Lecture 1 Flashcards
Numbers
- More than 72 extant genera
- More than 376 living species
- Estimated 200 known extinct species
- But 6500 estimated overall
- 66 species discovered since 1990
Taxonomy Order
Kingdom, Phylum, Class, Order, Family, Genus and most specific Species.
Binomial nomenclature
The use of 2 names to describe a species and genus, EG, Homo sapiens.
Strepsirrhinis
Wet nosed primates, they have a rhinarium, down facing nostrils, a groove and gap in their incisors and a maxillary process.
Strepsirrhinis include:
Lemurs, Lorisis, Ayeayes, and they only have a post prbital bar with partial closure.
Haplorhini
Dry nose, up turned nostrils.
Haplorhinis include:
New world monkeys, old world monkeys, great apes all the way to humans. They have full closure of the post orbital bar.
What is a primate?
Very diverse and therefore hard to define. As primates are in a large geological regions (south america, Africa, Asia) means that they’ve evolved independently causing diversity.
Mobility of Digits and hands
Prehensile hands and feet (grasping), opposing pollux (thumb) and hallux (big toe). Primates have nails and claws and apical pads (finger pads).
Face change from mammals
Reduced snout and olfactory systems.
Visual changes
Binocular vision, overlap of visual fields leads to improved depth perception and ability to break camouflage. More visual acuity.
Most primates see dichromatic colour vision but many see in trichromatic colour.
Teeth
Primitive mammals 3.1.4.3
Whereas primates have 2.1.3.3 or 2.1.2.3. Reduced dental formula and simple molars.
Life History
Extended life history, Primates invest a lot in a few offspring, quality offspring that are born developed but dependent. Long gestation and juvenile periods.
Derived and Primitive
Derived- Evolutionary innovations that evolved de novo in the group.
Primitive- Features shared by a group that are inherited from a more ancient ancestor.
Why characteristic features of primates evolved:
Arboreal Hypothesis
Branch grasping, Less to sell in the trees than on the ground, but sharp eyes were needed, Big brains needed to navigate in complex three dimensional environment.
Issue with arboreal hypothesis
Not all other arboreal animals have forward facing eyes, grasping hands and nails.
Why characteristic features of primates evolved:
Terminal Branch Feeding Hypothesis
Co-evolved with angiosperms (Flowering plants)
Grasping hands and feet to feed at the ends of branches
Main Problem with Terminal Branch Feeding Hypothesis
Visual adaptations remain unexplained. Cartmill: visual specialisations are not needed when your prey is a banana.
Why characteristic features of primates evolved: Nocturnal leap-grasping
Grasping adaptations and stereoscopic vision for judging depth as misjudging would cause serious injury.
Problem with Nocturnal leap-grasping
Stereoscopy doesn’t really increase depth perception at long distances.
Why characteristic features of primates evolved: Snake-detection
hypothesis
Visual systems evolved to better detect snakes as they can break camouflage and depth perception at close range.
Grasping hands and feet for angiosperm exploitation to feed the bigger brain.
Primate Morphology: Locomotion
Leaping: Vertical Clinging and leaping and quad leaping.
Quadrupedalism: Branch, Ground and knuckle walking.
Suspensory: Semi-Brachiation and Quadrumanualism (exclusive to orangs)
Bipedilism
Suspensory locomotion
Brachiation, use upper limbs to swing body under horizontal surface.
Semi-brachiation, brachiation with suspensory climbing and prehensile tails.
Bipedalism
Habitual bipedalism is exclusive to humans but many primates do it for a a brief time.
