Andrew H Lee, Ph.D.

I am an evolutionary morphologist with expertise in bone histology, biomechanics, and growth. This expertise gives me a unique perspective that integrates form, function, and time. With this perspective, I seek to understand why skeletons have certain microscopic features.

By using the annual growth lines preserved in dinosaur bones to estimate growth rates, my work shows that large dinosaurs matured about five times faster than living reptiles scaled to comparable size. Even small dinosaurs grew about 40% faster than living reptiles. A potential ecological advantage of rapid growth is the increase in lifetime reproductive success. These findings clarify how dinosaurs were successful for 150 million years as well as the precedent for rapid growth in their descendants, birds.

More is known about bone histology in extinct species than in living ones. Therefore, my current research focuses on living species. I am currently testing whether laminar bone is an adaptation to flight. Laminar bone is thought to resist twisting loads and is prevalent in some of the wing bones of birds. But it is absent in bats. The absence of laminar bone in bats is best explained by relatively slow growth compared to birds. This work suggests that growth is an important constraint on wing bone histology. To test this further, my students use a variety of tools including traditional histology, microCT, fluorescent microscopy, bone strain analysis, and principal component beta regression to understand how laminar bone develops in growing birds. This work will clarify how avian skeletons are adapted to flight and inform bio-inspired design.

Most of my research questions have required massive amounts of data. To assist me, I have recently trained and implemented artificial neural networks to process microCT scans of bone. One of my goals related to neural net research is to develop a generalized model that works on any bone whether it was scanned with medical CT or microCT. Students working on neural net projects in my lab will gain experience in preparing reference data to train models and in evaluating model performance.

My fields of expertise:
Bone histology and biomechanics
Evolution and ecology
Micro-CT analysis

AI and deep learning