In 1507, a group of scholars working in France produced an extraordinary map of the world, the first to put the still-recent discoveries of Columbus and others into a new continent separate from Asia, and to call that continent “America.” With the Waldseemuller map, the New World was born.

But there was something else. What would later come to be called South America and Central America were surprisingly well-shaped, not only on the east coast, where explorers had already sailed, but also on the west coast which no European was known to have seen.

The ice cream cone bulge that sticks out into the Pacific at the junction of modern-day Chile and Peru is readily visible and in almost exactly the right geographical spot not only in the main map, but also in an inset printed along its top.

It is an improbable coincidence, if it is a coincidence, for the map was published six years before Vasco Balboa’s 1513 trip across the Isthmus of Panama and 12 years before Ferdinand Magellan’s 1519-22 trip around the world.

Was someone there earlier?

“When I saw the angle break, I was astounded,” said former CIA political-military analyst Peter Dickson. “It was accurate within half a degree. How in the name of God could they have gotten that feature that close?”

Dickson, an amateur geographer and scholar of the Age of Discovery, this week is giving a Columbus Day lecture at the Library of Congress to talk about what he thinks happened that Portugal, Spain’s great rival, sponsored a secret expedition around 1500 that traveled through the Strait of Magellan, around Cape Horn and up the coast of the Americas. Dickson’s views will appear later this fall in the journal Exploring Mercator’s World.

Dickson’s theory arises from a comparison of latitudes and longitudes on the Waldseemuller map to actual coordinates. The map’s measurements including South America’s southward taper routinely achieve at least 90 percent accuracy, he said.

The map’s authenticity is virtually beyond question. Swiss-born intellectual Martin Waldseemuller, working with a mostly German team in the French town of St. Die, wanted to update Ptolemy’s classic Geography, last revised in the 1490s. New and spectacular discoveries had been reported almost yearly since Columbus’s first voyage in 1492.

Waldseemuller’s team printed 1,000 copies of the original map. The lone surviving copy was found in 1901 in a castle in Germany, where it was part of a private collection.

Dickson finds himself in a position similar to that of Gavin Menzies, a British amateur historian. Menzies has used map evidence and medieval celestial charts to suggest that Chinese Admiral Zheng sailed around the world between 1421 and 1423, and visited the Caribbean nearly 71 years before Columbus.

His theory has not yet gained wide acceptance, and an informal canvass of cartographers and Renaissance scholars suggests Dickson will also encounter heavy going.