Early proliferation of avicularia in the cretaceous cheilostome bryozoan wilbertopora a diversification event guided by ecological exploration

Leventhal, S., Stowe, K., and Simpson, C., 2023. Early proliferation of avicularia in the Cretaceous cheilostome bryozoan Wilbertopora: a diversification event guided by ecological exploration. In: Bryozoan Studies 2022: Proceedings Of The Nineteenth International Bryozoology Association Conference (Dublin, Ireland, 22-26 August 2022) (1st ed.), (Eds, Key, M. M., Porter, J., S., & Wyse Jackson, P. N. ). CRC Press. doi.org/10.1201/9781003454915-10

Cheilostome bryozoans are a diverse clade of colonial animals that first appeared during the Jurassic period. For the first 100 Myr of their existence, colonies of cheilostomes were monomorphic, composed entirely of autozooids. Divergent body types, termed avicularia, first appeared in colonies in the early Cretaceous period, in the genus Wilbertopora. Over the course of the Cretaceous, Wilbertopora diversified into 27 species, spanning the early Albian through Maastrichtian stages. In this study, we quantify autozooid and avicularia shape and size to evaluate how the morphological disparity of zooid types in colonies changes over the course of Wilbertopora’s diversification. We find that taxonomic diversity and morphological disparity are largely decoupled, with disparity outpacing diversity for much of Wilbertopora’s evolutionary history. Increases in disparity are primarily driven by evolution of avicularian morphology, indicating that Wilbertopora’s avicularia may have served an array of purposes in different lineages.

---