PHYTOLITHS AND CUTICLES:
Cells of plant epidermis, either siliceous (phytoliths) or lignified (cuticles).
CUTICLES
Developed at Colorado State Univ., Fort Collins, as range-management technique. Used
to determine the diet of livestock.
PALEOSCATOLOGY: has been used to study the diet of extinct animals through the dung
preserved in arid Southwestern saves (Hansen, 1978; Ackersten et al, 1988).
Methods: blender, screening
Identification:
stomata: control gas exchange
trichomes (leaf hairs)
cork cells (provide leaf support)
silica cells (support, discourage foliavolres)
EXAMPLES:
- Modern grazing animals in the lower Grand Canyon (cattle, burrows, bighorn sheep)
have diets similar to that of the extinct ground sloth (Long, Hansen and Martin, 1974)
- Extinct mammoths depended heavily on wet-ground grasses for their diet, based
on cuticle analysis by Terry Foppe (unpubl.) of the dung preserved in Bechan Cave
in Glen Canyon.
PHYTOLITH ASSEMBLAGE = f(P,D,R,I)
- PRODUCTION
Silica is deposited in the secondary plant wall of some plants, particularly grasses and
occasionally in wood. Phytoliths most abundant in grasslands and steppes.
- DISPERSAL
large fragments move short distances (fragile)
small fragments (silt sized) may be distributed by wind.
- PRESERVATION
Resistant to oxidation, but the silica can be dissolved by ground-water movement
- IDENTIFICATION
Many plants don't produce phytoliths: only a partial indication of plants in area
Non-related species produce the same types : "dumbbells, saddles, bowls, boats, bottoms"
Some Taxonomic categories can be recognized: panicoid, festucoid, chloroid
A few forms are diagnostic to species level: e.g., maize
Methods:
- oxidize sample (boil in H2O2)
- wet sieve (phytoliths silt size)
- flotation (tetrabromoethane, ZnBr2) phytoliths have specific gravity of 1.5-2.3, quartz 2.65
EXAMPLES:
- Thick accumulations of ash in an iron-age archeol. site -- abundant wheat phytoliths.
Liebowitz and Folk (1980) believe that straw was used to produce fires intense
enough to smelt iron.
- Relative amounts of festucoid (C3, cold-indicating) vs. panicoid (C4, warm-loving) grasses
in loesses indicate progressive development of midwest grassland (Carbone, 1977).
- High phytolith concentration during cold periods in deep-sea cores of the mid-Atlantic
indicate grassland vs. woodland, increased aridity in the northern Africa. (Parmente and Folger, 1974)
- Phytoliths of wet-ground grasses are larger, increased abundance in loesses could
indicate greater moisture (Yeck, 1969).
- Unique phytoliths (cross-bodies) indicate 4450 yr B.P. corn cultivation in Ecuador
(Pearsall, 1977)
- Does NOT reflect vegetation patterns in Mediterranean (Bremond et al., 2004)
- Radiocarbon dating of (carbon contained in) phytoliths (Piperno and Stothert, 2003)
Phytoliths Readings
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