Laetoli

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The tracks covered in 2006
The Laetoli Trail (cast)
Footprints in comparison: the green lines connect points with the same pressure load.
left: Australopithecus (3.6 million years old)
middle: Homo erectus (1.5 million years old)
right: anatomically modern human being

Laetoli is an important palaeontological site of fossils from the Pliocene in northern Tanzania . It is located in the East African Trench about 45 kilometers south of the Olduvai Gorge and about 200 km west of Arusha , in the area of ​​the Ngorongoro Conservation Area . The site received international attention in 1978 after fossil footprints of three upright individuals of the hominini were discovered there. The volcanic ashes of this area are now reported to be around 3.6 million years old.

According to Tim White's reading, the name Laetoli is a modification of “Olaitole”, the name of a nearby watercourse; according to Mary Leakey , however, it is derived from the Maasai name for the blood flowers ( Haemanthus ); in the 1970s the site was also written Laetolil .

Research history

The site, now known as Laetoli , has been known to experts as a fossil site since the 1930s, but its full importance for paleoanthropology was not recognized until the 1970s.

The area extends to the left and right of the Garusi River over a length of about ten kilometers and is about three kilometers wide. The existing deposits in layers of predominantly volcanic origin ( tuff ) are more than 130 meters thick in some places, the fossils mostly emerge through erosion on the slopes. Several dozen different sites (“localities”) are defined within the approximately 30 square kilometers area.

The area first received scientific attention in 1935, when Louis Leakey was working in the Olduvai Gorge and was made aware of the fossils of Laetoli by a local named Sanimu . Leakey and his team - including Mary Leakey - then spent a few days in Laetoli and collected various mammalian fossils, including the canine of a primate , which was only described as hominin ( belonging to Australopithecus ) in 1981 and had been ignored for 44 years until then Collection of the Natural History Museum (archive number BMNH M.18773).

In 1938/39 the German researcher Ludwig Kohl-Larsen then visited the site. There he discovered in 1939, among other things, a hominine upper jaw fragment with two premolars (Garusi 1, also: Garusi Hominid 1) and a third upper jaw molar (Garusi 2), but without assigning a new taxon . His fossils were first described in 1950 by Hans Weinert , who referred to them as Meganthropus africanus . Later, a canine tooth was identified as hominin in Larsen's collection (Garusi 4), and all three fossils were eventually recognized as the first Australopithecus afarensis fossils found .

In 1959 Louis and Mary Leakey returned to Laetoli and again collected mammalian fossils, but did not discover any other remains of the hominini; a third visit of the two took place in 1964. It was not until 1974, however, after a hominine premolar had been discovered under the direction of Mary Leakey in Laetoli (archive number LH 1 = Laetoli Hominid 1), that interest in a more thorough exploration of the site grew, especially since several well-preserved lower jaws of young people and of adult hominini were found. However, their taxonomic allocation remained unclear at first, as there was no reliable data for determining the age of the fossils. In 1976, 13 other fossil finds could be assigned an age for the first time based on a potassium-argon dating carried out by Garniss Curtis : about 3.59 to 3.77 million years. More recent dates show that the 33 finds known by 2010 were around 3.63 to 3.85 million years old.

In 1978 Donald Johanson, together with Yves Coppens and Tim White, first described the species Australopithecus afarensis . For the first scientific description , a lower jaw from Laetoli LH 4 found by the Leakey team in 1974 and described in Nature in 1976 was selected as the holotype , as additional evidence or paratype are given own finds from the Afar region such as AL 288-1, better known as Lucy .

The footprints

Comparison of footprints:
above: human walking upright
; middle: human walking like a chimpanzee with bent knee joint
below: Australopithecus

In 1976 Andrew Hill , a professor of paleontology at Yale University , discovered during a visit to Laetoli in a volcanic tuff lying on the earth's surface - called Tuff 7 - depressions that he saw as the prints of fossil raindrops that had been encountered, as well as animal tracks from birds and mammals and invertebrates. Hill found the tracks while crouching in front of a clump of elephant dung that a colleague threw at him. 1977 further traces were discovered in Laetoli, which were interpreted as hominin with reservation. In July 1978, the chemist Paul Irving Abell (member of Mary Leakey's team) discovered two parallel traces of undoubtedly upright hominini individuals that had been preserved for more than 20 meters. The western track comes from a single hominine individual and initially showed 22 prints, in 1979 the neighboring eastern track of 12 prints was finally recognized as the track of two individuals running one behind the other in the same track: this was the oldest evidence of bipedia to date in early hominini. More hominine footprints were later secured, so that around 70 are known today. The double track is assigned to Australopithecus afarensis by many researchers .

The creators of the tracks - including small monkeys, antelopes, elephants, rhinos, horses, a cat, guinea fowl and a beetle - walked side by side about 3.6 million years ago over fresh volcanic ash from the Sadiman volcano, 20 km away, which was moistened by light rain . The soaked ash hardened in the sun and was covered by further layers of ash.

Upon completion of the scientific study, the footprints were in 1979 to protect against the effects of weather covered. In 1995/96 the traces were uncovered again, out of concern that the roots of the plants growing above them could destroy the valuable finds. On this occasion, the footprints were measured again, photographed and drawn and then sealed again under several layers of sand and earth.

Since 1998, Terry Harrison of New York University has directed further excavations in the Laetoli area; More than 10,000 fossils were collected, including various hominini bones, including the first finding of a Paranthropus aethiopicus in Tanzania, whose age is given as 2.66 million years.

See also

literature

  • Tim D. White : New fossil hominids from Laetolil, Tanzania. In: American Journal of Physical Anthropology. Volume 46, No. 2, 1977, pp. 197-229, doi: 10.1002 / ajpa.1330460203
  • Tim D. White: Additional fossil Hominids from Laetoli, Tanzania: 1976–1979 specimens. In: American Journal of Physical Anthropology. Volume 53, No. 4, 1980, pp. 487-504, doi: 10.1002 / ajpa.1330530405
  • Mary D. Leakey and John M. Harris (Eds.): Laetoli: A Pliocene site in Northern Tanzania. Clarendon Press, Oxford Science Publications, Oxford 1987, ISBN 0-19-854441-3
  • David Martin: Olduvai and Laetoli. African Publishing Group (International), Harare 2002, ISBN 1-77916-048-8
  • David A. Raichlen et al .: Laetoli Footprints Preserve Earliest Direct Evidence of Human-Like Bipedal Biomechanics. In: PLoS ONE. 5 (3), 2010, e9769, doi: 10.1371 / journal.pone.0009769 (freely accessible full text version )
  • Robin H. Crompton et al .: Human-like external function of the foot, and fully upright gait, confirmed in the 3.66 million year old Laetoli hominin footprints by topographic statistics, experimental footprint formation and computer simulation. In: Journal of the Royal Society Interface. Online publication of July 20, 2011, doi: 10.1098 / rsif.2011.0258

Web links

Individual evidence

  1. ↑ Donald Johanson and others: Lucy and her children. Elsevier, 2nd updated edition, Munich 2006, pp. ISBN 978-3-8274-1670-4
  2. ↑ a b c d Mary Leakey et al .: Fossil hominids from the Laetolil Beds. In: Nature , Volume 262, 1976, pp. 460-466, doi : 10.1038 / 262460a0
  3. ↑ The presentation of the research history essentially follows Tim White , Gen Suwa : Hominid Footprints at Laetoli: Facts and Interpretation. In: American Journal of Physical Anthropology , Volume 72, No. 4, 1987, pp. 485-514, doi : 10.1002 / ajpa.1330720409
  4. ↑ Tim White : Primitive Hominid Canine from Tanzania. In: Science , Vol. 213, No. 4505, 1981, pp. 348-349, doi : 10.1126 / science.213.4505.348
  5. ↑ Hans Weinert : About the new early and early human finds from Africa, Java, China and France. In: Zeitschrift für Morphologie und Anthropologie , Volume 42, 1950, pp. 113–148
  6. ↑ Terry Harrison : Hominins from the Upper Laetolil and Upper Ndolanya Beds, Laetoli. Chapter 7 in: Terry Harrison (Ed.): Paleontology and Geology of Laetoli: Human Evolution in Context. Volume 2: Fossil Hominins and the Associated Fauna, Vertebrate Paleobiology and Paleoanthropology. Springer Science + Business Media, 2011, p. 141, doi : 10.1007 / 978-90-481-9962-4_7
  7. Jump up ↑ Donald Johanson , Tim White and Yves Coppens : A new Species of the Genus Australopithecus (Primates: Hominidae) from the Pliocene of Eastern Africa. In: Kirtlandia , No. 28, 1978, pp. 1-14
  8. ^ Mary Leakey, RL Hay: Pliocene footprints in the Laetolil Beds at Laetoli, northern Tanzania. In: Nature , Volume 278, 1979, pp. 317-323, doi: 10.1038 / 278317a0
  9. ↑ Michael Herbert Day and Ernie H. Wickens: Laetoli Pliocene hominid footprints and bipedalism. In: Nature. Volume 286, No. 5771, 1980, pp. 385-387, doi: 10.1038 / 286385a0 .

Coordinates: 2 ° 59 ′ 46.4 ″  S , 35 ° 21 ′ 8.6 ″  E