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J Kappelman

Publications and source records attributed to J Kappelman.

11 recordsLinked to original sources
PubMed2005

Relocation of the 1936 Mojokerto skull discovery site near Perning, East Java.

The fossil calvaria known as the Mojokerto child's skull was discovered in 1936, but uncertainties have persisted about its paleoenvironmental context and geological age because of difficulties in relocating the discovery site. Past relocation efforts were hindered by inaccuracies in old base maps, intensive post-1930s agricultural terracing, and new tree and brush growth. Fortunately geologic cross sections and site photographs from 1936-1938-not fully utilized in past relocation fieldwork-closely circumscribe site geography and geology. These documents match the conditions at just one sandstone outcrop. It is situated on the southern margin of a topographic nose at the upper end of a approximately 18 m-wide gully ( approximately 0663760 m E, 9183430 m N, UTM Zone 49 M), approximately 15 m southeast of the Kumai et al. (1985) relocation. The relocated discovery bed is approximately 3.3 m of fossiliferous pebbly sandstone, a river-channel deposit cut into tuffaceous mudstone. The sandstone and mudstone beds correspond to original site descriptions. Pebbly sandstone is also found within the skull. The calvaria is well-preserved and taphonomically similar to large and fragile specimens found among several hundred vertebrate fossils excavated from the sandstone in 2001-2002. Since no well-preserved fossils were found intact at the surface of the sandstone, the good condition of the Mojokerto skull suggests that it was buried fully when discovered. The relocated hominin bed is the uppermost fluvial sandstone of a marine-deltaic sequence in the upper Pucangan Formation. The Mojokerto child probably died along the ancient seacoast, judging from the large extent of the deltaic facies and evidence that the calvaria experienced minimal transport. The relocated discovery bed is approximately 20 m stratigraphically above the horizon from which the widely cited 1.81+/-0.04 Ma (40)Ar/(39)Ar date for the skull was obtained. Additional field and laboratory results will be required to determine the skull's age.

Animals↗
PubMed2002

Assessing the accuracy of high-resolution X-ray computed tomography of primate trabecular bone by comparisons with histological sections.

Different lines of evidence suggest that trabecular bone architecture contains a functional signal related to an organism's locomotor behavior. An understanding of the interspecific and intraspecific variation in extant nonhuman primate trabecular structure is needed to evaluate its usefulness as a tool to reconstruct the locomotor habits of extinct primates. High-resolution X-ray computed tomography (HRXCT) is a new imaging approach with a resolution in the tens of microns that allows nondestructive access to the internal structure of bony elements. Previous studies indicate that such resolution is necessary to accurately quantify structural parameters of trabecular bone. The primary goal of this study was to test the accuracy of HRXCT by comparing stereological measurements from HRXCT images and histological thin sections of cancellous bone taken from the proximal femur and humerus of baboons. To this end, 11 bone samples were scanned on an HRXCT scanner and then thin-sectioned to reveal the scanned plane. HRXCT images were thresholded using a modified half-maximum height protocol. The stereological measurements included bone volume fraction (BV/TV), trabecular number (Tb.N), bone surface to volume ratio (BS/BV), trabecular thickness (Tb.Th), and trabecular spacing (Tb.Sp). The measurement errors on the HRXCT images were 10.90% for BV/TV, 6.06% for Tb.N, 14.19% for BS/BV, 14.33% for Tb.Th, and 7.09% for Tb.Sp, but none of these measurements were significantly different from the histological standards (alpha = 0.05). A second goal of this study was to examine the influence of thresholding, a necessary step in any morphometric study using computed tomography, on the accuracy of the quantitative morphometry. Threshold values derived from a modified half-maximum height protocol showed that parameters derived from the region of interest (area in which stereological measurements were later taken) produced better reconstructions of the actual bone structure than threshold values derived from more inclusive areas of bone. We conclude that HRXCT can accurately reconstruct the complex architecture of trabecular bone, and that thresholding is a nontrivial step in trabecular bone studies, with even slight changes in the protocol greatly affecting the morphometric data. HRXCT represents a valuable analytical tool that should be of interest to a great many researchers in physical anthropology because it allows nondestructive access to internal morphology, thereby preserving valuable and limited skeletal collections.

Animals↗
PubMed2001

Morphometric variation in the hominoid orbital aperture: a case study with implications for the use of variable characters in Miocene catarrhine systematics.

Variable characters are ubiquitous in hominoid systematics and present a number of unique problems for phylogenetic analyses that include extinct taxa. As yet, however, few studies have quantified ranges of variation in complex morphometric characters within extant taxa and then used those data to assess the consistency with which discrete character states can be applied to poorly represented fossil species. In this study, ranges of intrageneric morphometric variation in the shape of the hominoid orbital aperture are estimated using exact randomization of average pairwise taxonomic distances (ATDs) derived from size-adjusted centroid, height-width, and elliptic Fourier (EF) variables. Using both centroid and height-width variables, 19 of the 21 possible ATDs between individuals representing seven extinct catarrhine taxa (Aegyptopithecus, Afropithecus, Ankarapithecus, Ouranopithecus, Paranthropus, Sivapithecus and Turkanapithecus) can be observed within a single extant hominoid subspecies, although generally with low probabilities. A resampling study is employed as a means for gauging the effect that this intrataxonomic variation may have on the consistency with which discrete orbital shape character states can be delimited given the small sample sizes available for most Miocene catarrhine taxa preserving this feature (i.e., n=1). For each type of morphometric variable, 100 cluster (UPGMA) analyses of pairwise ATDs are performed in which a single individual is randomly selected from each hominoid genus and analyzed alongside known extinct taxa; consensus trees are computed in order to obtain the frequencies with which different shape clusters appeared in each of the three analyses. The two major clusters appearing most frequently in all three consensus trees are found in only 57% (centroid variables), 49% (height-width variables), and 36% (EF variables) of these trees. If ranges of variation within represented extinct taxa could also be estimated, these frequencies would certainly be far lower. Hominoids clearly exhibit considerable intrageneric, intraspecific, and even intrasubspecific variation in orbit shape, and substantial morphometric overlap exists between taxa; consequently, discrete character states delimiting these patterns of continuous variation are likely to be highly unreliable in phylogenetic analyses of living and extinct species, particularly as the number of terminal taxa increases. Morphological phylogenetic studies of extant catarrhines that assess the effect of different methods (e.g., use of objective a priori weighting or frequency coding of variable characters, inclusion vs. exclusion of variable characters, use of specific vs. supraspecific terminal taxa) on phylogenetic accuracy may help to improve the techniques that systematists employ to make phylogenetic inferences about extinct taxa.

Animals↗
PubMed1999

The paleoenvironment of Sivapithecus parvada.

Remains of the hominoid Sivapithecus parvada and a diversity of mammalian taxa are preserved at locality Y311 (ca. 10 Ma) in the Siwalik Nagri Formation of northern Pakistan. Bovids (Bovidae, Artiodactyla) are the most abundant mammals next to tragulids (Tragulidae, Artiodactyla) at locality Y311 and provide a means for reconstructing the paleoenvironments that would have been available to Sivapithecus parvada. A functional model indicates a linkage between habitat and several femoral characters among extant bovids. Based on this model, we infer that forested habitats predominated at locality Y311 but that some less densely covered areas may also have been present. Paleoenvironments in the earlier Chinji Formation appear comparable to those at locality Y311, although the presence of a continuous canopy in the former is more certain. Thus, adaptive changes in the bovid fauna from the Chinji through the Nagri Formations appear to have preceded the shift to predominantly C4 grasslands which, based on other lines of evidence, occurred locally (and possibly globally) between 8 and 6 Ma. The paleoenvironments of locality Y311 and the Chinji Formation localities appear different from the paleoenvironment of Kenyapithecus at Fort Ternan in Kenya, where the presence of continuous canopy is unlikely. The Fort Ternan fauna is dominated by two genera of bovids. One of these is adapted to light cover while the other appears better adapted to heavy cover. Sivapithecus and Kenyapithecus lived in different ecological settings probably characterized by varying degrees of vegetative cover.

Animals↗
PubMed1998

First hominoid from the Miocene of Ethiopia and the evolution of the catarrhine elbow.

The first known fossil ape from the early-middle Miocene of Fejej, Ethiopia, is described here. The specimen, FJ-18SB-68, is a partial ulna from a locality dated by 40Ar/39Ar and paleomagnetic methods to a minimum age of 16.18 MYA. Compared to a variety of extant and fossil ulnae, FJ-18SB-68 is most similar to Turkanapithecus, Proconsul, and Pliopithecus, and appears to have been an arboreal quadruped with substantial forearm rotational mobility. Among the extant ulnae, canonical variates analysis successfully discriminates platyrrhines from catarrhines and within the latter, cercopithecoids from hominoids. Basal catarrhines (e.g., Aegyptopithecus) are platyrrhine-like in their morphology. Two basic trends appear to evolve from this generalized template: one with less mobile and more habitually pronated forearms, as seen in living and fossil cercopithecoids (including Victoriapithecus and Paracolobus), and another with greater forearm rotational mobility in fossil and modern hominoids. Primitive Miocene apes, including Proconsul, Turkanapithecus, and FJ-18SB-68, share with extant hominoids a more laterally positioned and laterally facing radial notch and an incipient trochlear keel. This morphology, along with a large insertion area for m. brachialis, suggests a departure from the more habitually pronated hand posture of monkeys and may indicate greater climbing abilities in these arboreally quadrupedal apes. Later Miocene apes, such as Oreopithecus and Dryopithecus share additional morphological features with hominoids, indicating considerable suspensory and climbing capabilities.

Animals↗
PubMed1996

A new specimen of Ankarapithecus meteai from the Sinap Formation of central Anatolia.

Hominoid fossils from the Middle and Late Miocene are exceedingly rare, yet such material is necessary for determining hominoid phylogeny. We report here the discovery of a fossil hominoid partial skull from the Upper Miocene Sinap Formation of central Turkey that is the most complete known from the period of 18 to 3 Myr. Our fieldwork places the hominoid locality within a precisely dated geochronological and biostratigraphical framework that permits detailed comparisons with other fossil hominoids. Earlier discoveries of more fragmentary remains of Ankarapithecus meteai suggested affinities with the Asian hominoids Sivapithecus and Pongo. This new and nearly complete specimen reveals a combination of facial, mandibular, and dental features including a relatively narrow interorbital region, extensive frontal and maxillary sinuses, moderately developed supraorbital tori, square orbits, robust mandibular corpus, and incisor heteromorphy that is not matched in any extant or fossil hominoid. This configuration of features seems to support its placement as a stem member of the great ape and human clade.

Adult↗
PubMed1994

Metatarsophalangeal joint function and positional behavior in Australopithecus afarensis.

Recent discussions of the pedal morphology of Australopithecus afarensis have led to conflicting interpretations of australopithecine locomotor behavior. We report the results of a study using computer aided design (CAD) software that provides a quantitative assessment of the functional morphology of australopithecine metatarsophalangeal joints. The sample includes A. afarensis, Homo sapiens, Pan troglodytes, Gorilla gorilla, and Pongo pygmaeus. Angular measurements of the articular surfaces relative to the long axes of the metatarsals and phalanges were taken to determine whether the articular surfaces are plantarly or dorsally oriented. Humans have the most dorsally oriented articular surfaces of the proximal pedal phalanges. This trait appears to be functionally associated with dorsiflexion during bipedal stride. Pongo has the most plantarly oriented articular surfaces of the proximal pedal phalanges, probably reflecting an emphasis on plantarflexion in arboreal positional behaviors, while the African hominoids are intermediate between Pongo and Homo for this characteristic. A. afarensis falls midway between the African apes and humans. Results from an analysis of metatarsal heads are inconclusive with regard to the functional morphology of A. afarensis. Overall, the results are consistent with other evidence indicating that A. afarensis was a capable climber.

Adult↗
PubMed1988

Morphology and locomotor adaptations of the bovid femur in relation to habitat.

Extant bovids inhabit a wide diversity of environments that range from forest to savanna and display locomotor patterns that are habitat specific. I report here on an investigation of the linkage between these locomotor patterns and habitat based on a study of the morphology of the bovid femur. Femoral head shape, shaft dimensions, and knee structure are examined and support a statistically significant separation of the different morphological complexes present in bovids from forest, broken cover, and savanna habitats. Morphological differences are primarily related to locomotor patterns as reflected in the degree of cursoriality displayed by bovids in different habitats. Cursorial bovids from savanna environments have laterally expanded femoral heads that act to limit the degree of abduction and axial rotation at the hip, and elliptically shaped distal femora that increase the moment arm of the extensor muscles that cross the knee. Forest bovids have spherically shaped femoral heads. This morphology permits a much higher degree of abduction and axial rotation at the hip and appears to provide greater maneuverability in a vegetationally complex habitat. Bovids living in broken cover environments that fall between the extremes of closed canopy forest and savanna display an intermediate set of femoral characters. This approach to the relationship between habitat and locomotion offers a potentially powerful means with which to examine the interplay between structural form and function in bovid evolution.

Adaptation, Physiological↗
PubMedDate not supplied

Bovids as indicators of Plio-Pleistocene paleoenvironments in east Africa.

Reconstructions of the paleoenvironments of early hominids offer a framework for understanding hominid ecological and behavioral adaptations. Habitat reconstructions typically rely upon various biological or physical habitat indicators, and here we present reconstructions of the Plio-Pleistocene paleohabitats of Koobi Fora and Olduvai Gorge as based on fossil bovids (Artiodactyla: Bovidae). Bovids are the most common faunal element at most Neogene hominid and hominoid fossil localities and have been widely studied. This study addresses the functional morphology of the bovid femur through discriminant function analysis and provides additional support for the observation that certain features of the femur demonstrate clear correlations with the amount of vegetative cover in different modern habitats. The reconstructions for both Koobi Fora and Olduvai Gorge suggest that the full range of environments inhabited by living bovids was present during the Plio-Pleistocene. Koobi Fora appears to have had a somewhat higher percentage of more closed habitats than the relatively more open habitats of Olduvai Gorge. These habitat reconstructions are in broad agreement with other reconstructions based on a purely taxonomic approach to the bovid remains. Grounding our reconstructions of paleoenvironments in studies of functional morphology can help to develop a richer idea of the habitats and resources available to early hominids.

Africa, Eastern↗