Little Foot

Littlefoot ( " little foot " ) is the most complete skeleton yet discovered an early representative of the Hominini. It was discovered in a limestone formation in Sterkfontein ( South Africa) and is placed in the specialized publications to the genus Australopithecus. The nickname " little foot " was created because of this fossil in 1995, first four belong together ankle bones were described. From the nature of these foot bones was deduced that her owner was able to walk upright. However, the big toe was still opponierbar.

The recovery of the bones proved to be extremely difficult and time-consuming since they are completely embedded in concrete -like hard breccia of dolomite and radiolarite. The recovery is therefore still not fully completed (end of 2011).

Fund history

The four ankle bones were in 1980 - collected in a previous decades industrially mined limestone cave ( Silberberg Grotto ), but has been evaluated to 1994 only superficially - unrecognized among numerous other mammal bones. Only after 1992 on the initiative of Phillip Tobias in this cave a large rock fragments had been blown off, which contained an unusual accumulation of fossils, which until then recovered from the cave fossils of Ronald J. Clarke were taken thoroughly inspected. On September 6, 1994, he opened one with Silberberg Grotto D 20 labeled cardboard box, which contained among other things, a plastic bag with the label carnivore foot bones ( foot bones of predators ). One of these foot bones Clarke identified immediately as a hominin, and the further we browse the collection he found three other hominin foot bones, which were described in the following year scientific. Since the left ankle bone, the left navicular bone, the left sphenoid and left metatarsal bones had been recognized as belonging together, more unevaluated stocks were first sighted and eight other foot and discovered hand bones in it until June 1997, which could possibly be attributed to the same fossil. One of these bones - a fragment of a right tibia - had a relatively fresh breaking point, which could be the earliest emerged in the 1920s with a blast to the mining of limestone.

Then Clarke asked the beginning of July 1997, two taxidermists of his institute, Stephen Motsumi and Nkwane Molefe, scan the original discovery of fossils, 25 feet below the surface of the Silberberg Grotto, again. Indeed, the two discovered in this cave with the dimensions of a medium-sized church on July 3 - after only two days Search using hand lamps - the counterpart to the already known fragment. In close proximity to this right tibia fragment the two taxidermists discovered the protruding from the bottom fragment of a left tibia, its sequel had been located among years earlier recovered from the cave fossils, also a left fibula. Since the skeletal remains of both legs were in anatomically correct arrangement, suspected the taxidermists that it could be a complete skeleton, which had been embedded with the face down into the limestone.

In the following months laid Clarke and his two assistants with the help of a hammer and small chisel initially more they stay free. First remnants of the upper body - a humerus - discovered Stephen Motsumi on 11 September 1998, and on 17 September, the head of the individual was finally visible: one connected to the lower jaw skull whose left side is facing up.

A left forearm and the associated left hand discovered and partially exposed - One year later, in July and August 1999, were - once again in anatomically correct arrangement. Clarke reported this discovery six months later and explained now, all previous analyzes seemed to indicate that the fossil corpse apparently completely displaced by ground movements at most marginally, nor had been damaged by predators. Furthermore, we have discovered in the area of the hand and the wrist bone narrow, former cavities, which are filled with calcium carbonate. This suggests that the body was probably wrapped before its complete decay of rock deposits.

Way of life

Already in 1995 published the first description of the four first discovered bones of the foot, the authors had explained this Australopithecus can indeed walk upright, but had also been able to live on trees and by means of grasping movements - thanks to the still opposable toe - to climb in this round. The construction of the foot differs only slightly from that of a chimpanzee. Thanks to all the 1998 foot bones discovered Clarke saw confirmed in this initial assessment. The Laetoli footprints are known from Australopithecus and the arrangement of discovered in the Silberberg Grotto foot bones have according to his Fund description to a high degree of alignment. In his 1999 published description of the fossil hand bones Clarke pointed out that both the length of the palm as well as the length of each finger bone was significantly shorter than that of chimpanzees and gorillas; the hand was, "like that of modern humans," referred to as " relatively unspecialized ". With reference to predator finds that lived at the time of australopithecines in Africa, Clarke joined the opinion of Jordi Sabater Pi in, who had argued in 1997, a night stay on the ground was too dangerous for Australopithecus, so he probably - similar to today chimpanzees and gorillas - have built nests on trees. His physique, it 'll also appear possible that Australopithecus had also daytime temporarily stopped on trees, to look for food.

The end of 2008 published Clarke, a reconstruction of the circumstances in which the fossil was able to stay so unusually well preserved. In contrast to the other bones found in the same cave, which had evidently been swept over longer periods of time to their final storage location of the find horizon by Little Foot were in the vicinity, no other fossils, but in the underlying Fund horizons. Also, the fossil no damage by predators; So it was not abducted as prey into the cave. Nevertheless, individual bones are broken, without that this can be attributed to the quarrying in the early 20th century. From these findings and from detailed analyzes of the rock layers at the site of the fossil Clarke concluded, therefore, that the Australopithecus - as before other animals - have fallen through a hole in the roof of the cave in this must and died there. A short time later, the hole was probably blocked by inside door shielded tungsten halogen material, so that no water can enter and wash away the bones of the carcass.

Dating

As difficult and as a result so far proved unsatisfactory determining the age of the find, since there are no volcanic layers in the range of reference against which a reliable absolute dating was possible. An estimated age of 3,0 million to 3.5 million years old at shown why the fossil known as the hitherto oldest find of a representative of Hominini in South Africa - Therefore, in July 1995 - on the basis of relative dating based on fossil Cercopithecidae and some carnivores was; this age attribution fit exactly to the well-known since 1978 and dated considered safe hominin footprints of Laetoli. In a second analysis of the associated finds this dating has been criticized as being too old in March 1996 and instead named as the probable age of 2.5 million years. A similar conclusion was a study according to Littlefoot is " younger than 3 million years " in 2002. A year later, but even an age of more than 4 million years ago was then published on the basis of the aluminum -beryllium method. The end of 2006, however, a recent study using the uranium - lead dating yielded an age of 2.17 ± 0.17 million years. This dating was confirmed by a 2011 published paleomagnetic analysis of the embedding layer package, which has resulted in a minimum age of 2.2 million years and a maximum age of 2.58 million years. A previous paleomagnetic dating from about 3.3 million years ago was based on a false assumption on minimum overhanging layers. 2014 but was then argued again, the fossil was " at least 3 million years " old.

Taxonomic classification

To date, the Fund ( archive number Stw 573) no particular species of the genus Australopithecus has been allocated. In the first description Fund in July 1995 stated precisely: " The bones probably belong to the early members of Australopithecus africanus or another type of early hominids ." After 1998 had been discovered and exposed a portion of the skull, Ron Clarke had now indicated that the Fund probably the genus Australopithecus was assigned to though, but match its " unusual features " with no Australopithecus type described previously.

It was not until the end of 2008 Clarke then lay down definitively, described numerous characteristic differences between on the one hand Littlefoot, on the other hand, Australopithecus africanus and Australopithecus afarensis and ordered the fossil of a second, his time in South Africa living next to Australopithecus africanus and so far unnamed way. He grabbed at the same time so that considerations of Robert Broom and Raymond Dart, which already diverse in the 1930s finds from Taung, Sterkfontein and Makapansgat (the " Cradle of Humankind " ) had provided to different species; later the common name Australopithecus africanus had for these observations but enforced internationally.

After the finding of some two million year old Australopithecus sediba, which was discovered only 15 km away from Sterkfontein in the Malapa Cave in 2008, it was assumed that Littlefoot could have been an ancestor of Australopithecus sediba; a detailed description of Littlefoot, the basis of which the relationship could be discussed professionally with other species, however, was announced by Clarke until the end of 2012.