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ANT203 test 3 notes.pdf

Course Code
Xueda Song
Study Guide

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Interpreting fossil remains
need geological knowledge, relative dating, chronometric dating, statistical analysis
(with computerized phylogenetic techniques), broad knowledge of primates and
mammals, and of other sciences
consider taphonomic processes (sedimentation and formation of site, including
transformation of organisms after death), context
factors in taphonomy include soil ph, drainage, water, geology, weathering
(sun, wind), bioturbation (animal and insect activity), roots, subsequent
human activity (e.g. looting)
Dating methods
Relative dating
law of superposition: a lower stratum is older than a higher stratum
biostratigraphy (faunal correlation)
compare faunal remains to those from other sites with known dates
flourine analysis
flourine in ground water is incorporated during fossilization
can only be used on bones, which have to be from the same location
Chronometric (absolute) dating
Potassium / argon
decay of potassium into argon gas
half-life: 1.25 billion years
good for rocks exposed to high heat, like from volcanic activity
decay of isotopes ¹²C and ¹C
half-life of 5730 years
used to date organic materials like cloth, wood, and bone
only works on materials younger than 75,000 years
relies on principle of radiometric decay
stone contains trace amounts of radioactive elements which are
released when the stone is heated
by heating the sample and measuring its glow, it can be dated
based on shifting of earth's magnetic poles
take sample of sediment containing magnetically charged particles,
with exact compass orientation recorded
correlate sample with sequence of magnetic orientations
"Molecular clock"
based on genetic mutations, which occur at regular rate
used for time since LCA, divergences, cladistic relationships

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during the Late Mesozoic, the superorder Euarchonta diverged from mammals
refers to sister orders of tree shrews, flying lemurs, and primates
based on molecular and morphological evidence, primates originated (diverged from the
LCA) sometime between 90 - 65 mya
most primate evolution unfolded in the Cenozoic Era, split into seven epochs:
Paleocene, 65 mya primate-like mammals, Plesiadapiformes
Eocene, 55.8 mya first true primates, Promisians
Oligocene, 33 mya early Catarrhines
Miocene, 23 mya monkeys, apes, and first human-like beings emerge
Pliocene, 5.3 mya early humans diversify
Pleistocene, 1.8 mya early Homo emerges
Holocene, 0.01 mya the present epoch
Archaic Primates
65-52 mya
a major radiation of archaic primates, Plesiadapiforms, namely:
rodent-like incisors, but not continuously growing or self-
probably originated in North America and spread to Europe
post-cranial anatomy indicates arboreal adaptations
recently discovered skeleton had nails, not claws
also Altiatlasus, which is not conclusively classified (Euprimate?)
Eocene Euprimates
55.8 mya
five distinctive traits, which suggest adaptation to a warmer, lush climate of
broad-leaved evergreen forests:
forward-facing eyes
greater encephalization
postorbital bar
nails, not claws
opposable big toe
Lemur-like Adapoids
most primitive Euprimates (dental formula 2:1:4:3)
Amphipithecids (Asia)
mandibles/teeth seem derived, but just convergent evolution
Notharctids (North America and two species from Europe)
Cantius, Darwinius ("Ida")

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largest nonanthropoid primate from Afro-Arabia
first primate to exploit folivorous feeding niches in Africa?
1st n-h fossil named, described by Cuvier in the 19th century
slow, arboreal quadruped with incipient dental comb
diurnal, folivorous
Tarsier-like Omomyoids
found in Asia (oldest), Europe, and North America (youngest), suggesting
an East to West migration
Eocene was a period of rapid diversification for all mammals; North America and
Asia were connected and shared species, while Africa, Antarctica, Australia, and
South America remained isolated by water
Eocene Early Anthropoids
anthropoids originated no earlier than 77 mya
likely originated in Africa, but maybe Asia
from the Fayum Depression in Egypt:
Biretia (37 mya)
most complete early African anthropoid
nocturnal (unusual) judging by large orbits
Catopithecus (35 mya)
anthropoid, with derived Catarrhine features (dental 2:1:2:3)
Oligocene True Anthropoids
include Catopithecus, the earliest anthropoids genus with a preserved skull,
revealing early catarrhine cranial anatomy (key: fully enclosed orbits)
include Parapithecus, and are the family of anthropoids most closely
related to Platyrrhines
include Aegyptopithecus (33-23 mya), a genus that has historically been
proposed as the ancestor of both Old World monkeys and hominoids,
exhibiting a derived Catarrhine dental formula (2:1:2:3), a great degree of
sexual dimorphism (speaks to social structure)
now Saadanius (29-28 mya) instead proposed as this ancestor
Early Platyrrhines: New World Anthropoids
earliest Platyrrhines arrived in South America around 37-32 mya, probably
"rafting" and island hopping across the Atlantic during the Eocene, when Africa
and South America were closer (plus lower ocean levels) than they are today
earliest possible genus is Branicella (maybe too primitive to be related to modern
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