Abstract Detail

Paleobotanical Section

Hieger , Timothy J [1], Serbet, Rudolph [2], Harper , Carla J [3], Taylor, Thomas N [4], Taylor, Edith L [4].

Cheirolepidiaceae diversity: an anatomically preserved pollen cone from southern Victoria Land, Antarctica.

To date, the vast majority of material described for the extinct conifer family, Cheirolepidiaceae, has been reported predominately from compression/impressions and mostly Cretaceous sediments, and with even fewer studies from Jurassic localities. Although the presence of permineralized Jurassic plants  are rare, the 2012 Antarctic field season yielded a diverse assemblage of plant and animal remains from Carapace Nunatak (Lower Jurassic), southern Victoria Land. The complex geology of Carapace Nunatak reflects a volcanically active environment during the Jurassic. The chert specimens are composed of varying sedimentary deposits including siliceous blocks of alternating fusinized layers of plant remains with fine-grained sediments and heterogeneous blocks of light-to-dark contrast with various plant and animal remains. Among these elements are ferns, conifers, cycadophytes, and arthropods which co-occur within isolated chert blocks, and several cheirolepidiaceous pollen cones. The purpose of this contribution is to describe the first permineralized anatomically preserved cheirolepidiaceous pollen cones from the Jurassic of Antarctica and the Southern Hemisphere. Specimens were prepared using standard serial cellulose acetate peel techniques using transmitted light microscopy and SEM analysis. The cones are ellipsoidal, up to 5.5 mm long and consist of helically arranged microsporophylls, each with a slender stalk containing a single vascular bundle; the distal lamina is peltate and most closely resembles those of the Classostrobus-type. Up to 6 pollen sacs are arranged in a whorl at the base of the sporophyll stalk.  In situ pollen is of the Classopollis-type with a distal cryptopore, sub-equatorial furrow (rimula), internal equatorial striations, and a proximal trilete. Individual pollen grains range from 32-28 µm in equatorial diameter with an average diameter of 30 µm; a few outlier grains are up to 60 µm and some as small as 18 µm in diameter. In addition to these well-preserved pollen cones there is a large diversity of vegetative conifer remains within the Carapace material including leaf and stem fragments. The discovery of the pollen cones in combination with vegetative remains, provides additional information on the reproductive biology of the Cheirolepidiaceae and increases the probability of developing a whole-plant concept for this Jurassic permineralized conifer. This study bridges the gap between southern and northern Gondwanan continents and provides evolutionary insight into this biogeographically important extinct conifer group.

1 - University of Kansas, Department of Ecology and Evolutionary Biology, and Biodiversity Institute, 1200 Sunnyside Ave, Room 6022, Lawrence, KS, 66044, USA
2 - University Of Kansas, Division Of Paleobotany, NAT HIST MUS & BIODIV RES INST, 1200 Sunnyside Avenue, Lawrence, KS, 66045, USA
3 - University Of Kansas, Ecology And Evolutionary Biology, 2041 Haworth Hall, 1200 Sunnyside Avenue, Lawrence, KS, 66045, USA
4 - University of Kansas, Department of Ecology and Evolutionary Biology, and Biodiversity Institute, 1200 Sunnyside Ave, Lawrence, KS, 66045, USA

Keywords:
Cheirolepidiaceae
pollen cone
conifers
Antarctica
Classopollis
Classostrobus
Jurassic.

Presentation Type: Oral Paper:Papers for Sections
Session: 8
Location: Whitewater/Grove
Date: Monday, July 28th, 2014
Time: 9:00 AM
Number: 8003
Abstract ID:604
Candidate for Awards:Isabel Cookson Award,Maynard F. Moseley Award