Inquiry methods have been successful in improving science literacy in students of all ages. Model-Based Inquiry (MBI) is an instructional model that engages students in the practices of science through the collaborative development of scientific models to explain an anchoring phenomenon. Student ideas are tested through engagement in content-rich tasks and the evaluation of alternative ideas and models. A MBI unit culminates in students constructing evidence-based explanations of the phenomenon. Here we present a MBI evolution unit developed and implemented in an introductory biology course for nonscience majors at a community college. Over a period of nine class meetings, students were immersed in the study of "Tiktaalik" roseae, a transitional fossil between fish and land tetrapods. During this unit students engaged heavily in the practices of modeling, argumentation, and explanation. We examined the development of their modeling abilities and found growth in this area. We encourage others to try MBI in their own science courses.