Research
Biomechanical Modeling
This active project involves building a biomechanical model of the lower limb of Australopithecus afarensis, a ~3.2 million year old hominin. This model will use existing models of human (Homo sapiens) and chimpanzee (Pan troglodytes) lower limbs for reference, establishing limits of hominin locomotor capabilities at a critical stage of human evolution. What bipedalism may have looked like for this taxon is heavily debated. Biomechanical modeling and simulation are quantitatively rigorous methods that have the unique ability to approach this type of uncertainty. This work was initiated at California State University, Los Angeles through the support of a National Science Foundation SBE Postdoctoral Fellowship.
Mammalian Limb Bones
This project explores life history and environmental correlates to the development of mammalian trabecular bone in the radius and tibia. Though bone structure has been shown to relate largely to locomotion, there are several equivocal studies that impart the importance of understanding how other external factors may be shaping bone development. Using >90 mammalian taxa both large and small, this project is mining large mammalian databases (PanTHERIA; Isler et al., 2012) for life history and environmental data to associate with bone data in a phylogenetic context. This work was carried out at the National Museum of Natural History through a Peter Buck Postdoctoral Fellowship and is in preparation for publication.
Primate Hands and Feet
Using both internal trabecular patterning and external bone shape of hand and foot elements, this project is documenting bony change in relation to changes in locomotion through ontogeny in five primate taxa, including modern humans. Consisting of several sub-projects, this work has been completed. The first sub-project has been published (see below, Ragni, 2020) and the remainder are now in review or preparation for publication.
Chimpanzee tarsal featuring a volume of interest (VOI) for trabecular analysis
The above video shows a microCT image of a chimpanzee foot bone (the lateral cuneiform). After a 360 degree rotation, the borders of the bone are "dissolved" to show the spherical VOI selected for use in trabecular analysis. All images created in Volume Graphics StudioMax 3.1. This video shows how the trabecular bone is visualized. I use quantitative methods to characterize the trabecular bone and compare patterning through development and between locomotor groups.
AAPA 2020 presentation, "The ontogeny of shape and integration in the hands and feet of catarrhine primates"
The above video is my 2020 AAPA presentation from the Skeletal Biology session. This sub-project focuses on how the shape of bones shifts through ontogeny across taxa and locomotor groups. This work is in preparation for publication.
Click the links below to check out more work related to this project.
Click the links below to check out more work related to this project.
Dental Microwear
Dental microwear is the patterning of microscopic scratches and pits on your teeth made from chewing certain foods. By scanning the surface of teeth with a confocal microscope, we are able to quantify the patterns on each tooth. The patterns correspond to different types of diet. These scans represent three different Brazilian monkeys' molars.
By studying modern primate microwear and understanding their diet, we can study a fossil primate's microwear and infer what their diet may have been like. For example, if the microwear patterning of an extinct primate is similar to one of the molar scans above, we can reasonably infer that its diet may have been similar to one of these Brazilian monkeys.
Click the link below to read more about this project.
By studying modern primate microwear and understanding their diet, we can study a fossil primate's microwear and infer what their diet may have been like. For example, if the microwear patterning of an extinct primate is similar to one of the molar scans above, we can reasonably infer that its diet may have been similar to one of these Brazilian monkeys.
Click the link below to read more about this project.