The phylogeny below shows relationships between birds and four different dinosaur genera. Based on the logic of phylogenetic systematics, which of the following statement(s) is/are accurate?

A) Dinosaurs and birds form a monophyletic group.
B) In order for dinosaurs to be a valid taxon, birds must also be called dinosaurs.
C) Dinosaurs are a paraphyletic group.
D) all of the above
E) none of the above

All statements are accurate based on the principles of phylogenetic systematics. A) Birds and dinosaurs share a common ancestor, forming a monophyletic group. B) Since birds are descended from dinosaurs, for dinosaurs to be a valid taxon (a group containing all descendants of a common ancestor), birds must be included, thus they should also be considered dinosaurs. C) Without including birds, dinosaurs would be considered a paraphyletic group because they would exclude some descendants (birds) of their most recent common ancestor.