Asked it the following to test it:

What caused the cooling at the end of the cenezoic that lead to the glacial quarternary period?

Took a while, actively showed the source articles it was looking into while it was processing which were clickable. Here’s a pdf of the response which is long, and well referenced, pretty interesting IMO, but here’s the initial overview:

The cooling at the end of the Cenozoic Era — which culminated in the glacial-interglacial cycles of the Quaternary Period — is one of Earth’s most profound climate transitions. This was not a single event but a stepwise process driven by interconnected mechanisms operating over tens of millions of years. The primary cause was a long-term decline in atmospheric CO₂ (pCO₂), driven fundamentally by plate tectonic processes that altered the global carbon cycle. Oceanic gateway openings and orbital variations played important modulating roles.

Which my partner, whose taken some climate classes in college, said sounds right. If anyone thinks this is wrong please feel free to call it out.