Earliest First American found in underwater cave ?

Explorers cave-diving in the Yucatan have found a human skull and the remains of a mastodon. 

Excerpts from the National Geographic report:

Hoyo Negro was reached by the PET team after the divers travelled more than 4,000 feet [1,200 meters] through underwater passages using underwater propulsion vehicles, or scooters, which enabled them to cover long distances in the flooded cave system...

While the team of explorers conducted various dives for the purpose of mapping and surveying of this newly discovered pit, they noticed some peculiar bones sitting on the bottom. They first came across several megafauna remains and what was clearly a mastodon bone, while subsequent dives proved even more exciting when they spotted a human skull resting upside down with other nearby remains at about 140 feet [43 meters] depth...

Approximately 12,000 years ago, at the end of the Pleistocene epoch, Earth experienced great climatic changes. The melting of the ice caps caused a dramatic rise in global sea levels, which flooded low lying coastal landscapes and cave systems. Many of the subterranean spaces that once provided people and animals with water and shelter became inundated and lost until the advent of cave diving...

Radiometric dating of the human bones from Hoyo Negro will have to wait for now, but its location within the cave, and its position relative to the mastodon remains, are suggestive of its antiquity.

The results of this finding should definitively establish the existence of pre-Clovix humans in the New World.  I have always felt that Tom Dillehay's excavations at Monte Verde (Chile) had established a pre-Clovis timeline, but others have questioned his data.  The fact that Hoyo Negro has a skull - not just artifacts - should be definitive.