Bone tissue is commonly used to reconstruct life histories of fossil vertebrates, but our understanding of bone histology is limited by a lack of baseline data that test the relationships between bone microstructure and biology in living animals.  In order to clarify the relationships between bone microstructure and the controlling parameters of evolutionary history and environment, we studied the microscopic variation in bones (1) within single skeletons; (2) among backboned animals living in the same ecosystem; and (3) between the same types of organisms living in times of resource abundance and paucity. 

A diversity of modern zoo animals and Triassic and Cretacous fossil faunas from Argentina, Madagascar, and Montana formed the basis of the sample for the project. The modern sample included a diversity of more than fifty reptile, avian, and mammalian taxa, ranging in body size, age, body temperature, and ecological niche. The fossil sample included the world’s oldest known dinosaurs, as well as multiple faunas from the end of the age of dinosaurs.  Some of these sampled skeletons (e.g., tegu lizard, egyptian tortoise, the sauropod dinosaur Rapetosaurus, the theropod Majungasaurus, and a host of crocodiles and turtles) have been the subjects of undergraduate senior capstone projects in the Biology and Geology Departments at Macalester College and have been presented to the scientific community at professional meetings and published in the peer-reviewed literature. Many other histological datasets will continue to fuel the research of undergrads for years to come at Macalester College.  With each project, our database of histological variation continues to grow and is inherently comparative and synthetic. During the grant period we established the requisite data set for deep investigation of the complicated interwoven signatures of form, function, ontogeny, environment, and evolution.  The data suggest that there is a high degree of variability within single skeletons, and that aging vertebrate animals from single bones may lead to erroneous conclusions. There is a signal of drought expressed in the bone tissue of modern and fossil organisms, which can also confound signals of age and generalized growth pattern. Ultimately, this study will have far-reaching implications for scientists who use bone tissue to explore both modern and ancient biological systems.

The research component of this project was tightly integrated with an educational outreach component that:  1) integrated the research into undergraduate courses at Macalester College; 2) involved undergraduates in collaborative research; 3) connected Macalester College undergraduates to academic enrichment programs aimed at under-resourced K-12 students in the Minneapolis-St. Paul metro area; and 4) created public science exhibition and educational materials in partnership with the Science Museum of Minnesota. All told, 21 different undergraduate students were involved in project research, including 18 women.   Eight of these students are either currently in (or recently graduated from) graduate programs related to paleobiology. Seven of these students are currently working in jobs that include a heavy science or educational emphasis (e.g., museum educator, school guidance counseling, medical school), and in some cases, these directions followed their work with K-12 under-resourced students in the Minneapolis-St. Paul metro area.  Educational outreach to K-12 students was also realized through collaborations with the Macalester College Civic Engagement Center and the development of educational materials and “pop-up exhibits” at the Science Museum of Minnesota. These materials created by the PI, undergraduates, and museum staff brought topics surrounding the history of life on earth, the importance of scientific collections, and both the 'how' and the significance of scientific methods and inquiry to a broad audience within the Twin Cities metro. 

Last Modified: 09/14/2017
Modified by: Kristina A Curry Rogers