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Are Birds Dinosaurs? Are Birds Fish?

Richard Stallman

Fossils discovered in recent decades have established that birds are descended from dinosaurs. Bizarrely, some paleontologists claim this requires us to redefine the word "dinosaurs" to include birds. They lecture us repeatedly that birds are "real, live dinosaurs". If we don't go along with their change of definition, they say we are ignorant or obtuse.

That reasoning is mistaken, as we can see by applying it to another similar question. Birds, like their ancestors the dinosaurs, are descended from fish. Applying the same argument, we would have to conclude that birds are also "real, live fish". The argument apparently can't tell fish from fowl.

Where is the flaw in the argument? The question of birds' ancestry is an objective matter that paleontologists can investigate and draw conclusions about. However, the definition of "dinosaur" is a matter of social convention. New facts might suggest reconsidering the word's definition, but whether to change it is a matter of what's useful.

Our customary use of "dinosaurs" was not a mistake; it was the meaning paleontologists generally promoted for that group of species, until some of them advocated a change. This meaning causes no confusion and does no harm to anyone (**). To change it calls for a good reason.

Do they offer a good reason? The radical paleontologists point out that the larger group which includes dinosaurs and birds is useful in a particular way: it is a clade. That means it consists of a certain past population together with all its descendants. That group calls for a scientific name, and we may want to give it a name in ordinary English too, but there is no reason that name need be "dinosaurs".

Meanwhile, the group we have traditionally called "dinosaurs" is still useful to talk about. Even the radical paleontologists that want to take away its name refer to the group frequently, using the cumbersome term "non-avian dinosaurs". This group calls for a name, too.

There three ways we can give names to the two groups.

The paleontologists that prefer the second option don't generally try to argue that it is superior to the first; rather they claim that the first option is out of the question, but they give no reason for that. If we accept both options, the first one is clearly superior.

Unless someone presents a convincing argument for the second option, let's choose the first: leave "dinosaurs" unchanged, and coin a new name for the larger group that includes birds also. I propose "dinavians" — it has a nice sound.

** Contrast this with the confusing practice of calling the GNU/Linux system "Linux", which sprang from an error, causes confusion between the GNU/Linux system and the kernel Linux, misrepresents how the system was developed and where, misattributes the GNU Project's work to someone else, and has been criticized since shortly after it began.

See and, plus the history in

Copyright 2018 Richard Stallman
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