Locating paleoanthropological sites
How are sites found?
 Systematic surface surveys and
reconnaissance
 Remote sensing: satellite imaging
and ground penetrating radar
How do we recover
paleoanthropological remains?
 Excavations
 Surface collections: 100% surface
collection
How do we find sites
The Geologic Profile
Taphonomy
• Defined taphonomy in 1940 as:
– The study of accummulation and
modification of osteological
assemblages from a site formatyion
perspective
Ivan Antonovich Yefremov or
Effremov
• Taphonomy – from two Greek
words:
– Taphos (death) and onomia
(study or knowledge)
• Study of death or how organisms
die and become incorporated in the
fossil record
Goals of Taphonomy
• Reconstruct paleoenvironments
• Determine and establish factors
that cause the differential
destruction or attrition of bones
• Determine and establish
selective transportation of
remains in an assemblage
• Establish agents of bone
accumulations and
modifications: human vs.
nonhuman
Fossilization process and recovery
Organism dies or
sheds body parts
NECROLOGY
Organic (soft tissue)
parts decay
Sedimentary process
interact with
remaining (inorganic)
parts
BIOSTRATINOMY
Burial process
Chemical alteration
and lithification
Recovery/collection
process
DIAGENESIS
• How do remains become incorporated
into the geologic record?
Examples of taphonomic variables
Weathering
Cracks, split-lines, and
exfoliation (surface flaking).
Desquamation Bleached and/or charred-like
surfaces.
Splitting
Open and deep breaks,
commonly longitudinal to bone
fiber.
Staining
Modification by microorganisms
(vein-like, flake-like structures,
and crusty structures.
Cracking
Narrow breaks, longitudinal
and/or perpendicular to bone
fibre.
Insect traces
Clusters of mandible marks
(grooves) or isolated grooves
associated with pit marks
Flaking
Outermost layers of bone
Boring
surfaces break away or peel off.
Deep holes bored by insects (lack
of crushed bone on bottom)
Etching/pitting
Localized form of corrosion
(multiple holes or cavities).
Slight color variation.
Trampling
Scratches (randomly oriented),
grooves and fragmentation
(multiple splinters)
Abrasion
Polishing resulting in rounding
of bone elements and loss of
surface details. Shallow
scratches (thin and linear
grooves)
Dendritic patterns of shallow
channel-like marks.
Gnawing
Punctures (oval depressions with
crushed bone on bottom),
scooping marks (removal of bone
material), and set of parallel
grooves.
Root Etching
Cracking, splitting & flaking
Microorganism staining
Orange lichen (A&B) mainly genus Caloplaca); Black lichen (C) –
caused by Peltura and probably Caloplaca growing in upper
surface of the other; and orange lichen with green algae and veinlike structures of unknown lichen (D)
Microscopic bone surface modification (Locality 7S)
A. Chemical weathering
B. Root etching
Microscopic bone surface modification
A. puncture mark
B. Striations (groove)
Gnawing (groove marks)
Rodent-gnawed bones. (A) Elongated parallel grooves along one of the bone’s
margins (30x); and (B) Horn core fragment showing extensive gnawing and
pitting along one of its margins (30x).
What is paleoecology?
A study of past ecological settings using proxy data
• Ecology
– Source: currently living
organisms in an intact
ecosystem
– Precise and comprehensive
description of environments
and organism in an ecosystem
– Potentially all faunal and floral
components are available in
the observed biocenosis
• Paleoecology
– Source: Fossil assemblages
– Mostly characterization of a
former milieu: making
inferences on environmental
and organismic fact
– Fossils are the only data
available (nature of the fossil
record)
Paleoecological research
• Aims
– at analyzing long-term past ecological trends
(development of communities in certain
environments)
• Understanding
– Antemortem events: all processes that affected a
fossil organism
– Postmortem events: taphonomic approach studying
diagenesis
Linking the past & present
After Foley (1987)
Things to consider in paleoecological studies
after Hardt et al. 2007
Terms
• Biocoenosis:
– group of co-occurring live organisms
• Thanatocoenosis:
– group of co-occurring dead organisms
Bone assemblage analyses
• Characterizing the vertebrate accumulations
– How did the assemblage form
• Taphonomic characteristics of the assemblage
– Identifications
– counts of taxa and body parts
•
•
•
•
•
•
Number of specimens (NISP)
Number of individuals (NI)
Number of species
Minimum number of identified individuals (MNI)
Relative abundance of species
Body size, age spectra
– mapping of spatial arrays of bones in situ
• Skeletal articulation
• Representation of skeletal parts
• Size of bone accumulation, spatial density, pattern of arrangement
– description of bone modification
Quantifying abundances of taxa in the fossil record for paleoecological
studies
•
Basic Measurements
– Number of Identified Specimens
(NISP)
• Previously used as a standard measure
of taxonomic abundance – e.g. Tabun
cave (Bate, 1937)
•
Issues
– Differential procurement affects
count “Schlepp effect”
– NISP vary from species to species
due to identification process
– Differential breakage pattern
(butchering techniques, size, etc)
– Differential preservation
– Completeness of the remains
– Collection techniques
0.0
Skeletal parts
Skeletal parts representation at Localities 8 and 9, Upper Laetolil Beds
Vertebrae
Tibiae
Teeth
Scapulae
Ribs
Radius
Phalanges
Pelvis
Metapodials
Mandibles
Humeri
Horncores
Femora
Skull
Calcanei
Tali
% MNE
25.0
20.0
15.0
10.0
5.0
Locality 8
Locality 9
Fossil bone orientation pattern at Localities 8 and 9 Upper Laetolil Beds
What types of environments are Ideal
for fossilization process?
A
C
B
D
Some fossil faunal remains from Localities 8 and 9, Upper Laetolil Beds.
How do we know the age of archaeological
or paleoanthropological remains?
Anthropologists rely on
geochronologists for dating
process of sediments and
artifacts
 An accurate time scale in
paleoanthropology is very crucial for
the understanding the evolutionary
history of our species.
 The appreciation of reliable methods
of dating has the potentials to radically
alter interpretations of evolutionary
relationships.
Example of a stratigraphic
correlation placing fossils in
relative and absolute age
The Caves of Malapa, South Africa compared to Olduvai Gorge
Tanzania
Dolomitic vs. volcanic
derived sediments
Establishing the Antiquity of the finds

1.
There are two ways in which
paleoanthropologists may choose to determine
the age of any finds
Relative Dating Methods
•
•
•
Lithostratigraphy – correlation of rocks
characteristics over a large region
Tephrostratigraphy – correlation on the basis of
tephra (volcanic ash)
Biostratigraphy – correlation based on fauna
succession and their evolutionary history
2.
Calibrated Relative Dating Methods
(correlated to absolute chronology)
• Obsidian hydration
• Amino acid racemization
• Paleomagnetism (use of geomagnetic
polarity time scale)
1.
Chemical techniques
• F-U-N trio (Fluorine, Uranium, and
Nitrogen) in bone remains
Relative dating
•
The Principle of Original Horizontality: When sediments are laid down on
Earth’s surface, they form horizontal or nearly horizontal layers. This means that
non-horizontal rock layers were tilted or folded after they were originally
deposited.
•
The Principle of Lateral Continuity: Rock layers extend for some distance over
Earth’s surface—from a few meters to hundreds of kilometers, depending on the
conditions of deposition. The point is that scientists can relate layers at one location
to layers at another. This is critical for stratigraphic correlation (see below).
•
The Principle of Superposition: As layers accumulate through time, older layers
are buried beneath younger layers.
•
The Principle of Faunal Succession: This principle is attributed to William Smith,
an English engineer in the late 1700s. Smith noticed that the kinds of fossils he
found changed through a vertical succession of rock layers, and furthermore, that
the same vertical changes in fossils occurred in different places
Chronometric or Absolute Dating Method
• A technique that utilizes radioisotopic
calibration of different elements such as Carbon
(C), Potassium (K), and Argon (Ar)
• The method exploits some aspects of radioactive
decay of K and Ar, where initially an action sets
the clock to zero
– Such as heating of a rock containing Ar during
volcanic eruption, then radioactive decay steadily
accumulates, thus recording the passage of time.
Some radioactive elements used
PARENT ISOTOPE
HALF-LIFE
STABLE DAUGHTER
Uranium-235
704 Million Years
Lead-207
Potassium-40
1.25 Billion Years
Argon-40
Uranium-238
4.5 Billion Years
Lead-206
Thorium-232
14.0 Billion Years
Lead-208
Lutetium-176
35.9 Billion Years
Hafnium-176
Rubidium-87
48.8 Billion Years
Strontium-87
Samarium-147
106 Billion Years
Neodymium-143
Radiometric dating
• Radiometric dating involves the use of isotope
series, such as:
– rubidium/strontium
– thorium/lead
– potassium/argon
– argon/argon
– uranium/lead
• all of which have very long half-lives, ranging from 0.7
to 48.6 billion years.
Geomagnetic polarity
• Paleomagnetic dating of earth’s geomagnetic
polarity time scale (GPTS)
– Measures changes in periodicity and intensity of
earth’s magnetic field
– Changes usually take place about 5,000 years to
occur
– They are measured as either normal or reversed
polarity events
Methods used in chronometric dating
• Potassium-Argon (K40/Ar40)
• Argon-Argon (Ar39/Ar40 )
• Fission-Track on volcanic glass particularly in
Uranium series (Ur238/Ur239)
• Thermoluminescence (TL) such as in quartz and
feldspar minerals
• Electron Spin Resonance (ESR) – e.g. on tooth
enamels
• Radiocarbon (C14) decay: ratio of C12 to C14
• Amino acid racemization (L-amino  D-amino
acids ratios over time)
Advancement in dating methods  SCLF techniques