Morotopithecus

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Morotopithecus
Upper jaw of Morotopithecus bishopi (seen from below)

Upper jaw of Morotopithecus bishopi (seen from below)

Temporal occurrence
early Miocene
20.6 million years
Locations
Systematics
Monkey (anthropoidea)
Old World Monkey (Catarrhini)
Human (Hominoidea)
incertae sedis
Morotopithecus
Scientific name
Morotopithecus
Gebo , MacLatchy , Kityo , Deino , Kingston & Pilbeam , 1997
species
  • Morotopithecus bishopi

Morotopithecus is an extinct genus of primates that was foundin East Africa during the early Miocene . According to the first description published in 1997, fossils discoveredin Uganda , near the city of Moroto , near the border with Kenya ,that were assigned to this genus, comefrom sedimentary layers that are at least 20.6 million years old. The validity of the naming of the finds and their reconstruction are controversial, as they wereascribeda great resemblance to Afropithecus .

Naming

Morotopithecus is an artificial word . The name of the genus is derived from the place where it was found in the Ugandan city of Moroto and from the Greek word πίθηκος ( pronounced píthēkos in ancient Greek : "monkey"). The epithet of the only scientifically described species so far , Morotopithecus bishopi , refers to the British geologist Walter William (Bill) Bishop (1921–1966) who died at the age of 45 . Morotopithecus bishopi therefore means "Bishop's Moroto monkey".

WW Bishop worked for the Uganda Geological Survey in the late 1950s and as curator of the Uganda Museum in Kampala from 1962 to 1965 , and in 1962 published the first scientific description of the site of the Miocene fossils from Moroto.

Initial description

As a holotype of the genus and at the same time the type species Morotopithecus bishopi , in the first description by Daniel L. Gebo et al. a broken, but almost completely preserved and almost completely dentate upper jaw of a presumably male individual (archive number UMP 62-11), which is kept in the Uganda Museum of Paleontology. In the first description, the paratypes named , among other things, several lower jaw fragments, an upper maxillary canine , several vertebral fragments, some fragments of thighbones and a shoulder blade fragment.

Characteristics and age

Finds of human species (Hominoidea) from the fossil-bearing layer Moroto II were first described by Walter William Bishop in 1963 and 1964 and were then referred to as Proconsul major . Other authors had assigned the fossils to the genus Afropithecus . Further excavations in 1994 and 1995 brought new finds to light which, according to the first description by Morotopithecus, provided additional meaningful information regarding the taxonomy , phylogenesis and morphology of the human-like fossils from Moroto.

In addition, the dating of the two find layers Moroto I and Moroto II has been improved. In 1969, potassium-argon dating was used to calculate the age of 12.5 ± 0.4 and 14.3 ± 0.3 million years. In 1981, on the basis of biostratigraphic analyzes, an age of 14.5 to 16.5 and in 1986 finally 17.5 million years were published. In contrast, the first description of Morotopithecus published in 1997 named - based on the 39 Ar- 40 Ar method  - an age of 20.61 ± 0.05 million years for Moroto I and at least 20 million years for Moroto II.

Features of the teeth and facial bones were identified as distinguishing features from the genera Proconsul and Afropithecus . Nevertheless, both the face and the teeth show similarities with other primitive great apes , while the lower spine shows echoes of the great apes living today. The description of the genus and type species was based on the fossil MUZM 80 (MUZM = Makerere University Zoology Museum), which was only discovered in 1994/95 , of which parts of two thigh bones have been preserved, the original length of which was estimated to be 270 millimeters. From this and from the upper jaw bones of the holotype, it was deduced that the male individuals weighed around 40 to 50 kg during their lifetime, which corresponds approximately to the body weight of today's chimpanzees , and could reach a height of 120 to 150 cm.

From the structure of the shoulder bones, the thigh bones and the spine, it was concluded that these animals could both shimmy on trees and stand upright in them. From the structure of the teeth it was deduced that the animals ate a vegetable diet.

For all of these features has been closed in the first description that Morotopithecus a sister group of apes belong, that is, stand closer to them than other related human-like as the Miocene Graecopithecus , Otavipithecus , Afropithecus and kenyapithecus .

However, this assessment was criticized as too far-reaching as early as 1997, as it was based on only two skeletal finds, one of which was also very incomplete. This small number of finds was again referred to in a summary in 2002. In 2002 it was also objected that the reconstruction of the upper jaw that had been declared a holotype in the 1960s was flawed. Among other things, the snout in its original state was much longer than in the reconstruction of the fossil, and the alignment of the canines also had to be corrected. Taking these objections into account, Morotopithecus could also be interpreted as a merely local variant of Afropithecus .

Individual evidence

  1. ^ Daniel L. Gebo, Laura MacLatchy, Robert Kityo, Alan Deino, John Kingston, and David Pilbeam : A Hominoid Genus from the Early Miocene of Uganda. In: Science . Volume 276, No. 5311, 1997, pp. 401-404, doi: 10.1126 / science.276.5311.401
  2. ^ A b Martin Pickford : New reconstruction of the moroto hominoid snout and a reassessment of its affinities to Afropithecus turkanensis. In: Human Evolution. Volume 17, No. 1-2, 2002, pp. 1-19, doi: 10.1007 / BF02436425
  3. ^ Biren A. Patel, Ari Grossman: Dental metric comparisons of Morotopithecus and Afropithecus: Implications for the validity of the genus Morotopithecus. In: Journal of Human Evolution. Volume 51, No. 5, 2006, pp. 506-512, doi : 10.1016 / j.jhevol.2006.07.002
  4. ^ Julie C. Cormack: Setting their sights / sites in Uganda: Walter William Bishop and Edward James Wayland. In: Peter Andrews , Peter Banham (Eds.): Late Cenozoic Environments and Hominid Evolution: a Tribut to Bill Bishop. The Geological Society of London, 1999, p. 7, ISBN 1-86239-036-3
  5. ^ WW Bishop, F. Whyte: Tertiary Mammalian Faunas and Sediments in Karamoja and Kavirondo, East Africa. In: Nature . Volume 196, 1962, pp. 1283-1287, doi: 10.1038 / 1961283a0
  6. ↑ Davis Allbrook, WW Bishop: New Fossil Hominoid material from Uganda. In: Nature. Volume 197, 1963, pp. 1187-1190, doi: 10.1038 / 1971187a0
  7. ^ WW Bishop: More Fossil Primates + other Miocene Mammals from North-East Uganda. In: Nature. Volume 203, No. 495, 1964, pp. 1327-1331, doi : 10.1038 / 2031327a0
  8. ↑ for example David W. Cameron: Sexual dimorphism in the early Miocene species of Proconsul from the Kisingiri Formation of east Africa: A morphometric examination using multivariate statistics. In: Primates. Volume 32, No. 3, 1991, pp. 329-343, doi: 10.1007 / BF02382674
  9. ^ A b An Ancestor of Human Ancestors Found. ( Memento of September 4, 2006 in the Internet Archive ) On: harvard.edu of April 24, 1997. - In the original wording of a quote from co-author Pilbeam, who had already written his doctoral thesis on Moroto fossils: “while the face and teeth of Morotopithecus were similar to those primitive apes, its lower spine resembled that of living apes. "
  10. ↑ Laura Maclatchy: The oldest ape. In: Evolutionary Anthropology. Volume 13, No. 3, 2004, pp. 90-103, doi: 10.1002 / evan.10133
  11. ↑ Ann Gibbons, Elizabeth Culotta: Paleoanthropology: Miocene Primates Go Ape. In: Science. Volume 276, No. 5311, 1997, pp. 355-356, doi: 10.1126 / science.276.5311.355b
  12. ↑ Terry Harrison: Late Oligocene to middle Miocene catarrhines from Afro-Arabia. In: Walter C. Hartwig (Ed.): The Primate Fossil Record. Cambridge University Press, 2002, p. 330