Terri J. Cleary, Roger B. J. Benson, Susan E. Evans & Paul M. Barrett (2018)
Lepidosaurian diversity in the MesozoicâPalaeogene: the potential roles of sampling biases and environmental drivers.
Royal Society Open Science 2018 5: 171830
DOI: 10.1098/rsos.171830
Lepidosauria is a speciose clade with a long evolutionary history, but there have been few attempts to explore its taxon richness through time. Here we estimate patterns of terrestrial lepidosaur genus diversity for the TriassicâPalaeogene (252â23âMa), and compare observed and sampling-corrected richness curves generated using Shareholder Quorum Subsampling and classical rarefaction. Generalized least-squares regression (GLS) is used to investigate the relationships between richness, sampling and environmental proxies. We found low levels of richness from the Triassic until the Late Cretaceous (except in the KimmeridgianâTithonian of Europe). High richness is recovered for the Late Cretaceous of North America, which declined across the KâPg boundary but remained relatively high throughout the Palaeogene. Richness decreased following the EoceneâOligocene Grande Coupure in North America and Europe, but remained high in North America and very high in Europe compared to the Late Cretaceous; elsewhere data are lacking. GLS analyses indicate that sampling biases (particularly, the number of fossil collections per interval) are the best explanation for long-term face-value genus richness trends. The lepidosaur fossil record presents many problems when attempting to reconstruct past diversity, with geographical sampling biases being of particular concern, especially in the Southern Hemisphere.