Lately there has been a wave of criticism of the concept of living fossils. First, recent research has challenged the status of paradigmatic living fossil taxa, such as coelacanths, cycads, and tuataras. Critics have also complained that the living fossil concept is vague and/or ambiguous, and that it is responsible for misconceptions about evolution. This paper defends a particular phylogenetic conception of living fossils, or taxa that exhibit deep prehistoric morphological stability; contain few extant species; and make a high contribution (...) to phylogenetic diversity. The paper shows how this conception of living fossils can make sense of recent research on contested cases. The phylogenetic living fossil concept has both theoretical and practical importance: theoretical, because it picks out an important explanatory target for evolutionary theory; and practical, because it picks out taxa that we might wish to prioritize for conservation. The best way to defend the concept of living fossils is to get clearer about the reasons for defending living fossil taxa. (shrink)

Despite the iconic roles of coelacanths, cycads, tadpole shrimps, and tuataras as taxa that demonstrate a pattern of morphological stability over geological time, their status as living fossils is contested. We responded to these controversies with a recommendation to rethink the function of the living fossil concept. Concepts in science do useful work beyond categorizing particular items and we argued that the diverse and sometimes conflicting criteria associated with categorizing items as living fossils represent a complex problem space associated with (...) answering a range of questions related to prolonged evolutionary stasis. Turner defends the living concept against a variety of recent skeptics, but his criticism of our approach relies on a misreading of our main argument. This misreading is instructive because it brings into view the value of three central themes for rethinking the living fossil concept—the function of concepts in biology outside of categorization, the methodological importance of distinguishing parts and wholes in conceptualizing evolutionary phenomena, and articulating diverse explanatory goals associated with these phenomena. (shrink)