The First Age of Reptiles? Comparing Reptile and Synapsid Diversity, and the Influence of Lagerstätten, During the Carboniferous and Early Permian

Terrestrial ecosystems during the Pennsylvanian (late Carboniferous) and Cisuralian (early Permian) are usually described in literature as being dominated by synapsids, mammal-line amniotes. The pelycosaurs (a paraphyletic grouping of synapsid families) have been considered more speciose, abundant, ecologically diverse than contemporary reptile-line However, this dominance has never subjected to quantitative testing accounting for sampling bias. Moreover, recent years amniote phylogeny undergone numerous revisions, with suggestions that varanopids recumbirostran microsaurs fall within reptiles, diadectomorphs may be pelycosaurian-grade synapsids. An examination local species richness (alpha diversity) synapsids reptiles at different spatial scales shows these taxonomic revisions substantial impacts on relative diversity patterns reptiles. Synapsids only found consistently through early Permian when using “traditional” taxonomy. updates produce estimates where reptile is consistent with, or some cases higher biases preservation affect patterns. Where favors smaller vertebrates, e.g., Richards Spur, South Grandfield, overwhelmingly dominate. If vertebrates expected make up bulk diversity, they do present day, such lagerstätten representative true Therefore, interval should reconsidered, First Age Reptiles.