Cenozoic Primates (final) Flashcards
(18 cards)
What are the 2 suborders of primates?
Prosimians : Tarsiers, lemurs, lorises
Anthropoids : Monkeys and apes (includes humans)
When did primates evolve?
They evolved by the Late Cretaceous
- began small but were large by Eocene
What are the general trends in primate evolution? (6)
- skeletal changes
- change in mode of locomotion
- increase in brain size
- shift towards smaller, fewer, and more specialized teeth
- development of stereoscopic vision (depth perception)
- grasping hand with opposable thumb evolved
*these were not linear changes
*define primates in terms of their arboreal ancestry
Explain the Prosimian group and their characteristics
Prosimians (before ape)
Oldest primate lineage > fossil record dated to Paleocene > Eocene - abundant in northern continents > today, found only in tropical areas
- small, arboreal
- five-digit hands
- claws or nails
- typically omnivorous
- large eyes, norturnal
What is the Anthropoid group? What are the 3 Superfamilies in this group?
Anthropoids (resembling human beings)
Superfamilies:
1. Ceboidea (NEW WORLD MONKEYS)
- ex. spider monkey
- originated in the Americas
*prehensile tail, flat face, widely separated nostrils
- Cercopithecoidea (OLD WOLD MONKEYS)
- ex. baboon
- originated in Africa and Asia
*downward nostrils, grasping hands, and non-prehensile tail
*we are more closely related to these - Hominoidea (apes and humans)
- ex. chiimpanzee
- diverged from Old World monkeys before Miocene
Explain how the climate and environment impacted the Hominoidea evolution?
They evolved in Africa
- climates cooled and became drier after Late Eocene
- rain forests replaced by mixed forests, savannas, and open grasslands
- extinction of forest dwellers, adaptations for plains dwellers and *upright posture
What are the 2 families of Hominoidea?
- Family Hylobatidae: (lesser apes)
- ex. Gibbons - Family Hominidae: (great apes)
> Subfamily Ponginae
- ex. organgutans
> Subfamily Homininae (Hominoids)
- ex. chimps, gorillas, humans and our extinct ancestors
What are the specific evolutionary traits of Hominins (chimps and humans)
- fossil record extends to nearly 7 million years
- enlarged brains
- feature reduced canine teeth
- have omnivorous diets
- have upright posture
- are bipedal
- developed increased manual dexterity
- evolved to use sophisticated tools
- details of hominin evolution are debated because of gaps in fossil record
What is the significance of the Sahelanthropus tchadensis Hominin fossil?
Hominin skull:
Primitive and advanced features
- small brain and chimp-like teeth
- nose and brow ridges flatter and smaller than apes
What is the significance of the Ardipithecus hominins?
Showed Hominin characteristics:
- dexterous hand for grasping
- foot had opposable big toe; lacked flexibility
- probably walked bipedally, but could climb and maneuver in trees
What is the significance of the Australopithecus (anamensis and afarensis) hominins?
A. anamensis:
- likved about 4.2 mya, biped
- evolved from Ardiphithecus
A. afarensis:
- lived about 3-3.9 mya, biped
- brain size not much larger than chimpanzee
- teeth adapted for eating fruit and seeds
- fossil ex. “Lucy” > preserved femur that was damaged and believed that she fell out of a tree
What did the Genus Homo evolve from?
They evolved from Australophithecus afarensis or Australopithecus africanus (coexisted with africanus for 200 000 years)
Explain the Genus Homo - what were the two species
Homo habilis = earliest species
- around 2mya near the african regions
- larger brain and smaller teeth than ancestors
Homo erectus = came next
- erectus and habilis coexisted for 500 000 years
- erectus survived until 100 000 years ago
- erectus first left Africa 1.8 mya ** first example of these species migrating to other continents
** also first start seeing evidence of them using fire to their advantage
Explain the H. neanderthalensis species (when/where did they evolve and what were their characteristics)
- in Europe 200,000 to 30,000 years ago
- may be subspecies of H. sapiens or a separate species (debate about where they fit in)
- brains slightly larger than modern humans and a different shape
- more massive and muscular than modern humans
- had short lower limbs
- were adapted for cold climates
What is the Cro-Magnon group?
- also called Anatomically Modern Humans (AMH) or Early Modern Humans (EMH) > same physical form as us
- replaced Neanderthals in Europe about 35000 years ago
- lived in caves and rock shelters (classic cave people)
- developed art and better technology
- evolution to modern humans from this point was cultural/technological more than biological
What are some debated examples of modern human evolutions in the present day?
- ability to drink milk as adults
- people born without wisdom teeth
- disease resistance
- getting taller
- menopause occurring later in life
- larger head sizes at birth (because of Caesarean sections)
(are these natural evolutions or are they just driven by health care and efficient transportation and immigration)?
Explain the future in terms of climate records - What is the main cause of this warming?
Climate records suggest anthropogenic warming during the 20th century has likely accentuated natural global warming that began at the end of the Little Ice Age
- main cause of anthropogenic warming is though to be the burning of fossil fuels and the production of C02 (a greenhouse gas)
What are 3 consequences of Anthropogenic warming
- Sea-Level Rise:
- mostly due to melting ice caps
- coastal regions will be the most effected - solutions involve engineering projects that are mostly temporary and expensive - Precipitation Patterns:
- can affect agriculture which has consequences for sociopolitical stability in parts of he world - “6th Extinction” might be happening right now (human-driven extinctions)
- increasing change of ecosystem collapse - can take thousands of years to recover from a mass extinction
