Clues, Polar ice is thickest at the magnetic poles rather than the solar poles...
What causes water to react to magnetic fields...
How did Woolly mammoths die with flowers preserved in their stomachs... How, without digesting? Did the earths magnetic poles ever reverse... How, what could cause that?... Connect the dots.
Velokovski's close approach of the protoplanet Venus (He correctly predicted both the temperature and composition of Venus’ atmosphere before any probes were sent. The prevailing view at that time was that Venus was a warmer version of Earth).
The Northern Ice Cap had massive freshwater lakes - think the Great Lakes super sized - which collapsed into the warmer oceans sending water vapor into the stratosphere, which then fell back to Earth supercooled, flash freezing the beasts.
Theories abound, but none can be verified, currently.