Purdue University Graduate School
PhD_Thesis_Zehady_Abdullahkhan_3May2020.pdf (8.4 MB)


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posted on 2020-05-04, 00:37 authored by Abdullah Khan ZehadyAbdullah Khan Zehady

The Geologic TimeScale Creator (TSCreator) project has compiled a range of paleo-environmental and bio-diversity data which provides the opportunity to explore origination, speciation and extinction events. My PhD research has four major interconnected themes which include the visualization methods of evolutionary tree and the impacts of climate change on the evolution of life in longer and shorter timeframes: (1) Evolutionary range data of planktonic foraminifera and nannofossils over the Cenozoic era have been updated with our latest geological timescale. These evolutionary ranges can be visualized in the form of interactive, extensible evolutionary trees and can be compared with other geologic data columns. (2) A novel approach of integrating morphospecies and lineage trees is proposed to expand the scope of exploration of the evolutionary history of microfossils. It is now possible to visualize morphological changes and ancestor-descendant lineage relationships on TSCreator charts which helps mutual learning of these species based on genetic and bio-stratigraphic studies. (3) These evolutionary datasets have been used to analyze semi-periodic cycles in the past bio-diversity and characteristic rates of turnover. Well-known Milankovitch cycles have been found as the drivers of fluctuations in the speciation and extinction processes. (4) Within a shorter 2000-year time period, global cooling events might have been a factor of human civilization turnover. Using our regional and global cultural turnover time series data, the effect of climate change on human culture has been proposed. The enhancement of the evolutionary visualization system accomplished by this research will hopefully allow academic and non-academic users across the world to research and easily explore Earth history data through publicly available TSCreator program and websites.


Degree Type

  • Doctor of Philosophy


  • Earth, Atmospheric and Planetary Sciences

Campus location

  • West Lafayette

Advisor/Supervisor/Committee Chair

Dr. Wen-wen Tung

Advisor/Supervisor/Committee co-chair

Dr. James Ogg

Additional Committee Member 2

Dr. Robert Nowack

Additional Committee Member 3

Dr. William S. Cleveland

Additional Committee Member 4

Dr. Ananth Grama