emarkable diversity of fossil flowers from the early Paleocene (Danian) Salamanca Formation, Chubut, Argentina.

GANDOLFO, M. A.; JUD, N.A.; ARI IGLESIAS; WILF P.

Minnesota

Congreso; Botany 2018 Thriving with Diversity; 2018

Botanical Society of America

Gondwanan plant communities from the early Paleocene are poorly known, and this limitsour understanding of geographic variation in the recovery of plant communities followingthe end-Cretaceous extinction event. Recent work on well-preserved angiospermreproductive structures from the Salamanca Formation in Chubut Province, Argentina isproviding important new data on the composition for Patagonian floras. Over the last twoyears, we have described an extinct member of the Rhamnaceae and two extinct membersof Cunoniaceae based on fossil flowers. In parallel, we have described a new species ofMenispermaceae based on a fossil fruit and identified a new species of Azolla based onfertile sporophytes. There are at least 11 remaining flower morphotypes of uncertainaffinity from two fossil localities, Palacio del los Loros (PL2) and Rancho Grande (RG).Flowers from PL2 have pollen preserved in the anthers or on the perianth parts. All theflowers are less than 1 cm across and most of the undescribed types have reduced petals orlack petals. Nine of the 11 flower morphotypes have characters typical of core-eudicotangiosperms (one or two whorls of 5 perianth parts, sepals with three veins, andtricol(por)ate pollen). Two have characters typical of monocots (perianth parts in 3 andnumerous veins supplying the sepals). The description and identification of these flowerscontributes to a more complete understanding of the early Paleocene floras of southernSouth America and permits inferences about biogeographic connection and recoverydynamics in the southern hemisphere following the end-Cretaceous extinction event.