Ardipithecus ramidus

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Ardipithecus ramidus
Digital reconstruction of the skull fragments from "Ardi"

Digital reconstruction of the skull fragments from " Ardi "

Temporal occurrence
Lower Pliocene
4.4 million years
Locations
Systematics
Human (Hominoidea)
Apes (Hominidae)
Homininae
Hominini
Ardipithecus
Ardipithecus ramidus
Scientific name
Ardipithecus ramidus
( White , Suwa & Asfaw , 1994)

Ardipithecus is the name of a 4.4 million year old type of ape from the genus Ardipithecus , whose fossils so far only in Ethiopia were found. It is one of the oldest known species in the line of evolution of the hominini . Ardipithecus ramidus possibly belongs to the direct ancestors of the genera Australopithecus and Homo or is at least very close to them.

The special significance of the fossil record of Ardipithecus ramidus is that decades-old hypotheses about the human tribal history , according to which the ankle gait of chimpanzees and gorillas is an original characteristic, have been questioned.

Naming

Ardipithecus is an artificial word . The name of the genus was derived in 1995 partly from the Afar language (from ardi "earth"), partly from Greek (from "πίθηκος", pronounced in ancient Greek píthēkos "monkey"). The epithet ramid "root" is also borrowed from the Afar language. Ardipithecus ramidus consequently means “ground monkey at the root of man”. Ardipithecus ramidus is the type species of the genus Ardipithecus .

Initial description

Ten associated teeth from an upper jaw and a lower jaw were named as the holotype of Ardipithecus ramidus in the first description in September 1994 (archive number ARA-VP-6/1). Numerous other teeth and some other skeletal fragments from 17 individuals have been identified as paratypes.

The findings were interpreted in 1994 as evidence of the most primitive species of the genus Australopithecus and named Australopithecus ramidus . Between November 1994 and January 1995, however , further significant bones were discovered in the same find horizon - 50 meters from the location of the holotype teeth. Among them were a lower jaw and numerous bones of the upper body and limbs belonging to a single individual: the individual who 15 years later became known as " Ardi ". In particular, the additionally recovered teeth, which were relatively small in relation to the bones, differed greatly from the dentition of all Australopithecus finds known up to that point ; Therefore, in May 1995, the research group felt compelled to assign the fossils to the new genus Ardipithecus and thus to place them next to (but before) the genus Australopithecus .

In 1995 a. a. as compared to the back teeth relatively long canines mentioned; In 2009 the interpretation of the canines was revised on the basis of 145 teeth from 21 individuals and - on the contrary - an early onset tendency to reduce the size of canines in the hominini was described; From this far-reaching conclusions about the social behavior of Ardipithecus were drawn .

discovery

On December 17, 1992, the Japanese paleoanthropologist Gen Suwa ( University of Tokyo ) discovered a first fragment: the root of an upper posterior molar (ARA-VP-1/1). Shortly afterwards, at the end of 1992 / beginning of 1993, the group of ten teeth belonging together was discovered, and the finds of other individuals that were later identified as paratypes were recovered.

So far the only places where they have been found are Aramis , approx. 100 km south of Hadar , west of the Awash River in the Afar Triangle , and Gona , 60 km north of Aramis. The vast majority of the finds come from Aramis; they emerged as a result of rain erosion on the slopes that flank the Awash in this area today on both sides. The dating of the finds is extremely reliable, as volcanic material was deposited both directly above and below the fossilized layer of Aramis. Its age was determined with the help of potassium-argon dating ( 39 Ar- 40 Ar method) in each case 4.42 million years. In 2005 the “Gona Paleoanthropological Research Project” identified 4.51 to 4.32 million years for Gona; these finds were recovered between 1999 and 2003 and came from at least nine individuals. In 2009, eleven studies were finally published in the journal Science with the participation of 47 scientists. 110 Aramis finds from at least 36 individuals were analyzed. They were again assigned an age of 4.4 million years.

All Ardipithecus ramidus finds from Aramis come from a three to six meter thick, fine-grained fossil alluvial soil that was created in a relatively short period of only 100 to a maximum of 10,000 years. Both the fine grain of the sediment layer and the condition of the fossil bones (the lack of traces of wear) indicate that they were not or only negligibly drifted by water. The analysis of the geological conditions was also interpreted to the effect that the fossils were deposited in a shallow floodplain - far away from the main river bed at the time.

The Ardi fossil : Drawing after an illustration in Science
The skeletal fragments of "Ardi"

The fossil "Ardi"

→ Main article: Ardi

His discoverers nicknamed the discovery of a particularly complete female skeleton, published in October 2009, with the nickname Ardi. Its first remains were discovered back in 1994; for Ardi, "the oldest hominine skeleton" known so far ( Tim White ), a weight of 51 kg and a height of about 120 cm was calculated. Important findings on the anatomy of Ardipithecus ramidus and - derived from this - on the way of life of this species and the evolution of the early hominini were obtained from the analysis of this skeleton. In December, the editorial team of the journal Science chose its comprehensive and interdisciplinary processing as the most important scientific publication of 2009.

anatomy

The study of the physique of Ardipithecus ramidus provided numerous indications that the chimpanzees are far less suitable as models for the physique of the early hominini than had previously been assumed by many researchers. In particular, from the shape of the skull fragments, it was concluded that they are related to Australopithecus and Homo .

Walking upright

According to the first description published in 1994, Ardipithecus ramidus had relatively long, ape-like finger joints, which identify it as a tree dweller. At first it remained unclear whether Ardipithecus ramidus could already walk upright. In the descriptions of the finds from Gona published in 2005 and 2019, the ability to walk upright was derived from the shape of the found bones of toes and the partially preserved skeleton GWM67 / P2. Since large parts of the head, hands and feet as well as the pelvis have been preserved from "Ardi" , according to the team of authors of the studies published in 2009, it is now certain that Ardipithecus ramidus was still predominantly a tree dweller, but that it also moves upright on the ground could, albeit in a more original phylogenetic manner than Australopithecus afarensis .

denture

The analysis of the bones also showed that the male and female individuals of Ardipithecus ramidus resembled each other much more closely than is known from the later Australopithecus species; apparently the sexual dimorphism in Ardipithecus was only weakly developed. The researchers came to this conclusion in 2009 because the large number of teeth found enabled them to be sure that they included teeth of both sexes. Thus are the maxilla - canines of Ardipithecus ramidus about the same as the canines of extant female chimpanzee ( Pan troglodytes ) and the male bonobos ( Pan paniscus ), but all previously discovered fossil canines lack the long, dagger-like crown of chimpanzee canines. Correspondingly, no front teeth (premolars P₃) and no tooth gaps ( diastemata ) are detectable in the lower jaw, into which the long upper canine teeth of other types fit and are sharpened on the neighboring lower jaw teeth through constant abrasion (so-called honing ).

The distinctive, elongated crown of the upper canine teeth is known from many fossil and contemporary male monkeys and is considered a feature shared by the common ancestors of all monkeys living today. This feature has therefore been lost in Ardipithecus ramidus and later further reduced in the representatives of the genus Australopithecus and Homo . The researchers use this change to draw conclusions about social behavior. The dagger-like canines of the upper jaw are regularly used in the male monkeys living today. a. as a 'weapon' in ranking battles within one's own group and in battles with individuals from other groups. The "dramatic feminization" of male canines suggests that due to sexual selection , social behavior , especially agonistic behavior and imposing behavior , had changed "long before the hominini had an enlarged brain and used stone tools."

The enamel of the posterior molars of Ardipithecus ramidus is thinner than that of Australopithecus , but slightly thicker than the enamel of either species of chimpanzee. It has been inferred that Ardipithecus ramidus probably omnivorous was so - was not specialize in fruit as a food source, but also - - different from the chimpanzees unlike the gorillas and the australopithecines -. Not This in turn according to the researchers leads to highly fibrous foods to concluded that the feeding habits of chimpanzees and gorillas only evolved after their evolutionary lines were separated from those of hominini.

Habitat

Trees alternating with grassland (like here in Malawi ) also formed the habitat of Ardipithecus

From fossil bone finds from other animal species, the authors of the first description had already concluded that the habitat of Ardipithecus ramidus must have been forested and rich in water. The findings of the "Gona Paleoanthropological Research Project" described in 2005 confirmed this representation. These finds came from arboreal colobus and colobus monkeys , deciduous kudu , pigs , horses and rhinos and - relatively rarely - from grass-eating antelopes and baboon- like monkeys.

The findings published in 2009 refined our knowledge of the habitat of Ardipithecus ramidus considerably, as more than 150,000 plant and animal fossils had been collected. More than 6000 finds could be assigned to vertebrates at least at family level - including shrews , gerbils and bats as well as hyenas ( Ikelohyaena abronia ), bears ( Agriotherium ) and elephants . Another special feature are the 370 remains of at least 29 mostly land-dwelling bird species from 16 families, as birds in strata that carry hominid fossils are very rare elsewhere; According to the researchers, their remains come mostly from the wool of owls . Numerous larger bones show bite marks from carnivores , the ends of the large tubular bones are often missing, and only a few skulls have been found; therefore, fully preserved skeletons are extremely rare. From this it is concluded that there was a comparable competition for carcasses in the habitat of Ardipithecus ramidus as there was today in the Ngorongoro crater . Overall, however, herbivores dominate among the identified species, especially those that mainly feed on leaves and fruits.

Even the plant remains, based on the data published in 2005, indicated a varied landscape of forests, bushes, wetlands and savannah- like areas, as was derived from the accompanying finds by Sahelanthropus . In 2009 it was also reported that petrified wood from hackberry trees ( Celtis sp. ), Figs ( Ficoxylon ) and palm trees had been detected, which, however, did not dominate the biotope, but are known to fossilize particularly well. The proof of pollen was u. a. for various grasses (including both sweet grasses and sour grasses ) as well as for representatives of the genus Myrica . From the ratio of pollen from grass on the one hand, palm trees and dicotyledonous trees on the other , it was deduced that a maximum of 40 to 65 percent of the area was covered by trees. Since the area was temporarily flooded by the neighboring river system during the lifetime of Ardipithecus ramidus , some fish (most often predatory catfish and members of the genus Barbus ) and numerous crocodile teeth were found. According to the authors, there were no signs of rainforest vegetation, steppe-like dry vegetation or pure grassland.

As a result of the synopsis of their geological and botanical analyzes, the researchers wrote “that Ardipithecus ramidus did not live in an open savannah , which was once considered the predominant habitat of the earliest hominini, but in an environment that was more humid and cooler than today [ in today's Afar Triangle] and habitats from closed woodland and loosened trees. ”The studies in which the birds and the small and large vertebrates were examined came to similar conclusions.

The findings published in 2009, but also the analyzes published in 2005, contributed to the fact that the so-called savanna hypothesis - an attempt to explain the origin of the upright gait among hominini from life in a savannah landscape - is considered refuted.

food

Already from the externally recognizable nature of the teeth and the thickness of their enamel layer, it could be deduced that Ardipithecus ramidus was neither adapted to particularly hard, abrasive nor to particularly soft, predominantly fruit-based foods and is therefore most likely to be considered omnivorous . In addition, the ratio of the two stable carbon isotopes 12 C and 13 C in the tooth enamel of five individuals was analyzed with the help of an isotope study , from its difference (δ 13 C value) - as well as from the ratio of the two stable oxygen isotopes 18 O / 16 O (δ 18 O value) - conclusions can be drawn about eating habits: C 3 plants (for example grasses) absorb less 13 C than C 4 plants , and conclusions can also be drawn from the δ 18 O value Temperature and humidity of a biotope possible. The measurement results of Ardipithecus ramidus were then compared with the findings from similar investigations of the tooth enamel of other fossil animal species from the same find layer, whose living and eating habits are known to be beyond doubt: u. a. Otter ( Enhydriodon ), bear ( Agriotherium ), giraffes ( Giraffa and Sivatherium ) and horse ( Eurygnathohippus ). As a result, these measurements and comparisons confirmed that Ardipithecus ramidus regularly looked for its food in deciduous forests and only to a much lesser extent in grasslands; this clearly distinguishes it from Australopithecus africanus and Australopithecus robustus as well as from the earliest representatives of the genus Homo .

Scientific importance

Metatarsal from the big toe of the Ardi fossil (cast)

Since the discovery of " Lucy " in 1974 it has been known that the individuals of Australopithecus afarensis around 3.2 million years ago only had a brain that was about the size of a chimpanzee, but "already upright as we walk" could. The intermediate stages through which the upright gait developed remained a mystery for more than 30 years due to the lack of meaningful fossil evidence. It was not until the analyzes of the fossils of Ardipithecus ramidus published in 2009 that solid insights into the development of hominini in the transition from four-footed tree dwellers to bipedal dwellers in open savannahs were obtained.

The “greatest surprise” was the finding that Ardipithecus “is not a transitional form between Australopithecus and an ancestor who resembled the chimpanzees and gorillas living today.” There was no evidence of the ankle gait of chimpanzees and gorillas, nor of their protruding snouts or for their dagger-like elongated canines. The relatively immobile wrist of chimpanzees and gorillas also turned out to be the result of a special evolutionary adaptation in the lines of development leading to these two species, that is, as a “ derived ” (“progressive”) characteristic. Conversely, man's relatively small canine teeth and his highly flexible hands can now be described as more original (“more primitive”) features compared to the corresponding adaptations of chimpanzees and gorillas. Previously, many paleoanthropologists had used the physique of the two African great ape species as a model for the last common ancestor of humans and chimpanzees - also with regard to agonistic behavior .

The construction of the feet, the big toes of which could be widely spread apart and therefore used to clasp branches, did not merely refute the savannah hypothesis ; The arrangement of the foot bones also supports the hypothesis of the development of upright walking on trees as an adaptation to the acquisition of food.

One of the lead authors of the studies published in Science in October 2009 , C. Owen Lovejoy , who previously worked on the reconstruction of Lucy's skeleton , summarized the results of these studies as follows:

“Since the time of Darwin, the African great apes living today have mostly been the godfathers when the early human evolution has been reconstructed. These models illustrate basic human behaviors as enhancements of behaviors seen in chimpanzees and / or gorillas (e.g., upright feeding posture, male dominance, tool use, culture, hunting, and warfare). Ardipithecus essentially falsifies such models, for the African great apes living today are highly derived relatives of our last common ancestor. "

Elsewhere, C. Owen Lovejoy said of the consequences of Ardipithecus' analysis :

“People often think that we are descended from great apes, but we are not; the great apes descend from us in some ways. "

Related species

After several similarly old fossils were found in 2001 in the Ethiopian Afar Depression , these were initially designated as the subspecies Ardipithecus ramidus kadabba and Ardipithecus ramidus as Ardipithecus ramidus ramidus . In 2004 Ardipithecus ramidus kadabba was placed as a separate species ( Ardipithecus kadabba ) next to Ardipithecus ramidus . At the same time, however, it was noted that Sahelanthropus and Orrorin belong to the same group of forms as Ardipithecus and - after finding more finds - could possibly be assigned to a single genus.

In February 2005, Austrian researchers working with Horst Seidler discovered the well-preserved upper part of a hominine thigh bone in the southern Ethiopian rocky desert of Galili, the head and neck of which suggest an upright individual. The age of this fossil has been dated from 4.38 to 3.92 million years; whether it belongs to Ardipithecus ramidus or a related species is unclear.

Controversy

Hypothesis on the evolution of the australopithecines , as represented by Friedemann Schrenk , for example, based on the current finds .

Immediately after the description of the find, "this strange type of walk" was described by Ardi as "amazing": "The construction of this foot, with which Ardi is supposed to strut around on tree branches - I am not yet quite clear how it should work" For example, the German paleoanthropologist Friedemann Schrenk was quoted. Team boss Tim White had previously pointed out that "you have to go to the Star Wars space bar if you want to find a being that moves as idiosyncratically as Ardi did". However, the much older Oreopithecus bambolii also had a similarly prominent big toe.

In May 2010, Science then published two brief statements identified as technical comments , which raised doubts about the correctness of the interpretation of the fossil bones and the circumstances of the find. The anatomist and primatologist Esteban Sarmiento argued that the characteristics attributed to the Ardipithecus fossils are not suitable to clearly identify them as direct ancestors of the later hominini; rather, the anatomical features and genetic calculations based on the molecular clock suggested, in his opinion, that Ardipithecus ramidus lived 4.4 million years ago before the two lines of development that led to the African great apes on the one hand and humans on the other. If Ardipithecus lived after the two lines of development had separated, he might be placed at the base of the African great apes. Tim White immediately rejected the criticism and pointed out in particular that the separation of the lines of development of chimpanzees and hominini occurred much earlier (7 to 5 million years ago), according to the overwhelming opinion of paleoanthropologists. In addition, the features of the pelvis, the teeth and the lower jaw identified Ardipithecus as close relatives of Australopithecus , as they only shared these features with him and it was unlikely that this combination of features had developed several times independently of each other.

In the second technical comment , a group of researchers from several US universities argued that Ardis Habitat was by no means as densely wooded as White and coworkers claimed. Rather, one can deduce from the accompanying finds that it was a typical, open savannah landscape (tree or bush savannah) with 25 percent or less area under the treetops as well as isolated alluvial forests and wooded river banks. The critics came to this conclusion on the one hand because of the predominance of C 4 plants compared to C 3 plants in soil samples from the find region, which in their opinion speaks for a predominance of open grasslands. On the other hand, they pointed out that - contrary to what White and co-workers claim - more fossils of grass-eating ungulates than of foliage and fruit-eating species have been discovered. In particular, the complete absence of duckers was taken as an indication of a poorly forested area; The large number of tree-dwelling monkeys as well as the evidence of a fossil kudu species ( Tragelaphus cf. moroitu ) can, however , be explained by the existence of gallery forests . This criticism was also immediately rejected. The large number of fossils of tree-living monkeys discovered cannot be explained solely by the existence of narrow zones of forested banks. In addition, many grass-eating animal species have actually been detected; the number of proven individuals of these species is, however, much lower than the number of individuals of those species whose teeth were adapted to foliage and fruit as food.

In February 2011, Bernard Wood and Terry Harrison also criticized in a review article the assignment of Ardipithecus ramidus and Orrorin tugenensis and Sahelanthropus tchadensis to the taxon hominini as premature. The relatively small incisors and upper canines, the absence of the diastema, the position of the foramen magnum , the relatively short snout and the structure of the pelvis are an indication of a possible belonging to the early hominini; However, these features are by no means exclusive features of the hominini, but also, for example, for Oreopithecus bambolii , which - like Ramapithecus punjabicus - was initially placed at the base of the hominini, but was later classified unequivocally apart from the hominini due to other features. It cannot be ruled out, therefore, that the similarity of the characteristics of Ardipithecus , Orrorin and Sahelanthropus with those of the oldest species, Australopithecus anamensis, which is undoubtedly hominin , is to be assessed as a synapomorphism and indicates convergent developments . However, this possibility had also been left open by Tim White's working group as “Hypothesis 3”; however - after comparison with the hypothesis that Ardipithecus ramidus was a direct ancestor of Australopithecus anamensis / Australopithecus afarensis - it was shown to be less likely. In 2019 Ardipithecus ramidus was again interpreted only as a "sister taxon" of all later hominini.

Web links

Commons : Ardipithecus ramidus  - collection of images, videos and audio files

Individual evidence

  1. ↑ a b c Tim White , Gen Suwa, Berhane Asfaw : Australopithecus ramidus, a new species of early hominid from Aramis, Ethiopia. In: Nature . Volume 371, No. 6495, 1994, pp. 306-312; doi: 10.1038 / 371306a0 , full text (PDF; 611 kB) ( Memento from April 13, 2013 in the Internet Archive )
  2. ↑ Ann Gibbons: A New Kind of Ancestor: Ardipithecus Unveiled. In: Science . Volume 326, 2009, p. 36, doi: 10.1126 / science.326.5949.36
  3. ↑ a b Corrigendum. Tim White, Gen Suwa, Berhane Asfaw: Australopithecus ramidus, a new species of early hominid from Aramis, Ethiopia. In: Nature. Volume 375, No. 6526, 1995, p. 88; doi: 10.1038 / 375088a0 ( full text (PDF) )
  4. ^ Gen Suwa et al .: Paleobiological Implications of the Ardipithecus ramidus Dentition. In: Science. Volume 326, No. 5949, 2009, pp. 69, 94-99, doi: 10.1126 / science.1175824
  5. ↑ a b c d Giday Wolde-Gabriel et al .: The Geological, Isotopic, Botanical, Invertebrate, and Lower Vertebrate Surroundings of Ardipithecus ramidus. In: Science. Volume 326, 2009, pp. 65, 65e1-65e5, doi: 10.1126 / science.1175817
  6. ↑ 4,419 ± 0.068 million and 4,416 ± 0.031 million years
  7. ↑ Sileshi Semaw et al .: Early Pliocene hominids from Gona, Ethiopia. In: Nature. Volume 433, No. 7023, 2005, p. 301, doi: 10.1038 / nature03177
  8. ↑ In: Science. Volume 326, No. 5949, from October 2, 2009, cover photo , table of contents
  9. ↑ Tim D. White et al .: Macrovertebrate Paleontology and the Pliocene Habitat of Ardipithecus ramidus. In: Science. Volume 326, 2009, p. 67, doi: 10.1126 / science.1175822
  10. ^ Ardi displaces Lucy as oldest hominid skeleton. Ethiopian desert yields fossils that paint new picture of human evolution. On: eurekalert.org from October 1, 2009
  11. ↑ Ann Gibbons: Breakthrough of the Year: Ardipithecus ramidus. In: Science. Volume 326, December 18, 2009, pp. 1598–1599, doi: 10.1126 / science.326.5960.1598-a
  12. ↑ a b Our ancestors walked tall. In: New Scientist . October 10, 2009, p. 17
  13. ^ Gen Suwa et al .: The Ardipithecus ramidus Skull and Its Implications for Hominid Origins. In: Science. Volume 326, 2009, No. 5949, p. 68, 68e1–68e7, doi: 10.1126 / science.1175825
    literally it says: “Anatomical comparisons and micro-computed tomography-based analysis of this and other remains reveal pre- Australopithecus hominid craniofacial morphology and structure. "
  14. ^ William H. Kimbel et al .: Ardipithecus ramidus and the evolution of the human cranial base. In: PNAS . Volume 111, No. 3, 2014, pp. 948-953, doi: 10.1073 / pnas.1322639111
    'Ardi' skull reveals links to human lineage. On: eurekalert.org of January 6, 2014
  15. ↑ Sileshi Semaw et al .: Early Pliocene hominids from Gona, Ethiopia. In: Nature. Volume 433, No. 7023, 2005, pp. 301-305 doi: 10.1038 / nature03177
  16. ^ Scott W. Simpson, Naomi E. Levin, Jay Quade et al .: Ardipithecus ramidus postcrania from the Gona Project area, Afar Regional State, Ethiopia. In: Journal of Human Evolution. Volume 129, 2019, pp. 1–45, doi: 10.1016 / j.jhevol.2018.12.005
    New findings shed light on origin of upright walking in human ancestors. On: eurekalert.org of February 28, 2019
  17. ↑ a b Tim D. White, Berhane Asfaw, Yonas Beyene, Yohannes Haile-Selassie , C. Owen Lovejoy , Gen Suwa, Giday Wolde-Gabrie: Ardipithecus ramidus and the Paleobiology of Early Hominids. In: Science. Volume 326, No. 5949, 2009, pp. 75-86; doi: 10.1126 / science.1175802
  18. ↑ Elaine E. Kozma et al .: Hip extensor mechanics and the evolution of walking and climbing capabilities in humans, apes, and fossil hominins. In: PNAS. Volume 115, No. 16, 2018, pp. 4134-4139, doi: 10.1073 / pnas.1715120115
  19. ^ Gen Suwa et al .: Paleobiological Implications of the Ardipithecus ramidus Dentition. In: Science. Volume 326, 2009, pp. 69, 94-99, doi: 10.1126 / science.1175824
  20. ^ Gen Suwa et al .: Paleobiological Implications of the Ardipithecus ramidus Dentition. In: Science. Volume 326, 2009, p. 69
  21. ^ Antoine Louchart et al .: Taphonomic, Avian, and Small-Vertebrate Indicators of Ardipithecus ramidus Habitat. In: Science. Volume 326, 2009, pp. 66, 66e1-66e4, doi: 10.1126 / science.1175823
  22. ↑ a b Tim D. White et al .: Macrovertebrate Paleontology and the Pliocene Habitat of Ardipithecus ramidus. In: Science. Volume 326, 2009, pp. 67, 87-93, doi: 10.1126 / science.1175822
  23. ↑ Tim D. White et al .: Macrovertebrate Paleontology and the Pliocene Habitat of Ardipithecus ramidus. In: Science. Volume 326, 2009, p. 90
  24. ↑ a b Ann Gibbons: Breakthrough of the Year: Ardipithecus ramidus. In: Science. Volume 326, 2009, pp. 1598-1599, doi: 10.1126 / science.326.5960.1598-a
  25. ↑ SKS Thorpe et al .: Origin of Human Bipedalism As an Adaptation for Locomotion on Flexible Branches. In: Science. Volume 316, 2007, pp. 1328-1331, doi: 10.1126 / science.1140799 ; cf. on this: upright on the branch. From: Süddeutsche Zeitung from June 1, 2007
  26. ↑ C. Owen Lovejoy: Reexamining Human Origins in Light of Ardipithecus ramidus. In: Science. Volume 326, 2009, pp. 74, 74e1–74e8, doi: 10.1126 / science.1175834
    In the original: “Referential models based on extant African apes have dominated reconstructions of early human evolution since Darwin's time. These models visualize fundamental human behaviors as intensifications of behaviors observed in living chimpanzees and / or gorillas (for instance, upright feeding, male dominance displays, tool use, culture, hunting, and warfare). Ardipithecus essentially falsifies such models, because extant apes are highly derived relative to our last common ancestors. "
  27. ↑ Kent State University Professor C. Owen Lovejoy helps unveil oldest hominid skeleton. On: eurekalert.org from October 1, 2009
  28. ^ Yohannes Haile-Selassie : Late Miocene hominids from the Middle Awash, Ethiopia. In: Nature. Volume 412, No. 6843, 2001, pp. 178-181, doi: 10.1038 / 35084015
  29. ↑ Yohannes Haile-Selassie, Gen Suwa, Tim White: Late Miocene Teeth from Middle Awash, Ethopia, and early hominid dental evolution. In: Science. Volume 303, No. 5663, 2004, pp. 1503-1505; doi: 10.1126 / science.1092978
  30. ↑ Elizabeth Culotta: Two legs good. In: Science. Volume 322, 2008, pp. 670–671
    Bone find is intended to clarify the mystery of walking upright. On: orf.at of March 10, 2005
  31. ↑ Ulf von Rauchhaupt: Man appeared in the Pliocene. On: FAZ.net from October 5, 2009 and in Frankfurter Allgemeine Sonntagszeitung from October 4, 2009
  32. ↑ Among other things, quoted on: sueddeutsche.de of October 1, 2009: The oldest ancestor of man: Our new number one.
  33. ↑ Esteban E. Sarmiento: Comment on the Paleobiology and Classification of Ardipithecus ramidus. In: Science. Volume 328, No. 5982, 2010, p. 1105, doi: 10.1126 / science.1184148
  34. ↑ Tim D. White, Gen Suwa, C. Owen Lovejoy: Response to Comment on the Paleobiology and Classification of Ardipithecus ramidus. In: Science. Volume 328, No. 5982, 2010, p. 1105, doi: 10.1126 / science.1185462
  35. ↑ Thure E. Cerling, Naomi E. Levin, Jay Quade, Jonathan G. Wynn, David L. Fox, John D. Kingston, Richard G. Klein, Francis H. Brown: Comment on the Paleoenvironment of Ardipithecus ramidus. In: Science. Volume 328, No. 5982, 2010, p. 1105, doi: 10.1126 / science.1185274
  36. ↑ Tim D. White, Stanley H. Ambrose, Gen Suwa, Giday Wolde-Gabriel: Response to Comment on the Paleoenvironment of Ardipithecus ramidus. In: Science. Volume 328, No. 5982, 2010, p. 1105, doi: 10.1126 / science.1185466
  37. ↑ Bernard Wood , Terry Harrison : The evolutionary context of the first hominins. In: Nature. Volume 470, 2011, pp. 347-352, doi: 10.1038 / nature09709
  38. ↑ In the legend to Figure 5 by Tim D. White et al., Ardipithecus ramidus and the Paleobiology of Early Hominids , it says literally : “Hypothesis 1 interprets all known evidence to represent a species lineage evolving phyletically across its entire range. Hypothesis 2 depicts the same evidence in an Ardipithecus-to-Australopithecus transition (speciation) occurring between ~ 4.5 and ~ 4.2 Ma in a regional (or local) group of populations that might have included either or both the Afar and Turkana rifts. Hypothesis 3 accommodates the same evidence to an alternative, much earlier peripheral allopatric “rectangular” speciation model (cladogenesis through microevolution accumulated in a peripheral isolate population, becoming reproductively separated). Other possibilities exist, but at the present time, none of these hypotheses can be falsified based on the available evidence. […] Therefore, at one end of a spectrum of phylogenetic possibilities, Ar. ramidus may have been directly ancestral to the more derived chronospecies pair Au. anamensis → Au. afarensis. "
  39. ↑ Carrie S. Mongle, David S. Strait and Frederick E. Grine: Expanded character sampling underscores phylogenetic stability of Ardipithecus ramidus as a basal hominin. In: Journal of Human Evolution. Volume 131, 2019, pp. 28-39, doi: 10.1016 / j.jhevol.2019.03.006
This article was added to the list of excellent articles on November 13, 2012 in this version .