Abstract Detail

Mesozoic and Cenozoic plant evolution and biotic change: A symposium in honor of Ruth Stockey

Tomescu, Alexandru M.F. [1].

Looking behind the tracheophyte curtain: a renewed focus on the bryophyte fossil record.

The scarce bryophyte fossil record was once thought to reflect low preservation potential determined by the delicate nature of the plants. More recently, there has been increasing realization that the preservation potential of bryophytes is on par with that of vascular plants, as suggested by resilient chemistry of their cell walls and demonstrated by experiments simulating taphonomy. In this perspective, the spottiness of the bryophyte fossil record appears to be largely due to a lack of search image and of overall focus on this group in paleobotanical studies. Much to the contrary of these trends, work on the diverse Cretaceous and Eocene permineralized tracheophyte floras of western North America by Ruth Stockey and collaborators has also drawn attention to an abundant presence of fossil bryophytes. Over the last five years, our studies of these floras have revealed a broad bryophyte diversity and characterized several new taxa. The Appian Way locality has yielded a new Eocene family of leafy liverworts, adding to the limited fossil record of the group. The Early Cretaceous Apple Bay locality has produced thalloid liverworts and numerous mosses. The Apple Bay mosses characterized to date represent the oldest unequivocal Leucobryaceae and Polytrichaceae, expanding the stratigraphic ranges and providing minimum ages for these lineages. Two other Apple Bay mosses represent a new family of extinct pleurocarps with uniquely tricostate leaves, which may have had a circumboreal distribution throughout the Mesozoic. Some of these mosses have yielded the oldest or only known fossil records of delicate structures such as gametangia and gemmae. Additional mosses currently being characterized from Apple Bay include a type with tristichous phyllotaxis and two more tricostate types. This impressive amount of diversity now ranks the Apple Bay flora among the most diverse fossil bryophyte floras worldwide and can contribute significantly to understanding of evolution in different bryophyte lineages. Currently, we are starting to incorporate fossil taxa characterized at Apple Bay in studies of phylogeny. More importantly, careful documentation of bryophyte diversity, initiated by studies of the Vancouver Island floras, has stimulated renewed efforts in bryophyte paleobotany that have led to the discovery of additional bryophyte paleofloras in the Early Cretaceous of California (which may soon rival the Apple Bay flora in bryophyte diversity) and the Jurassic of Patagonia. The emerging picture is that of a high potential for future discoveries of fossil bryophytes, fueled by renewed interest and supported by an updated search image.

1 - Humboldt State University, Department of Biological Sciences, 1 Harpst Street, Arcata, California, 95521, USA

Keywords:
Bryophyte
fossil
Cretaceous
Eocene
Jurassic
moss
fossil record.

Presentation Type: Colloquium Presentations
Session: C6
Location: Salon 5/The Shaw Conference Centre
Date: Wednesday, July 29th, 2015
Time: 3:45 PM
Number: C6009
Abstract ID:379
Candidate for Awards:None