Abstract Detail

Recent Topics Posters

DeWitt, Shelby [1], Araiza, Margarita [2], Kelly, Brooke [2], Ryberg, Patricia Elizabeth [3].

Species diversity and seasonality in a high-latitude Permian ecosystem.

During the Permian time period, the continent of Gondwana was dominated by the plant group Glossopteridales. The group is identified by the leaf Glossopteris which is tongue shaped with a distinctive midrib and anastomosing secondary venation. Varved sediments across Gondwana indicate that Glossopteris was deciduous. Both impression and permineralized forms of Glossopteris are found in Antarctica deposits which has allowed for plant reconstructions. Two impression specimens found in the Antarctic Skaar Ridge locality of the Beardmore Glacier have multiple layers in which vegetative Glossopteris leaves alternate layers with reproductive pollen structures. This study is to determine if there is a significant difference in species abundance between each layer. Four different genera, Glossopteris, Eretmonia, Arberiella, and scale leaves, were identified and counted on each layer. The species richness and diversity was calculated for each layer.
One specimen had four exposed layers with species richness of Glossopteris dominating the top (0.6) and third layer (0.65) while the second layer was dominated by reproductive structures (0.67). The second specimen had seven layers, two of which were dominated by Glossopteris (0.9, 0.62), the rest by reproductive structures (0.6–0.68). There were fewer Glossopteris leaves when pollen was abundant but scale leaves were the most abundant element on these layers.
The pristine preservational state of the Glossopteris leaves indicates that materials are autochthonous. The presence of exclusively male reproductive structures suggests that the glossopterid plant may have been monoecious with separate pollen and ovulate producing plants. No complete pollen cone was observed in the sediment signifying that sporophylls may become disarticulated after pollen was released. The layers that were dominated by reproductive material were actually dominated by scale leaves, which may not have been part of the pollen structure, but terminal leaves on a stem.
While there is no significant dominant genus between sterile and fertile layers, when scale leaves are not included in calculating species richness, the presence of reproductive genera is almost completely absent on layers dominated by Glossopteris. This may indicate the production of reproductive structures in alternating seasons, or Glossopteris leaves were shed twice in a season. In conclusion, these Skaar Ridge specimens provide support of seasonality of glossopterids, and also indicate that pollen structures were shed at a specific time during the season.

1 - Park University, Natural and Physical Sciences, 8700 NW River Park Dr, Parkville, MO, 64152, USA
2 - Park University, Natural and Physical Sciences, 8700 NW River Park Dr., Parkville, MO, 64152, USA
3 - Park University, Natural and Physical Sciences, 8700 NW River Park Drive, Parkville, MO, 64152

Keywords:
Permian
Glossopteris
Seasonality
Pollen.

Presentation Type: Recent Topics Poster
Session: P, Recent Topics Posters
Location: Exhibit Hall/Savannah International Trade and Convention Center
Date: Monday, August 1st, 2016
Time: 5:30 PM
Number: PRT017
Abstract ID:1206
Candidate for Awards:None