Cone-shaped microfossils, such as Protohertzina and Ceratophyton, appeared in lower Cambrian strata and became ubiquitous elements of many fossil assemblages, as they were preserved in both skeletal forms as well as organic compressions. However, due to the absence of a unified descriptive protocol, cone-shaped microfossils of different origins are commonly ascribed to a single taxon lacking systematic value. Here, we combine comparative morphological methods and geometric-morphometric analysis in order to develop a general morphological classification of diverse Cambrian cone-shaped microfossils. Additionally, an interpretation of their possible functions is provided despite their vague affinities. The grasping spines (chaetae) of extant chaetognaths and claws of onychophorans and tardigrades are included in geometric-morphometric analysis to find out functional analogies of cone-shaped microfossils. By this method, a common morphospace is developed for recent and fossil cone-shaped elements and extreme morphotypes are identified. Among them, cone morphotypes I and IV (narrow straight and curved) can be identified as mouthparts similar to chaetognath grasping spines, whereas morphotypes II and III (broad straight and curved) are attributed to locomotory and protective appendages alike lobopodian claws and spines. In addition, growth series of these cone-shaped microfossils are introduced.
