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Angular momentum is conserved, but that doesn't mean the quake didn't change the rotation speed -- if the result was a "settling" of the ocean floor the moment of inertia would shrink and the rotation would speed up.

Of course the tidal friction with the moon changes the earth's rotation speed because it is the angular momentum of the entire earth-moon system that is conserved -- although the rotation slows down, the moon gets correspondingly further away (3 millimeters further away every month). At the time of the first dinosaurs, 250 million years ago, the moon was 5 or 6 thousand miles closer (which is still a small change compared to the current variation in the moon's distance from earth -- annular eclipses were still possible then, and total eclipses will still be possible for another 500 million years).

Angular momentum is conserved, but that doesn't mean the quake didn't change the rotation speed -- if the result was a "settling" of the ocean floor the moment of inertia would shrink and the rotation would speed up.

Yeah, I know, my comment was in response to the authors claim that Earths rotation speed had " permanently" changed. That statement is clearly wrong.

At the time of the first dinosaurs, 250 million years ago, the moon was 5 or 6 thousand miles closer (which is still a small change compared to the current variation in the moon's distance from earth -- annular eclipses were still possible then, and total eclipses will still be possible for another 500 million years).

Isn't that backwards? Wouldn't annular eclipses be more likely when the moon is further (future) than closer (past)?