When you look at a phylogenetic tree of reptile classes, turtles, lizards and snake, and crocodiles are grouped together and birds are set off to the side but with a common ancestor for both groups. This would

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The description fits a paraphyletic tree because it includes some, but not all, descendants of a common ancestor. Birds are descendants of the same common ancestor as reptiles but are set off to the side, indicating they are not included in the group. This makes the tree paraphyletic. However, modern taxonomy based on evolutionary relationships places birds within the same clade as reptiles, specifically within the Archosauria, which includes crocodiles and dinosaurs. Therefore, including birds with reptiles (turtles, lizards, snakes, and crocodiles) would indeed make it a monophyletic group, which includes all descendants of a common ancestor.

When You Look at a Phylogenetic Tree of Reptile Classes