EVOLUTION OF FORM AND FUNCTION
I am currently working on a few collaborative projects on the evolution of the amniote respiratory system. We are using methods from various different scientific disciplines to gain insight into the anatomy and physiology of the lungs of extant amniotes and attempt to reconstruct the evolutionary history of one of the most morphologically diverse vertebrate organs.
PULMONARY STRUCTURAL DIVERSITY in REPTILES & BIRDS
My current research is attempting to address the following questions:
1) Why is there so much structural diversity in the diapsid respiratory system?
2) How does this diversity form?
1) Anatomy: CT, µCT, latex and gross dissection
3) Paleontology (diversity surveys & secondary inferences)
4) Functional studies
A joint project with CG Farmer and Ross Metzger (UCSF) is aimed at investigating: 1) the branching patterns of the developing alligator lung; and 2) the impacts of oxygen levels on lung development in "reptiles". Alligators are well known for their phenotypic plasticity, and are thus are a good model organism for experimental study.
A series of beautiful manusciripts were published in the late 1930s and early 1940s describing portions of lung development in alligators, sea turtles, chamaeleons and a few other taxa by the German researcher I. Broman. We are trying to replicate and elaborate upon these studies in order to describe the anatomy of the developing bronchial tree and test hypotheses of homology between the lungs of reptiles and birds.
Examination of the thoracic rib and vertebral anatomy of extant archosaurs indicates a relationship between the postcranial axial skeleton and pulmonary anatomy allowing for predictions of the respiratory morphology of extinct taxa. The data from this research thus far suggest a progression from a dorsally immobile thin-walled lung in basal dinosauriform archosaurs towards a small volume-constant avian-style lung in saurischian dinosaurs.
Future plans for this project include: (1) an analysis of the vertebral column of basal archosaurs to reconstruct the plesiomorphic pulmonary state for Archosauria, and (2) a similar analysis of crocodylomorphs to determine when (or if there is evidence of when) the crocodilian hepatic-piston lung evolved.