The Evolution Of Australopithecus

Homo erectus was first found in Africa and the fossilized remains dated 1.8 and 1.0 million years old. The Homo erectus traits are very similar toward the modern human traits. Homo erectus brain size was smaller than the Homo sapiens. Homo erectus had a brain size of approximately 650 cc and Homo sapiens had a brain size of approximately 1251

Australopithecus Africanus: Shape is almost identical to A. Afarensis, however the cranial capacity is much more in this skull

The changes in morphology that resulted from selection for bipedalism included a readjustment of the pelvis and changes in the major locomotive muscle attachments. Habitual bipedalism necessitated a reduction in the gap between the sacroiliac joint and acetabulum, with a reduced sagittal breadth. Though the pelvis of early hominids differs from that of modern humans, but still had the traits necessary for habitual bipedalism. The Australopithecine pelvis is more similar to humans than to chimpanzees (Lovejoy, 1988): The blade of the illium is longer and wider in chimpanzees than in Australopithecus or Homo. This obvious difference is due to the functions of the pelvis in each species’ body, like being a weight bearing bone versus. Australopithecus afarensis, particularly Lucy, had a mosaic of anatomical traits featuring both human and apelike features. The short pelvis and broad iliac blades which curve around the side forming the area of gluteal muscle attachment confirmed that Au. afarensis was at least a habitual biped (Lovejoy,

They found that Au. ramidus had very similar characteristics to Sahelanthropus Tchadensis an ancestor that dates to 6-7 million years ago. Ardi had a foot that was primitive and had an opposable big toe which was most likely used to grab on branches. She also had a long and curvy spine just like humans. Its pelvis was large like those of apes and had short and broad shoulders suggesting it had a lower center of mass and could possibly walk on one leg at a time. But it is also thought that it was still spending a lot of time in the trees as well. Thus, why it is thought to be intermediate form of bipedalism it lived in both worlds, walking upright, and climbing trees, equal success in both biospheres. Although Ardi is not the connection to apes it still served to prove that the ancestor of apes was a lot more primitive than we believed. There are still several questions to be answered in this puzzle called our ancestry. It may seem that more questions arise as more clues are found, but that is science, there would be no intrigue left if all questions were

Extinction: Most species become extinct because they can’t cope with the environmental change, and also because of introduced species that turned into competitors for

Michel Brunet and his team found the fossil in the sand dunes of northern Chad after “a decade of digging”(Whitfield 2002). This discovery is most definitely a new one and one that will cause the reinterpretation of all previous hominid research. What makes this find so spectacular is that the structure of the skull suggests a being that walked upright, though it lived in a time when apes and chimpanzees also existed. “Sahelanthropus has many traits that shout ‘hominid’. These include smaller canines, and thicker tooth enamel than apes. And the point at the back of the skull where neck muscles attach suggests that Toumai walked upright”(Whitfield 2002). The key to this discovery, Brunet believes, is the back of the skull that suggests a muscle attachment for upright walking ability, which supports the scientist’s theory that

Afropithecus is a fairly large extinct ape- 50kg, characterized by a lack of a prehensile tail, long snout with procumbent incisors, generalized limb proportions and thick molar enamel. The braincase of Afropithecus is fairly small in size compared to other Miocene apes and Old World Monkeys from the same area. The primitive characteristics of Afropithecus suggest a relation to early catarrhines- such as Aegyptopithecus. And the post-cranial fossil record suggest that it was both arboreal and quadrupedal, similar to the proconsul that Afropithecus is categorized

Some other primate attributes consist of: bearing just one offspring per conception, claws developed into leveled fingernails; as well as bigger brain/body ratio compared to some other mammals, and also likelihood to keep body erect.

A recent discovery of four fossil primate teeth from the species Afrasia djijidae of the late middle Eocene Pondaung Formation of Myanmar has stirred up the debate of our primate origins. This new finding suggests that members of this clade originated in Asia then dispersed to Africa sometime during the middle Eocene, shortly before their first appearance in the African fossil record. Afrasia Djijdae is morphologically similar to Afrotarsius (North African Anthropoid). Afroasia’s dentition is very similar yet more primitive to Afrotarsius. After these phylogenetic analysis the two anthropoids have been deemed

First, evidence from the hominid fossil Ardy and archaeological evidence from the same area where Ardy was found points to the evolution of bipedalism in a woodland environment. This goes against the previous assumption that bipeds adapted to a more desolate environment. Additionally, it was also previously believed that bipedalism started with organisms that walked on two legs and their knuckles as a today’s chimp walk. However, there is no evidence in Ardy’s bones that it ever walked using its knuckles. On the other hand, Ardy possesses a short, broad hipbone which allows for bipedalism, but also a much longer lower half of the pelvis which would be more useful for climbing. Consequently, while Ardy could walk on two legs, it could not walk as well as future bipeds such as the fossil Lucy or modern humans. Lucy is often described as “the ape who stood up” and is further down the evolutionary track toward modern humans. This evolutionary adaptation to stand and walk on two legs opened great doors for humankind. Most important was the fact that walking on two limbs rather than four freed up our very special hands and empowered humankind to build tools and reshape the world as no creature could

The earliest known and accepted fossils are categorized as Australopithecus or the southern ape. A well known and famous fossil known as Lucy belongs to this fossil group, fossils of Australopithecus's have been found in areas such as Ethiopia, Kenya, Tanzania, Chad, and South Africa and are dated as far back as 4.2 - 2.3 MYA. These primates are known as bipedal apes meaning they walked upright, members of this primate group also had facial features that were apelike, had brains half the size of chimpanzees, and weighed on average of one-hundred and five pounds. It is thought these primates adapted to arboreal and terrestrial environments because dental exams of their teeth indicate a diet rich in vegetables, fruits, and leaves. On the contrary members of the Paranthropus primates have fossils that have also been recognized these fossils have been found in places like: Kenya, Tanzania, and South Africa which are dated as far back as 2.8 - 1MYA. This species was thought

However the minority of species that branch off from the human evolutionary tree and are either claimed by extinction or evolved down a second evolutionary branch, and what differences existed in them that differed from our ancestors. The species such as Australopithecus Boisei lived in the same time period to that of Australopithecus Africanus and Aferensis. However based off the information (See research booklet) it I notice that the A. Boisei has a significantly decreased brain to body weight

In terms of lower limb proportions comparing Australopithecines and Paranthropus, only a few post cranial remains have been discovered. Comparing the post cranial remains of these genera to those of modern day non-human and human apes can give great insight to the locomotion and stature of Paranthropus and Australopithecines.

Approximately 4 million years ago a wonderful evolutionary phenomenon was happening in Africa. Early hominids, man’s ancestors, were beginning a giant leap in their evolution. These hominids were moving out of the forest and beginning to walk upright, out on the open plains (Fagan, 98). This change from quadrupedalism was the most significant adaptation that ever happened to these early hominids. It caused many adaptations that make man what he is today. This process occurred in early hominids for many different reasons, each reason helping to perfect the upright walking posture. Bipedalism is thought to have occurred because of changes in environment, feeding habits, thermal regulation, and

The Australopithecines were the first to walk upright, or became bipedal, although rather clumsily. Their walk was unsteady, judging by their bone structure (Figure 1.), and they most likely were quadrupedal the majority of the time. The Australopithecines had a brain about the size of an orange, high up cheekbones, and big molars. They were about three feet tall, and had small thumbs. Australopithecines, while definitely possessing some human characteristics, humans are still much closer to the chimps. Australopithecines were vegetarians; even if they knew that animals were edible, they still had no reliable means of killing animals for food. About 2 million years ago, highly evolved Australopithecines made the