Is there a way to determine if the content displayed is from the last row of a grid?

Is there a way to determine if the content displayed is from the last row of a grid? I’m trying to create a list of authors for a bibliography. Some entries have a single author, some have multiple authors. If there are multiple authors, I want to put a comma between the authors’ names. However, I don’t want the comma to display after the last author in the series.

Any suggestions?

ExpressionEngine 2.11.6