限制，当达到这个限制时，海龟的丰富度会下降。和冠组cryptodires，包括trionychians (trionchids and Basilemys sp.) 和kinosternoid (cf. Yelmochelys rosarioae)。随着对这些分类群的认可，Aguja 组（例如，参见 Yelmochelys rosarioae）和墨西哥（例如，Denazinemys nodosa）有了新的记录。增加了对 Aguja 组和墨西哥的白垩纪海龟丰富度的了解，并证实了沿北美地区变化丰富度的提议。这种纬度变化表明，在任何时候，海龟都会有一个受气候控制的北部分布限制，当达到这个限制时，海龟的丰富度会下降。报告了 Aguja 组（如 Yelmochelys rosarioae）和墨西哥（如 Denazinemys nodosa）的新记录。增加了对 Aguja 组和墨西哥的白垩纪海龟丰富度的了解，并证实了沿北美地区变化丰富度的提议。这种纬度变化表明，在任何时候，海龟都会有一个受气候控制的北部分布限制，当达到这个限制时，海龟的丰富度会下降。报告了 Aguja 组（如 Yelmochelys rosarioae）和墨西哥（如 Denazinemys nodosa）的新记录。增加了对 Aguja 组和墨西哥的白垩纪海龟丰富度的了解，并证实了沿北美地区变化丰富度的提议。这种纬度变化表明，在任何时候，海龟都会有一个受气候控制的北部分布限制，当达到这个限制时，海龟的丰富度会下降。