41585
The formation of the Isthmus of Panama , about 3 Mya , joined South America to North America , allowing canids to invade South America , where they diversified .
 Isthmus of Panama, South America, North America, South America
Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
Text: {0} 
Answer:
 Isthmus of Panama, South America, North America, South America