Five new clips from Warner Bros. and Legendary Films’ Godzilla appeared online over the weekend, two of which feature hints at an epic kaiju battle between Godzilla and a giant flying lizard creature, possibly among others.
 
The second monster, referred to as an "alpha predator" (unless they’re referring to Godzilla) looks a bit like Rodan.  However, in the second clip, the unidentified creature is referred to as a MUTO (Massive Unidentified Terrestrial Organism).  "It is, however, no longer terrestrial, it is airborne," intones Admiral Stenz (David Strathairn). 

The "among others" comes from the Legendary log line, which states "An epic rebirth to Toho's iconic Godzilla, ...pits the world's most famous monster against malevolent creatures who, bolstered by humanity's scientific arrogance, threaten our very existence."
 
The movie opens May 14th.  More Godzilla goodness can be seen here (see "New 'Godzilla' Trailer & IMAX Poster").