Answer: The USCIS acknowledged that an alien applicant does not have to be the first author on an article to claim credit for it, and to apply for Green Card in the EB1 immigrant categories. This is because USCIS knows “the inherently collaborative nature of modern scientific inquiry, in which researchers rarely labor in isolation,” as indicated in an AAO decision.
But the USCIS Service Centers do send Request For Evidence (RFE) letter asking for proof that the alien beneficiary is a key independent researcher in a group project. Therefore, you should clearly document your role in a research team, especially if you are not first author on articles that result from your project or research work. (also see http://www.greencardapply.com/question/question07/question07_1205.htm)