Neosaimiri
| Neosaimiri | ||||||||||||
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| Temporal occurrence | ||||||||||||
| Middle Miocene | ||||||||||||
| 13.8 to 11.8 million years | ||||||||||||
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| Systematics | ||||||||||||
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| Scientific name | ||||||||||||
| Neosaimiri | ||||||||||||
| Stirton 1951 | ||||||||||||
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Neosaimiri is a fossil- handed genus of primates from the Capuchin family thatoccurredin the Middle Miocene in South America . Bones found in Colombia related to this genus were dated around 13 million years ago. The only species of the genusdescribed so faris Neosaimiri fieldsi , a presumably close relative of the Saimiri genus(" squirrel monkey ") that lives today. The similarity between the characteristics of Neosaimiri fieldsi and the recent squirrel monkey is so great that some researchers have suggested calling the species of fossils Saimiri fieldsi .
Initial description
The holotype of the genus and at the same time the type species Neosaimiri fieldsi is the fragment of the front part of a left lower jaw (archive number: UCMP 39205) with five preserved teeth, which come from a young individual. The fossil, discovered in 1949, was first scientifically described by Ruben Arthur Stirton in 1951 and assigned to the newly introduced genus Neosaimiri fieldsi . This fragment is the only lower jaw known from Neosaimiri to date . Due to the great morphological similarities with the characteristics of the recent genus Saimiri , Neosaimiri was interpreted by Stirton as a direct ancestor of Saimiri - with the greatest proximity to Saimiri sciureus .
More finds
In 1986 the fragment of a humerus was discovered from the same layer as the holotype and in 1990 it was placed on Neosaimiri because of its great resemblance to Saimiri sciureus , and an ankle bone was described in 1990 . In 1991, however, the American primatologist Alfred L. Rosenberger argued in the International Journal of Primatology that the genus postulated by Stirton had repeatedly been taken for granted in publications, but had never been analyzed independently with regard to its delimitation from the characteristics of the Saimiri genus . Rosenberger attributed this to the fact that, due to the old age of the fossils, it was customarily assumed that there must be distinguishing features between the two genera. After Rosenberger compared various lower jaws of recent squirrel monkeys with the holotype of Neosaimiri , he came to the conclusion that neither the structure of the teeth, in particular the premolars and molars and their marginal ridges (cingulum), nor their anchoring in the lower jaw differ from the circumstances Let Saimiri distinguish. From this he concluded "that the available fossil material [the holotype] does not provide a solid basis for maintaining Neosaimiri as a separate genus." (P. 299) The teeth of the lower jaw UCMP 39205 described by Stirton in 1950 were in 1991 the only known teeth of Neosaimiri .
Three years later, however, this changed, because as early as 1989 and 1990 a Colombian-Japanese team had recovered more than 200 additional fossils from the La Venta site, which were ascribed to Neosaimiri fieldsi in 1994 . These finds included individual teeth from the lower jaw, for the first time also from the upper jaw and milk teeth, as well as the toothed fragment of a right lower jaw, which was initially attributed to the species Laventiana annectens . Once again, the great similarity between the fossil and recent tooth shape was emphasized, but features were again described that make Neosaimiri distinguishable from Saimir ; For example, in the fossil genus smaller incisors in relation to the molars and a considerable difference in size between molars 1/2 and 3. Furthermore, indications of a sexual dimorphism were found in Neosaimiri , and the essential evolutionary change between the fossil and recent genus was found to be The tendency towards a reduction in size of molars 1 and 2 and an enlargement of the incisors in the course of evolution was described.
It was not until 1997 that 17 of the bones discovered in 1989 and 1990 from the area below the skull were scientifically described, so that now a total of 20 such fossils by Neosaimiri have been scientifically described; In 1997 D. Jeffrey Meldrum added a shin to the two previously known bones . These bone finds were also described as very similar to the bones of Saimiri , and based on the features of the joints, it was concluded that Neosaimiri - like Saimiri - lived quadruped on the branches of trees and often covered greater distances while jumping. In 2011, an American evolutionary biologist obtained clues about the diet of Neosaimiri from the structure of the teeth : According to this, the individuals of this genus were predominantly fruit-eaters , who occasionally ate leaves and insects.
When the genus Panamacebus was first described in the journal Nature in 2016 , the authors distinguished it from Neosaimiri and at the same time confirmed its status as an independent genus.
In 2020, fossil teeth from a second site, the TAR-31 site in the northern Peruvian region of San Martín , were assigned to the genus Neosaimiri - as " N. cf. fieldsi ". The description of the find contained the note that although the teeth show characteristics of Neosaimiri fieldsi , they also have different characteristics, so that the final determination of the type depends on further finds.
Web links
Individual evidence
- ↑ a b Entry Neosaimiri fieldsi Stirton 1951 on fossilworks.org , last accessed on April 21, 2019.
- ^ A b Ruben Arthur Stirton : Ceboid monkeys from the Miocene of Colombia. In: University of California Publications in Geological Sciences. Volume 28, No. 11, 1951, pp. 315-356.
- ^ D. Jeffrey Meldrum, John G. Fleagle and Richard F. Kay: Partial humeri of two Miocene Colombian primates. In: American Journal of Physical Anthropology. Volume 81, No. 3, 1990, pp. 413-422, doi: 10.1002 / ajpa.1330810310 , full text
- ^ Daniel L. Gebo et al .: New platyrrhinetali from La Venta, Columbia. In: Journal of Human Evolution. Volume 19, 1990, pp. 737-746, doi: 10.1016 / 0047-2484 (90) 90005-V
- ^ Alfred L. Rosenberger et al .: Dental variability in Saimiri and the taxonomic status of Neosaimiri fieldsi, an early squirrel monkey from La Venta, Colombia. In: International Journal of Primatology. Volume 12, No. 3, 1991, pp. 291-301, doi: 10.1007 / BF02547590 , full text
- ↑ Masanaru Takai: New specimens of Neosaimiri fieldsi from La Venta, Colombia: a middle Miocene ancestor of the living squirrel monkeys. In: Journal of Human Evolution. Volume 27, No. 4, 1994, pp. 329-360, doi: 10.1006 / jhev.1994.1049
- ↑ Masato Nakatsukasa et al .: Functional Morphology of the Postcranium and Locomotor Behavior of Neosaimiri fieldsi, a Saimiri-like Middle Miocene Platyrrhine. In: American Journal of Physical Anthropology. Vol. 102, No. 4, 1997, pp. 515-544, doi : 10.1002 / (SICI) 1096-8644 (199704) 102: 4 <515 :: AID-AJPA7> 3.0.CO; 2-Q
- ↑ Siobhán B. Cooke: Paleodiet of Extinct Platyrrhines with emphasis on the Caribbean Forms: Three-Dimensional Geometric Morphometrics of mandibular second molar. In: The Anatomical Record. Volume 294, No. 12, 2011, pp. 2073-2091, doi: 10.1002 / ar.21502 , full text
- ↑ Detailed comparisons of Panamacebus lower teeth to those of Cebus. On: nature.com from April 20, 2016
- ↑ Laurent Marivaux et al .: New record of Neosaimiri (Cebidae, Platyrrhini) from the late Middle Miocene of Peruvian Amazonia. In: Journal of Human Evolution. Volume 146, 2020, 102835, doi: 10.1016 / j.jhevol.2020.102835 .