49 results on '"Kelley, Jay"'
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2. New Fossil Suid Specimens from the Terminal Miocene Hominoid Locality of Shuitangba, Zhaotong, Yunnan Province, China
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Hou, Sukuan, Su, Denise F., Kelley, Jay, Deng, Tao, Jablonski, Nina G., Flynn, Lawrence J., Ji, Xueping, Cao, Jiayong, and Yang, Xin
- Published
- 2019
- Full Text
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3. Evidence for increased hominid diversity in the Early to Middle Pleistocene of Indonesia
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Zanolli, Clément, Kullmer, Ottmar, Kelley, Jay, Bacon, Anne-Marie, Demeter, Fabrice, Dumoncel, Jean, Fiorenza, Luca, Grine, Frederick E., Hublin, Jean-Jacques, Nguyen, Anh Tuan, Nguyen, Thi Mai Huong, Pan, Lei, Schillinger, Burkhard, Schrenk, Friedemann, Skinner, Matthew M., Ji, Xueping, and Macchiarelli, Roberto
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- 2019
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4. From super-yachts to web isolation
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Kelley, Jay
- Published
- 2017
- Full Text
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5. Faunal and Environmental Change in the Late Miocene Siwaliks of Northern Pakistan
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Barry, John C., Morgan, Michèle E., Flynn, Lawrence J., Pilbeam, David, Behrensmeyer, Anna K., Raza, S. Mahmood, Khan, Imran A., Badgley, Catherine, Hicks, Jason, and Kelley, Jay
- Published
- 2002
6. A partial hominoid innominate from the Miocene of Pakistan : Description and preliminary analyses
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Morgan, Michèle E., Lewton, Kristi L., Kelley, Jay, Otárola-Castillo, Erik, Barry, John C., Flynn, Lawrence J., and Pilbeam, David
- Published
- 2015
7. THE SITE OF SHUITANGBA (YUNNAN, CHINA) PRESERVES A UNIQUE, TERMINAL MIOCENE FAUNA
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JABLONSKI, NINA G., SU, DENISE F., FLYNN, LAWRENCE J., JI, XUEPING, DENG, CHENGLONG, KELLEY, JAY, ZHANG, YUGUANG, YIN, JIYUN, YOU, YOUSHAN, and YANG, XIN
- Published
- 2014
8. Juvenile hominoid cranium from the late Miocene of southern China and hominoid diversity in Asia
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Kelley, Jay and Gao, Feng
- Published
- 2012
9. Dental Development and Life History in Living African and Asian Apes
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Kelley, Jay, Schwartz, Gary T., and Walker, Alan
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- 2010
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10. Juvenile hominoid cranium from the terminal Miocene of Yunnan, China
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Ji, XuePing, Jablonski, Nina G., Su, Denise F., Deng, ChengLong, Flynn, Lawrence J., You, YouShan, and Kelley, Jay
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- 2013
- Full Text
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11. Life-History Inference in the Early Hominins Australopithecus and Paranthropus
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Kelley, Jay and Schwartz, Gary T.
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- 2012
- Full Text
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12. Beyond Gorilla and Pongo: alternative models for evaluating variation and sexual dimorphism in fossil hominoid samples
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Scott, Jeremiah E., Schrein, Caitlin M., and Kelley, Jay
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Gorillas -- Analysis ,Anthropology/archeology/folklore - Abstract
Sexual size dimorphism in the postcanine dentition of the late Miocene hominoid Lufengpithecus lufengensis exceeds that in Pongo pygmaeus, demonstrating that the maximum degree of molar size dimorphism in apes is not represented among the extant Hominoidea. It has not been established, however, that the molars of Pongo are more dimorphic than those of any other living primate. In this study, we used resampling-based methods to compare molar dimorphism in Gorilla, Pongo, and Lufengpithecus to that in the papionin Mandrillus leucophaeus to test two hypotheses: (1) Pongo possesses the most size-dimorphic molars among living primates and (2) molar size dimorphism in Lufengpithecus is greater than that in the most dimorphic living primates. Our results show that M. leucophaeus exceeds great apes in its overall level of dimorphism and that L. lufengensis is more dimorphic than the extant species. Using these samples, we also evaluated molar dimorphism and taxonomic composition in two other Miocene ape samples--Ouranopithecus macedoniensis from Greece, specimens of which can be sexed based on associated canines and P3s, and the Sivapithecus sample from Haritalyangar, India. Ouranopithecus is more dimorphic than the extant taxa but is similar to Lufengpithecus, demonstrating that the level of molar dimorphism required for the Greek fossil sample under the single-species taxonomy is not unprecedented when the comparative framework is expanded to include extinct primates. In contrast, the Haritalyangar Sivapithecus sample, if it represents a single species, exhibits substantially greater molar dimorphism than does Lufengpithecus. Given these results, the taxonomic status of this sample remains equivocal. KEY WORDS bootstrap; dental variation; Lufengpithecus; Ouranopithecus; Sivapithecus
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- 2009
13. Evaluating the 'dual selection' hypothesis of canine reduction
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Plavcan, J. Michael and Kelley, Jay
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Dental anthropology -- Research ,Teeth -- Abrasion ,Sex differences -- Analysis ,Anthropology/archeology/folklore - Published
- 1996
14. Palaeoanthropology: Neanderthal teeth lined up
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Kelley, Jay
- Published
- 2004
15. Sexual dimorphism in canine shape among extant great apes
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Kelley, Jay
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Dimorphism (Animals) -- Research ,Apes -- Physiological aspects ,Teeth -- Research ,Identification -- Methods ,Morphology (Animals) -- Research ,Anthropology/archeology/folklore - Abstract
There have been numerous attempts to sex fossil specimens using the canine dentition. Whether focused on canine size or canine shape, most of these efforts share two deficiencies: lack of quantification of male-female differences in the adopted criteria and a failure to adequately explore among extant species the discriminatory power of these criteria. Here, canine shape indices relating to relative canine height, upper canine root/crown proportionality, and relative length of the lower canine mesial ridge were calculated for males and females of all species and subspecies of extant great apes and two species of gibbons. The accuracy of these indices for identifying the sex of the extant ape specimens was investigated through discriminant analysis and the use of bivariate plots of the two upper and two lower canine indices. The indices were found to be highly accurate in identifying the sex of great ape individuals, not only in single-species and subspecies samples but in mixed-species samples as well; assignment error rates were mostly between 0 and 4%. Accuracy was lowest in Pan (error rates as high as 15%) and highest in Pongo (one error). In most cases, error rates were lower in the upper canines. The effectiveness of these shape indices for sexing might be related to the degree of absolute canine size dimorphism; the indices did not effectively segregate males and females among minimally canine-dimorphic gibbons. The mixed-species results reveal that same-sex index values are remarkably concordant across great ape species, as are the patterns of spatial segregation of males and females in the bivariate plots. Results suggest that, while the indices can be used with some confidence to sex individual fossil specimens, their greatest utility will be for identifying the sex of groups of canines united by size and morphology. KEY WORDS Pan, Gorilla, Pongo, Hylobates, Apes, Canine teeth, Sexing, Sexual dimorphism
- Published
- 1995
16. Sex determination in Miocene catarrhine primates
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Kelley, Jay
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Dimorphism (Animals) -- Research ,Teeth, Fossil -- Research ,Primates, Fossil -- Research ,Morphology (Animals) -- Research ,Anthropology/archeology/folklore - Abstract
Canines of fossil hominoids and primitive catarrhines from several early, middle, and late Miocene sites were analyzed according to the shape indices described in Kelley (1995) and compared to those of males and females of extant great apes. In bivariate plots of the fossil canines utilizing the indices, 90% of the upper canines and 85% of the lower canines fell within or just outside the exclusively male or exclusively female territories delimited by the extant great apes. The remainder fell in the male-female overlap zones. Sex assignments based on these distributions were nearly 100% concordant with classifications according to canine height, suggesting a high degree of accuracy. There were various taxon-specific shifts in bivariate space among fossil genera, reflecting subtle differences in canine shape between taxa within the overall pattern of similarity to extant great apes as a whole. In many cases these shifts are matched by particular extant-ape species and subspecies, while other fossil taxa have no exact analogue for canine shape among the extant great apes. However, the pattern of spatial segregation of canines identified as either male or female at each of the sites largely mirrors that of males and females within the extant-ape sample, indicating that Miocene catarrhines shared with extant great apes a common pattern of shape differences between male and female canines, regardless of taxon-specific morphologies. These observations demonstrate that the canines of fossil catarrhines can be sexed with a high degree of confidence based solely on intrinsic features of shape. This will permit more reliable characterizations of morphological sexual dimorphism among fossil species. It is also argued that canine shape is a more reliable indicator of sex in fossil taxa than are canine/molar size ratios. KEY WORDS Canines, Hominoid, Miocene, Sexual dimorphism, Taxonomy
- Published
- 1995
17. Equatorius: A New Hominoid Genus from the Middle Miocene of Kenya
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Ward, Steve, Brown, Barbara, Hill, Andrew, Kelley, Jay, and Downs, Will
- Published
- 1999
18. Late Miocene Climate Cooling Contributed to the Disappearance of Hominoids in Yunnan Region, Southwestern China.
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Li, Pei, Zhang, Chunxia, Kelley, Jay, Deng, Chenglong, Ji, Xueping, Jablonski, Nina G., Wu, Haibin, Fu, Yang, Guo, Zhengtang, and Zhu, Rixiang
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APES ,CHEMICAL weathering ,HOMINIDS ,COOLING ,CLIMATOLOGY ,CLIMATE change ,PLIOCENE Epoch ,PLATEAUS - Abstract
The relationship between long‐sequence climate change and Miocene hominoid evolution in the Yunnan region of southwestern China has recently received some attention, partly because this region has been regarded as a "refugium" for hominoids at the end of the Miocene. Here, we carry out a high‐resolution reconstruction of climate evolution in the Zhaotong Basin of Yunnan through the late Miocene to Pliocene using chemical weathering indices and other proxies. The results reveal gradual cooling within generally warm and humid conditions from 8.8–6.2 Ma; three more marked cooling episodes from 6.2–5.0 Ma; cool and humid conditions from 5.0–2.8 Ma; finally, cold and humid conditions from 2.8–2.62 Ma. The evidence is compatible with a scenario in which terminal Miocene cooling episodes within a prevailing warm and humid climate, and associated changes in vegetation, may have been critical factors in the disappearance of hominoids from this region. Plain Language Summary: Orangutans are the only Asian great apes living today, the sole remnants of a far more important radiation that occurred during the Miocene, when several species of apes are recorded from Asia, from Turkey into Pakistan, and India, and China. The Yunnan region of southwestern China has long been regarded as a "refugium" for late Miocene hominoids, as most species became extinct in Africa, Europe, and South Asia. But what caused Miocene hominoids to disappear in the Yunnan region at the southeastern margin of the Tibetan Plateau? We reconstructed a high‐resolution climate records from sediment chemical weathering, and our results suggest that warm and humid climate conditions prevailed during the known period of hominoid occupation in the region, but episodes of climate cooling at 6.2 Ma may have disrupted "refugium" and resulted in the disappearance of hominoids from the region. Key Points: Generally warm and humid climate conditions during the late Miocene in southwest China provide a "refugium" for hominoids in this regionThere were four stages of climate change during the late Miocene through Pliocene in the region, including four episodes of cooler climateThe terminal Miocene cooling episodes may have been factors in the disappearance of hominoids from this region [ABSTRACT FROM AUTHOR]
- Published
- 2020
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19. Extreme sexual dimorphism in a Miocene hominoid
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Kelley, Jay and Qinghua, Xu
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Apes, Fossil -- Research ,Dimorphism (Animals) -- Research ,Paleontology -- Miocene ,Teeth, Fossil -- Research ,Environmental issues ,Science and technology ,Zoology and wildlife conservation - Published
- 1991
20. A new otter of giant size, Siamogale melilutra sp. nov. (Lutrinae: Mustelidae: Carnivora), from the latest Miocene Shuitangba site in north-eastern Yunnan, south-western China, and a total-evidence phylogeny of lutrines.
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Wang, Xiaoming, Grohé, Camille, Su, Denise F., White, Stuart C., Ji, Xueping, Kelley, Jay, Jablonski, Nina G., Deng, Tao, You, Youshan, and Yang, Xin
- Subjects
FOSSIL mustelidae ,PREDATORY aquatic animals ,MIOCENE paleontology ,PHYLOGENY ,SPECIES diversity - Abstract
Otters (subfamily Lutrinae) are semi-aquatic predators in the family Mustelidae. Modern otters have a worldwide distribution but their fossil record is poor, often consisting of fragmentary jaws and teeth. Multiple lineages have developed bunodont dentitions with enlargements of molars, usually for cracking molluscs or other hard foods. Some lineages have evolved badger-like teeth and, as a result, were often confused with melines (Old World badger clade).Siamogale thailandicaGinsburg, Invagat, & Tassy, 1983 from the middle Miocene basin of Mae Moh in northern Thailand is one such species, whose fragmentary dental remains have thus far impeded our understanding. A new species of fossil otter,Siamogale melilutrasp. nov., represented by a nearly complete cranium, mandible and partial skeletons of at least three individuals, was recovered from the latest Miocene (∼6.2 Ma) lignite beds of the Shuitangba Site in north-eastern Yunnan Province, south-western China. Computed tomography (CT) restoration of the crushed skull reveals a combination of otter-like and badger-like cranial and dental characteristics. The new species belongs to the Lutrinae because of its possession of a large infraorbital canal and ventral expansion of the mastoid process, among other traits. A distally expanded M1, however, gives a badger-like appearance. In overall morphology the Shuitangba otter is closest toSiamogale thailandica. A previously described jaw (‘Lutra’aonychoides) from the early Pliocene of the Yushe Basin in north China is also here referred toS. melilutra. No previous attempt has been made to provide a global phylogenetic framework for otters. We present the first combined morphological and molecular (nuclear and mitochondrial DNAs) character matrices of five extant (Pteronura,Lontra,Enhydra,Aonyx,Lutra) and eight extinct genera (Tyrrhenolutra,Paralutra,Paludolutra,Enhydritherium,Siamogale,Vishnuonyx,Sivaonyx,Enhydriodon) to better understand the evolution of bunodont otters. Parsimony and Bayesian analyses consistently recover an eastern Asian clade that includes forms from Shuitangba, Yushe and Mae Moh, all of which are referred toSiamogale. http://zoobank.org/urn:lsid:zoobank.org:pub:5C637018-0772-4C78-AA4B-783B71085D9D [ABSTRACT FROM PUBLISHER]
- Published
- 2018
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21. A highly derived pliopithecoid from the Late Miocene of Haritalyangar, India.
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Sankhyan, Anek R., Kelley, Jay, and Harrison, Terry
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MIOCENE Epoch , *HOMINIDS , *SEDIMENTS , *TOOTH anatomy - Abstract
The Late Miocene sequence at Haritalyangar, Himachal Pradesh, India, has produced abundant remains of the hominid Sivapithecus and the sivaladapids Sivaladapis and Indraloris. Also recovered from these sediments is an isolated and worn upper molar that was made the holotype of Krishnapithecus krishnaii and assigned to the Pliopithecoidea. However, the heavy wear and absence of definitive pliopithecoid features on the tooth rendered the assignment to this superfamily unconvincing. Here, we describe two lower molars from Haritalyangar that bear unmistakable pliopithecoid features and that are plausibly assignable to the same species as the type specimen of K. krishnaii. They convincingly demonstrate for the first time the presence of the Pliopithecoidea in South Asia. The new molars also reveal that K. krishnaii was perhaps the largest known pliopithecoid and that it possessed highly derived postcanine dental morphology. Because of its highly derived nature, it is difficult to determine its relationships within Pliopithecoidea, but a sister taxon relationship with either the Dionysopithecidae or Pliopithecinae is equally plausible; it is only distantly related to the Crouzeliinae. It is sufficiently distinct, however, from all other pliopithecoids to warrant placement in a separate family. [ABSTRACT FROM AUTHOR]
- Published
- 2017
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22. Evaluation of a high rate hybrid energy storage module (HESM).
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Cohen, Isaac J., Wetz, David A., Kelley, Jay P., Heinzel, John, and Donahue, Simon
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- 2014
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23. Design and Active Control of a Microgrid Testbed.
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Turner, Greg, Kelley, Jay P., Storm, Caroline L., Wetz, David A., and Lee, Wei-Jen
- Abstract
Researchers at the University of Texas at Arlington (UTA) have installed a novel Microgrid testbed architecture that will be used for educational and research purposes. This paper documents the architecture of the UTA grid, the development of the national instruments based active control system, and some of the research progress made thus far. The specific commercial off the shelf components that make up the hardware in the system, which is actually broken up into three independent smaller grids, is described. A custom interconnection architecture will also be discussed that enables the three individual Microgrids to operate independently or in an actively interconnected mode of operation. The implementation of system control software will be presented in terms of the state machine used to develop the software. Finally, experimental data gathered from the dynamic performance of the Microgrid will be presented. [ABSTRACT FROM PUBLISHER]
- Published
- 2015
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24. The impact of power quality when high power pulsed DC and continuous AC loads are simultaneously operated on a MicroGrid testbed.
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Kelley, Jay P., Wetz, David A., Reed, James A., Cohen, Isaac J., Turner, Gregory K., and Lee, Wei-Jen
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- 2013
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25. Nine million-year-old ape-like fossils found at Haritalyangar, India.
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SANKHYAN, ANEK R., KELLEY, JAY, and HARRISON, TERRY
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FOSSIL primates , *LEMURS , *APES , *PALEONTOLOGY , *FOSSILS - Abstract
The article reports that Middle Siwalik sediments exposed at Haritalyangar. India are best known for the diversity of fossil primates that no longer inhabit the Sub-Himalaya, including the late surviving large hominoids Sivapithecus and Indopithecus as well as primitive lemuriform primate. The fossils come from the middle level of the Haritalyangar stratigraphic section, which has a lithostratigraphic profile typical of the Middle Siwaliks of the Potwar Plateau in Pakistan.
- Published
- 2017
26. Evaluation of a Hybrid Energy Storage Module for Pulsed Power Applications.
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Cohen, Isaac J., Kelley, Jay P., Wetz, David A., and Heinzel, John
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ELECTRIC batteries research , *POWER resources , *MOBILE operating systems , *SUPERCAPACITORS , *POWER density - Abstract
Before pulsed power systems can be fielded in either mobile or small footprint stationary applications, the prime power source must be optimized for both size and operational efficiency. In large footprint laboratories, prime power supplies are connected to a local utility grid to charge intermediate storage systems. In mobile platforms, alternative energy sources, such as electrochemical batteries or supercapacitors, must be used to backup smaller fossil fuel generators. The prime power source used in a pulsed power system must store high energy, to maximize the number of shots stored, and be able to source high power to recharge the intermediate store as fast as possible. Finding a single electrochemical energy storage device that has the right energy and power density for most applications is nearly impossible. Therefore, usage of batteries, which possess high energy density, along with electrochemical capacitors, which offer high power density, in a hybrid energy storage module (HESM) configuration is a promising way of combining both of these features into a single supply. Usage of this topology reduces the stress on the batteries, thereby prolonging their life, and also increases the instantaneous power capabilities of the system. This paper presents the design and validation of an actively controlled HESM built using commercial off the shelf power electronics and simple control strategies. [ABSTRACT FROM PUBLISHER]
- Published
- 2014
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27. Comparative dental development in Hispanopithecus laietanus and Pan troglodytes
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Dean, M. Christopher and Kelley, Jay
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- 2012
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28. Root Growth during Molar Eruption in Extant Great Apes.
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Kelley, Jay, Dean, M. Christopher, and Ross, Sasha
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MOLARS ,TOOTH roots ,TOOTH eruption ,APES ,HUMAN beings ,BONES - Abstract
While there is gradually accumulating knowledge about molar crown formation and the timing of molar eruption in extant great apes, very little is known about root formation during the eruption process. We measured mandibular first and second molar root lengths in extant great ape osteological specimens that died while either the first or second molars were in the process of erupting. For most specimens, teeth were removed so that root lengths could be measured directly. When this was not possible, roots were measured radiographically. We were particularly interested in the variation in the lengths of first molar roots near the point of gingival emergence, so specimens were divided into early, middle and late phases of eruption based on the number of cusps that showed protein staining, with one or two cusps stained equated with immediate post-gingival emergence. For first molars at this stage, Gorilla has the longest roots, followed by Pongo and Pan. Variation in first molar mesial root lengths at this stage in Gorilla and Pan, which comprise the largest samples, is relatively low and represents no more than a few months of growth in both taxa. Knowledge of root length at first molar emergence permits an assessment of the contribution of root growth toward differences between great apes and humans in the age at first molar emergence. Root growth makes up a greater percentage of the time between birth and first molar emergence in humans than it does in any of the great apes. [ABSTRACT FROM AUTHOR]
- Published
- 2009
29. Identification of a single birth cohort in Kenyapithecus kizili and the nature of sympatry between K. kizili and Griphopithecus alpani at Paşalar
- Author
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Kelley, Jay
- Subjects
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INCISORS , *TEETH , *ANIMAL morphology , *SPECIES - Abstract
Abstract: The sample of the less common hominoid species at Paşalar, Kenyapithecus kizili, is characterized by a number of unusual attributes. All ten of the upper central incisors attributed to this species show a distinct, identical pattern of two linear enamel hypoplasias. The two hypoplasias occur on the same portion of the labial crown face, revealing that the two hypoplasia-causing events occurred at the same stage of development in all individuals. The morphology of the two hypoplasias and the amount of time between them, as determined by both their separation and counts of perikymata, are also the same on all teeth. In addition, all of the approximately 70 teeth assigned to K. kizili appear to come from young adults based on degrees of wear; there are no younger or older individuals (diagnostic morphology at most tooth positions would be evident even with heavy wear). Thus, all of the K. kizili individuals (minimum number of individuals is nine: seven males, two females) appear to have died at essentially the same age. It is concluded that the most plausible interpretation of all these features is that the incisor hypoplasias were caused by the same two events in all the K. kizili individuals and that these individuals therefore represent a single birth cohort. As such, and because they died at essentially the same age, they would also have died at the same time, which is consistent with the catastrophic nature of the Paşalar deposits. The number of coincidences needed to explain all of the attributes of the K. kizili sample if these animals were born in, and died in, different years seems highly improbable. Moreover, the lack of a typical age-class structure for the K. kizili sample, or any age-class structure at all beyond the one age class of young adult, strongly suggests that the species was not resident in the area that contributed to the Paşalar accumulation, and that K. kizili was not permanently sympatric with the other Paşalar hominoid, Griphopithecus alpani. Rather, the nine K. kizili individuals must have been transients in, or recent immigrants to, the area at the time of the events that led to the formation of the site. Recent observations on social associations in male chimpanzees offer at least a possible interpretive framework to explain this unprecedented occurrence in the primate fossil record. [Copyright &y& Elsevier]
- Published
- 2008
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30. A new hominoid species from the middle Miocene site of Paşalar, Turkey
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Kelley, Jay, Andrews, Peter, and Alpagut, Berna
- Subjects
- *
FOSSILS , *TEETH , *DENTAL anthropology , *ANIMAL morphology - Abstract
Abstract: A new species of fossil hominoid is described from the middle Miocene deposits at Paşalar, Turkey. It is the less common of the two Paşalar species discussed by Martin and Andrews (1993), making up approximately 10% of the individuals in the Paşalar hominoid sample according to analyses of the minimum number of individuals. To the diagnostic features of I1 described by Alpagut et al. (1990) and Martin and Andrews (1993) can now be added further diagnostic features of all the anterior teeth, as well as both upper premolars and P3. These include discrete, nonmetric features and metric differences at all the noted tooth positions. Attempts to distinguish the upper and lower molars of the two species have so far been unsuccessful, with the possible exception of M3. The morphology of the new species is similar in most respects to that of Kenyapithecus wickeri from Fort Ternan, especially concerning maxillary morphology. They share robust and moderately deep maxillary alveolar processes, a restricted maxillary sinus with an elevated and uncomplicated floor, lacking the compartmentalization evident to varying degrees in many other taxa, and a zygomatic process that originates and turns laterally fairly high above the alveolar margin. There are also a number of distinctive similarities in the dentition, particularly for I1, C1, P4 and P3. The I1 morphology in particular, with greatly hypertrophied lingual marginal ridges bounding a uniformly thickened basal crown area, is distinctive among Miocene hominoids. All of these similarities serve to reinforce the differences noted by others between the derived morphology of K. wickeri and the more primitive morphology of Equatorius africanus from Maboko and Kipsaramon. The new species differs from K. wickeri in morphological details of most of the anterior and premolar teeth that are known for both species, despite the general morphological similarity, and in the size of I1 versus I2. One striking feature of the new species is a relatively large incisive fossa, although it cannot be determined if this is associated with an open palatine fenestra, as in many early Miocene hominoids, or a minimally overlapping palate and nasoalveolar clivus, as in some middle and late Miocene hominoids. [Copyright &y& Elsevier]
- Published
- 2008
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31. Middle Miocene Dispersals of Apes.
- Author
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Andrews, Peter and Kelley, Jay
- Published
- 2007
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32. Age at first molar emergence in early Miocene Afropithecus turkanensis and life-history evolution in the Hominoidea
- Author
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Kelley, Jay and Smith, Tanya M.
- Subjects
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DENTAL anthropology , *PRIMATES - Abstract
Among primates, age at first molar emergence is correlated with a variety of life history traits. Age at first molar emergence can therefore be used to broadly infer the life histories of fossil primate species. One method of determining age at first molar emergence is to determine the age at death of fossil individuals that were in the process of erupting their first molars. This was done for an infant partial mandible of Afropithecus turkanensis (KNM-MO 26) from the ∼17.5 Ma site of Moruorot in Kenya. A range of estimates of age at death was calculated for this individual using the permanent lateral incisor germ preserved in its crypt, by combining the number and periodicity of lateral enamel perikymata with estimates of the duration of cuspal enamel formation and the duration of the postnatal delay in the inception of crown mineralization. Perikymata periodicity was determined using daily cross striations between adjacent Retzius lines in thin sections of two A. turkanensis molars from the nearby site of Kalodirr. Based on the position of the KNM-MO 26 M1in relation to the mandibular alveolar margin, it had not yet undergone gingival emergence. The projected time to gingival emergence was estimated based on radiographic studies of M1eruption in extant baboons and chimpanzees.The estimates of age at M1emergence in KNM-MO 26 range from 28.2 to 43.5 months, using minimum and average values from extant great apes and humans for the estimated growth parameters. Even the absolute minimum value is well outside the ranges of extant large Old World monkeys for which there are data (12.5 to <25 months), but is within the range of chimpanzees (25.7 to 48.0 months). It is inferred, therefore, that A. turkanensis had a life history profile broadly like that of Pan. This is additional evidence to that provided by Sivapithecus parvada (Function, Phylogeny, and Fossils: Miocene Hominoid Evolution and Adaptations, 1997, 173) that the prolonged life histories characteristic of extant apes were achieved early in the evolutionary history of the group. However, it is unclear at present whether life-history prolongation in apes represents the primitive catarrhine pace of life history extended through phyletic increase in body mass, or whether it is derived with respect to a primitive, size-adjusted life history that was broadly intermediate between those of extant hominoids and cercopithecoids. Life history evolution in primates as a whole may have occurred largely through a series of grade-shifts, with the establishment of fundamental life-history profiles early in the histories of major higher taxa. These may have included shifts that were largely body mass dependent, as well as those that occurred in the absence of significant changes in body mass. [Copyright &y& Elsevier]
- Published
- 2003
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33. Dental remains of Equatorius africanus from Kipsaramon, Tugen Hills, Baringo District, Kenya
- Author
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Kelley, Jay, Ward, Steve, Brown, Barbara, Hill, Andrew, and Duren, Dana L.
- Subjects
- *
DENTAL anthropology - Abstract
Forty-one isolated large hominoid teeth, as well as most of the mandibular and three maxillary teeth associated with a partial skeleton, were recovered from middle Miocene Muruyur sediments near Kipsaramon in the Tugen Hills, Baringo District, Kenya. The isolated teeth were collected as surface finds and the skeleton was excavated in situ at locality BPRP#122 dated between 15·58 Ma and 15·36 Ma. The majority of the teeth recovered at BPRP#122 are referable to a minimum of five individuals of the hominoid Equatorius africanus. Three of the teeth, however, are provisionally assigned to Nyanzapithecus sp. The new hominoids from Kipsaramon add to an increasing inventory of specimens that suggest greater large hominoid taxonomic diversity from the middle Miocene of Kenya than was previously recognized. It is suggested that there are two large-bodied hominoid species present at Mabako, only one of which is assignable toEquatorius. [Copyright &y& Elsevier]
- Published
- 2002
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34. A partial hominoid innominate from the Miocene of Pakistan: Description and preliminary analyses
- Author
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Morgan, Michele Elizabeth, Lewton, Kristi L., Kelley, Jay, Otarola-Castillo, Erik, Barry, John Chase, Flynn, Lawrence John, and Pilbeam, David
- Subjects
Sivapithecus ,innominate ,Miocene hominoid ,torso shape ,positional behavior - Abstract
We describe a partial innominate, YGSP 41216, from a 12.3 Ma locality in the Siwalik Group of the Potwar Plateau in Pakistan, assigned to the Middle Miocene ape species Sivapithecus indicus. We investigate the implications of its morphology for reconstructing positional behavior of this ape. Postcranial anatomy of extant catarrhines falls into two distinct groups, particularly for torso shape. To an extent this reflects different although variable and overlapping positional repertoires: pronograde quadrupedalism for cercopithecoids and orthogrady for hominoids. The YGSP innominate (hipbone) is from a primate with a narrow torso, resembling most extant monkeys and differing from the broader torsos of extant apes. Other postcranial material of S. indicus and its younger and similar congener Sivapithecus sivalensis also supports reconstruction of a hominoid with a positional repertoire more similar to the pronograde quadrupedal patterns of most monkeys than to the orthograde patterns of apes. However, Sivapithecus postcranial morphology differs in many details from any extant species. We reconstruct a slow-moving, deliberate, arboreal animal, primarily traveling above supports but also frequently engaging in antipronograde behaviors. There are no obvious synapomorphic postcranial features shared exclusively with any extant crown hominid, including Pongo., Human Evolutionary Biology
- Published
- 2014
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35. Hominoid Dental Variability and Species Number at the Late Miocene Site of Lufeng, China.
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Kelley, Jay and Etler, Dennis
- Subjects
- *
CUSPIDS , *SPECIES , *PHYLOGENY , *TEETH ,SEX differences (Biology) - Abstract
The large hominoid sample from the late Miocene site of Lufeng, China, has been variously claimed to contain either one or two species, but very few metric data in support of either position have been published. We calculate coefficients of variation for the dental remains both for the two presumed species and for the pooled sample as a whole using the summary statistics published by Wu & Oxnard (Wu & Oxnard: American Journal of Primatology 5:303-344, 1983a, Nature 306:258-260, 1983b). These are compared to the same measures of single-sex and combined-sex samples of extant hominoids. We also present metric characterizations of male and female canines of extant great apes, with which we evaluate the gender composition of the Lufeng canine sample. In a two-species alternative, the two presumed species have measures of variability and canine representation that are more compatible with single-sex samples representing males and females, respectively. The pooled dental sample has measures of variability within the ranges of single species of extant great apes. We conclude there is a single large hominoid species represented at Lufeng that is highly sexually dimorphic. The phylogenetic relationships of this species are briefly considered. It is generally primitive in craniodental morhpology and is unlikely to be a member of the Sivapithecus-Pongo clade. [ABSTRACT FROM AUTHOR]
- Published
- 1989
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36. Incisor Microwear and Diet in Three Species of Colobus.
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Kelley, Jay
- Published
- 1990
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37. Evaluating the `dual selection' hypothesis of canine...
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Plavcan, J. Michael and Kelley, Jay
- Subjects
- *
CUSPIDS - Abstract
Presents information on the study of large canine teeth in primates and their maintenance and development. Information on evidence found; Methods and materials used; What canines are used for; Results of study.
- Published
- 1996
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38. Age at first molar emergence in Pan troglodytes verus and variation in the timing of molar emergence among free-living chimpanzees.
- Author
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Kelley, Jay, Schwartz, Gary T., and Smith, Tanya M.
- Subjects
- *
CHIMPANZEES , *FOSSIL hominids , *MOLARS , *SUBSPECIES , *HOMINIDS - Abstract
Age at lower first molar (M 1) emergence is a commonly used proxy for inferring life-history scheduling in fossil primates, but its utility is dependent on knowing to what extent extant populations vary in this datum and how this variation correlates with the scheduling of life-history variables. Here, we address the first of these issues among extant chimpanzees. While age at M 1 emergence has been documented in several live individuals from the Kanyawara population of Pan troglodytes schweinfurthii in Uganda, it has been estimated for only one individual of Pan troglodytes verus , based on a deceased animal from the Taï Forest in Côte d'Ivoire. To further explore interpopulation variation in this variable in chimpanzees, and using dental histology, we calculated ages at death for two wild-shot individuals of P. t. verus with erupting M 1 , both collected in Liberia during the mid-1950s, and estimated ages at M 1 emergence from the ages at death. The overall range for these two individuals is ∼4.2–4.6 yr, compared with an age of ∼3.7 yr for the individual from the Taï Forest, and <2.5–3.3 yr for the several individuals of P. t. schweinfurthii. While the absolute range of ∼2 yr in these samples combined is little greater than in captive chimpanzees, the disparity between the samples of P. t. schweinfurthii and P. t. verus is striking, although it cannot be determined if this disparity represents a subspecies difference or simply population differences expressed in two different subspecies. While life-history data are unavailable for the population to which the Liberian chimpanzees belonged, the difference in M 1 emergence ages between these individuals and those from Kanyawara still suggests caution when attempting even broad life-history inference in fossil apes and hominins based on age at M 1 emergence. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
39. New fossils of Mesopithecus from Hasnot, Pakistan.
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Khan, Muhammad Akbar, Kelley, Jay, Flynn, Lawrence J., Babar, Muhammad Adeeb, and Jablonski, Nina G.
- Subjects
- *
FOSSIL teeth , *MOLARS , *FOSSILS , *PLATEAUS , *MONKEYS - Abstract
Here, we report on a new collection of mostly isolated molars of a colobine monkey from near Hasnot on the Potwar Plateau of Pakistan. The specimens are from three late Miocene localities, with ages constrained to between 7.9 and 7.1 Ma. Morphological and metrical comparisons of the new Hasnot molars with those of previously recognized Mesopithecus species and living Asian colobines lead to the conclusion that the Hasnot colobine is most probably Mesopithecus , but not Mesopithecus pentelicus. The most morphologically distinctive aspect of the Hasnot specimens is the lower third molars, which exhibit large and bulbous protoconids set off by deeply incised mesial buccal and median buccal clefts and large, broad distobuccally placed hypoconulids. Colobine specimens previously recovered from the Potwar Plateau have been assigned to Mesopithecus sivalensis , but because these specimens have not yet been fully described, a detailed comparison with the new Hasnot specimens is not yet possible. For these reasons, we assign the new Hasnot colobine fossils to cf. Mesopithecus sp. Mesopithecus was one of the most widespread and successful of late Miocene primates. As a colobine equipped with features of the molar teeth, limbs, and, presumably, gut enabling it to succeed in more highly seasonal woodland environments, Mesopithecus was able to rapidly disperse into and adapt to the conditions in South Asia brought about by profound climatic and concomitant environmental change during the latest Miocene. [ABSTRACT FROM AUTHOR]
- Published
- 2020
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40. Fossils, Teeth and Sex
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Kelley, Jay
- Subjects
Fossils, Teeth and Sex (Book) -- Book reviews ,Books -- Book reviews - Published
- 1989
41. Hominoid anterior teeth from the late Oligocene site of Losodok, Kenya.
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Hammond, Ashley S., Foecke, Kimberly K., and Kelley, Jay
- Subjects
- *
APES , *INCISORS , *CUSPIDS , *OLIGOCENE paleoclimatology , *DENTAL materials - Abstract
Abstract Kamoyapithecus hamiltoni is a potential early hominoid species described from fragmentary dentognathic specimens from the Oligocene site of Losodok (Turkana Basin, northwestern Kenya). Other catarrhine dental materials have been recovered at Losodok, but were not initially included in the Kamoyapithecus hypodigm. Here we present descriptions of the unpublished canine and incisor specimens from Losodok, and revisit the published specimens in light of recent changes in understanding of hominoid anterior dental evolution. The new fossils include a canine (KNM-LS 18354) that is morphologically compatible with being a female of Kamoyapithecus (KNM-LS 8). Randomization analyses of both Gorilla gorilla and middle Miocene Griphopithecus alpani demonstrate that the size difference between KNM-LS 8 and KNM-LS 18354 is also compatible with their being male and female canines of the same species. Significantly, a canine tip (KNM-LS 18352) attributed to Kamoyapithecus documents the distinctive burin tip morphology now recognized as characterizing Proconsul sensu stricto, which may indicate a close relationship between Kamoyapithecus and Proconsul. We also re-examined the enigmatic KNM-LS 1, a smaller lower canine assumed to derive from Losodok but for which historical provenience data are completely lacking. Elemental data derived from portable X-ray fluorescence spectroscopy show that KNM-LS 1 is almost certainly from Losodok rather than from nearby Miocene sites (i.e., Moruorot, Esha, Kalodirr). KNM-LS 1 displays a nyanzapithecine-like morphology and is shown by randomization analyses to be too small to be associated with the Kamoyapithecus canines. This demonstrates that there is a second hominoid taxon present at Losodok that records one of the earliest occurrences of the Nyanzapithecinae. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
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42. Integration of pulsed loads into a Microgrid architecture.
- Author
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Kelley, Jay P., Wetz, David A., Turner, Greg K., and Cohen, Isaac
- Published
- 2013
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43. Variation in age at M1 emergence and life history in wild chimpanzees.
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Kelley, Jay, Schwartz, Gary T., and Smith, Tanya M.
- Subjects
- *
CHIMPANZEES , *DENTITION , *DENTAL maturity , *SKULL morphology , *DENTAL enamel , *DENTAL anthropology - Abstract
Age at first molar (M1) emergence is commonly used to infer the general pace of life history in extinct ape and human species. However, there is essentially no information on variation in age at M1 emergence within species to complement the growing body of knowledge on intraspecific variation in life history. Recently reported ages at M1 emergence in five living subjects from the Kanyawara community of Pan troglodytes schweinfurthii in Uganda range from <2.5 to 3.3 years, less than the age from a single deceased Pan troglodytes verus individual from the Taï Forest in Côte d'Ivoire (~3.7-3.8 years), the only other reliable M1 emergence age for wild chimpanzees. Using standard histological methods, we determined ages at death for two wild-shot juveniles of P. t. verus from central Liberia, both with erupting M1s, and estimated their M1 emergence ages at ~4.2-4.4 and ~4.5-4.6 years, substantially later than those of the P. t. schweinfurthii individuals and outside the range of captive chimpanzees (2.1-4.0 years). The combined range of M1 emergence ages from just the small Kanyawara and Liberian chimpanzee samples thus spans nearly the entire range of values known for captive and wild great apes as a whole, a surprising result. While little is known about Liberian chimpanzee life history, data for P. t. verus from the Taï Forest and P. t. schweinfurthii from Kanyawara reveal a somewhat longer average interbirth interval in Kanyawara females. This observation is the reverse of what would be expected given the M1 emergence ages in the two populations and based on the correlation between age at M1 emergence and various life-history traits in primates as a whole. We examine these results with respect to factors impacting the different populations. Supported by the Institute of Human Origins (JK, GTS) and the USA National Science Foundation (TMS). [ABSTRACT FROM AUTHOR]
- Published
- 2014
44. Rates of dentine formation and root extension in Dryopithecus and Pan compared.
- Author
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Dean, Chris and Kelley, Jay
- Abstract
Three previously described molar teeth attributed to Dryopithecus laietanus were reanalysed with a particular view to determining rates of dentine formation and root extension, and comparing these with new data for Pan troglodytes. Increments of daily root dentine formation close to the granular layer of Tomes (GLT) were imaged in IPS-1781 (M1) and the gradient of increasing rates recorded in zones of 100µm deep to the GLT. The average rate of ~20 measurements per 100µm zone rose from ~2.0 to 2.5µm/day over 200µm deep to the GLT. These were similar to rates measured in P. troglodytes where between 80 and 90 daily increments could occasionally be counted directly within this 200µm zone. These average daily rates were used to reconstruct rates of root extension along the cementdentine junction (CDJ) from the enamel cervix apically. Root extension rates in Dryopithecus rose from 4.1µm per day at the cervix to a maximum of 8.9µm per day at 4828µm root length (equivalent to 4.27 years of M1 formation) and then fell back to 5.1µm per day at 8000µm. The timing of the peak in root extension rate falls within the range observed in 14 P. troglodytes M1s and this in turn corresponds closely with the range of gingival eruption ages documented for captive and free-living Pan. These new data suggest that rates of root extension, even in isolated teeth, may contribute to the ongoing debate about gingival emergence times in living and fossil primates. [ABSTRACT FROM AUTHOR]
- Published
- 2013
45. Portable x-ray fluorescence spectroscopy geochemical sourcing of Miocene primate fossils from Kenya.
- Author
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Foecke, Kimberly K., Hammond, Ashley S., and Kelley, Jay
- Subjects
- *
FLUORESCENCE spectroscopy , *X-ray spectroscopy , *X-ray fluorescence , *MIOCENE Epoch , *FOSSILS , *MUSEUM acquisitions , *PROVENANCE (Geology) - Abstract
Understanding the biogeography and evolution of Miocene catarrhines relies on accurate specimen provenience. It has long been speculated that some catarrhine specimens among the early collections from Miocene sites in Kenya have incorrect provenience data. The provenience of one of these, the holotype of Equatorius africanus (NHM M16649), was previously revised based on x-ray fluorescence spectroscopy. Here we use nondestructive portable x-ray fluorescence spectroscopy to test the provenience of additional catarrhine specimens that, based on morphology and/or incomplete provenience information, were identified as possibly having been collected at a different site from that recorded at museum accession. We test the hypotheses that two specimens purportedly from the Early Miocene site of Rusinga (KNM-RU 1681 and KNM-RU 1999) are instead from Maboko, three specimens purportedly from the Middle Miocene site of Fort Ternan (KNM-FT 8, KNM-FT 41, and KNM-FT 3318) are instead from Songhor, and one specimen accessioned as being from Songhor (KNM-SO 5352) is from that site. Elemental data reveal that two of the specimens (KNM-FT 3318 and KNM-RU 1681) are likely to have been collected at sites other than their museum-accessioned provenience, while two others (KNM-RU 1999, and KNM-FT 41) were confirmed to have correct provenience. Results for both KNM-FT 8 and KNM-SO 5352, while somewhat equivocal, are best interpreted as supporting their accessioned provenience. Our results have implications for the distribution of certain catarrhine species during the Miocene in Kenya. Confirmation of the provenience of the specimens also facilitates taxonomic attribution, and resulted in additions to the morphological characterizations of some species. The protocol presented here has potential for wider application to assessing questions of provenience for fossils from other locations and periods. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
46. A systematic revision of Proconsul with the description of a new genus of early Miocene hominoid.
- Author
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McNulty, Kieran P., Begun, David R., Kelley, Jay, Manthi, Fredrick K., and Mbua, Emma N.
- Subjects
- *
PROCONSUL (Fossil primates) , *MIOCENE Epoch , *PHYLOGENY , *HUMAN evolution , *FOSSIL apes - Abstract
For more than 80 years, Proconsul has held a pivotal position in interpretations of catarrhine evolution and hominoid diversification in East Africa. The majority of what we ‘know’ about Proconsul , however, derives from abundant younger fossils found at the Kisingiri localities on Rusinga and Mfangano Islands rather than from the smaller samples found at Koru—the locality of the type species, Proconsul africanus —and other Tinderet deposits. One outcome of this is seen in recent attempts to expand the genus “ Ugandapithecus ” (considered here a junior subjective synonym of Proconsul ), wherein much of the Tinderet sample was referred to that genus based primarily on differentiating it from the Kisingiri specimens rather than from the type species, P. africanus . This and other recent taxonomic revisions to Proconsul prompted us to undertake a systematic review of dentognathic specimens attributed to this taxon. Results of our study underscore and extend the substantive distinction of Tinderet and Ugandan Proconsul (i.e., Proconsul sensu stricto) from the Kisingiri fossils, the latter recognized here as a new genus. Specimens of the new genus are readily distinguished from Proconsul sensu stricto by morphology preserved in the P. africanus holotype, but also in I 1 s, lower incisors, upper and lower canines, and especially mandibular characteristics. A number of these differences are more advanced among Kisingiri specimens in the direction of crown hominoids. Proconsul sensu stricto is characterized by a suite of unique features that strongly unite the included species as a clade. There have been decades of contentious debate over the phylogenetic placement of Proconsul (sensu lato), due in part to there being a mixture of primitive and more advanced morphology within the single genus. By recognizing two distinct clades that, in large part, segregate these character states, we believe that better phylogenetic resolution can be achieved. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
47. New Sivapithecus postcranial specimens from the Siwaliks of Pakistan
- Author
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Madar, Sandra I., Rose, Michael D., Kelley, Jay, MacLatchy, Laura, and Pilbeam, David
- Subjects
- *
SIVAPITHECUS (Fossil primates) , *FEMUR - Abstract
Several new postcranial elements of Sivapithecus from the Siwaliks of Pakistan are described. These include a distal femur from the U-level of the Dhok Pathan Formation, a navicular from the Chinji Formation, and seven manual and pedal phalanges from the Nagri Formation. The functional morphology of these elements adds new detail to the reconstruction ofSivapithecus positional behavior. Femoral cross-sectional geometry indicates that the shaft was adapted to support mediolaterally directed loading. Femoral condylar asymmetry and a broad but shallow trochlea are distinctly ape-like, revealing capabilities for both rotation and withstanding eccentric loading in the knee. The navicular is characterized by features relating to a broad mid-tarsus and broad distal articulations for the cuneiforms. It also lacks a navicular tubercle as in Pongo. These features suggest that the foot was capable of a powerful grip on large supports, with an inversion/supination capability that would permit foot placement in a variety of positions. The morphology of the new phalanges, including evidence for a relatively large pollex, similarly suggests powerful grasping, consistent with prior evidence from the hallux and tarsus. The functional features of the new specimens permit refinement of previous interpretations of Sivapithecus positional capabilities. They suggest a locomotor repertoire dominated by pronograde activities and also such antipronograde activities as vertical climbing and clambering, but not by antipronograde suspensory activities as practiced by extant apes. [Copyright &y& Elsevier]
- Published
- 2002
- Full Text
- View/download PDF
48. Mesopithecus pentelicus from Zhaotong, China, the easternmost representative of a widespread Miocene cercopithecoid species.
- Author
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Jablonski, Nina G., Ji, Xueping, Kelley, Jay, Flynn, Lawrence J., Deng, Chenglong, and Su, Denise F.
- Subjects
- *
LIGNITE mining , *WATER birds , *HIP joint , *MACAQUES , *OTTERS , *PRIMATES , *FEMUR - Abstract
A dentate mandible and proximal femur of Mesopithecus pentelicus Wagner, 1839 are described from the Shuitangba lignite mine in Zhaotong Prefecture, northeastern Yunnan Province, China. The remains were retrieved from sediments just below those that yielded a juvenile Lufengpithecus cranium and are dated at about ∼6.4 Ma. The mandible and proximal femur were found in close proximity and are probably of the same individual. The lower teeth are metrically and morphologically closely comparable with those of confirmed M. pentelicus from Europe, and on this basis, the specimen is assigned to this species. The anatomy of the proximal femur indicates that the Shuitangba Mesopithecus was a semiterrestrial quadruped that engaged in a range of mostly arboreal activities, including walking, climbing, and occasional leaping, with an abducted hip joint. The Shuitangba Mesopithecus is dentally typical for the genus but may have been more arboreal than previously described for M. pentelicus. M. pentelicus is well known from late Miocene (MN 11–12) sites in Europe and southwest Asia. Its estimated average rate of dispersal eastward was relatively slow, although it could have been episodically more rapid. The presence of a colobine, only slightly lower in the same section at Shuitangba that produced Lufengpithecus , is one of the only two well-documented instances of the near or actual co-occurrence of a monkey and ape in the Miocene of Eurasia. At Shuitangba, M. pentelicus occupied a freshwater-margin habitat with beavers, giant otters, swamp rabbits, and many aquatic birds. The presence of M. pentelicus in southwest China near the end of the Miocene further attests to the ecological versatility of a species long recognized as widespread and adaptable. The modern colobines of Asia, some or all of which are probable descendants of Mesopithecus , have gone on to inhabit some of the most highly seasonal and extreme habitats occupied by nonhuman primates. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
49. Molar crown formation in the Late Miocene Asian hominoids, Sivapithecus parvada and Sivapithecus indicus
- Author
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Mahoney, Patrick, Smith, Tanya M., Schwartz, Gary T., Dean, Christopher, and Kelley, Jay
- Subjects
- *
GLANDS , *BIOLOGICAL transport , *LIFE sciences - Abstract
Abstract: During the past decade, studies of enamel development have provided a broad temporal and geographic perspective on evolutionary developmental biology in Miocene hominoids. Here we report some of the first data for molar crown development in one hominoid genus, Sivapithecus. The data are compared to a range of extant and extinct hominoids. Crown formation times (CFTs), daily rates of enamel secretion (DSR), Retzius line number and periodicity, and relative enamel thickness (RET) were calculated in a mandibular first molar of Sivapithecus parvada and a maxillary first molar of Sivapithecus indicus from the Siwalik sequence of Pakistan. A CFT of 2.40 years for the protoconid of S. parvada and 2.25 years for the protocone of S. indicus lie within the range of first molar (M1) formation times for the majority of Miocene hominoids (1.96–2.40 years, excluding Proconsul heseloni), and are similar to an M1 from Gorilla (2.31 years) and M1s from Pan (2.22–2.39 years). This is unlike the longer CFTs in modern humans, which appear to be linked with their extended growth period. In contrast to extant great apes and humans, daily rates of enamel secretion are rapid in the Sivapithecus M1s during the early stages of growth, which seems to be a common pattern for most Miocene apes. The rapid accumulation of cuspal enamel in the Sivapithecus molars produced thicker enamel than either Pan or Gorilla in a comparable period of time. Future studies on larger samples of living and fossil hominoids are needed to clarify trends in crown development, which may be better understood in the context of life history strategies coupled with good data on body mass and brain size. [Copyright &y& Elsevier]
- Published
- 2007
- Full Text
- View/download PDF
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