PRIMATES

PRIMATES

1. characteristics

   • primates = mostly TROPICAL or SUBTROPICAL 
   • skull
     • bony POSTORBITAL bar with eyes directed FORWARD 
     • orbits encircled by bone 
     • BUNODONT and BRACHYODONT cheekteeth 
     • teeth = COMPLEX, adapted for grinding/shearing 
     • snout is REDUCED along with olfactory lobes of brain 
     • sense of smell REDUCED compared to ancestors 
     • ENLARGED braincase for LARGER brain 
     • petrosal-covered auditory bulla
     • highly OSSIFIED symphysis restricts jaws to VERTICAL movement 
   • skeleton
     • innermost digits of at least ONE pair
     • digits with NAILS rather than CLAWS in most 
     • hallux with a FLAT nail or absent 
     • PLANTIGRADE locomotion, usually PENTADACTYL 
     • PLANTIGRADE = feet flat on the ground; PENTADACTYL = five digits 
   • soft anatomy
     • well-marked cecum 
     • pendulous penis 
     • scrotal testes 

2. evolution

   • refined hands and digits 
   • dexterity enhanced 
   • nails replace claws
   • sensitive pads on digits with FRICTION pads
   • SHORTENED snout 
   • ABSOLUTE and RELATIVE brain sizes increased, elaboration of CEREBRAL CORTEX 
   • enhanced vision (can sense DEPTH), dependence on BINOCULAR, STEREOSCOPIC, COLOR vision 
   • reduced reliance on OLFACTION 
   • slowed reproductive rate; delayed sexual maturity; LONGER life span
   • shift from ANIMAL MATTER diet to reliance on FRUITS, SEEDS, and FOLIAGE 
   • progressive development of UPRIGHT posture allowing facultative BIPEDALISM 
   • HAPLORHINI, STREPSIRRHINI = SUBORDERS ON EXAM 

3. fossil history

   • first primates appeared probably about 70 MYA 
   • GREAT DEBATE about exact time
   • morphology-based: 65 MYA
   • DNA-based: 90 MYA
   • mathematical-models: 81.5 MYA
   • probably small and squirrel-like with ELONGATE SKULL, LONG DIGITS with CLAWS 
   • ARBOREAL ancestry explains adaptations of forward-facing eyes, enlarged visual cortex of brain, skeletal adaptations of limbs and digits, hands replacing mouth for food gathering and handling 

4. economics & conservation

   • primates sometimes conserved for RELIGIOUS reasons
   • sometimes a food source, overhunted
   • non-human primates as models of human disease (POLIO in RHESUS MACAQUES)
   • HABITAT DESTRUCTION is the greatest threat to continued existence 
   • FORESTS: lumber, fuel, agriculture 
   • MINING: especially coltan in Congo, where gorilla habitat destroyed and animals killed for food by miners 
   • CONSERVATION EFFORTS: established habitat preserves + captive breeding, reintroductions 

5. Strepsirrhines

   • moist, hairless skin (rhinarium) around nostrils 
   • TOOTHCOMBS 
   • BICORNATE uterus 
   • EPITHELIOCHORIAL placenta 
   • SMALL neonates 
   • postorbital BAR 
   • Cheirogaleidae (dwarf and mouse lemurs), Lemuridae (lemurs), Lepilemuridae (sportive lemurs), Indridae (woolly lemurs), Daubentioniidae (Aye-aye), Lorisidae (lorises, pottos), Galagonidae (galagos or bushbabies)

6. Haplorrhines

   • dry, furred skin around nostrils 
   • SPATULATE incisors, flat at surface 
   • FUSED, simple uterus 
   • HEMOCHORIAL placenta 
   • LARGE neonates 
   • postorbital PLATE 
   • Tarsiidae (tarsiers), Cebidae (marmosets, tamarins, capuchins, squirrel monkeys), Atelidae (howler, spider, woolly monkeys), Aotidae (night or owl monkeys), Pitheciidae (titis, sakis, uakaris), Cercopithecidae (guenons, mandrills, macaques, baboons, magabeys, colobus, proboscis monkeys), Hylobatidae (gibbons or "lesser apes"), Hominidae (gorilla, chimpanzees, orangutan, humans - LARGEST PRIMATES)