תוספות ברכות כט: ד"ה "מברך על הפתיתין"
. . .וכן הלכה כרבי יוחנן דהא רב ורבי יוחנן הלכה כרבי יוחנן וכל שכן לגבי רב הונא שהלכה כמותו שהיה תלמידו של רב דדוקא באמוראי בתראי אמרינן הלכה כבתראי.
The law follows R. Yochanan since when Rav and R. Yochanan disagree the law follows R. Yochanan, all the more so here when he is arguing with Rav Huna, Rav's student. It is only with regards to the later Amoraim that we says the law follows the last authority.
[Translation by Rabbi Steve Greenberg]
Suggested Discussion Questions:
What is the significance of the law following the later authority?
How does this relate to the statement of R. Zeira?
Why should this principle apply only during specific periods?
Time Period: Medieval (Geonim through the 16th Century)