Comments by "EebstertheGreat" (@EebstertheGreat) on "The Traits That Spawned the Age of Mammals" video.

  1. Random question about crown groups: if the tuatara goes extinct, will crown lepidosaurs become synonymous with squamates? After all, all extant lepidosaurs will then be lizards and snakes. That is, since crown (and stem) groups are defined by living representatives, do their definitions naturally change over time, as species go extinct? Or once defined, is a crown group fixed?
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  2.  @curtiswfranks  Yeah, this seems to be the best way to go. For instance, we could define crown lepidosaurs as the most recent common ancestor of the tuatara and the green iguana and all its descendants (equivalently, the smallest clade containing the tuatara and green iguana). That way, it doesn't matter if the tuatara or green iguana still exists.
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