That's nothing to make a fuss about IMO, bitcoin is volatile and the last time rise and drop showed that already, and the time when it dropped to $2100 etc etc..., regarding Altcoins, it's either following the BTC drop, people changing back to exchange to USD or a big trader sold some big altcoins.
Bitcoin has a large effect to the things that happen in the Altcoin region since pretty much all the Altcoins that are out there like to be paired with Bitcoin in most Bitcoin exchanges. Bitcoin is what keeps the price of Altcoins stay afloat because there is not that many people that want an Altcoin just for the purpose of having an Altcoin that has no value.