1. PALEONTOLOGY How do we locate, recover, and date fossil remains?
What are the features of the primate skeleton, and how can our knowledge of them help us identify fossil remains?

2. Stephen Jay Gould
“…paleontologists have discovered several superb examples of intermediary forms and sequences, more than enough to convince any fair-minded skeptic about the reality of life's physical genealogy." (Natural History, May 1994)
23 Books: Ontogeny and Phylogeny, Ever Since Darwin, The Panda’s Thumb, The Mismeasure of Man, Hen’s Teeth and Horse’s Toes, The Flamingo’s Smile, Time’s Arrow, Time’s Cycle, An Urchin in the Storm, Wonderful Life, Bully for Brontosaurus, Eight Little Piggies, Dinosaur in a Haystack, Full House, Questioning the Millennium, Leonardo’s Mountain of Clams and the Diet of Worms, Rocks of Ages, The Lying Stones of Marrakech, The Structure of Evolutionary Theory, I Have Landed, The Hedgehog, The Fox, and the Magister’s Pox
US paleontologist, evolutionary biologist, historian of science ( )

3. THE FOSSIL RECORD: PRESERVATION
Not a representative sample of all of the species that have lived on earth
Some species and body parts preserve better than others
TAPHONOMY = study of the processes that affect the remains of dead animals

4. THE FOSSIL RECORD: FINDING FOSSILS
* More likely to be found in areas with little vegetation and lots of erosion (i.e. lake bottoms)
* Due to issues regarding the preservation and discovery of fossils, the fossil record of early primates is “limited and spotty”

5. DATING CONCEPTS
PALEONTOLOGY = study of ancient life through the fossil record
Anthropology & Paleontology --interested in establishing a chronology for primate and human evolution
Much dating depends on STRATIGRAPHY = study of the sequence of geographical layers

6. RELATIVE DATING
Uses natural layers or strata to establish a relative chronology—material from this layer is older than the material from that layer
Association with known fossils, biostratigraphy = most common method of fossil dating

7. ABSOLUTE DATING (p.202!)
Produce dates in years, so differences in age can be quantified
Radiometric techniques = based on known rates of radioactive decay in elements found in or around fossils
Radiocarbon (Half-life of 14C is 5,730 yrs.), dates organic remains from 100s to 40,000 ya (half life = time needed for ½ amount of 14C to decay). Over 130 labs worldwide!
Potassium Argon (K/A) dates volcanic rock from about 500,000 to billions ya

8. Lawrence Livermore National Laboratory
CAMS: The Center for Accelerator Mass Spectrometry

9. ABSOLUTE DATING
Electron Spin Resonance (ESR) = Measures # of electrons excited to higher energy levels by natural radiation & trapped at those levels, dates teeth & cave deposits from about 1000 ya to 1 mya
Luminescence = Same as ESR, but trapped energy is released using heat or light, dates pottery, bricks, burned rock from about 5000 ya to 1 mya

10. Electron Spin Resonance (ESR) Facility: UCSC
examines structure & properties of metal-containing inorganic complexes, peptides, proteins, enzymes, nanoparticles & membranes
Bruker ELEXSYS 580 X-band spectrometer operates in either continuous-wave or pulsed mode, with variable temperature control
Useful for limited sample sizes often encountered in biology
Managed by Professor Glenn Millhauser (Dept. of Chemistry and Biochemistry)

11. Hypothetical Stratigraphic Sequence
If Humanlike remains were found between two layers of volcanic rock, how could we date the remains?
K/Ar (potassium/argon) dating
Remains are younger than the volcanic deposit below and older than the one above

12. Absolute Dating Techniques
Abbrev-iation
Materials Dated
Effective Time Range
Carbon 14
14C
organic materials
up to 40,000 years
Potassium-Argon
K/A and 40K
volcanic rock
older than 500,000 years
Uranium Series
238U
minerals
between 1,000 and 1,000,000
Thermo-luminescence TL
rocks and minerals
between 5,000 and 1,000,000 years
Electron Spin Resonance
ESR
between 1,000 and 1,000,000 years

13. Continents At End of the Mesozoic
Placement of the continents at the end of the Mesozoic and beginning of the Cenozoic, about 65 mya

14. Cenozoic Timescale

15. Taphonomy
What was found: accumulation of bones, including hominid bones, in South African caves
Non-hominid bones, antlers, teeth: early tools used by bipedal “killer apes” to hunt and forage?
What taphonomic research now shows: “killer apes” were prey not predator!
Reconstruction shows: leopard eating remains of early hominid in tree above entrance to cave

16. Skeletal Anatomy
Skeletons of:
Modern Human
Gorilla
Domestic Cat

17. Comparative Primate Anatomy
Differences in stance:
Indri: Vertical clinging and leaping
Macaque: Generalized quadrupedalism
Gorilla: Semi-erect knuckle walking
Chimp: Knuckle-walking and tree climbing
Human: Fully erect bipedalism

18. Cranial Anatomy
Hominoid primates share same overall construction of the skull
Proportions of the various bones of the skull, however, vary, as do the expression of various ridge-like features on surface of the bone
What do you think are some of the reasons for these differences?
Brow ridge
Frontal
Sagittal crest

19. Axial Skeleton (Trunk) of OW Primates

20. Changes in the anatomy of the trunk

21. Hominoid Comparative Anatomy

22. Changes in Human Skeleton
Skull more balanced on spine
Smaller neck muscles
Spine articulates under skull
Multiple curves of spine
Narrower rib cage

23. Changes in Human Skeleton (cont.)
Shorter wider pelvis
Proportionately longer legs
Upper leg angled inward so knees closer to midline
Big toe in line with other toes
Center of gravity in pelvic basin