The fossilized birth-death (FBD) model is a naturally appealing way of directly incorporating fossil information when estimating diversification rates. However, an important yet often overlooked property of the original FBD derivation is that it distinguishes between two types of sampled lineages. Here we first discuss and demonstrate the impact of severely undersampling, and even not including fossils that represent samples of lineages that also had sampled descendants. We then explore the benefits of including fossils, generally, by implementing and then testing two-types of FBD models, including one that converts a fossil set into stratigraphic ranges, in more complex likelihood-based models that assume multiple rate classes across the tree. Under various simulation scenarios, including a scenario that exists far outside the set of models we evaluated, including fossils rarely outperforms analyses that exclude them altogether. At best, the inclusion of fossils improves precision but does not influence bias. Similarly, we found that converting the fossil set to stratigraphic ranges, which is one way to remedy the effects of undercounting the number of k-type fossils, results in turnover rates and extinction fraction estimates that are generally underestimated. While fossils remain essential for understanding diversification through time, in the specific case of understanding diversification given an existing, largely modern tree, they are not especially beneficial.

中文翻译：

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化石并没有显着改善，甚至可能损害对多样化率异质性的估计

在估计多样化率时，化石出生-死亡 (FBD) 模型是一种直接结合化石信息的自然吸引人的方式。然而，原始 FBD 推导的一个重要但经常被忽视的特性是它区分了两种类型的采样谱系。在这里，我们首先讨论和论证严重采样不足的影响，甚至不包括代表也对后代进行采样的谱系样本的化石。然后，我们通常通过实施并测试两种类型的 FBD 模型（包括将化石组转换为地层范围的模型），在更复杂的基于可能性的模型中探索包含化石的好处，这些模型假设整个树中有多个速率类别。在各种模拟场景下，包括一个远远超出我们评估的模型集的场景，包括化石很少优于完全排除它们的分析。充其量，包含化石可以提高精确度，但不会影响偏差。同样，我们发现将化石组转换为地层范围（这是一种补救低估 k 型化石数量影响的方法）会导致周转率和灭绝分数估计值普遍被低估。虽然化石对于理解随着时间的推移的多样化仍然是必不可少的，但在给定一棵现有的、主要是现代树的情况下理解多样化的具体情况下，它们并不是特别有益。包含化石可以提高精确度，但不会影响偏差。同样，我们发现将化石组转换为地层范围（这是一种补救低估 k 型化石数量影响的方法）会导致周转率和灭绝分数估计值普遍被低估。虽然化石对于理解随着时间的推移的多样化仍然是必不可少的，但在给定一棵现有的、主要是现代树的情况下理解多样化的具体情况下，它们并不是特别有益。包含化石可以提高精确度，但不会影响偏差。同样，我们发现将化石组转换为地层范围（这是一种补救低估 k 型化石数量影响的方法）会导致周转率和灭绝分数估计值普遍被低估。虽然化石对于理解随着时间的推移的多样化仍然是必不可少的，但在给定一棵现有的、主要是现代树的情况下理解多样化的具体情况下，它们并不是特别有益。