Cave plague replaced its ancestor cave fever. A deadly mutation caused this illness to turn from a simple illness to a deadly plague! Like its ancestors its spread through the blood from the cave night glider however rather than just making the host sick it will cause the hosts immune system to attack itself and lead to failure in its organs. Thus it become perfect prey for more cave night gliders to feed on it.
Since this was a small enclosed biome the ecosystem could not handle such a powerful plague and collapsed. All the plents died as well the cave night glider themselves and of course the cave plague. All that was left was the frabooball, lithoamoeba, sporetower lithoamoeba, cavepede, cavamari and blind earback which were not plents at all and were not affected by the missing plents. The albino seprpentsaur was already at the brink of exactions thanks to the earbacks eating their eggs. Having lost most of its food sources it went extinct as well.