Abstract Detail

Ericaceae: Systematics, Ecology and Evolution

Smith, MacKenzie [1], Manchester, Steven [2].

Ericalean fruits from the Cenozoic of western North America.

Ericales is a large order today with 24 families and more than 11,545 species, but the fossil record is relatively sparse. Previously reported Cretaceous representatives establish the presence of this order about 90 million years ago, but the Cenozoic distribution of ericalean families remains poorly documented, with many reports based on leaf fossils providing limited systematic resolution. Here, we call attention to previously overlooked fossil representatives of the order from the Paleocene, Eocene and Miocene of western North America based on molds and impressions of capsular fruits. Some of the diagnostic features obtained from these fossils were not easily observable prior to the availability of CT scanning technology. The first fossils presented here are known from multiple molds from the Paleocene Fort Union Formation of Sand Draw, Wyoming and have unknown familial affinity. The closed capsules are found isolated and contain an apically flattened, five-pointed columella with apically cleft valves. At the center of each cleft, a piece of the valve extends inward along the septum covering the spaces in between the points of the star-shaped columella. Numerous small, elongate flattened seeds are seen in some of the locules. The second occurrence is represented by several compression/impression fossils from the middle Eocene Clarno Formation of north-central Oregon near the town of Antelope. These fruits are almost identical to those found in Sand Draw. No seeds are found with the fruits and all capsules are open. These fruits are found associated with (but not attached to) leaves serrated margins with the theoid tooth type characterized by a deciduous seta at the tip of each tooth, a condition confined to the Ericales, Asteropeiaceae, Bonnetiaceae and Caryocaraceae. The third example, known from a single specimen, is from the middle Miocene Latah Formation of Emerald Creek, Idaho. It is an infructescence borne on a raceme bearing close resemblance to the genus Oxydendrum (sourwood, Ericaceae). Today, this genus is monotypic and only found in the southeastern US. Together, these fossils expand our understanding of biodiversity through time, community structure (with association of other plant fossils from their localities) and geographic range changes.

1 - University of Florida, Biology, 220 Bartram Hall, P.O. Box 118525, Gainesville, FL, 32611, USA
2 - Florida Museum Of Natural History, Po Box 117800, Gainesville, FL, 32611, United States

Keywords:
Ericales
wetern North America
Cenozoic
fossils
fruits
capsules.

Presentation Type: Colloquium Presentations
Session: C07a, Ericaceae: Systematics, Ecology, and Evolution Part 1
Location: 114/Mayo Civic Center
Date: Tuesday, July 24th, 2018
Time: 10:45 AM
Number: C07a003
Abstract ID:528
Candidate for Awards:Isabel Cookson Award