Howdy Warrenb
Yes that is very interesting. However it wouldn't be considered 'ancient', as noted it would be considered the classical or pre-classical period,
or as radical American states, Epiclassical.
I suspect it will turn out to either be a subsidiary culture of a known one or perhaps a 'last remnant' of one we thought had earlier disappeared.
It might even be a completely unknown one and as noted in the quote below that wouldn't be unexpected.
As the article states on page two
Creative Era
Michael Smith, an archaeologist at Arizona State University, agreed.
"The notion that there would be an independent culture in [the Epiclassic] period is not surprising at all," he said.
"It was a very creative period, with rich development."
Future excavations of Huapalcalco should solidify the link to a new pre-hispanic culture, and help archaeologists glean clues about this lost time,
Hernández said.
"The [Epiclassic] period is considered a time of dynamic development—new trade, cities, and development," said Arizona State's Smith, "but one
we don't know much about."
Kidflash
Its always challenging to date buildings but there are ways. Usually in Mexico you date by pottery, stylistic, C-14 or strat or best yet an
inscription. You would need to find the papers on this find to determine their dating regime.
AATS: cultures only rarely take over other structures-and pronounce them theirs- they usually identify them as being from the others and consider them
unlucky. Note that megalithic monuments were not usually reused, the Greeks, Persians, Romans, Byzantines and Arabs didn't take over and say the
Pyramids were built by them. In most cases the captured area was destroyed and rebuilt over or the building modified (as the Arabs and Christians did
to various churches/mosques) but its existence as a captured object was clearly defined.