Anatomical Sciences (ANATG 1516/1517)

Basic Sciences Integrated Sequence (BASIG 1501/1510 - 1509/1518)

Introduction to Histology (HISTG 502/503)

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.

Selected Publications:

(" denotes student author)

Main RP, Simons ELR, & Lee AH. (2021) Interpreting mechanical function in extant and fossil long bones; p. 688–723 In Vertebrate Skeletal Histology and Paleohistology. eds. de Buffrénil V, de Ricqlès AJ, Zylberberg L, and Padian K. CRC Press, Boca Raton FL.

McGuire RS", Ourfalian R", Ezell K, & Lee AH. (2020) Development of limb bone laminarity in the homing pigeon (Columba livia). PeerJ 8:e9878.

Kuehn AL", Lee AH, Main RP, & Simons ELR. (2019) The effects of growth rate and biomechanical loading on bone laminarity within the emu skeleton. PeerJ 7: e7616.

Hunt A", Al-Nakkash L, Lee AH*, & Smith HF*. (2019) Phylogeny and herbivory are related to avian cecal size. Scientific Reports 9: 4243. * Contributed equally

Houssaye A, Waskow K, Hayashi S, Cornette R, Lee AH, & Hutchinson JR. (2016) Biomechanical evolution of solid bones in large animals: a microanatomical investigation. Biological Journal of the Linnean Society 117: 350–371.

Lee AH & Simons ELR. (2015) Wing bone laminarity is not an adaptation for torsional resistance in bats. PeerJ 3:e823.

Blob RW, Espinoza NR, Butcher MT, Lee AH, D’amico AR, Baig F, & Sheffield KM. (2014) Diversity of limb bone safety factors for locomotion in terrestrial vertebrates: evolution and mixed chains. Integrative and Comparative Biology 54: 1058–1071.

Association of American Anatomists

Society for Integrative and Comparative Biology

Society of Vertebrate Paleontology

2022: The Company of Biologists. “Deciphering the nature, function and evolutionary significance of chondroid bone in the skeletogenesis of avian and non-avian dinosaurs.”  (£3,000 – co-PI)

CDMA Basic Sciences Lecturer of the Year - 2023