Pairwise Divergence Time for "bald eagle" and "white-tailed eagle"
First, two species or higher taxa are queried (e.g., cat and dog). Next, TimeTree looks for these species in the TTOL to find their most recent common ancestor (MRCA). When one or both of the species are not present in TTOL, the NCBI taxonomy is scanned to find the closest relatives of the species or higher taxa requested by the user. Then, those taxa are used as proxies to find the MRCA for the given query. Finally, the divergence time for the MRCA is retrieved from the TimeTree database.
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TimeTree summary times are calculated using a robust average known as the Huber estimator. Like a simple average, it incorporates the contributions of all data points, but is less susceptible to the dominating influence of extreme values.
Due to conflicting time estimates between studies, ancestral nodes can be assigned younger ages than their descendants. A smoothing technique is used to adjust these times so the resulting tree is ultrametric, as described in Kumar et al. (2022).
Molecular Time Estimates (4 Studies)
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6.0
Whole-genome analyses resolve early branches in the tree of life of modern birds.