2 de noviembre de 2005

Fósiles de homínidos II: Género Homo (en inglés)

Fósiles humanos
Recopilado por Prof. Dr. Julio López Saco
Homo habilis Discovered by the Leakeys in the early 1960's at Olduvai Gorge in Tanzania. A number of fragmentary specimens were found (Leakey et al. 1964).

OH 7, "Jonny's Child", found by Jonathon Leakey in 1960 (Leakey 1961), consisted of a lower jaw and two cranial fragments of a child, and a few hand bones. Estimated age is 1.8 million years, and the brain size was about 680 cc.

OH 8: found in 1960, consisted of a set of foot bones, complete except for the back of the heel and the toes. Estimated age is about 1.8 million years. They have a mixture of human and ape traits, but are consistent with bipedal locomotion. (Aiello and Dean 1990)

OH 13, "Cindy": found in 1963, consisted of a lower jaw and teeth, bits of the upper jaw and a cranial fragment. Estimated age is 1.6 million years, and the brain size was about 650 cc.

OH 16, "George": found in 1963, consisted of teeth and some very fragmentary parts of the skull. (George was unfortunately trampled by Masai cattle before he was found, and much of the skull was lost.) Estimated age is 1.7 million years, and the brain size was about 640 cc.

OH 24, "Twiggy", Homo habilisDiscovered by Peter Nzube in 1968 at Olduvai Gorge in Tanzania. It consisted of an fairly complete but very badly crushed cranium and seven teeth. It is about 1.85 million years old and has a brain size of about 590 cc.

KNM-ER 1470, Homo habilis (or Homo rudolfensis?)Discovered by Bernard Ngeneo in 1972 at Koobi Fora in Kenya (Leakey 1973). Estimated age is 1.9 million years. This is the most complete habilis skull known. Its brain size is 750 cc, large for habilis. It was originally dated at nearly 3 million years old, a figure that caused much confusion as at the time it was older than any known australopithecines, from whom habilis had supposedly descended. A lively debate over the dating of 1470 ensued (Lewin 1987; Johanson and Edey 1981; Lubenow 1992). The skull is surprisingly modern in some respects. The braincase is much larger and less robust than any australopithecine skull, and is also without the large brow ridges typical of Homo erectus. It is however very large and robust in the face. A number of leg bones were found within a couple of kilometers, and are thought to probably belong to the same species. The most complete, KNM-ER 1481, consisted of a complete left femur, both ends of a left tibia and the lower end of a left fibula (the smaller of the two lower leg bones). These are quite similar to the bones of modern humans. (Creationist arguments)

KNM-ER 1805, "The Mystery Skull", Homo habilis??Discovered by Paul Abell in 1973 at Koobi Fora in Kenya (Leakey 1974). Estimated age is 1.85 million years. This find consisted of much of a heavily built cranium containing many teeth. Its brain size is about 600 cc. Some features, such as the sagittal crest, are typical of A. boisei, but the teeth are too small for that species. (Willis 1989; Day 1986) Various workers have assigned it to almost every conceivable species, but many studies have attributed it to Homo habilis (e.g. Wood 1991). A recent cladistic study has placed it outside of Homo and most similar to robust australopithecines, though different from any named species. (Prat 2002)

KNM-ER 1813, Homo habilis?Discovered by Kamoya Kimeu in 1973 at Koobi Fora in Kenya (Leakey 1974). This specimen is similar to 1470, but is much smaller, with a brain size of 510 cc. Estimated age is 1.8-1.9 million years. Some scientists believe this a case of sexual dimorphism, others believe that the brain architecture is different and that 1813 is another species of Homo, and others believe it is an australopithecine. Like the previous skull, 1805, this one is in the "Suspense Account". (Willis 1989)

Stw 53, Homo habilis?Discovered by Alun Hughes in 1976 at Sterkfontein in South Africa (Hughes and Tobias 1977). Estimated age is 1.5 to 2 million years. It consisted of a number of cranium fragments including teeth. Many stone tools were found in the same layer.

OH 62, "Dik-dik hominid", Homo habilisDiscovered by Tim White in 1986 at Olduvai Gorge in Tanzania (Johanson and Shreeve 1989; Johanson et al. 1987). Estimated age is 1.8 million years. The find consisted of portions of skull, arm, leg bones and teeth. Almost all the features of the skull closely resemble habilis fossils such as OH 24, ER 1813 and ER 1470, rather than the australopithecines. But the estimated height is very small, maybe about 105 cm (3'5"), and the arms are very long in proportion to the legs. These are australopithecine traits, and in fact the skeletal bones are very similar to those of Lucy. This find is significant because it is the only fossil in which limb bones have been securely assigned to habilis. Because of the small size, this was almost certainly a female. As with the australopithecines, males would have been considerably larger.

OH 65, Homo habilisDiscovered in 1995 at Olduvai Gorge in Tanzania. This fossil consisted of a complete upper jaw and part of the lower face, dated at 1.8 million years. Because of its similarities to the fossil ER 1470, its finders have suggested that OH 65 may lead to a reclassification of the habiline fossils. (Blumenschine et al. 2003, Tobias 2003)

Trinil 2, "Java Man", "Pithecanthropus I", Homo erectus (was Pithecanthropus erectus)Discovered by Eugene Dubois in 1891 near Trinil on the Indonesian island of Java. Its age is uncertain, but thought to be about 700,000 years. This find consisted of a flat, very thick skullcap, and a few teeth (which may belong to orang-utans). The following year a femur was found about 12 meters away (Theunissen 1989). The brain size is about 940 cc. The femur is fully modern, and many scientists now believe that it belongs to a modern human. (Creationist arguments)

"Peking Man Site", Homo erectus (was Sinanthropus pekinensis)Between 1929 and 1937, 14 partial craniums, 11 lower jaws, many teeth, some skeletal bones and large numbers of stone tools were discovered in the Lower Cave at Locality 1 of the Peking Man site at Zhoukoudian (formerly Choukoutien), near Beijing (formerly Peking), in China. Their age is estimated to be between 500,000 and 300,000 years old. (A number of fossils of modern humans were also discovered in the Upper Cave at the same site in 1933.) The most complete fossils, all of which were braincases or skullcaps, are:
Skull III, discovered at Locus E in 1929 is an adolescent or juvenile with a brain size of 915 cc.
Skull II, discovered at Locus D in 1929 but only recognized in 1930, is an adult or adolescent with a brain size of 1030 cc.
Skulls X, XI and XII (sometimes called LI, LII and LIII) were discovered at Locus L in 1936. They are thought to belong to an adult man, an adult woman and a young adult, with brain sizes of 1225 cc, 1015 cc and 1030 cc respectively. (Weidenreich 1937)
Skull V: two cranial fragments were discovered in 1966 which fit with (casts of) two other fragments found in 1934 and 1936 to form much of a skullcap with a brain size of 1140 cc. These pieces were found at a higher level, and appear to be more modern than the other skullcaps. (Jia and Huang 1990) (Creationist arguments)
Most of the study on these fossils was done by Davidson Black until his death in 1934. Franz Weidenreich replaced him and studied the fossils until leaving China in 1941. The original fossils disappeared in 1941 while being shipped to the United States for safety during World War II, but excellent casts and descriptions remain. Since the war, other erectus fossils have been found at this site and others in China.

Sangiran 2, "Pithecanthropus II", Homo erectusDiscovered by G.H.R. von Koenigswald in 1937 at Sangiran on the Indonesian island of Java. This fossil is a braincase that is very similar to the first Java Man skull cap, but more complete and smaller, with a brain size of only about 815 cc.

OH 9, "Chellean Man", Homo erectusDiscovered by Louis Leakey in 1960 at Olduvai Gorge in Tanzania (Leakey 1961). Estimated age is 1.5 million years. It consisted of a partial braincase with massive browridges and a brain size of 1065 cc.

OH 12, "Pinhead", Homo erectusDiscovered by Margaret Cropper in 1962 at Olduvai Gorge in Tanzania. It is similar to but less complete than OH 9, and smaller, with an estimated brain size of only 750 cc. It is estimated to be between 800,000 and 1200,000 years old. Anton (2004) has found a few more pieces of this skull, but it remains very fragmentary.

Sangiran 17, "Pithecanthropus VIII", Homo erectusDiscovered by Sastrohamidjojo Sartono in 1969 at Sangiran on Java. This consists of a fairly complete cranium, with a brain size of about 1000 cc. It is the most complete erectus fossil from Java. This skull is very robust, with a slightly projecting face and huge flaring cheekbones. It has been thought to be about 800,000 years old, but a recent dating has given a much older figure of nearly 1.7 million years. If the older date is correct, it means Homo erectus migrated out of Africa much earlier than previously thought.

KNM-ER 3733, Homo erectus (or Homo ergaster)Discovered by Bernard Ngeneo in 1975 at Koobi Fora in Kenya. Estimated age is 1.7 million years. This superb find consisted of an almost complete cranium. The brain size is about 850 cc, and the whole skull is similar to the Peking Man fossils. The discovery of this fossil in the same stratum as ER 406 (A. boisei) delivered the coup de grace to the single species hypothesis: the idea that there has never been more than one hominid species at any point in history. (Leakey and Walker 1976)

KNM-WT 15000, "Turkana Boy", Homo erectus (or Homo ergaster)Discovered by Kamoya Kimeu in 1984 at Nariokotome near Lake Turkana in Kenya (Brown et al. 1985; Leakey and Lewin 1992; Walker and Leakey 1993; Walker and Shipman 1996). This is an almost complete skeleton of an 11 or 12 year old boy, the only major omissions being the hands and feet. (Some scientists believe erectus matured faster than modern humans, and that he was really about 9 years old (Leakey and Lewin 1992).) It is the most complete known specimen of erectus, and also one of the oldest, at 1.6 million years. The brain size was 880 cc, and it is estimated that it would have been 910 cc at adulthood. The boy was 160 cm (5'3") tall, and would have been about 185 cm (6'1") as an adult. This is surprisingly tall, indicating that many erectus may have been as large as modern humans. Except for the skull, the skeleton is very similar to that of modern boys, although there are a number of small differences. The most striking is that the holes in his vertebrae, through which the spinal cord goes, have only about half the cross-sectional area found in modern humans. One suggested explanation for this is that the boy lacked the fine motor control we have in the thorax to control speech, implying that he wasn't nearly as fluent a speaker as modern humans are (Walker and Shipman 1996).

D2700, Homo georgicusDiscovered in 2001 at Dmanisi in Georgia. Estimated age is 1.8 million years. It consisted of a mostly complete skull, including a lower jaw (D2735) belonging to the same individual. (Vekua et al. 2002, Balter and Gibbons 2002) At around 600 cc, this is the smallest and most primitive hominid skull ever discovered outside of Africa. This skull and two others discovered nearby form a near-perfect transition between H. habilis and ergaster.

ATD6-69, Homo antecessor?Discovered at Atapuerca in Spain. This is a partial face of a child who was probably about 10 to 11.5 years old. This fossil is over 780,000 years old. (Bermudez de Castro et al. 1997)

"Heidelberg Man", "Mauer Jaw", Homo sapiens (archaic) (also Homo heidelbergensis)Discovered by gravel pit workers in 1907 near Heidelberg in Germany. Estimated age is between 400,000 and 700,000 years. This find consisted of a lower jaw with a receding chin and all its teeth. The jaw is extremely large and robust, like that of Homo erectus, but the teeth are at the small end of the erectus range. It is often classified as Homo heidelbergensis, but has also sometimes been considered to be a European Homo erectus.

"Rhodesian Man", "Kabwe", Homo sapiens (archaic) (was Homo rhodesiensis)Discovered by a laborer in 1921 at Broken Hill in Northern Rhodesia (now Kabwe in Zambia) (Woodward 1921). This was a complete cranium that was very robust, with large brow ridges and a receding forehead. Estimated age is between 200,000 and 125,000 years. The brain size was about 1280 cc. (Creationist arguments)

Arago XXI, "Tautavel Man", Homo sapiens (archaic) (also Homo heidelbergensis)Discovered at Arago in southern France in 1971 by Henry de Lumley. Estimated age is 400,000 years. The fossil consists of a fairly complete face, with 5 molar teeth and part of the braincase. The brain size was about 1150 cc. The skull contains a mixture of features from archaic Homo sapiens and Homo erectus, to which it is sometimes assigned.

Petralona 1, Homo sapiens (archaic)Discovered by villagers at Petralona in Greece in 1960. Estimated age is 250,000-500,000 years. It could alternatively be considered to be a late Homo erectus, and also has some Neandertal characteristics. The brain size is 1220 cc, high for erectus but low for sapiens, and the face is large with particularly wide jaws. (Day 1986)
Atapuerca 5, Homo sapiens (archaic)Discovered in the Sima de los Huesos ("Pit of Bones") at the Atapuerca cave site in northern Spain in 1992 and 1993 by Juan-Luis Arsuaga. It is about 300,000 years old, with a brain size of 1125 cc. The face is broad with a huge nasal opening, and resembles Neandertals in some traits but not in others. This is the most complete pre-modern skull in the entire hominid fossil record. (Arsuaga et al. 1993; Johanson and Edgar 1996)

Feldhofer, Neanderthal 1, Homo sapiens neanderthalensisDiscovered by Johann Fuhlrott in 1856 in a small cave at Feldhofer in the Neander Valley in Germany. The find consisted of a skullcap, thigh bones, part of a pelvis, some ribs, and some arm and shoulder bones. The lower left arm had been broken in life, and as a result the bones of the left arm were smaller than those of the right. Fuhlrott recognized it as a primitive human, but the German establishment headed by Rudolf Virchow rejected this view, incorrectly claiming that it was a pathological modern human. (Trinkaus and Shipman 1992) In 1999, the original site was rediscovered, and more bones from the same specimen were recovered. (Creationist arguments)
(There were actually two earlier Neandertal finds. A partial cranium of a 2.5 year old child found in 1829 in Belgium was not recognized until 1936. An adult cranium found on Gibraltar in 1848 gathered dust in a museum until it was recognized as a Neandertal in 1864.)

"Spy 1 and 2", Homo sapiens neanderthalensisDiscovered by Marcel de Puydt and Max Lohest in 1886 at the Grotto of Spy (pronounced Spee) d'Orneau in Belgium. Estimated age is about 60,000 years. This find consisted of two almost complete skeletons. The excellent descriptions of the skeletons established that they were very old, and largely discredited the idea that the Neandertal physique was a pathological condition, but also erroneously concluded that Neandertal Man walked with bent knees.

"Krapina Site", Homo sapiens neanderthalensisDiscovered by Dragutin Gorjanovic-Kramberger in 1899 near Krapina in Croatia. This site yielded significant remains from two to three dozen individuals, and teeth and jaw fragments from dozens more. When Gorjanovic published on his finds in 1906, it confirmed for once and for all that Neandertals were not pathological modern humans.

"Old Man", Homo sapiens neanderthalensisDiscovered by Amedee and Jean Bouyssonie in 1908 near La-Chapelle-aux-Saints in France. It is about 50,000 years old, with a brain size of 1620 cc. This nearly complete skeleton was reconstructed by Marcellin Boule, who wrote a definitive and highly influential paper on it which managed to be totally wrong in many of its conclusions. It exaggerated the apelike characteristics of the fossil, popularizing the stereotype, which would last for decades, of a stooping ape-man shuffling along on bent knees. This specimen was between about 30 and 40 when he died, but had a healed broken rib, severe arthritis of the hip, lower neck, back and shoulders, and had lost most of his molar teeth. The fact that he survived as long as he did indicates that Neandertals must have had a complex social structure.

"Shanidar Site", Homo sapiens neanderthalensisRalph Solecki discovered 9 Neandertal skeletons between 1953 and 1960 at the Shanidar cave in Iraq. They are thought to be between 70,000 and 40,000 years old. One of them, Shanidar 4, had apparently been buried with offerings of flowers (although this interpretation has been disputed). In 1971 Solecki wrote a book, "Shanidar, the First Flower People", reversing the earlier stereotypes of semi-human brutes. Another skeleton, Shanidar 1, was partially blind, one-armed and crippled. His survival also is evidence of a complex social structure.

"Saint-Cesaire Neandertal", Homo sapiens neanderthalensisDiscovered by Francois Leveque in 1979 near the village of Saint-Cesaire in France. It consisted of a badly crushed skeleton. The skull was mostly complete, with only the back of the cranium missing. It is dated at about 35,000 years old, and is one of the latest Neandertals known. This find was of special interest because it was found with tools that had previously been assumed to belong to the Cro-Magnon culture, instead of the usual Neandertal tool kit.

LB1, "Hobbit", Homo floresiensisDiscovered by an Australian/Indonesian team in 2003 at the Liang Bua cave on the Indonesian island of Flores. This find consisted of an almost complete skull and a partial skeleton consisting of leg bones, parts of the pelvis, hands and feet, and some other fragments. LB1 was an adult, probably female, about 1 meter (3'3") tall with an extremely small brain size of 417cc. The skull has human-like teeth with a receding forehead and no chin. The fossil is 18,000 years old and was found with stone tools. This species is thought to be a dwarf form of Homo erectus. (Brown et al. 2004, Morwood et al. 2004, Lahr and Foley 2004)

"Cro-Magnon Site", Homo sapiens sapiens (modern)Discovered by workmen in 1868 at Cro-Magnon in France. Estimated age is 30,000 years. The site yielded skeletons of 5 buried individuals, along with stone tools, carved reindeer antlers, ivory pendants, and shells. The Cro-Magnons lived in Europe between 35,000 and 10,000 years ago. They are virtually identical to modern man, being tall and muscular and slightly more robust than most modern humans. They were skilled hunters, toolmakers and artists famous for the cave art at places such as Lascaux, Chauvet, and Altamira.