Abstract Detail

Fossil plants at the intersection of evo-devo and phylogeny: celebrating the contributions of Gar W. Rothwell to biodiversity and evolution

GANDOLFO , MARIA A [1], NIXON, KEVIN C [2], Crepet, William [2], Grimaldi, David [3].

A Late Cretaceous Fagalean Inflorescence preserved in amber from New Jersey, USA.

We described a pistillate inflorescence preserved in amber from the Early Upper Cretaceous (Turonian, -90-94 million years ago) of central New Jersey, USA. The inflorescence is a pedunculate, pistillate three-flowered dichasium, subtended by two toothed glabrous bracts opposite to each other; the peduncle is covered with glandular hairs. The flowers are hypogynous, zygomorphic, and syncarpous; their perianth is funnelform and composed of six free lanceolate tepals. The central flower is bicarpellate and its ovary is flattened and have lateral margins covered with hairs. The lateral flowers are tricarpellate, triangular in cross-section, and have flexuous styles and free stigmas. The flowers are subtended by four distinct cupule valves that are biseriate. Morphologically, the inflorescence has features of Nothofagaceae, but also has distinctive characters that suggest it is intermediate between Nothofagus and other Fagales. We investigate the relationships of this new fossil by mapping its characters onto a widely accepted molecular-based tree of modern basal Fagales using standard methods of character optimization. The phylogenetic position of this fossil inflorescence is determined by the presence of unique features that are only found in “basal” members of Fagales. Based on the available evidence, the fossil is best interpreted as an early stem Fagales, with features that suggest a transition from a more generalized Nothofagus-like fagalean ancestor, with some exclusive plesiomorphic features. The presence of the enlarged perianth and flexuous styles also indicates the possibility of insect pollination, which has been lost in all Fagales except for some members of subfamily Castaneoideae in Fagaceae sensu stricto (that otherwise are very different from this fossil). The poorly developed, bract-like cupule valves are interpreted as primitive (i.e., incipient) or as reduced from more developed cupules that are found in most modern Fagaceae and Nothofagaceae. The fossil is the oldest known inflorescence (flowers) and provides insight into characteristics of the early stem Fagales, the evolution of the cupule in Nothofagaceae and Fagaceae, and a reasonable biogeographic hypothesis for the differentiation of Southern (e.g., Nothofagaceae) and Northern Hemisphere Fagales. It also suggests that early stem Fagales that had not yet differentiated into modern families were present in the Late Cretaceous of North America.

1 - Cornell University, 410 Mann Library Building, Plant Biology Section, SIPS, Ithaca, NY, 14853, United States
2 - Cornell University, 412 Mann Library Building, Plant Biology Section, SIPS, Ithaca, NY, 14853, United States
3 - American Museum Of Natural History, Division of Invertebrate Zoology, Central Park West at 79th Street, New York, NY, 10024-5192, United States

Late Cretaceous.

Presentation Type: Colloquium Presentations
Abstract ID:871
Candidate for Awards:None

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