Europe's banks take center stage this week as earnings season gets underway, but with heavy losses across the sector on Friday, credit concerns appear to be making their way across the Atlantic at a particularly tricky time for the region's lenders.Stock Chart IconStock chart iconCredit concerns hit European banksLast week, the biggest names in American finance battled it out to make the most alarming quote of the week. The contenders: JPMorgan CEO Jamie Dimon, Citi Group CEO Jane Fraser and Apollo boss Mar ...