Master's Theses

Department

Biology

Degree Name

Master of Science (MS)

Abstract

Fossilized anthoecia, nutlets, and achenes were collected from four localities of late Miocene age in northwestern Ellis County, Kansas. Taxa recovered include: Boraginaceae: Biorbia fossilia (Berry) Cockerell, Cryptantha coronoformia (Elias) Segal, C. auriculata (Elias) Segal, and Prolithospermum johnstonii Elias; Cyperaceae: Scleria danksiae Ballenger, sp. nov.; Poaceae: Berriochloa aspera Thomasson, B. cf. B. glabra (Berry) Elias, and fragments of a number of undetermined species of Berriochloa. Scanning electron microscopy was used to study the anatomy of the pericarp of the achenes of living and fossil Scleria. Living specimens are characterized by an external nacreous surface. This surface has been eroded from the fossils exposing inflated, rachymorphous-like cells. Internal to these cells in both fossil and extant specimens is a layer of hollow, thin-walled cells. The innermost surface of the achene pericarp of both living and fossil forms is lined with apparent sclerenchymatous cells that have their long axis oriented perpendicular to the height of the achene. The overall size, shape, and cell wall detail of Scleria danksiae is similar to living Scleria canescana, Boeck. S. scindens, Nees and S. secans (L.) Urban. Sediments at the study sites probably were deposited by a combination of wind and water. Although clear evidence (e.g. primary structures) of either type of deposition is lacking in the lower two beds at site JRT 49 a and b and lower three beds at site JAB 1 (beds at all three sites consist of silt, sand, and ash), the upper beds at JRT 49 and JAB 1 suggest two episodes of stream depositions, both containing interclasts up to .125 m. in diameter. At JRT 48, sediments are probably stream deposited based on the presence of coarse sands with angular interclasts. The presence of hackberries, borages, sedges, and abundant grasses suggests a warm, semi-arid to sub-tropical environment with deciduous forests along rivers thinning to savanna areas nearby. No identifiable vertebrate remains were recovered, but previous work involving the late Tertiary biota of Kansas indicates a more mesic environment than what is not characteristic of this region. The age assigned to the fossil plants is tentative because of the absence of vertebrates. However, the presence of Prolithospermum johnstonii suggests that JRT 48 is probably Hemphillian in age, whereas JRT 49a and b and JAB 1 may be Clarendonian based on the large collection of Cryptantha coronoformis.

Keywords

Biology

Advisor

Joseph Thomasson

Date of Award

Summer 1988

Document Type

Thesis - campus only access

Rights

© The Author(s)

Comments

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