The document summarizes key australopithecine species and their evolution. It discusses Australopithecus anamensis, A. afarensis, A. africanus, Paranthropus aethiopicus, P. boisei, P. robustus, and A. garhi. It describes their fossil records, anatomies, habitats, locomotion, and relationships. A. garhi is significant as the earliest known tool-making hominin. Debate continues regarding the lineages and relationships between the gracile and robust australopithecine forms.

1. Australopithecus, Homo habilis and
Homo Ergaster

2. The Place of Australopithecines
● The situation of australopithecines as
the immediate antecedents of the
genus Homo is well established
● Nonetheless, it must be recognised that
there is significant diversity in the
specimens and that their distributions
and ages also differ
● A general distinction between gracile
forms and robust forms has been
made, with the former leading onward
to the development of Homo habilis and
Homo ergaster, whereas the latter were
an evolutionary cul-de-sac that
developed more similarities with the
apes
● Some forms of robust
australopithecines, commonly called
Paranthropus, continued to flourish until
as late as 1.2 million years ago in
South Africa

3. Directions of Australopithecine Evolution

4. Distribution
● The distribution of australopithecines and
Paranthropus overlaps largely with the
region where Homo first emerged
● All the specimens have been found in a
broad arc from East Africa to South
Africa, with a curious outlier in southern
Chad
● Although there were certainly local
differences in the environment, we can
characterise this region as one where
savannah and open woodland prevailed
● This obviously was important for the
subsistence opportunities afforded to
these species and also for the adaptive
advantages of being bipedal and
exploiting arboreal environments
● It is therefore adaptation to these
environments that probably triggered
many of the changes in morphological
characteristics

5. The Fossil Evidence
Principal Finds of Australopithecines and Their
Characteristics

6. Australopithecus anamensis
● The first fossilized specimen of the
species, though not recognised as
such at the time, was a single arm
bone found in Pliocene strata in the
Kanapoi region of East Lake Turkana
in 1965
● In 1995, Meave Leakey and her
associates, noting salient differences
between Australopithecus afarensis
and the new finds, assigned them to a
new species, A. anamensis, which
derives its name from the Turkana
word anam, meaning 'lake'
● It was determined that this species
was independent and does not
represent an intermediate species of
any type
● In 2006, a new A. anamensis find was
officially announced, extending the
range of A. anamensis into north east
Ethiopia

8. Relationship to Later Species
● It is believed that Australopithecus
anamensis often climbed trees
● Tree climbing was one behavior retained by
early hominins until the appearance of the
first Homo species about 2.5 million years
ago
● A. anamensis shares many traits with
Australopithecus afarensis and is likely its
direct predecessor
● A. anamensis is thought to have lived from
4.1 and 3.9 million years ago
● The older specimens were found between
two layers of volcanic ash, dated to 4.17
and 4.12 million years, coincidentally when
A. afarensis appears in the fossil record
● The A. anamensis find is dated to about 4.2
million years ago, the Ar. ramidus find to
4.4 million years ago, placing only 200,000
years between the two species

10. Australopithecus afarensis
● The remains from A. afarensis are
relatively plentiful, and we are
fortunate that perhaps the most
complete early hominim skeleton is
of this species, namely, the
spectacular find of 'Lucy'
● This species lived between 3.8 and
2.9 million years ago and therefore
immediately follows A. anamensis
in the fossil record
● The distribution of this species is
currently limited to East Africa, the
most famous finds being made at
Hadar, Omo, and Koobi for a
● It is widely maintained that this
species led on to the Homo genus
whereas other members of the
Australopithecine family were
evolutionary cul-de-sacs

11. Physiology
● A. afarensis has reduced canines and
molars in comparison to those of the
apes, although they are still relatively
larger than in modern humans
● This species also has a relatively small
cranial capacity (~380–430 cm³) and a
prognathic face
● The small cranial capacity was
something of a shock to many of the
palaeoanthropologists, for they
assumed that an increase in brain size
was the first major adaptive change
leading onward to the genus Homo and
bipedalism
● There is considerable debate regarding
the locomotor behaviour of A. afarensis
● Some believe that A. afarensis was
almost exclusively bipedal, while others
believe that the creatures were partly
arboreal

12. Locomotion and Habitat
● The anatomy of the hands, feet and
shoulder joints support an interpretation
of A. afarensis being at least partly an
arboreal dweller
● The curvature of the phalanges
resembles that of modern-day apes, and
is most likely reflective of their ability to
efficiently grasp branches and climb
● The presence of a wrist-locking
mechanism might suggest that they
engaged in knuckle-walking
● The shoulder joint is also oriented more
cranially than in modern humans
● Combined with the relatively long arms
A. afarensis are thought to have had,
this is thought by many to be reflective
of a heightened ability to use the arm
above the head in climbing behaviour

13. Bipedalism
● Many traits, however, suggest that A.
afarensis was bipedal
● The traits are so strongly developed
that it suggests that bipedalism
emerged well before A. afarensis
appeared, which is being corroborated
by the finds of Sahelanthropus
tchadensis which have been dated to
ca. 7 million years
● The pelvis is far more human-like than
ape-like, whereas he iliac blades are
short and wide, the sacrum is wide and
positioned directly behind the hip joint,
and there is clear evidence of a strong
attachment for the knee extensors
● While the pelvis is not wholly human-
like (being markedly wide with flared
with laterally orientated iliac blades), it
is suitable for regular and sustained
bipedal locomotion

14. Australopithecus bahrelghazali
● The species designation of
Australopithecus bahrelghazali is a new
one, currently gaining more and more
support among palaeoanthrologists
● Arguments against the case for it being
its own species are based upon its
resemblances to Australopithecus
afarensis
● A. bahrelghazali was discovered by
Michel Brunet in 1993, in the ancient
riverbed of Bahr el Ghazal in Chad,
located 2,500 kilometers west of the East
African Rift Valley
● This is currently the first and only
australopithecine specimen to be found in
North-Central Africa, and is also the
furthest west of any specimen found to
date
● Australopithecus bahrelghazali dates to
between 3.5 and 3.0 million years ago

16. Australopithecus africanus
● This species flourished between 3
million and 2 million years ago and
had a much broader geographic
distribution than A. afarensis
● It is also well represented in the fossil
record, affording numerous specimens
that permit a much more accurate
reconstruction of their anatomical
structure than is often possible for
other hominim species
● Some of the main finds have been
made in South Africa, suggesting that
Australopithecines began to expand
outwith East Africa and were
adaptively successful, colonising
different environments
● Most notable are the finds of the
Taung child, Sterkfontein, Gladysvale
and Makapansgat

17. Anatomical Structure
● A. africanus was similar in most respects
to A. afarensis, being bipedal and having
arms slightly longer than the legs
● This species also had curved phalanges,
like A. africanus, interpreted as either an
adaptive advantage for climbing trees or a
vestigial feature
● It also had a relatively small cranial
capacity, but again comparable to that of
A. afarensis
● Some ostensible 'primitive' features have
suggested to some that this species was
not a direct descendant of Homo, but
rather was the first in a line that was
leading to more robust forms of
Australopithecine
● We therefore see Australopithecine
emerging into two groups: one more
gracile and one more robust

18. Paranthropus aethiopicus
● This species was formerly known as A.
aethiopicus, but the robustness of its
features and the divergence from the
Australopithecines that were becoming
more gracile led to some re-classifying
this line as 'Paranthropus'
● The species inhabited East Africa from
2.7 – 2.0 million years ago and is best
represented by the skull and bones found
at West Turkana (KNM WT 17000),
known as the 'black skull' due to the
discolouration caused by high levels of
manganese
● Lower jaw and teeth fragments have been
uncovered from some specimens
● It is therefore possible to state that P.
aethiopicus had a large sagittal crest and
zygomatic arch adapted for heavy
chewing, which resembled the
mastication complex of gorillas

19. Robust Forms: A Divergent Line ?
● Some are uncomfortable with the
argument that Australopithecines began
to diverge into a more robust type that
ultimately failed, whereas the more
gracile forms evolved into the genus
Homo
● It is argued that some of the forms of
Paranthropus derived from separate
forms of Australopithecine—namely,
Paranthropus robustus evolving from A.
africanus whereas the others from A.
afarensis—and therefore invalidates the
existence of Paranthropus as a separate
genus
● Ultimately, the trajectory of evolution
seems to suggest that the robust forms
commonly assigned to Paranthropus
diverged from the gracile forms and
followed a different course of evolution
that did not contribute to the emergence
of Homo

20. Australopithecus afarensis
Australopithecus africanus Paranthropus aethiopicus
Paranthropus boisei
?
Paranthropus robustus
Australopithecus garhi
Homo habilis

21. Paranthropus boisei
● This species is more recent that some
forms in the genus Homo, being dated to
as recently as 1.75 million years
● The first specimens, found at Olduvai
Gorge, were classified as Zinjanthropus
boisei, but the discovery of more
Australopithecines and Paranthropus
finds led to a reclassification
● The brain volume is quite small, about
500 and 550 cm³, not much larger in
comparison to Australopithecus afarensis
and Australopithecus africanus
● It had a skull highly specialized for heavy
chewing and several traits seen in
modern day gorillas, with a sagittal crest
and heavy dentition
● P. boisei inhabited savannah woodland
environments and the carbon isotope
ratios of P. boisei suggest that it had a
diet dominated by C4 vegetation

22. Paranthropus robustus
● This species lived in South Africa
between 2.0 and 1.2 million years
ago
● P. robustus had large sagittal crests,
jaws, jaw muscles, and post-canine
teeth that were adapted to serve in
the dry environment that they
inhabited
● The teeth of these primates were
larger and thicker than any gracile
australopithecine found
● On the skull, a bony ridge is located
above from the front to back
indicating where the jaw muscles
joined
● P. robustus males may have stood
only 1.2m (4 feet) tall and weighed
54 kg (120 lb) while females stood
just under 1 meter (3 feet 2 inches)
tall and weighed only 40 kg (90 lb)

24. Australopithecus garhi
The Earliest Tool Maker and Progenitor of the
Genus Homo

25. Importance of the Species
● A species known as Australopithecus
garhi was found in Ethiopia in 1996
● This species dates between 2.6
million and 2.5 million years; a
broader temporal determination for its
persistence cannot be made at
present because of the paucity of
fossils
● It is particularly significant, though,
because it is the earliest hominim
species that can unequivocally be
demonstrated to have made tools
● Most of the finds have been
concentrated in Ethiopia, at a series of
sites near Gona but also at Bouri
● Although clearly primitive and simple
tools, they show affinities with the
industry at Olduvai Gorge associated
with Homo habilis

26. Dentition and Cranial Capacity
● The traits of A. garhi fossils such as
BOU-VP-12/130 are somewhat
distinctive from traits typically seen in
Australopithecus afarensis and
Australopithecus africanus
● An example of the distinction can be
seen when comparing the Hadar
maxilla (A. afarensis) to the Bouri
specimen of A. gahri
● The cranial capacity of A. garhi
measures 450cc, the same size as
other australopithecines
● Studies made on the premolars and
molar teeth have a few similarities with
those of Paranthropus boisei since
they are larger than any other gracile
form of australopithecine
● It has been suggested that if A. garhi is
ancestral to Homo (ie. Homo habilis)
the maxillary morphology would have
undergone a rapid evolutionary change
in roughly 200,000 and 300,000 years

27. Gona, Ethiopia
● As there is so little skeletal evidence, it
must be expected that the observations of
differences between A. garhi and other
hominims will be refined and expanded
● The main point of discussion concerning A.
garhi is its status as the first hominim to
produce tools
● Excavations at Gona in Ethiopia have
resulted in the discovery of an handful of
sites affording tools that have been dated
between 2.6 million and 1.5 million years
● The earliest tools are associated with A.
garhi, but it is not certain which hominim
was responsible for the manufacture of the
later tool assemblages
● Most of these are based on small cores and
therefore conform to the 'chopper industry'
seen at Olduvai Gorge and elsewhere in the
earliest phases of the Lower Palaeolithic in
Africa

28. Dating the Earliest Tools
● We have little occasion to doubt the
early dates for these tools, nor for
concern over the accuracy of the
dates associated with the remains of
A. garhi, for the stratigraphic
succession affords several horizons of
tephra that permit good dating
opportunities
● The volcanic material also provided
the raw material for the production of
the tools—namely, small pebbles of
trachyte
● It is possible to follow some of the
tephra horizons elsewhere in the
region, and numerous dating assays
have confirmed the chronological
succession
● In short, the tools here are certainly at
least 500,000 years earlier than those
at Olduvai Gorge

29. The Industrial Tradition
● The tools were fashioned from small
pebbles of trachyte, being struck
once or twice, and used as
'choppers'
● We nonetheless also see the use of
small flakes detached from the
pebbles
● Although relatively primitive, they
differ little from the tools made at
Olduvai Gorge by Homo habilis
● The raw material was also
deliberately selected, as there are
other rocks available in the vicinity
● This implies that a conscious
decision was made to choose those
rocks with the best flaking properties
● They were probably used to process
vegetable food