What major evolutionary event tends to disrupt the organized rotation of a disc galaxy, often leading to an elliptical shape?

Answer

Massive mergers with other large galaxies

Massive mergers with other large galaxies tend to disrupt the delicate, ordered rotation of a disc, often leading to a more spheroidal, elliptical shape.

What major evolutionary event tends to disrupt the organized rotation of a disc galaxy, often leading to an elliptical shape?
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