Ardipithecus ramidus
WHITE, et al, 1994
Pliocene
4.4 mya
PALAU
2000
Ardipithecus ramidus
Yvert nº.
A. ramidus was named in September 1994
The most primitive hominid yet found, this species has more chimpanzee-like features than any other human ancestor. Ardipithecus ramidus may have walked upright. Other fossils discovered with A. ramidus suggest that the species lived in the forest.
first fossils found 1992
A mandible and partial postcranial skeleton of a single individual was found in 1994. Analysis and publication on this find has yet to be made. Once completed, this should provide significant insight into the positional repertoire of Ardipithecus ramidus, dispelling all doubt as to whether or not this truly was a bipedal hominid.
CLASSIFICATION
This early fossil hominid was initially placed within the Australopithecus genus, with a new specific epithet - ramidus (from the Afar word "ramid", meaning "root") [White, et al, 1994]. Tim White and associates have subsequently reassigned the hominid to a new genus, noting the apparently extreme dissimilarities between ramidus and all other known Australopithecines. They proposed Ardipithecus (from "ardi", which means "ground" or "floor" in the Afar language) to be the genus [White, et al, 1995].
GEOLOGICAL SETTING
The initial and most extensive publication [White, et al, 1994] concerning Ardipithecus. ramidus specified that 17 hominid fossils had been located by the end of 1993. These specimens were retrieved from a cluster of localities West of the Awash River, within the Afar Depression, Aramis, Ethiopia.
Hominid and associated fossil faunas, including wood, seed and vertebrate specimens, were found entirely within a single interval overlying the basal Gaala Tuff complex, and beneath the Daam Aatu Basaltic Tuff (these volcanic strata have produced dates of 4.389 and 4.388 million years, respectively) [Renne, et al, 1999]. This definitively places all Ardipithecine specimens just shy of 4.4 million years ago.
Additionally, the associated strata were most likely produced within the context of a heavily forested, flood plain environment. Evidence for this conclusion was derived from representative non-human fossil remains, particularly from those species whose present-day analogues are environment-specific.
Australopithecus anamensis
4.2 - 3.9 mya
CAMBODJE
2001
Australopithecus anamensis
Yvert nº.
Exhibiting some chimp-like characteristics, A. anamensis' jaws are more primitive than those of later hominids. And yet, its humerus (an arm bone) is quite human-like. Characteristics of its tibia (a lower leg bone) indicate that A. anamensis walked on two feet.
Australopithecus africanus
3.0 - 2.4 mya
SOUTH AFRICA
Dr. Robert Broom with his "Mrs. Ples"
PALAU
2000
Australopithecus africanus
CAMBODJE
2001
Australopithecus africanus
Yvert nº
UNITED KINGDOM
1982
Darwin on right A. Africanus
Scott nº. 965
Michel nº. 906
Yvert nº. 1023
SOUTH AFRICA
2006
FDC - (10.NOV.2006
2007
2008
CUBA
2008
Although similar in many ways to A. afarensis, this species had a slightly larger brain (but still only slightly larger than a chimp's brain), smaller canine teeth, and larger molars.
The wear of the teeth suggests that A. africanus ate fruits and foliage.
first fossils found 1924
The Transvaal region of South Africa was the home to the species Australopithecus africanus, which lived 3.3 to 2.5 million years ago.
This species was the first of the australopiths to be described; Raymond Dart named the genus and species in 1925 after his discovery of the famous Taung child.
Many features of the cranium of A. africanus are more evolved than that of earlier A. afarensis. These features include a more globular cranium and slightly higher ratio of brain size to body size.
Also the teeth and face appear less primitive. For years researchers considered the evolution of early humans to pass from A. afarensis to A. africanus and lead to early Homo.
However, some researchers now believe that facial features link A. africanus to the "robust" early human species of southern Africa, Paranthropus robustus.
Known as anterior pillars, which are located on either side of the nose, these features are found in A. africanus and P. robustus, and not in the eastern African species.
This implies that the designation of the genus Paranthropus may be incorrect.
Austalopithecus africanus was first discovered by Raymond Dart in 1925.
He found a beautifully preserved skull of a juvenile, three to four years old.
This skull, commonly known as the Taung Child, for Taung South Africa where it was found, is perhaps the best preserved fossil of A. africanus known.
Astralopithecus africanus has a somewhat dish shaped facial structure with teeth that are relatively large compared to modern humans.
While it has larger front teeth compared to the back the emphasis is on back tooth grinding.
As a result, a sagital crest is present on males for the attachment of large muscles.
This creature is rather lightly built and has a small cranial capacity of about 440 cc on the average. It first appeared approximately 2.5 million years ago and had a rather short 1 million year existence. Many anthropologists believe that A. africanus belongs on the line that leads to Homo.
Others say that it belongs on the defunct Australopithecine line. Perhaps the most compelling evidence I have viewed is the dental traits chart on page 277 of Donald Johanson's book "Lucy: The Beginnings of Human Kind."
It clearly shows that while the molars of Homo remain small like Australopithecus afarensis, the Australopithecine molars get larger and larger with each species beginning with A. africanus.
I invite you to go look this up and decide for yourself where this species belongs on the hominid family tree.
Paranthropus robustus
SOUTH AFRICA
2006
From around 2 million to 1.2 million years ago, southern Africa was inhabited by a robust species of early human. From the original finds in 1938 and later finds in 1948, it was evident that they represented very different early human morphologies than were seen in the known Australopithecus specimens.
Adaptations of the cranium were associated with a "heavy-chewing comnplex." This complex is thought to have made it possible for these early humans to eat large amounts of tough, fibrous foods. The zygomatic arches - cheek bones - are large and positioned ffoorward on face, creating a characteristic dish-shaped face. They flare very wide, creating a large space between the arch and the skull, and opening known as the temporal fossa. Two sets of muscles are associated with the grinding action necessary to process these types of food, the masseter complex, which attaches on the bottom of the zygomatic arch, and the temporalis muscles which pass under the arch and attach to the top of the skull. The foreward migration of the cheekbones creates more space for temporalis muscles to pass under the zygomatic arch, and the increased size of the arches provides more room to accommodate a larger masseter muscle. Another feature of the robust skull is the presence, at least in males, of a prominent sagittal crest, a bony ridge that runs along the length of the top of the skull. This bony ridge provides an anchoring point for the large temporalis muscles.
These unique adaptations lead Robert Broom to place the robust early humans from southern Africa into their own genus Paranthropus. Several species names have been proposed, including P. robustus or P. crassidens. In the 1960's paleoanthropologists began to note similarities between all of the early human species before the appearance of Homo. As such, many researchers began to place all early human species into a single genus (Australopithecus) and described each species as either a "gracile" or "robust" Australopith . The robust speciemns from southern Africa were then placed in the species "Australopithecus robustus." One resercher, Milford Wolpoff, even went so far as to propose that all robust forms were really just the males and the gracile forms the females of a single early human specie
