Paranthropus aethiopicus or Australopithecus aethiopicus is an extinct species of hominin, one of the robust australopithecines. The first specimen of Australopithecus aethiopicus, discovered is known as Omo 18. Omo 18 known as Paraustralopithecus aethiopicus was discovered in southern Ethiopia by French archeologists Camille Arambourg and Yves Coppens in 1967. Omo 18 serves as a predecessor to KNM-WT 17000, discovered by Alan Walker and named Australopithecus walkeri by Ferguson; the finding discovered in 1985 by Alan Walker in West Turkana, Kenya, KNM WT 17000, is one of the earliest examples of robust pliocene hominids. A key feature of Omo 18 is that it has a v-shaped jaw unlike the other Australopithecus species found. Although Omo 18 was the first skull discovered of these species, many paleoanthropologists ignored the finding on the basis that it was similar to the other species of australopithecines. Once KNM-WT 17000 was discovered, interest renewed in Omo 18 and it was reclassified.
Australopithecus aethiopicus belongs to the group known as the robust australopithecines along with Australopithecus robustus and Australopithecus boisei. The robust australopithecines share many characteristics of the cranium and mandible more robust jaws and teeth, flaring zygomatic arches, a prominent sagittal crest, a heavier supraorbital torus, indicating a shared evolutionary development. Australopithecus aethiopicus has notable features that differ from the other robust australopithecines, including a larger zygomatic arch, extended ramus of the mandible, a more prognathic face; these differences may have been developed during the evolution of aethiopicus, but it may suggest that A. aethiopicus has a different phylogenetic history than A. robustus and A. boisei. The skull is dated to 2.5 million years ago, older than the forms of robust australopithecines. Anthropologists suggest that P. aethiopicus lived between 2.5 million years ago. The features share many traits with Australopithecus afarensis.
With its face being as prognathic as A. afarensis, its brain size was quite small at 410 cc. Paranthropus aethiopicus was first proposed in 1967 to describe a toothless partial mandible found in Ethiopia by French paleontologists. Lower jaw and teeth fragments have been uncovered. P. aethiopicus had a large sagittal crest and zygomatic arch adapted for heavy chewing. Not much is known about this species since the best evidence comes from the "Black Skull" and the jaw. There is not enough material to make an assessment of how tall they were, but they may have been as tall as Australopithecus afarensis. Paranthropus aethiopicus is considered a megadont archaic hominin; the initial discovery was a toothless adult mandible in the Shungura formation of the Omo region of Ethiopia in 1967. The ash layers above and below the fossils give an approximate date of 2.3-2.5 mya. There is only one complete skull for this hominin, so it’s hard to make proper inferences about physical characteristics. However, it can be said that the available skull is similar to P. boisei, although the incisors are larger, the face more prognathic, the cranial base less flexed.
Not all anthropologists agree that P. aethiopicus evolved into both Paranthropus boisei and Paranthropus robustus, since the skull more resembles that of A. afarensis. The one clue that makes P. aethiopicus a possible ancestor to both P. boisei and P. robustus is the similarity in jaw size. P. aethiopicus is known to have woodland. More evidence must be gathered about P. aethiopicus in order to describe its physiology. The bizarre primitive shape of the "Black Skull" gives evidence that P. aethiopicus and the other australopithecines are on an evolutionary branch of the hominid tree, distinctly diverging from the Homo lineage. Bower, Bruce. "Family Feud: Enter the Black Skull." Science News 131: 58-59. JSTOR. Web. 23 Oct. 2012. Johnson and Scott Bjelland. "Australopithecus Aethiopicus." - A Robust Australopithecine. N.p. n.d. Web. 22 Oct. 2012. <http://archaeologyinfo.com/australopithecus-aethiopicus/>. Melanie A. McCollum. “The Robust Australopithecine Face: A Morphogenetic Perspective.” Science, volume 284, No.
5412, pages 301-305, Wood and Nicholas Lonergan. "The Hominin Fossil Record: Taxa and Clades." Journal of Anatomy 212.4: 354-376. Web. 2012 October 16. <http://onlinelibrary.wiley.com/doi/10.1111/j.1469-7580.2008.00871.x/pdf>. List of fossil sites List of human evolution fossils Post-canine megadontia Human Timeline – Smithsonian, National Museum of Natural History
The Pliocene Epoch is the epoch in the geologic timescale that extends from 5.333 million to 2.58 million years BP. It is the youngest epoch of the Neogene Period in the Cenozoic Era; the Pliocene is followed by the Pleistocene Epoch. Prior to the 2009 revision of the geologic time scale, which placed the four most recent major glaciations within the Pleistocene, the Pliocene included the Gelasian stage, which lasted from 2.588 to 1.806 million years ago, is now included in the Pleistocene. As with other older geologic periods, the geological strata that define the start and end are well identified but the exact dates of the start and end of the epoch are uncertain; the boundaries defining the Pliocene are not set at an identified worldwide event but rather at regional boundaries between the warmer Miocene and the cooler Pliocene. The upper boundary was set at the start of the Pleistocene glaciations. Charles Lyell gave the Pliocene its name in Principles of Geology; the word pliocene comes from the Greek words πλεῖον and καινός and means "continuation of the recent", referring to the modern marine mollusc fauna.
H. W. Fowler called the term Pliocene a "regrettable barbarism" and an indication that "a good classical scholar" such as Lyell should have requested a philologist's help when coining words. To summarize the usage of these "regrettable barbarisms" in the labelling of the Cenozoic era: with the understanding that these are all new relative to the Mesozoic and Paleozoic eras. In the official timescale of the ICS, the Pliocene is subdivided into two stages. From youngest to oldest they are: Piacenzian Zanclean The Piacenzian is sometimes referred to as the Late Pliocene, whereas the Zanclean is referred to as the Early Pliocene. In the system of North American Land Mammal Ages include Hemphillian, Blancan; the Blancan extends forward into the Pleistocene. South American Land Mammal Ages include Montehermosan and Uquian. In the Paratethys area the Pliocene contains the Romanian stages; as usual in stratigraphy, there are many other local subdivisions in use. In Britain the Pliocene is divided into the following stages: Gedgravian, Pre-Ludhamian, Thurnian, Bramertonian or Antian, Pre-Pastonian or Baventian and Beestonian.
In the Netherlands the Pliocene is divided into these stages: Brunssumian C, Reuverian A, Reuverian B, Reuverian C, Tiglian A, Tiglian B, Tiglian C1-4b, Tiglian C4c, Tiglian C5, Tiglian C6 and Eburonian. The exact correlations between these local stages and the ICS stages is still a matter of detail; the global average temperature in the mid-Pliocene was 2–3 °C higher than today, carbon dioxide levels were the same as today, global sea level was 25 m higher. The northern hemisphere ice sheet was ephemeral before the onset of extensive glaciation over Greenland that occurred in the late Pliocene around 3 Ma; the formation of an Arctic ice cap is signaled by an abrupt shift in oxygen isotope ratios and ice-rafted cobbles in the North Atlantic and North Pacific ocean beds. Mid-latitude glaciation was underway before the end of the epoch; the global cooling that occurred during the Pliocene may have spurred on the disappearance of forests and the spread of grasslands and savannas. Continents continued to drift, moving from positions as far as 250 km from their present locations to positions only 70 km from their current locations.
South America became linked to North America through the Isthmus of Panama during the Pliocene, making possible the Great American Interchange and bringing a nearly complete end to South America's distinctive large marsupial predator and native ungulate faunas. The formation of the Isthmus had major consequences on global temperatures, since warm equatorial ocean currents were cut off and an Atlantic cooling cycle began, with cold Arctic and Antarctic waters dropping temperatures in the now-isolated Atlantic Ocean. Africa's collision with Europe formed the Mediterranean Sea, cutting off the remnants of the Tethys Ocean; the border between the Miocene and the Pliocene is the time of the Messinian salinity crisis. Sea level changes exposed the land bridge between Asia. Pliocene marine rocks are well exposed in the Mediterranean and China. Elsewhere, they are exposed near shores. During the Pliocene parts of southern Norway and southern Sweden, near sea level rose. In Norway this rise elevated the Hardangervidda plateau to 1200 m in the Early Pliocene.
In Southern Sweden similar movements elevated the South Swedish highlands leading to a deflection of the ancient Eridanos river from its original path across south-central Sweden into a course south of Sweden. The change to a cooler, seasonal climate had considerable impacts on Pliocene vegetation, reducing tropical species worldwide. Deciduous forests proliferated, coniferous forests and tundra covered much of the north, grasslands spread on all continents. Tropical forests were limited to a tight band around the equator, in addition to dry savannahs, deserts appeared in Asia and Africa. Both marine and co
Australopithecus anamensis is a hominin species that lived four million years ago. Nearly one hundred fossil specimens are known from Kenya and Ethiopia, representing over 20 individuals, it continued an evolving lineage. Fossil evidence determines that the Australopithecus anamensis is the earliest hominin species in the Turkana Basin; the first fossilized specimen of the species, though not recognized as such at the time, was a single fragment of humerus found in Pliocene strata in the Kanapoi region of West Lake Turkana by a Harvard University research team in 1965. Bryan Patterson and William W. Howells's initial paper on the bone was published in Science in 1967. Patterson and colleagues subsequently revised their estimation of the specimen's age to 4.0–4.5 mya based on faunal correlation data. In 1994, the London-born Kenyan paleoanthropologist Meave Leakey and archaeologist Alan Walker excavated the Allia Bay site and uncovered several additional fragments of the hominid, including one complete lower jaw bone which resembles that of a common chimpanzee but whose teeth bear a greater resemblance to those of a human.
Based on the limited postcranial evidence available, A. anamensis appears to have been habitually bipedal, although it retained some primitive features of its upper limbs. In 1995, Meave Leakey and her associates, taking note of differences between Australopithecus afarensis and the new finds, assigned them to a new species, A. anamensis, deriving its name from the Turkana word anam, meaning "lake". Leakey determined. Although the excavation team did not find hips, feet or legs, Meave Leakey believes that Australopithecus anamensis 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 may well be its direct predecessor. Fossil records for A. anamensis have been dated to between 4.2 and 3.9 million years ago, with recent findings from stratigraphic sequences dating to about 4.1–4.2 million years ago. Specimens have been 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 fossils include upper and lower jaws, cranial fragments, the upper and lower parts of a leg bone. In addition to this, the aforementioned fragment of humerus found thirty years ago at the same site at Kanapoi has now been assigned to this species. In 2006, a new A. anamensis find was announced, extending the range of A. anamensis into north east Ethiopia. One site known as Asa Issie provided 30 A. anamensis fossils. These new fossils, sampled from a woodland context, include the largest hominid canine tooth yet recovered and the earliest Australopithecus femur; the find was in an area known as Middle Awash, home to several other more modern Australopithecus finds and only six miles away from the discovery site of Ardipithecus ramidus, the most modern species of Ardipithecus yet discovered. Ardipithecus was a more primitive hominid, considered the next known step below Australopithecus on the evolutionary tree; 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 and filling in yet another blank in the pre-Australopithecus hominid evolutionary timeline.
Australopithecus anamensis was found in Kenya at Allia Bay, East Turkana. Through analysis of stable isotope data, it is believed that their environment had more closed woodland canopies surrounding Lake Turkana than are present today; the greatest density of woodlands at Allia Bay was along the ancestral Omo River. There was believed to be more open savanna in the basin uplands. At Allia Bay, it is suggested that the environment was much wetter. While it is not definitive, it could have been possible that nut or seed-bearing trees could have been present at Allia Bay, however more research is needed. Studies of the microwear on Australopithecus anamensis molar fossils show a pattern of long striations; this pattern is similar to the microwear on the molars of gorillas. The microwear patterns are consistent on all Australopithecus anamensis molar fossils regardless of location or time; this shows that their diet remained the same no matter what their environment. The earliest dietary isotope evidence in Turkana Basin hominin species comes from the Australopithecus anamensis.
This evidence suggests that their diet consisted of C3 resources however with a small amount of C4 derived resources. Within the next 1.99- to 1.67-Ma time period, at least two distinctive hominin taxa shifted to a higher level of C4 resource consumption. At this point, there is no known cause for this shift in diet. List of human evolution fossils Media related to Australopithecus anamensis at Wikimedia Commons Human Timeline – Smithsonian, National Museum of Natural History
The Permian is a geologic period and system which spans 47 million years from the end of the Carboniferous Period 298.9 million years ago, to the beginning of the Triassic period 251.902 Mya. It is the last period of the Paleozoic era; the concept of the Permian was introduced in 1841 by geologist Sir Roderick Murchison, who named it after the city of Perm. The Permian witnessed the diversification of the early amniotes into the ancestral groups of the mammals, turtles and archosaurs; the world at the time was dominated by two continents known as Pangaea and Siberia, surrounded by a global ocean called Panthalassa. The Carboniferous rainforest collapse left behind vast regions of desert within the continental interior. Amniotes, who could better cope with these drier conditions, rose to dominance in place of their amphibian ancestors; the Permian ended with the Permian–Triassic extinction event, the largest mass extinction in Earth's history, in which nearly 96% of marine species and 70% of terrestrial species died out.
It would take well into the Triassic for life to recover from this catastrophe. Recovery from the Permian–Triassic extinction event was protracted; the term "Permian" was introduced into geology in 1841 by Sir R. I. Murchison, president of the Geological Society of London, who identified typical strata in extensive Russian explorations undertaken with Édouard de Verneuil; the region now lies in the Perm Krai of Russia. Official ICS 2017 subdivisions of the Permian System from most recent to most ancient rock layers are: Lopingian epoch Changhsingian Wuchiapingian Others: Waiitian Makabewan Ochoan Guadalupian epoch Capitanian stage Wordian stage Roadian stage Others: Kazanian or Maokovian Braxtonian stage Cisuralian epoch Kungurian stage Artinskian stage Sakmarian stage Asselian stage Others: Telfordian Mangapirian Sea levels in the Permian remained low, near-shore environments were reduced as all major landmasses collected into a single continent—Pangaea; this could have in part caused the widespread extinctions of marine species at the end of the period by reducing shallow coastal areas preferred by many marine organisms.
During the Permian, all the Earth's major landmasses were collected into a single supercontinent known as Pangaea. Pangaea straddled the equator and extended toward the poles, with a corresponding effect on ocean currents in the single great ocean, the Paleo-Tethys Ocean, a large ocean that existed between Asia and Gondwana; the Cimmeria continent rifted away from Gondwana and drifted north to Laurasia, causing the Paleo-Tethys Ocean to shrink. A new ocean was growing on its southern end, the Tethys Ocean, an ocean that would dominate much of the Mesozoic era. Large continental landmass interiors experience climates with extreme variations of heat and cold and monsoon conditions with seasonal rainfall patterns. Deserts seem to have been widespread on Pangaea; such dry conditions favored gymnosperms, plants with seeds enclosed in a protective cover, over plants such as ferns that disperse spores in a wetter environment. The first modern trees appeared in the Permian. Three general areas are noted for their extensive Permian deposits—the Ural Mountains and the southwest of North America, including the Texas red beds.
The Permian Basin in the U. S. states of Texas and New Mexico is so named because it has one of the thickest deposits of Permian rocks in the world. The climate in the Permian was quite varied. At the start of the Permian, the Earth was still in an ice age. Glaciers receded around the mid-Permian period as the climate warmed, drying the continent's interiors. In the late Permian period, the drying continued although the temperature cycled between warm and cool cycles. Permian marine deposits are rich in fossil mollusks and brachiopods. Fossilized shells of two kinds of invertebrates are used to identify Permian strata and correlate them between sites: fusulinids, a kind of shelled amoeba-like protist, one of the foraminiferans, ammonoids, shelled cephalopods that are distant relatives of the modern nautilus. By the close of the Permian, trilobites and a host of other marine groups became extinct. Terrestrial life in the Permian included diverse plants, fungi and various types of tetrapods; the period saw a massive desert covering the interior of Pangaea.
The warm zone spread in the northern hemisphere. The rocks formed at that time were stained red by iron oxides, the result of intense heating by the sun of a surface devoid of vegetation cover. A number of older types of plants and animals became marginal elements; the Permian began with the Carboniferous flora still flourishing. About the middle of the Permian a major transition in vegetation began; the swamp-loving
Homininae called "African hominids" or "African apes", is a subfamily of Hominidae. It includes two tribes, with their extant as well as extinct species: 1) the Hominini tribe ―and 2) the Gorillini tribe. Alternatively, the genus Pan is sometimes considered to belong to Panini. Homininae comprises all hominids; the Homininae cladogram has three main branches, which lead to gorillas, to humans and chimpanzees via the tribe Hominini and subtribes Hominina and Panina. There are two living species of Panina and two living species of gorillas, but only one extant human species. Traces of hypothetical Homo species, including Homo floresiensis and Homo denisova, have been found with dates as recent as 40,000 years ago. Organisms in this subfamily are described as hominine or hominines; until 1980, the family Hominidae meant humans only. Discoveries led to revised classifications, with the great apes united with humans as members of family Hominidae Further discoveries indicated that gorillas and chimpanzees are more related to humans than they are to orangutans, leading to their placement in subfamily Homininae as well.
The subfamily Homininae can be further subdivided into three branches: the tribe Gorillini, the tribe Hominini with subtribes Panina and Hominina. The Late Miocene fossil Nakalipithecus nakayamai, described in 2007, is a basal member of this clade, as is its contemporary Ouranopithecus, their existence suggests that the Homininae tribes diverged not earlier than about 8 million years ago. Today and gorillas live in tropical forests with acid soils that preserve fossils. Although no fossil gorillas have been reported, four chimpanzee teeth about 500,000 years old have been discovered in the East-African rift valley, where many fossils from the human lineage have been found; this shows. Homininae Udabnopithecus† Udabnopithecus garedziensis Tribe Dryopithecini† Oreopithecus Oreopithecus bambolii Nakalipithecus † Nakalipithecus nakayamai Anoiapithecus † Anoiapithecus brevirostris Dryopithecus † Dryopithecus wuduensis Dryopithecus fontani Hispanopithecus † Hispanopithecus laietanus Hispanopithecus crusafonti Neopithecus † Neopithecus brancoi Pierolapithecus† Pierolapithecus catalaunicus Rudapithecus† Rudapithecus hungaricus Samburupithecus† Samburupithecus kiptalami Tribe Gorillini Chororapithecus † Chororapithecus abyssinicus Genus Gorilla Western gorilla, Gorilla gorilla Western lowland gorilla, Gorilla gorilla gorilla Cross River gorilla, Gorilla gorilla diehli Eastern gorilla, Gorilla beringei Mountain gorilla, Gorilla beringei beringei Eastern lowland gorilla, Gorilla beringei graueri Tribe Hominini Sahelanthropus† Sahelanthropus tchadensis Orrorin† Orrorin tugenensis Subtribe Panina Genus Pan Chimpanzee, Pan troglodytes Central chimpanzee, Pan troglodytes troglodytes Western chimpanzee, Pan troglodytes verus Nigeria-Cameroon chimpanzee, Pan troglodytes ellioti Eastern chimpanzee, Pan troglodytes schweinfurthii Bonobo, Pan paniscus Subtribe Hominina Graecopithecus † Graecopithecus freybergi.
Note: Graecopithecus has been subsumed by other authors into Dryopithecus. The placement of Graecopithecus within the Hominina, as shown here, represents a hypothesis, but not scientific consensus. Ardipithecus† Ardipithecus ramidus Ardipithecus kadabba Kenyanthropus† Kenyanthropus platyops Praeanthropus†Praeanthropus bahrelghazali Praeanthropus anamensis Praeanthropus afarensis Australopithecus† Australopithecus africanus Australopithecus garhi Australopithecus sediba Paranthropus† Paranthropus aethiopicus Paranthropus robustus Paranthropus boisei Homo – immediate ancestors of modern humans Homo gautengensis† Homo rudolfensis† Homo habilis† Homo floresiensis† Homo erectus† Homo ergaster† Homo antecessor† Homo heidelbergensis† Homo cepranensis† Denisovans † Homo neanderthalensis† Homo rhodesiensis† Homo sapiens Anatomically modern human, Homo sapiens sapiens Homo sapiens idaltu† Archaic Homo sapiens † Red Deer Cave people† The age of the subfamily Homininae is estimated at some 14 to 12.5 million years.
Its separation into Gorillini and Hominini is estimated to have occurred at about 8 to 10 million years ago during the late Miocene, close to the age of Nakalipithecus nakayamai. There is evidence there was interbreeding of Gorillas and the Pan-Homo ancestors until right up to the Pan-Homo split. Recent studies of Ardipithecus ramidus and Orrorin tugenensis suggest some degree of bipedalism. Australopit
Paranthropus is a genus of extinct hominins that lived between 2.6 and 1.1 million years ago. Known as robust australopithecines, they were bipedal hominids descended from the gracile australopithecine hominids 2.7 million years ago. The genus is characterised by robust craniodental anatomy, including gorilla-like sagittal cranial crests which suggest strong muscles of mastication, broad, grinding herbivorous teeth. However, Paranthropus skulls lack the transverse cranial crests of modern gorillas; the low rate of enamel fractures on Paranthropus teeth suggest this characteristic craniodental anatomy evolved to cope with a diet of tough vegetation, rather than hard foods. A partial cranium and mandible of Paranthropus robustus was discovered in 1938 by a schoolboy, Gert Terblanche, at Kromdraai B in South Africa, it was described as a new species by Robert Broom of the Transvaal Museum. The site has been excavated since 1993 by Francis Thackeray of the Transvaal Museum. A date of at least 1.95 million years has been obtained for Kromdraai B.
Paranthropus boisei was discovered by Mary Leakey on July 17, 1959, at the FLK Bed I site of Olduvai Gorge in Tanzania. Mary was working alone, she rushed back to camp and, at the news, Louis made a remarkable recovery. They refrained from excavating. In Louis recorded a first name, Titanohomo mirabilis, reflecting an initial impression of close human affinity. Louis and Mary began to call it "Dear Boy". Recovery was halted on August 7. Dear Boy was found in context with Oldowan tools and animal bones; the fossil was published in Nature dated August 15, 1959, but due to a strike of the printers the issue was not released until September. In it Louis placed the fossil in William King Gregory's subfamily Australopithecinae, creating a new genus for it, species boisei, no longer used. "Zinj" is an ancient Arabic word for the coast of East Africa and "boisei" referred to Charles Watson Boise, an anthropological benefactor of the Leakeys. Louis based his classification on twenty differences from Australopithecus.
At that time palaeoanthropology was in an overall mood to lump species. The presentation of Zinj during the Fourth Pan-African Congress of Prehistorians in July in the Belgian Congo, at which Louis was forced to read the delayed Nature article, nearly came to grief for Louis over the creation of a new genus. Dart rescued him with the now famous joke, "... What would have happened if Mrs. Ples had met Dear Boy one dark night."The battle of the name went on for many years and drove a wedge between Louis and Sir Wilfrid LeGros Clark, from 1955, who took the Paranthropus view. On the other hand, it brought the Leakeys and Dr. Melville Bell Grosvenor of the National Geographic Society together; the Leakeys became international figures and had no trouble finding funds from on. The Zinj question became part of the Australopithecus/Paranthropus question. All species of Paranthropus were bipedal, many lived during a time when species of the genus Homo, were prevalent. Paranthropus first appeared 2.7 million years ago.
Most species of Paranthropus had a brain about 40 percent the size of that of a modern human. There was some size variation between the different species of Paranthropus, but most stood 1.3-1.4 m tall and were quite well muscled. Paranthropus is thought to have lived in wooded areas rather than the grasslands of Australopithecus. Paranthropus is thought to be bipedal based on its anatomical structure in its hips and feet that resemble both its ancestor, Australopithecus afarensis, modern humans; the pelvis is similar to A. afarensis but the hip joint, including the femoral head and acetabulum are smaller in Paranthropus. The similar hip structure between A. afarensis and Paranthropus implies that they had a similar walking gait, that Paranthropus moved like the "gracile australopiths". They show anatomical similarity to modern humans in the big toe of their foot and their well developed plantar aponeurosis; the hallux metatarsal shows increased base for more internal support, more distal articular surface which causes more connection and support to the other bones in the foot.
The extra support in the big toe and extensive plantar aponeurosis shows that Paranthropus had hyperextension of their toes for a "toe-off" gait cycle, characteristic of modern bipedalism in humans. The behavior of Paranthropus was quite different from that of the genus Homo, in that it was not as adaptable to its environment or as resourceful. Evidence exists in its anatomy, tailored to a diet of grubs and plants; this would have made it more reliant on favorable environmental conditions than members of the genus Homo, which consumed a much wider variety of foods. Therefore, because it was a specialist species, it had more difficulty adapting to a changing climate, leading to its extinction. Evolutionary biologist Richard Dawkins notes "perhaps several different species" of robust hominids, "as usual their affinities, the exact number of species, are hotly disputed. Names that have been attached to various of these creatures...are Australopithecus robustus, Australopithecus boisei, Australopithecus aethiopicus."Opinions differ whether the species P. aethiopicus, P. boisei and P. robustus should be included within the genus Australopithecus.
The emergence of the robusts could be either a display of divergen
Australopithecus sediba is a species of Australopithecus of the early Pleistocene, identified based on fossil remains dated to about 2 million years ago. The species is known from six skeletons discovered in the Malapa Fossil Site at the Cradle of Humankind World Heritage Site in South Africa, including a juvenile male, an adult female, an adult male, three infants; the fossils were found together at the bottom of the Malapa Cave, where they fell to their death, have been dated to between 1.980 and 1.977 million years ago. Over 220 fragments from the species have been recovered to date; the partial skeletons were described in two papers in the journal Science by American and South African paleoanthropologist Lee R. Berger from the University of the Witwatersrand and colleagues as a newly discovered species of early human ancestor called Australopithecus sediba. MH1 is disarticulated and 34% complete if skeletal elements known to be in an unprepared block are included while MH2 is 45.6% complete and exhibits partial articulation.
A paper concluded Australopithecus sediba is distinct from, but shares anatomical similarities to, both the older Australopithecus africanus and the younger Homo habilis. Australopithecus sediba may have lived in savannas but ate fruit and other foods from the forest—behavior similar to modern-day savanna chimpanzees; the conditions in which the individuals were buried and fossilized were extraordinary, permitting the extraction of plant phytoliths from dental plaque. The first specimen of A. sediba was found by paleoanthropologist Lee Berger's nine-year-old son, Matthew, on August 15, 2008. While exploring near his father's dig site in the dolomitic hills north of Johannesburg, on the Malapa Nature Reserve, Matthew stumbled upon a fossilized bone; the boy alerted his father to the who could not believe what he saw -- a hominid clavicle. Upon turning the block over, "sticking out of the back of the rock was a mandible with a tooth, a canine, sticking out, and I died", he recalled. The fossil turned out to belong to a 4 ft 2 in juvenile male, whose skull was discovered in March 2009 by Berger's team.
The find was announced to the public on April 8, 2010. Found at the Malapa archeological site were a variety of animal fossils, including saber-toothed cats and antelopes. Berger and geologist Paul Dirks speculated that the animals might have fallen into a deep 100–150-foot "death-trap" lured by the scent of water; the bodies may have been swept into a pool of water with a sandy bottom and rich with lime, allowing the remains to become fossilized. The fossil was dated using a combination of palaeomagnetism and uranium–lead dating which showed that the fossils are no older than ~2.0 Ma. The presence of animal species which became extinct at ~1.5 Ma indicates the deposit is no younger than 1.5 Ma. The sediments have a'normal' magnetic polarity and the only major period between 2.0 and 1.5 Ma when this occurred is the Olduvai sub-Chron between 1.95 and 1.78 Ma. Accordingly, the fossils were dated to ~1.95 Ma. Recent dating of a capping flowstone demonstrated this was not possible and the normal magnetic polarity sediments have since been correlated to the 3,000-year-long Pre-Olduvai event at ~1.977 Ma.
Because of the wide range of mosaic features exhibited in both cranial and post-cranial morphology, the authors suggest that A. sediba may be a transitional species between the southern African A. africanus and either Homo habilis or the H. erectus. The cranial capacity of MH1, estimated to be at 95% of adult capacity, is at the higher end of the range for A. africanus and far from the lower range of early Homo, but the mandible and tooth size are quite gracile and similar to what one would expect to find in H. erectus. However, the cusp spacing is more like Australopithecus. Regardless of whether Australopithecus sediba is a direct ancestor of early Homo or not, our understanding of the range of variation in early hominins has been increased with the finding of these new specimens. A. sediba compared to its ancestor species A. africanus on the whole is described by Berger et al. as more derived towards Homo than A. garhi showing a number of synapomorphies taken to anticipate the reorganization of the pelvis in H. erectus, associated with "more energetically efficient walking and running".
The femur and tibia are fragmentary, but the foot combines an advanced anklebone combined with a primitive heel. Its cranial capacity is estimated at around 420 -- about one-third of that of modern humans. A. sediba had a modern hand, whose precision grip suggests it might have been another tool-making Australopithecus. Evidence of the precision gripping and stone tool production can be seen from Homo-like features such as having a long thumb and short fingers; the nearly complete wrist and hand of an adult female from Malapa, South Africa presents Australopithecus-like features, such as a strong flexor apparatus associated with arboreal locomotion. A well-preserved and articulated ankle of A. sediba is humanlike in form and function and possesses some evidence for a humanlike arch and Achilles tendon. However, A. sediba is apelike in possessing a more gracile calcaneal body and a more robust medial malleolus