The yen briefly dropped past the 161 mark against the U.S. dollar to its lowest level in over 37 years on Friday morning despite Japanese authorities stepping up their warnings of possible intervention to stem the yen’s decline. The Japanese currency also fell past the 172 line against the euro, its lowest level since the European currency was introduced in 1999. At noon, the dollar fetched 160.93-94 yen compared with 160.72-82 yen in New York and 160.54-56 yen in Tokyo at 5 p.m. Thursday. The euro was quoted at $1.0692-0696 and 172.07-14 yen against $1.0699-0709 and 172.03-13 yen in New York …