This lab is designed for students entering a gross anatomy course. It allows students to practice using various tools and skills they will need throughout dissection while getting accustomed to different types of tissue. I have them working individually, so there are no questions as that requires clean hands. However, you could easily have students partner up and provide them a question/answer sheet to complete. You are welcome to incorporate this into your course, just please provide citations. Objectives: By the end of this lab, students will be able to:
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How many tooth hops does it take to accurately measure saw blade teeth-per-inch in bone? (AAPA 2020)4/6/2020 Abstract: Forensic anthropological research has demonstrated that tooth hop (TH) is a valuable measurement from saw-cut bones as it can be used to indicate the number of teeth-per-inch (TPI) of a saw. But how many hops in a chain do you need? It is hypothesized that more hops in a chain would increase accuracy when estimating blade TPI; however, the amount of bone impacts the presence of long chains. This study used one unused hand saw to cut seven pig humeri. Individual hops were measured and sorted into groups based on number of hops in their respective chains, single (n = 196), double (n = 141), or three-plus (n = 57). Random measurements were also collected between adjacent saw teeth for comparison (n = 49). ANOVA, comparing the effect of chain size on TH mean, shows no significant differences among groups measured from bone (p>0.05). However, when blade measurements were included, means were significantly different (p<0.05). Pairwise ANOVA results show that blade mean is significantly different from single and double groups but is not significantly different from the three-plus group. Thus, three or more hops in a chain did more accurately reflect blade TPI. However, when comparing standard deviations between blade and bone measurements, the analyst would have to report a confidence interval much wider than that of the actual blade to account for all variation introduced when cutting bone tissue. Ultimately, one-hop or two-hop chains should not be discarded as chains with three or more are rarer to find. Link to abstract submission: https://meeting.physanth.org/registration/286069
Defended March 19, 2020.
https://youtu.be/UOE6GVMHLrA Abstract: To be scientifically valid under the “Daubert standards,” scientific testimony must be tested, subjected to peer review and publication, have a known or potential error rate, have maintained standards for its proper operation, and be widely accepted within the relevant scientific community (Daubert v. Merrell Dow Pharmaceuticals, Inc. 1993). Forensic research has demonstrated that tooth hop (TH) is a valuable measurement from saw-cut bones as it can be used to indicate the teeth-per-inch (TPI) of a saw in postmortem dismemberment cases; however, error rates of TPI estimation are still in infancy and our knowledge of how bone tissue affects TH measurements is unclear. The purpose of this research is to investigate the effects of tissue variability (through use of different taxa of known sex and age) on the accuracy and precision of TH measurements in bone to estimate TPI of the saw blade. This will further aid in the creation of error rates associated with TH measurements while also assessing the validity of nonhuman proxies in saw mark research. This researcher measured TH from human (280), pig (797), and deer (689)long bones cut by two saw blades of different tooth type; human remains are from one individual, while pig and deer are from multiple. 50 distance-between-teeth measurements before and after sawing were collected from each saw blade for comparison. ANOVA and F-tests were used to compare mean TH measurements and variance, respectively, by saw-species, species, sex, and number of TH in a chain (versus isolated cases of TH), with significance determined at the p < 0.05 level. It is concluded that significant differences in TH (mm) do not reflect significant differences in associated TPI ranges of suspect blades. With this knowledge, fresh deer and pig proxies may be used in TH research, although deer is less advisable. Forensic case reports should report mean TPI ± 1 TPI (narrow) and mean TPI ± 2 TPI (wide) intervals with a sample size indicating number of tooth hops measured. Tooth hops in longer chains did not greatly affect results, so cases of isolated tooth hops may be used to estimate blade TPI. This first tutorial offers the ramblings of a graduate student about the identification of bird bones. Birds featured include: turkey, chicken, Canada goose, mallard duck, great-horned owl, barred owl, red-tailed hawk, American crow, blue jay, and domestic pigeon. Images depicted are scanned copies of my notes, so apologies if they are hard to read. Feel free to comment below or contact me for more information, questions, or criticisms.
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This page offers abstracts to academic work, tutorials on human and comparative vertebrate osteology, and more! Archives
August 2020
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