For exam, lecture 1 Flashcards
when did hominids show up
Pliocene
why did hominids show up in the pliocene
is the start of the change in climate that resembles more modern climate… have a cooling and doing out of the vegetation… conditions that are favourable to the hominin line are showing up
what is significant about the East African Rift System
facilitated the fossilization of a number of known hominin specimens.
where is the East African Rift System
The rift runs from the Afar Depression in NE Ethiopia, south to Malawi, and is typified by rift valleys and both active and inactive volcanoes
how is a rift valley created
A rift valley is created by magma forcing tectonic plates apart, creating a collapsed area between the flanks of the plates
Over time, the walls of the rift valley continue to erode, encouraging fossilization through periodic inundation and collapse
what is believed to be our direct ancestral line
Australopithecines
where are Australopithecines fossil remains are found
Their fossil remains are found only in East and Southern Africa
is there evidence Australopithecines migrated into Eurasia
no
how many species are included in the genus Australopithecus
5
which species are included in the genus Australopithecus
Au. anamensis (4.2–3.9 mya) Au. afarensis (3.6–3.0 mya) Au. garhi (2.5 mya) Au. africanus (3.0–2.2 mya) Au. sediba (1.98 mya)
what are the two areas Australopithecus are found
in east and southern africa
which species are found in east africa
Au. anamensis (4.2–3.9 mya)
Au. afarensis (3.6–3.0 mya)
Au. garhi (2.5 mya)
which species are found in south africa
Au. africanus (3.0–2.2 mya)
Au. sediba (1.98 mya)
when did Australopithecus anamensis exist
4.2-3.9 mya
wh first described Au. anamensis
Mary Leakey
where was Au. anamensis found
northern Kenya’s Great Rift Valley in 1994
what is the name Au. anamensis derived from
derived from “anem,” which means “lake” in Turkana.
what are the notable specimens of Au. anamensis
- part of an upper palate with canine teeth;
- part of a mandible with teeth;
- proximal and distal ends of a tibia (lower leg bone).
so far how man specimens and individuals have been recovered from the Lake Turkana area in Kenya and from Middle Awash, Ethiopia of Au. anamensis
than 80 specimens from around 20 individuals
what is the earliest known member of the genus Australopithecus
Au. anamensis
what is the Dentition of Au. anamensis
Dentition is generally primitive, and indicates a diet of fruits, nuts and roots. Molar rows are parallel, and the dental arcade is U‐shaped. Canine teeth are small, overall, but still show sexual dimorphism. Dental enamel is thick
what is the upper pallet like in Au. anamensis
The upper palate is shallow compared to later hominins and humans
what is the external auditory meatus (ear canal) like in Au. anamensis
is elliptical –- an ape-like trait.
what is important about ear canals in fossils
that you can see on the outside of the cranium… one of the traits that helps to put the species in the phylogeny with other hominis
how did Au. anamensis move and what proof Is there
Evidence for bipedalism is strong, but indirect. The proximal tibia shows signs of excess weight bearing. The distal tibia is wide and thick, acting as a shock absorber.
The arms are relatively long, indicating strong climbing ability.
The shape of the lower tibia suggests the femurs were angled, a feature of bipeds
what is Au. anamensis’ relationship to Ardipithecus
undetermined
Most researchers believe Au. anamensis is a direct ancestor of what
Au. afarensis
A minority of researchers believes the known Au. anamensis specimens should actually be re-‐ classified as what
Au. afarensis
when did Australopithecus afarensis exist
3.6-3.0 mya
what is is easily the best-documented australopithecine in the fossil record
Australopithecus afarensis
what is Australopithecus afarensis named for
The species is named for the “Afar” depression in which Hadar is situated
Notable specimens of Australopithecus afarensis include
- A significant portion of a 3.2-‐million-‐year-‐old female skeleton (nicknamed “Lucy”), found at Hadar in 1974 by Donald Johansen
- A 3.3-‐million-‐year-‐oldpartial skeleton of a child recovered from Dikika (near Hadar) by Zeresenay Alemseged in 2001
does the cranial morphology of Australopithecus afarensis resemble apes or humans
Cranial specimens show a majority of ape-like features
what is the cranial capacity of Australopithecus afarensis
Overall cranial capacity was relatively low (350– 500cc)
what were the facial prognathism and zygomatic arches like on Australopithecus afarensis
There is significant facial prognathism. The zygomatic arches are large and flaring.
what is the dentition of Australopithecus afarensis like
The dentition is similarly primitive. It had procumbent, relatively large incisors that were larger in males. The molar rows are parallel and the dental arcade is U- shaped. A diastema is present
how did Australopithecus afarensis move and what is the evidence
The post-‐cranial elements indicate regular, obligate bipedalism. Like in humans, femoral neck is long and the pelvis is short.
Strangely for a biped, the ilia are flared outward—like an ape’s. This would have strongly affected its gait, and may force us to reevaluate our ideas about “universal” bipedal movement/motion
what killed lucy
Very recent (August 2016) research has used CT scans of Lucy’s skeleton to show a fracture pattern consistent with a long, hard fall—most likely from a tree. The fractures were “greenstick,” indicative of pressure breaks
is the theory of lucy’s death accepted and why
Lucy’s discoverer (and many others) reject this otherwise plausible scenario, largely because it runs counter to the prevailing theory that by the time Au. afarensis was around, tree-‐climbing wasn’t a common part of the subsistence/settlement pattern
what are the most direct evidence of early bipedalism
The Laetoli footprints
when do The Laetoli footprints date to
date to around 3.7 mya
what are the Laetoli footprints
They represent the tracks of at least three bipedal individuals made in once-‐soft volcanic ash and mud
what species is responsible for the Laetoli footprints
While we aren’t certain which species is responsible for the footprints, it’s believed they were made by Au. afarensis
Among all the australopithecines, what is the most controversial in its classification
Au. garhi
what specimens do we have of Au. garhi and where did we find them
It is known from two partial crania and a partial post-‐cranial skeleton, all recovered at Bouri, Middle Awash, Ethiopia
where did Au. garhi get the name
“Garhi” means “surprise” in the local Afar language
what is the cc of Au. garhi
Its cranial capacity is relatively low— only slightly larger than that of Au. afarensis (~450cc)
what is the facial prognathism and sagittal crest like in Au. garhi
has a high degree of facial prognathism and a weak sagittal crest
what is the dentition of Au. garhi
Its dentition is notably odd. It has very wide canine teeth that are neither ape-‐nor human-‐like. Additionally, the molars are very robust
what is the Post-‐Cranial Morphology of Au. garhi
The femur (one of the few post‐cranial bones we have) is significantly longer than in either apes or other hominins. With or without the discovery of new Au. garhi specimens, the taxonomic status of the species may be reevaluated in the near future
what was found at Gona, Afar
Stone tools
when were the The earliest stone tools used
2.5 mya
what was the diet of Au. garhi like? what evidence is there
The earliest stone tools (2.5 mya) occur in the same geological formation but not at the same place as the garhi skull. Animal bones with stone-tool cut-marks also occur. This suggests meat acquisition by scavenging
is Au. garhi a tool maker
Because garhi is the closest hominin, it is assumed to be the tool-maker
what is the closes homin
Au. garhi
Hominin sites in Southern Africa are clustered closely around present-day what
Johannesburg and Pretoria, South Africa.
The majority of these are cave sites
who discovered the nearly complete fossil cranium of a child at Taung
In 1924, Australian paleoanthropologist Raymond Dart
where was Taung found
NW Province, South Africa
what did Raymond Dart think Taung was and was he correct
He believed it to be a transitional form between fossil apes and humans. He was correct—in a sense. However, most researchers at the time disagreed, expecting hominins to have large brains; Dart’s specimen did not.
what is The ‘Taung child’ was classified as
Au. africanus (“Southern African ape”);
was the Taung child a usual specimen
no
how old was Taung
3-4 years
what was the cc and facial prognatism of The ‘Taung child’
cc was low, as was its degree of facial prognathism.
what was the dentition of The ‘Taung child’ like
The dental arcade is parabolic, or V-‐ shaped (not U-‐shaped,as in earlier hominins). The canine teeth were small, and there was no diastema present
what was the foramen magnum of the Taung child
The foramen magnum is positioned behind directly behind the mandible, like in humans
how is the adult different than the Taung child
Subsequent analysis of multiple adult specimens of Au. africanus show similar cranial characteristics, such as low prognathism, in addition to lack of prominent supraorbital tori and a low degree of sexual dimorphism in the canine teeth
what was the dentition and diet of Australopithecus africanus like
However, molars and premolars are oddly large—more similar in size and robustness to the teeth of Paranthropines. This was likely a local adaptation to a specialized diet
when did Australopithecus sediba live
1.98 mya
what is the most recent australopithecine
Au. sediba is the newest (and chronologically most recent) australopithecine discovered. It is currently known from two crania and a partial skeleton
what are the Malapa hominins
Au. sediba – In the scientific literature, the two individuals are referred to as the “Malapa hominins,” after the shallow cave site in which they were discovered along with numerous other fossilized animals
what is Au. sediba named after
The species name “sediba” means “fountain” in the Sotho language
The two described individuals of Au. sediba are
- MH1—a juvenile male with a largely complete cranium and partial skeleton
- MH2—an adult female with a partial skeleton
how big was the body and brain of Au. sediba
Au. sediba stood around four feet tall, and had a relatively small brain—slightly larger than that of a chimp
what are the 2 hemispheres of the brain in Au. sediba like
endocranial casts show that the two hemispheres of the brain are not symmetrical: this is a trait associated with the genus Homo
what was the facial structure of Au. sediba like
The facial structure is similar to that of Au. africanus; however, Au. sediba had much smaller zygomatic arches
what are the pelvis and knee in Au. sediba like
Various features of the pelvis and knee are human-‐like, and indicate bipedalism
Lee Berger and his team argue about Au. sediba
1) Au. sediba is descended from Au. africanus;
2) is a direct ancestor of the genus Homo. However, they conceded it is possible that Au. sediba represents an evolutionary dead-end line
what has been suggested of MH1 and MH2
It’s been suggested that MH1 and MH2 represent a slightly more developed form of the same species—Au. africanus, and don’t warrant a new species classification
