Lab 10 Miocene Fossil Primates

Miocene Epoch

23.03-5.33 Ma

Where?

East Africa

Miocene Primate Traits:

• Forward-facing eyes

• Nose below eyes

• Post-orbital bar

• Nails on digits

• Divergent hallux

Miocene Haplorhine Traits

• Closed eye orbits

• Dry nose

• Internal lacrimal ducts

Miocene Catarrhine Traits

• 2.1.2.3 dental formula (2 premolars)

• Frontal-sphenoid cranial bone contact

• Ear tubes

Victoriapithecidae: (Superfamily Cercopithecoidea)

Have the diagnostic traits of the Superfamily Cercopithecoidea because they are Old World monkeys

Proconsulidae: (Superfamily Proconsuloidea)

Have the diagnostic traits of the Superfamily Hominoidea and appear to be the early apes that gave rise to later apes in Africa.

Miocene Cercopithecoidea Traits in Victoriapithecidae

• Bilophodont molar

• Narrow nasal base

• Large face relative to brain size (when viewed in profile)

• Quadrupedal with a tail

Miocene Hominoidea Traits in Proconsulidae

• Y-5 molar

• Wide nasal base

• Small face relative to brain size (when viewed in profile)

• Suspensory, NO tail

VICTORIAPITHECIDAE ADAPTIVE PROFILE:

• CERCOPITHECIDAE TRAITS: Bilophodont molar, Narrow nasal base, Large face relative to brain size (when viewed in profile), Quadrupedal with a tail

• ACTIVITY: Diurnal (examine the relative size of the eye orbit for skull length)

• DIET: Some frugivorous, some folivorous (TBM above 500 g, premolars & molars have low-rounded cusps OR high-crested cusps)

• LOCOMOTION: Quadrupedal (look at relative limb lengths)

• FOSSIL SPECIES: Victoriapithecus, Prohylobates

• GOOD MODERN PRIMATE MODEL:  African terrestrial and semi-terrestrial monkeys 

PROCONSULIDAE ADAPTIVE PROFILE

• HOMINOIDEA TRAITS: Y-5 molar, Wide nasal base, Small face relative to brain size (when viewed in profile), Suspensory, NO tail

• ACTIVITY: Diurnal (examine the relative size of the eye orbit for skull length)

• DIET: Some frugivorous, some folivorous (TBM above 500 g, premolars & molars have low-rounded cusps OR high-crested cusps)

• LOCOMOTION: Suspensory

• FOSSIL SPECIES:  Proconsul, Morotopithecus

• GOOD MODERN PRIMATE MODEL: The four modern ape groups have very specialized locomotor adaptations.  The Asian apes are specialized for arboreal locomotion.  Proconsulids were not as well-adapted for extreme brachiation as Asian gibbons or quadrumanous clambering Asian orangutans. The African apes are specialized for terrestrial locomotion and NONE OF THE PROCONSULIDS HAD THE KNUCKLE-WALKING ADAPTATIONS of the knuckle-walking African gorillas and chimps!  THEREFORE, THERE IS NO MODERN APE THAT SERVES WELL AS A MODEL FOR PROCONSULIDS!

THE AGE OF APES

The early and middle Miocene when they diversified and expanded in range across Africa, Europe, and Asia. 

In the late Miocene, forest retraction selected against these large-bodied catarrhines so that today there are only four groups remaining (Asian gibbons & orangutans, African gorillas & chimps).

ORIGINS OF MODERN HOMINOIDS

Molecular divergence data indicate that Asian gibbons are the oldest living apes

Molecular divergence data AND paleontological fossil data indicate that Asian orangutans are the second-oldest living apes.

Sivapithecus

• extinct ape that appears to have given rise to the orangutan

• also appears to be ancestral to the largest-known ape, Gigantopithecus

Gigantopithecus

Largest-known Ape

• May have been 600lbs

• NO skeletal remains

• Dental adaptations for tough, fibrous foods (bamboo & fruit)