Interesting piece in the NYT about the commingling of Eurasian species American after the "discovery" of the Americas.  Slightly odd as well, for apparently it all starts in 1620 or so (Jamestown) and or 1621 with Plymouth and the Mayflower:

Until the arrival of the Mayflower, continental drift had kept apart North America and Europe for hundreds of millions of years. Plymouth Colony (and its less successful predecessor in Jamestown) reunited the continents. Ecosystems that had evolved separately for millennia collided. The ensuing biological tumult – plants exploding over the landscape, animal species spiking in population or going extinct – had consequences as profound as those from the cultural encounter at the center of Brownscombe’s painting.

Rather a US centric view methinks….the arrival of smallpox ws the defining moment in the depopulation of the Americas and according to Jared Diamond that arrived in 1502 with a slave landed from Cuba.

American Indians were ambitious, sophisticated landscape managers. In South America, they drained vast areas of wetland; scattered networks of raised agricultural fields in Bolivia, Colombia and the Guianas; and converted much of Amazonia into an "anthropogenic" forest – a mix of gardens, orchards and agricultural forests. Visitors to the Andes still gawp at the Indian terraces that carpet the highlands – more than 2,000 square miles of them in Peru alone, according to the geographer William M. Denevan, most of them at more than 9,000 feet.

Again, a rather strange ommission. These different Amerind cultures had almost no knowledge of each other. Incas didn’t know about Aztecs, neither knew about the N Americans nor the Maya.
OK, OK, quibbles maybe, but if one is going to write about the impact of Eurasia on the Americas, shouldn’t you start from the right place? The right time?