I'd assume that some people are unable to cash out of Auroracoin directly, so they dumped AUR for BTC before people on the crypto markets were aware of what was

I'd assume that some people are unable to cash out of Auroracoin directly, so they dumped AUR for BTC before people on the crypto markets were aware of what was happening. This didn't drive the price of BTC up, but when they cashed out into USD it drove the price of BTC down. Alternatively, the events might not be related. Cryptos are very volatile.