{"id":104,"date":"2017-09-13T20:18:49","date_gmt":"2017-09-13T20:18:49","guid":{"rendered":"https:\/\/courses.lumenlearning.com\/suny-history-of-our-tribe\/chapter\/8-ardipithecus-ramidus-ardipithecus-kadabba\/"},"modified":"2017-10-03T15:53:04","modified_gmt":"2017-10-03T15:53:04","slug":"8-ardipithecus-ramidus-ardipithecus-kadabba","status":"publish","type":"chapter","link":"https:\/\/courses.lumenlearning.com\/suny-history-of-our-tribe\/chapter\/8-ardipithecus-ramidus-ardipithecus-kadabba\/","title":{"raw":"8. Ardipithecus ramidus, Ardipithecus kadabba","rendered":"8. Ardipithecus ramidus, Ardipithecus kadabba"},"content":{"raw":"
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GENUS: <\/b>Ardipithecus<\/i> (\u201cground ape\u201d)<\/h1>\r\n[caption id=\"attachment_286\" align=\"aligncenter\" width=\"750\"]\"image\" Figure 8.1\u00a0<\/em>Ardi by Keenan Taylor.[\/caption]\r\n\r\nDeposits within the Afar triangle\/depression<\/b> of Ethiopia (see Figure 8.2) have yielded multiple hominin species within the genera Ardipithecus <\/i>and Australopithecus<\/i>. This hotbed of hominin fossils is the northern limit of the East African Rift Zone<\/b>, where the Arabian and African plates converge. The first species of ardipith to be discovered in the area was Ar. ramidus<\/i> (4.4 mya), and the second and even older species was Ar. kadabba <\/i>(5.8 mya). When Ar. kadabba<\/i> was discovered by Yohannes Haile-Selassie<\/b>, he believed that it was similar enough to Ar. ramidus<\/i> that he included it in the same genus and species, thus warranting subspecies classification. Since Ar. ramidus<\/i> was already named, its classification became Ar. ramidus ramidus<\/i>, in the same manner that we became Homo sapiens sapiens<\/i> when it was decided that Neandertals should be included in our species and they became Homo sapiens neanderthalensis<\/i>. The original name is always preserved for the original fossil(s). It becomes known as the \u201ctype specimen<\/b>\u201d or \u201cholotype<\/b>\u201d and is used to describe the characteristics that define the species. The older subspecies then became Ar. ramidus kadabba<\/i>. Since that time, they have been split into two species within the genus: Ardipithecus<\/i>. Each will be discussed below.\r\n\r\n[caption id=\"attachment_261\" align=\"aligncenter\" width=\"454\"]\"6.7\" Figure 8.2\u00a0<\/em>The East African Rift Zone. The Afar triangle is featured in darker pink at the most northerly limit (see \u2018Erta \u2018Ale site). \u201cEAfrica\u201d by the USGS is in the public domain.\u00a0<\/a>[\/caption]\r\n\r\nSome paleoanthropologists have suggested that Ardipithecus<\/i> may be a better candidate for our ancestry than one or more of the australopiths. It has also been suggested that australopiths are descended from Ardipithecus<\/i> or that the ardipiths are a separate but related branch.\r\n

Ardipithecus ramidus <\/i>(4.4 mya)<\/b><\/h1>\r\n

(\u201cground ape\u201d \/ \u201cat the root\u201d in Afar language)<\/h2>\r\n[caption id=\"attachment_263\" align=\"aligncenter\" width=\"375\"]\"6.9\" Figure 8.3\u00a0<\/em>Map showing the fossil sites of the earliest hominids.\u00a0<\/b>\u201cMap of the fossil sites of the earliest hominids (35.8-3.3M BP)<\/a>\u201d by Kameraad Pjotr and Sting is licensed under CC BY-SA 3.0<\/a>.[\/caption]\r\n\r\n
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SITES<\/b><\/h3>\r\nAramis, Ethiopia\r\n

PEOPLE<\/b><\/h3>\r\nTim White and colleagues\r\n\r\n<\/div>\r\n

PHYLOGENY<\/b><\/h2>\r\nThe phylogeny of the ardipiths is unknown. We do not know if they left any descendants, but it is thought that Ardipithecus ramidus<\/i> is likely descended from Ardipithecus kadabba<\/i>.\r\n

DISCOVERY AND GEOGRAPHIC RANGE<\/b><\/h2>\r\nDuring the early 1990s, fossils were unearthed at the site of Aramis<\/b> in the Middle Awash region<\/b> of the Afar Triangle of Ethiopia (see Figure 8.3). Since that time, material from more than 50 individuals has been recovered, in particular the famous \u201cArdi<\/b>\u201d skeleton (see Figures 8.4 and 8.5) that is ~50% complete. Prior to the discovery, all or most early African hominin fossils were considered to be australopiths. Tim White and his colleagues determined that the material was distinctive enough to warrant new genus classification.\r\n\r\n[caption id=\"attachment_262\" align=\"aligncenter\" width=\"300\"]\"6.8\" Figure 8.4\u00a0<\/em>Digital reconstruction of Ardipithecus ramidus specimen.\u00a0<\/b>\u201cArdi<\/a>\u201d by T. Michael Keesey is licensed under CC BY 2.0<\/a>.[\/caption]\r\n\r\nFifteen years after its discovery, Ardi<\/b> was presented to the world in a frenzy of media coverage. She shook the world, not just within paleoanthropology, but for anyone interested in our past. She was an upright ape! Yes, we are all apes, but Ardi looked like what we think of as an ape. She had an ape face, small brain, long and strong arms and fingers, and ape-like feet. However, she stood upright with straight rather than flexed legs. The film Discovering Ardi<\/i> (2009, Discovery Communications) showcases her discovery, fossil processing and analyses, the artist\u2019s skeletal and full-body reconstructions, biomechanical computer-generated graphics, etc.\u2014everything for the modern tech-appreciative student!\r\n\r\n[caption id=\"attachment_264\" align=\"aligncenter\" width=\"350\"]\"6.10\" Figure 8.5\u00a0<\/em>Artist\u2019s representation of Ardipithecus ramidus. <\/b>\u201cArdipithecus Gesamt1<\/a>\u201d by Ori~ is licensed under CC BY-SA 3.0<\/a>.[\/caption]\r\n

PHYSICAL CHARACTERISTICS<\/b><\/h2>\r\nArdipiths were likely arboreal climbers, like the ancient \u201cbasal\u201d proconsulids. However, when they were on the ground, they walked bipedally, albeit with rather clumsy-looking feet. Characteristics that were initially used to designate hominin status were an anteriorly placed foramen magnum, aspects of the innominate and ulna, and especially the morphology of the humerus that suggested that it was not weight-bearing and therefore not involved in terrestrial locomotion.\r\n\r\nPrimitive characteristics of ardipiths can be seen in many body regions. Their brains were small. Depending on the source, their cranial base (the inferior portion of the occipital bone) was either flat like chimps and gorillas, or\u00a0angled and tucked under the upper part of the cranium (termed flexed cranial base\u00a0<\/b>or basicranial flexion<\/strong>). The enamel on their molars was thin like that of chimps and other extinct forest-dwelling apes. They retained several primitive characteristics that are related to arboreal climbing:\r\n