Davy Jones -- lead singer of The Monkees -- died after suffering a heart attack this morning ... TMZ has learned. An official from the medical examiner's office for Martin County, Florida confirmed with TMZ they received a call from Martin Memorial Hospital informing them that Jones had passed away. We're told Davy suffered the heart attack at a ranch near his Florida home, where he was visiting his horses. Davy began experiencing distress while he was sitting in his car, and that's where a ranch...