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Bob Strauss

Ratites and Dinosaur Evolution

By September 8, 2008

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Birds are descended from dinosaurs, so any discoveries about bird evolution have implications for the evolution of their reptilian ancestors. A good example is a recent paper about ratites, a family of flightless birds that includes ostriches, emus and rheas. It turns out that these birds didn't (as had long been assumed) evolve from a single flightless ancestor; rather, each evolved their body plans independently from separate ancestors, a clear instance of convergent evolution.

What does this imply for dinosaurs? Well, if a group of animals as well-studied as birds can still yield evolutionary surprises, all bets are off for the evolutionary relationships of their dinosaur ancestors. For example, it's distinctly possible that dinosaurs evolved into birds multiple times, and only one lineage survived to flourish in the present day, or that various kinds of sauropods evolved independently from different ancestors.

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