Greetings,
A VERY interesting find mi amigo! Yes it looks like a bronze coin of Caracalla. How did it get to where you found it is the real question.
There are good evidences of pre-Columbian contact with the Old World, but unfortunately Roman coins are not terribly convincing evidence due to the fact that they are terribly common. Caracalla is less common, but Roman coins can be purchased on Ebay for $1 each and even less in the uncleaned condition, especially late Roman bronzes which this is one example. Roman coin collectors even get these by the bucket-fuls from THers in Europe, the Middle East and North Africa and give them to school children as gifts, learning aids and keepsakes. It would be unusual to find a Caracalla in among the uncleaned lots, but not that un-heard of. That is why I ask where you found it - you don't have to be specific here, but if it turned up in a school yard, park where children play, or other area where children congregate and play, it is very likely that the coin was lost by a child in modern times. If on the other hand the coin was found in some area where no modern activity has taken place, no homes since the Europeans arrived, etc or was rather deeply buried, as in turned up by a bulldozer having scraped off several feet of topsoil and so forth, or more importantly close to a navigable river or port (not a man-made port mind you) then it is possible the coin was indeed lost in ancient times. As to whom may have transported it to America in ancient times, by the time of Caracalla (who was a Phoenician by birth) the best candidate Carthage had been destroyed; however it is very likely that one or more Roman ships or a Phoenician ship from the homeland of Caracalla may have accidentally made the crossing, thus stranding these Mediterranean folk in a very strange new land. So the actual site where it was found, and the depth, relationship of the site to nearby navigable rivers or sea ports, is a very important factor in determining whether the coin was dropped in modern times or in ancient times.
If you reported the coin found in an ancient Indian midden of clam shells, for instance, that presents a very strong case for ancient deposition - if found in a school playground, then it is far more likely to have been dropped there last Tuesday. I am very interested in your find, please keep me posted. 8) Cool find in any case, not your every day item!
your friend,
Roy A. Decker - Oroblanco