Flashcards in Homnids Deck (59)
Humans and extinct close relatives
(species after separation of chimps and humans)
Describe the fossil record of chimps ?
It is very poor.
How old is the Toumai (hope of life) skull ?
6 to 7 million years old
Found in Chad
Describe the key features of the Toumai.
Cranial capacity of 320-380
Foramen magnum oriented vertically- Bipedalism
Smaller canines, thicker tooth enamel than apes.
When did the separation of homnids and chimps occur ?
Molecular- 4-6 mya
Fossil- 6-7 mya
How old is Orroin tugenensis ?
6 million years old
Found in Kenya
What bipedal feature does Orroin tugenensis show ?
The femur is adapted to support an upright torso
What are the key features of the Ardipithecus ramidus fossils ?
Leg muscle attachments to the pelvis which are similar to humans
Short stiff toes for efficient walking!
Still opposable big toe
Give the name of the oldest fossil hominin
Found 4.4 mya, in Ethiopia
Describe the lifestyle of Ardipithecus ramidus
Due to retention of opposable big toe
Did spend some time walking but still tree climbers
What are the Australopithecines ?
A group of several species
Give the oldest specimen of the Australopithecines.
4.1 mya, Kenya
Describe the key features of the Australopithecines.
1.2 m tall
Double curved spine!
What is the cranial capacity of modern humans ?
What discovery in Tanzania confirmed bipedalism ?
Fossilised footprints of 2 Australopithecus afarensis
(no opposable thumb)
3.6 million years ago.
How do we know that the Australopithecine africanus (2.5 mya) had a varied diet ?
Based on analysis of carbon isotopes in their teeth.
Why did bipedalism evolve ?
Reduction in temperatures
Less rainfall- Tropical forest becomes fragmented.
Seasons of rain & drought meant unreliable food sources
had to forage.
African apes remained in the..... Hominins evolved to exploit.....
Wheeler, 1991, believed that the evolutionary advantage of bipedalism was...
An ability to stay cool in the sun (less forest, less shade)
Hunt, 1994, believed that the evolutionary advantage of bipedalism was....
An ability to collect food from trees more efficiently.
Harcourt-smith, 2011, believed that the evolutionary advantage of bipedalism was....
Tree-tree movement was less possible.
Upright was more efficient.
Carvahlo, 2012, believed that the evolutionary advantage of bipedalism was
Enabled more efficient carrying of valuable items
(Carry more, ^ food, ^ sex)
Describe the dental adaptions of the hominins.
Smaller incisors and canines than chimpanzees (less tearing)
Bigger and flatter molars (more grinding)
Describe the diet of the early hominins.
Ate seeds, nuts, roots, tubers
Give the adaptions of Paranthropus bosiei for powerful chewing.
Pronounce sagittal crest.
What were the Australopithecines replaced with 2 million year ago ?
What are the oldest specimens of Homo ?
Homo habilis, 1.9 million years ago.
Found in Olduvai Gorge
What is the difference between the early Homo and the Australopithecines ?
Homo have a cranial capacity of 700.
Give the date of the oldest stone tools.
3.3 million years old