Modern elasmobranchs have a long evolutionary history and an abundant fossil record that consists mainly of teeth. Many fossil taxa have living representatives. However, the representation of extant taxa in the fossil record is unknown. To begin to understand the geological history of extant elasmobranchs, we here assess the quality of their fossil record. We do so by assessing the Pull of the Recent (POR). The POR can bias the fossil record because the rather complete record of living taxa allows palaeontologists to identify fossil members of the modern clades and to bridge time bins where fossils are absent. We assessed the impact of the POR by quantifying the proportion of extant elasmobranchs that have a fossil record, but do not occur in the last 5 million years (Pliocene and Pleistocene). We found that the POR does not affect orders and families, but it does affect 24% of elasmobranch genera. Within the different elasmobranch orders, the Lamniformes display the most complete generic fossil record, with no impact of the POR. Although modest, the impact of the POR in extant elasmobranch genera is higher than that found in other taxa. Overall, the geological history of elasmobranchs contradicts the usual assumption that the fossil record becomes worse backwards in time. This is the case across geographical regions and tooth size, further suggesting that sampling intensity and outcrop availability might explain the POR effect on sharks and rays.

中文翻译：

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近代拉力对现存弹鳃的影响

现代弹鳃类动物具有悠久的进化历史和丰富的化石记录，主要由牙齿组成。许多化石类群都有活着的代表。然而，化石记录中现存分类群的代表是未知的。为了开始了解现存弹鳃类动物的地质历史，我们在这里评估了它们化石记录的质量。我们通过评估近期拉动 (POR) 来做到这一点。POR 可以偏向化石记录，因为相当完整的活分类群记录使古生物学家能够识别现代进化枝的化石成员，并在没有化石的时间段架起桥梁。我们通过量化具有化石记录但在过去 500 万年（上新世和更新世）中没有发生的现存弹鳃的比例来评估 POR 的影响。我们发现 POR 不影响目和科，但确实影响了 24% 的 elasmobranch 属。在不同的弹鳃目中，板状目展示了最完整的通用化石记录，没有 POR 的影响。虽然不大，但 POR 在现存的 elasmobranch 属中的影响高于在其他分类群中发现的影响。总体而言，弹性鳃类动物的地质历史与化石记录随时间推移变得更糟的通常假设相矛盾。地理区域和牙齿大小的情况都是如此，这进一步表明采样强度和露头可用性可能解释了 POR 对鲨鱼和鳐鱼的影响。虽然不大，但 POR 在现存的 elasmobranch 属中的影响高于在其他分类群中发现的影响。总体而言，弹性鳃类动物的地质历史与化石记录随时间推移变得更糟的通常假设相矛盾。地理区域和牙齿大小的情况都是如此，这进一步表明采样强度和露头可用性可能解释了 POR 对鲨鱼和鳐鱼的影响。虽然不大，但 POR 在现存的 elasmobranch 属中的影响高于在其他分类群中发现的影响。总体而言，弹性鳃类动物的地质历史与化石记录随时间推移变得更糟的通常假设相矛盾。地理区域和牙齿大小的情况都是如此，这进一步表明采样强度和露头可用性可能解释了 POR 对鲨鱼和鳐鱼的影响。