article_snippet.sent: The various continents, sitting atop huge plates akin to jigsaw puzzle pieces sliding over Earth's mantle estimate on the presence of small grains of a mineral called zircon unearthed in ancient river bedrock in northern Colombia that originated in Panama and were 13 million to 15 million years old.
article_snippet.sent: small grains of a mineral called zircon unearthed in ancient river bedrock in northern Colombia that originated in Panama and were 13 million to 15 million years old suggested the land bridge must have existed at that time, small grains of a mineral called zircon unearthed in ancient river bedrock in northern Colombia that originated in Panama and were 13 million to 15 million years old said. 'small grains of a mineral called zircon unearthed in ancient river bedrock in northern Colombia that originated in Panama and were 13 million to 15 million years old contend that a bridge, perhaps a transient one, was present since 13 to 15 million years ago,' said Montes. '
article_snippet.sent: Beds younger than about 13 to 15 million years contain abundant zircon grains with a typically Panamanian age,' said Montes. '
article_snippet.sent: Older beds do not. 'small grains of a mineral called zircon unearthed in ancient river bedrock in northern Colombia that originated in Panama and were 13 million to 15 million years old think these zircons were deposited by rivers flowing from the Isthmus of Panama when these zircons docked to South America, nearly 10 million years earlier than the date of 3 million years that is usually given for the connection.'