Primate evolution during the Cenozoic era'

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Primate evolution during the Cenozoic era. A.
Paleocene (65-53 mya). 1. Possible early
primate forms. a. Purgatorius. Found
at Purgatory Hill, Montana. Known only from
isolated teeth. Primitive dental morphology.
Difficult to tell evolutionary relationships to
later primates. Had integrated molars, like
primates. Other mammals have unintegrated
molars.
Tree Shrew
Early Primate Ancestor, late Mesozoic
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Smilodectes (Adipidae), 55mya
B. Eocene (53-37 mya) 1. "Primates of a Modern
Aspect" a. Appearance of prosimian-like
forms. 2. Lemur-like and Tarsier-like genera. 3.
Eocene primates have the following primate
characteristics a. Complete post-orbital
bar. b. Bony cup incomplete (as in modern
prosimians). c. Nails replace claws.
arboreal. d. Vertical clingers and leapers
hindlimbs of Notharctus are much longer than the
forelimbs. 4. North American forms
did not go into South America, but rather became
extinct.
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Lemur-like forms ADAPIDS a. Generalized
dentition. b. Notharctus (N. American) c. Adapis
(European) d. Diurnal (small eye orbits). e. Lack
a tooth comb (tooth comb evolved after the
Eocene). f. May have given rise to anthropoids.
Tarsier-like forms OMOMYIDS a. Carnivorous
dentition. b. Tetonius (N. American) c.
Necrolemur (European) d. High-crowned, pointed
cusps (insectivores). e. Nocturnal (large eye
orbits).
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C. Oligocene (37-22.5 mya) 1. Fayum site
in Egypt, dated to 30 mya. a. Fayum
was a swamp during the Oligocene. 2.
Oligopithecus. a. earliest
anthropoid. b. pithecus means ape.
3. Apidium a. earliest monkey.
b. Bilophodont molar pattern 4.
Aegyptopithecus 5. Branisella boliviana
(30mya)
Apidium
Branisella
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Aegyptopithecus a. Possibly the earliest ape
based on dentition. b. 28 mya (K/Ar dates). c.
Had 2123 dental pattern. d. Y-5 molar
pattern grooves separating cusps instead of
ridges. e. Cingulum Ridge on lingual (tongue)
side of tooth in maxilla and on buccal (cheek)
side of tooth in mandible.
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MIOCENE EPOCH (22.5 - 5 million years
ago) "Period of the Apes" Geographic expansion
and adaptive radiation of apes. Apes confined to
E. Africa and Namibia during the early Miocene.
Proconsul (22 mya) Generalized ape Confined
to Africa Ape features Y-5 dentition
Maxillary lingual and mandibular buccal
cingulums No tail Frugivorous
diet Monkey-like features Arms and legs
the same length Pelvis quadrupedal
Scapula, wrist Indicate that Proconsul was
not a brachiator.
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Dendropithecus (22 mya) Small bodied hominoid
Gibbon-like Apes move out of Africa after 16
million years ago. Dryopithecus Europe
"Forest ape" Resembled modern chimps and
gorillas Thin tooth enamel Large
anterior teeth Sivapithecus (12-7 mya) Asia
Resembles modern orangutan Narrow space
between eyes Oval eye orbits
"scooped-out" face Orangutans
differentiated from other apes 8-10
mya. Gigantopithecus (2,000,000 - 500,000 years
ago) Asia Largest apes much larger than
gorillas "Big foot" and "Abominable snowman"
legends? Gigantopithecus and direct human
ancestors contemporaries. Huge posterior teeth
Teeth once sold in Asian markets as dragon
teeth.
Dendropithecus
Gigantopithecus
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• Miocene ape radiation eventually lead to a great
  deal of variation.
• Where are the ancestors of modern African apes?
• Fossil evidence in Africa is incomplete at this
  time.
• No fossils of common chimp-human ancestor
  identified. Sediments for this time period in
  Africa not exposed.
• DNA evidence suggests that humans and chimps
  are separated by at least 5 - 7 million years.
  Split time based on the molecular clock
  (Differences in DNA sequences between chimps and
  humans).
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• POSSIBLE EARLIEST HOMINIDS
• Fossils found in East Africa
• Oldest are less than 5 my old.