Primates and Fossils: Understanding Geological Processes and Evolutionary History

1. Chapter 9Geology and Primate Origins

2. How to Become a Fossil • Taphonomy: The study of what happens to the remains of an animal from the time of its death to the time of discovery • Burial • Geologic processes • Biological processes

3. How to Become a Fossil (cont’d) Petrifaction Trace Fossils

4. The Importance of Context • Stratigraphy • Strata • The principle of original horizontality • The principle of superposition • The principle of cross-cutting relationships • The principal of faunal succession

6. The Importance of Context (cont’d) • The Geologic Time Scale (GTS) • The earth is ~ 4.5 billion years old • Human and primate evolution spans the last 65 million years (Cenozoic Era) • The GTS is divided into Eras, Periods, and Epochs

7. How Old is It? • Relative Dating Techniques • Lithostratigraphy • study/description of rocks in stratigraphic deposits • Tephrostratigraphy • Use of volcanic deposits in stratigraphy • Biostratigraphy • Chemical techniques within sites

8. How Old is It? (cont’d) • Calibrated Relative Dating Techniques • Geomagnetic Polarity • Normal vs. reverse polarity • The geomagnetic polarity time scale (GPTS) • Paleomagnetism • Sediments

9. How Old is It? (cont’d) • Chronometric Dating Techniques • Radiometric dating • Potassium-argon dating • Argon-argon dating • Fission track dating • Cosmogenic radionuclide techniques • Uranium Series techniques

10. How Old is It? (cont’d) • Chronometric Dating Techniques(cont’d) • Radiocarbon dating • Electron trap techniques • Thermoluminescence • Optically stimulated luminescence • Electron spin resonance

11. The Earth in the Cenozoic • Continents and Land Masses • 200 MYA the earth was divided into two major land masses • Laurasia: present-day North America, Europe, and Asia • Gondwanaland: Africa, South America, Antarctica, and Australia/India

12. Climate Change and Early Primate Evolution • Changes in the Paleocene: The origin of primates? • Plesiadapiforms • Small brains • Prognathic face • Postorbital bar • Diastema • Why Primates? • Visual predation

15. Climate Change and Early Primate Evolution(cont’d) True Primates of the Eocene Adapoids Omomyoids Continental Drift Strepsirhine-Haplorhine Split

16. Adapoids and Omomyoids • From around 54 mya, in the early Eocene • Two forms of primates emerged: Adapoids , the ancestors of Strepsirhines , and Omomyoids , ancestors of Haplorhines . • Adapoids – some nocturnal, some diurnal. • Small 0 3.5 ounces to 15 lbs.

17. Adapoid

18. Omomyoids • Perhaps as far back as 60 million years ago. • Large diversity.

19. CLIMATE CHANGE AND THE ORIGIN OF MONKEYS AND APES • The First Monkeys? • New World Monkeys • Old World Monkeys • What favored the origin of anthropoids? • The earliest apes

20. Climate Change and Early Primate Evolution Selection Pressures and the Divergence of Monkeys and Apes Evolution of brachiation Middle Miocene forests Dental evidence - a dietary shift

21. Climate Change and Early Primate Evolution (cont’d) The Monkey Tale: What Happened to Primate Diversity in the Miocene? Changing environments r-selected vs. k-selected

22. Molecular Evolution in Primates • Molecular phylogeny: a tree of relatedness among taxonomic groups based on a gene or protein • Molecular clock • Calibrated • Rate consistency