Comparative analysis of fetal pig decomposition processes in burials of variable depths and wrapping.

This research examined the effects that the variables of burial depth and presence of plastic wrapping had on the decomposition rate of fetal pig (Sus scrofa) remains in a New England environment. The decomposition of 56 fetal pigs was observed in four independent variable groups: 20 cm depth unwrapped, 20 cm wrapped, 60 cm unwrapped, and 60 cm wrapped, with exhumation at months 1, 2, 3, 6, 9, 12, and 18. The authors hypothesized that the rate of decay would be slower for wrapped remains and/or for remains at a greater burial depth. Analysis of these remains consisted of preburial and postburial mass, adipocere coverage, skeletal exposure, and decomposition quantified as Total Body Score (TBS). The difference between preburial and postburial mass was reported as a loss percentage to account for varying preburial masses. Wrapping was a significant influencer of mass loss percentage, with p = 0.0298 but not for the TBS, with p = 0.17565. Burial depth did not have a significant effect on either mass loss percentage or TBS, with p = 0.1956 and 0.08969, respectively. This study suggests that wrapping has a greater influence on decomposition patterns than burial depth in this environment, particularly the mass loss percentage. It is suggested that there are limitations with the use of TBS in Postmortem Interval (PMI) estimation, such as variable burial conditions and body characteristics.

Preliminary study of gull (Laridae) scavenging and dispersal of vertebrate remains, Shoals Marine Laboratory, Coastal New England.

The taphonomic effects of avian taxa upon forensic scenes has been little researched, and shore species including gulls (Laridae) have received even less attention, despite their well-known behavior as scavengers of human food waste. In order to begin assessing their potential impact, a pilot study was undertaken on Appledore Island, Maine, USA, at the Shoals Marine Laboratory. This location was chosen for its isolation from most other vertebrate scavengers and its large, seasonal breeding colonies of gulls, primarily great black-backed (Larus marinus) and herring (L. argentatus) gulls. Two locations with fresh bones were monitored for scavenging activity, using trail cameras and Tile Mate® tracking chips. In addition, portions of the breeding colonies nesting areas along the rocky coast were surveyed for bones that must have derived at some distance from human-generated trash sources. All (n = 16) fresh bones underwent dispersal by gulls, with an average distance of 10 m and a maximum distance (in one case) of 85 m. Multiple bones from trash sources were transported a minimum of 150 m if locally acquired and a minimum of 10 km if acquired from the mainland. These bones had a maximum length of 192 mm and mass of 46.0 g. Gulls, with their global distribution, have the potential to be significant dispersers of human skeletal remains and should undergo additional taphonomic research.

Bone dispersal by vertebrate taxa in an urban park environment in New England, USA.

The questions of the frequency, distance, and maximum size of the bones that carnivores, rodents, and other common taxa can disperse have been little addressed, especially in the later phases of skeletonization when individual bones are more subject to transport and loss. The present research utilized a sample of dry white-tailed deer (Odocoileus virginianus) bones in two locations in a forested urban environment dense with eastern gray squirrels (Sciurus carolinensis), chipmunks (Tamias striatus), coyotes (Canis latrans), raccoons (Procyon lotor), and other potential scavenging taxa. Game cameras were used to document their dispersal behavior. A total of 1731 visits were recorded, by a minimum of 12 mammalian and 9 avian taxa. Small amounts of dispersal impacted the bone samples continuously throughout the observation period, with 52.2% of all movement in the range of 1-5 cm. The bones were dispersed a maximum distance of 1252 cm, and the largest bone moved had an initial mass of 194.6 g. Rodent dry-bone gnawing behavior affected 72.7% of the sample. The project also assessed a smaller sample of Tile Mate® tracking chips for their utility in dispersal research, and these were found to have a useful potential though were not pivotal in acquiring the data presented here. Forensic surface search methods and interpretations of skeletal recovery patterns should take into consideration the ability of these common species to disperse even dry bones away from their initial locations, and this behavior may continue years after the time of initial deposition.

Correlation between saw blade width and kerf width.

Most studies of saw marks have focused on morphological characteristics and their utility in identifying saws suspected to have been utilized in cases of criminal dismemberment. The present study examined the extent to which metric analysis may be used to correlate saw blade measurements with minimum kerf widths (MKWs). A sample of 56 partially defleshed white-tailed deer (Odocoileus virginianus) long bones was utilized as proxy for human remains. The long bones were cut using a variety of commercially available saws, including 11 manual-powered and 5 mechanical-powered saws. A total of 496 false start kerfs (FSKs) were created. Two experiments were performed, with the first test examining the MKWs of FSKs produced on specimens that were restrained using a bench vise, while the second test analyzed the MKWs of FSKs produced on minimally restrained specimens. Statistical analysis using Hierarchical Linear Modeling (HLM) indicated a positive relationship between saw blade width (mm) and MKW, with blade width (p < 0.001) and the overall difference between the mechanical- and manual-powered saws (p = 0.029) tested, reaching statistical significance. A comparison of MKWs produced using manual-powered saws on restrained and minimally restrained bones suggests that restraint condition (p = 0.009) has a statistically significant effect. In comparisons of MKWs to blade widths, the average ratio for mechanical-powered saws is 18.7% greater than the average ratio for manual-powered saws. While the mode of the ratios was 1.42, thus supporting the general rule that MKW does not exceed 1.5 times blade width, multiple individual ratios did surpass 1.5.

Examination of Hacking and Blunt Force Skeletal Trauma.

Hacking trauma is prevalent in forensic cases involving genocide and dismemberment, but research into the identification of this type of trauma is lacking. The present study examines characteristics of hacking and blunt force skeletal trauma in order to determine if there is a point at which blunt force trauma becomes distinguishable from hacking trauma. Ten implements with a range of blade angles (i.e., the striking surface of the implement) were used in conjunction with a controlled-force hacking device to impact 100 limb bones of white-tailed deer (Odocoileus virginianus). Observations of the trauma included the occurrence and degree of fragmentation, the entrance widths of the impacts, and composite scores of six hacking characteristics, especially the distinctive V-shaped kerf. ANOVA tests and regression analyses were used to assess the relationships between these characteristics and the blade angles. A significant relationship (p-value = 0.011) was found between the composite hacking scores and the blade angles, indicating that blunt force and hacking trauma can be distinguished. The entrance widths of the impacts exhibited a significant relationship with the blade angles (p-value = 0.037). There was also a significant relationship between the visibility of a V-shaped kerf in the bones (p-value = 0.003), with visibility decreasing around the 60° blade angle. These data should assist in establishing guidelines to differentiate hacking and blunt force skeletal trauma in cases where the implement is on a spectrum between sharp and blunt.

Analysis of Class Characteristics of Reciprocating Saws.

Criminal dismemberment is accomplished using a variety of tools and frequently used to dispose or facilitate the transport of human remains in an attempt to hinder forensic investigation. The present research examined features that may differentiate cuts made in bone by various commercially available reciprocating saw blades. The partial limbs of adult white-tailed deer (Odocoileus virginianus) were used as a proxy for human remains and were cut using five reciprocating saw blades and a hand-powered hacksaw. The resulting false start and complete kerfs were examined macroscopically and microscopically. Kerf characteristics in which significant differences (p ≤ 0.05) between reciprocating blades were noted including minimum kerf width, kerf false start shape, presence of cut surface drift and harmonics, exit chipping size, and striation regularity. Interblade differences generally reflect class characteristics previously established for hand-powered blades. The present research may aid in the identification of reciprocating saw use in forensic contexts.

Organic staining on bone from exposure to wood and other plant materials.

Determining the depositional environment and the postmortem alterations to a set of remains are necessary aspects of a forensic investigation to explain the circumstances surrounding the death of an individual. The present study examines organic staining as a method for reconstructing the depositional environment of skeletal remains and the taphonomic agents with which they came into contact. Organic staining results largely from tannins leaching from plant materials and therefore can be seen on bone deposited in wooden coffin environments or on terrestrial surfaces. The present study examines the hypothesis that the degree of staining observed on skeletal elements would increase as the length of exposure to the organic matter increased and that different plant materials and environments would leave different patterns or colorations of staining. The sample consisted of 165 pig (Sus scrofa) femora divided into four groups exposed to differing experimental conditions, including burial in direct contact with soil or burial in a simulated coffin environment, immersion in water with wood samples, and surface deposition with plant matter contact. The bones were removed once a month from their experimental environments and the level of staining was recorded qualitatively using the Munsell Soil Color Chart. In all of the experimental environments, staining was present after two months of exposure, and the color darkened across the bone surface with each episode of data collection. The results from the present study indicate that staining can manifest on bone within a relatively short time frame once skeletonization occurs and a variety of colorations or patterns of staining can manifest based on the plant material. The present research also demonstrates the potential of organic staining to aid in estimations of the postmortem interval as well as a depositional environmental reconstruction through plant species identification.

A Comparative Taphonomic Analysis of 24 Trophy Skulls from Modern Forensic Cases.

Cranial remains retained from fallen enemies are commonly referred to as "trophy skulls," and many such crania were acquired as souvenirs by U.S. servicemembers during WWII and the Vietnam conflict. These remains increasingly have become the subject of forensic anthropological analysis as their possessors, typically veterans or their relatives, try to discard or repatriate them. The present research uses a qualitative analytical approach to review 24 cases of reported trophy skulls (14 previously unpublished cases and 10 from the literature) to determine which perimortem and postmortem characteristics are most useful for generating a taphonomic profile. Overall, the taphonomic signature of trophy remains includes traits relating to acquisition and preparation, ornamental display, and subsequent curation. Contextual evidence and the biological profile also are considered when determining the possible origin of human cranial remains as a trophy skull. Thorough taphonomic analysis will aid in identifying these types of remains as trophy skulls.

A Bayesian Approach to Age-at-Death Estimation from Osteoarthritis of the Shoulder in Modern North Americans.

Osteoarthritis (OA) is a marker of degeneration within the skeleton, frequently associated with age. This study quantifies the correlation between OA and age-at-death and investigates the utility of shoulder OA as a forensic age indicator using a modern North American sample of 206 individuals. Lipping, surface porosity, osteophyte formation, eburnation, and percentage of joint surface affected were recorded on an ordinal scale and summed to create composite scores that were assigned a specific phase. Spearman's correlation indicated a positive relationship between each composite score and age (right shoulder = 0.752; left shoulder = 0.734). Transition analysis revealed a tendency toward earlier degeneration of the right shoulder. Bayesian statistics generated phase-related age estimates based on highest posterior density regions. Best age estimates were into the seventh decade at the 90th and 50th percentile. The proposed method supplements traditional techniques by providing age estimates beyond a homogenous 50+ age cohort.

Taphonomic Analysis of Rodentia and Lagomorpha Bone Gnawing Based Upon Incisor Size.

Rodent and lagomorph species have a worldwide distribution and have the potential to alter remains from forensic cases by gnawing soft tissue and bones and through dispersal. The present research compiled metric data on the incisors widths of all rodent and lagomorph species whose ranges include Massachusetts, U.S.A., to compare their sizes to gnawing damage found on 17 cases of human remains from the Office of the Chief Medical Examiner, Boston, MA. Data on gnawing maximum striation widths also were collected from live laboratory, zoo, and wild specimens. Gnawing damage on the forensic cases could be attributed only to a particular size class of rodent or lagomorph, and identification to a particular species based on gnawing damage alone may be possible only in relatively rare cases. Multiple species examined here have broad distribution ranges, so their taphonomic alterations may impact bones from forensic cases throughout large portions of North America.

Taphonomic Effects of Mechanical Plowing on Buried Juvenile-Sized Remains.

Agricultural activity is a worldwide taphonomic process and can present unique challenges in the recovery of buried remains. Previous research has been mostly within the realm of site formation processes of archeological sites utilizing only surface material. This research expands upon the previous research by incorporating the distribution of subsurface material by the use of archeological excavation techniques. An experiment was conducted utilizing juvenile pig (Sus scrofa) skeletons buried in relative anatomical position at two different depths (15 cm below the surface [cmbs] and 22 cmbs). The burials were then subjected to different intervals of mechanical plowing: one, three, five, seven, or 10 plow passes. The skeletal material was recovered using pedestrian survey followed by hand excavation and screening of all sediments. This research shows that there is a significant relationship between the degree of plowing and the distance skeletal material is distributed and the percentage of material recovered undamaged.

Recovery Rates of Human Fetal Skeletal Remains Using Varying Mesh Sizes.

Human fetal skeletal elements of different gestational ages were screened with multiple mesh sizes (6.4 mm [1/4 inch], 3.2 mm [1/8 inch], 2.0 mm, and 1.0 mm) to determine their recovery rates. All remains were previously macerated, and no significantly damaged elements were used. The 6.4 mm mesh allowed a large loss of elements (63.2% overall), including diagnostic elements, while no diagnostic elements were lost when the 1 mm mesh (0.2%) was used. When using the 3.2 mm mesh, 16.2% of the bones were lost, including some diagnostic elements (primarily tooth crowns), while 7.5% were lost using the 2.0 mm mesh. The authors recommend that the potential loss of information incurred when utilizing larger mesh sizes be taken into consideration when planning recovery methods where fetal remains may be encountered and that a minimum of 1.0 mm mesh be utilized in recovery contexts known to include fetal remains.

Taphonomic Patterning of Cemetery Remains Received at the Office of the Chief Medical Examiner, Boston, Massachusetts.

A sample of 49 cases of cemetery remains received at the Office of the Chief Medical Examiner, Massachusetts (OCME-MA), in Boston was compared with published taphonomic profiles of cemetery remains. The present sample is composed of a cross section of typical cases in this region that ultimately are derived from modern to historical coffin burials and get turned over to or seized by law enforcement. The present sample was composed of a large portion of isolated remains, and most were completely skeletonized. The most prevalent taphonomic characteristics included uniform staining (77.6%), coffin wear (46.9%), and cortical Exfoliation (49.0%). Other taphonomic changes occurring due to later surface exposure of cemetery remains included subaerial weathering, animal gnawing, algae formation, and excavation marks. A case of one set of skeletal remains associated with coffin artifacts and cemetery offerings that was recovered from transported cemetery fill is also presented.

Evidence of fatal skeletal injuries on Malapa Hominins 1 and 2.

Malapa is one of the richest early hominin sites in Africa and the discovery site of the hominin species, Australopithecus sediba. The holotype and paratype (Malapa Hominin 1 and 2, or MH1 and MH2, respectively) skeletons are among the most complete in the early hominin record. Dating to approximately two million years BP, MH1 and MH2 are hypothesized to have fallen into a natural pit trap. All fractures evident on MH1 and MH2 skeletons were evaluated and separated based on wet and dry bone fracture morphology/characteristics. Most observed fractures are post-depositional, but those in the right upper limb of the adult hominin strongly indicate active resistance to an impact, while those in the juvenile hominin mandible are consistent with a blow to the face. The presence of skeletal trauma independently supports the falling hypothesis and supplies the first evidence for the manner of death of an australopith in the fossil record that is not attributed to predation or natural death.

Taphonomic alterations by the rodent species woodland vole (Microtus pinetorum) upon human skeletal remains.

This forensic case report describes the taphonomic effects of woodland vole (Microtus pinetorum) upon a set of skeletonized human remains recovered in Massachusetts, USA. Remains of an individual of this rodent species were discovered where it had been nesting inside the human cranium. Fine, parallel grooves indicative of small rodent gnawing were noted on multiple postcranial elements, and all isolated grooves were consistent in size with the incisors of this species. Other taphonomic alterations to these remains include some gnawing damage and dispersal by large carnivores. This case represents the first report of this rodent species affecting human remains.

A Santería/Palo Mayombe ritual cauldron containing a human skull and multiple artifacts recovered in western Massachusetts, U.S.A.

Santería and Palo Mayombe are West African-derived religions/sects with components of Catholicism, and both involve the ritual use of nonhuman skeletal remains which make them an increasing object of forensic interest. Palo Mayombe specifically involves also the use of human skeletal remains placed within ritual cauldrons or ngangas along with multiple ritual artifacts. A case of a nganga recovered from a periodically drained canal in Western Massachusetts, U.S.A. is presented. This nganga contained multiple items indicating its origin, including railroad spikes, coins, other metal objects, a stone, a glass bead, and multiple labeled and unlabeled sticks and was associated with a knife. It also contained skeletal remains of a bird and a snake as well as a nearly intact human skull of an adult male. The origin of the human remains is likely from a cemetery or as a former anatomical specimen. The find of this nganga is atypical in that it is away from the usual urban centers of Palo Mayombe in the U.S.A., and forensic practitioners should be aware that such sources of human remains may occur in their jurisdictions.