Characterizing the people who participate in and contribute to face-to-face and digital paleontological practices furthers our understanding of citizen science as an activity with outcomes for science and society. The Paleontological Identity Taxonomy, a new analytical tool, allowed for characterizing members of three online social spaces (two Twitter networks and an online social website). The results indicate that the majority of participants were interested in paleontology, but not credentialed. We use these results to discuss the design of effective scientific learning and communication in online social spaces, including how to recognize and support the diversity of community members’ practice-based expertise.