The detection of synoptical megatrends in the Phanerozoic fossil record requires a robust taxonomic database at the outset. However, large-scale taxonomic data are often unavailable or outdated, or insufficiently standardized, even for major macroinvertebrate groups. Additionally, large-scale syntheses usually require well-resolved genus-level data, which in turn is objectively defined by and anchored to its designated type species, making type species an indispensable part of taxonomic compilations. For the Class Bivalvia, large-scale, systematic compilations are available for all Phanerozoic genera, but a compendium of bivalve type species is lacking. Here, we provide a global, taxonomically standardized, and updated type species compendium of marine bivalves for the entire Phanerozoic. Our type species compilation enlists 2,822 valid genera, their temporal ranges, with details of the methods of typification. We further quantitatively evaluate whether the systematics of bivalve type species have been historically stable or not, using a modified “flux ratio”. Moreover, as type species are representatives of their genera, we statistically compare the longevity of the type species and its parent genus to assess whether the type actually represents the genus’s temporal range. Our results indicate that approximately 63% of original names assigned to bivalve type species have been reassigned. Moreover, only about 38% of bivalve type species span at least 50% of their genus’s temporal range, and the type species had their stratigraphic range at the early phases of the genus’s stratigraphic range. Our findings reiterate that, though type species are the representatives of respective genera, the temporal longevity of the types should not be used as a direct proxy for their generic longevity. Supplemental Data Table 1: https://journals.ku.edu/treatiseonline/libraryFiles/downloadPublic/351 Appendix 1: https://journals.ku.edu/treatiseonline/libraryFiles/downloadPublic/352
Sharma et al. (Thu,) studied this question.