Dr. Rebecca J. Gilmour

biological anthropologist & archaeologist

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    Schematic Sub-Adults - Age Estimation with Canvas

    This week's osteology active learning lecture had us practicing age-estimation in juvenile skeletal material - the catch being that we didn't have much actual skeletal material to practice with!

    My solution? I designed and printed life-sized subadult skeletons (with clearly marked epiphyseal lines) on canvas fabric to use as schematic proxies for age estimation! 

    Five meters of skeleton-print canvas (epiphyses included) designed by me, and printed by Spoonflower

    My idea for this exercise was to create a reusable template that students could use to practice reading ossification and fusion charts. Instead of using paper, the fabric is washable and resuable - as long as we use fabric-friendly washable markers (e.g., Crayola washable markers) these resources should, in theory, wash clean. This gives the templates way more functionality, but in a more sustainable way. I started by cutting the fabric into individual skeletons, then borrowed a serger from a local quilting shop and serged the edges to prevent the fabric from fraying. 

    Serging skeletons! Thanks to Needlework in Hamilton, Ontario for the use of their sewing machine!

    In preparation for the class I decided on a few ages for skeletons that I wanted students to have a go at practicing techniques on. I then coloured in each epiphyseal line according to its state of fusion for each particular age: 

    Green = Unfused

    Yellow = Fusing

    Red = Fused

    Purple epiphyses = Not yet ossified

    Bunny helped a little at this stage: 

     

    I supplemented each fabric skeleton with images representing dental formation and eruption that I found on the internet, as well as with hand and cranial x-rays from the Burlington Growth Study (freely available online). 

    I created a handout to describe the activity and its goals to the students (find it here!), and also distributed figures from Scheuer & Black (2000) to help students determine the age ranges at which the ossification centers appear and eventually fuse. 

    McMaster students working away with the schematic skeleton and supplementary materials (image posted with permission). 

    I think that overall the exercise ran very well. It resulted in some good discussion about preservation and demonstrated limitations in using epiphyseal ossification and fusion methods in the youngest archaeological individuals (e.g., the absence of ossification centers could be 1) because the center hasn't ossified yet, or 2) because it wasn't collected). It also acted to highlight issues associated with sex differences in fusion timing - not knowing the sex of our juvenile schematic skeletons (as in archaeological skeletons) meant we had wider possible age ranges - certainly a limitation!

    Because the skeltons are washable, this means that in future iterations of this exercise, I ask students to estimate the ages of skeletons that I pre-marked, but also theoretically give them blank skeletons and ask them to colour in the pattern of epiphyseal fusion they would expect to see in an individual of a specific age. I think this might get students thinking critically about variation in the patterns of epiphyseal fusion among individuals (i.e., that some of the same epiphyses could be fusing or fused when others are open in individuals of the same age range).

     

     

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