Functional signals in the bone microstructure of flying vertebrates and their importance in understanding the evolution of powered flight in feathered dinosaurs

Study Object: 
birds and dinosaur-bird transitional forms
Principal Aim: 
finding statistically supported histological correlates of powered flight, secondary flightlessness, and superprecociality in birds, and applying results to dinobirds by searching for similar patterns in their bone histology
methodology: 
after initial qualitative assessment under polarized light microscope, histomorphometric measurements of bone tissue characteristics based on thin sections and possibly microCT data; numerical analysis of measurements
Researcher: 
Dr. Edina Prondvai

Exciting new discoveries of feathered dinosaurs in the last decade have tremendously increased their popularity in scientific as well as public circles. These new fossils have put the origin and evolution of powered flight (propulsion with wing flapping) in birds into new scientific perspectives, including debates on an early four-winged flight configuration and secondary loss of flight capability in different feathered theropod dinosaurs. Types of locomotion, as well as other biological information like growth rates, ontogenetic stages, and habitat preferences, are reflected at several structural levels of an organism, including its bone tissues. This makes bone microanatomy and histology powerful sources of information for inferring function-related modifications in extinct vertebrates. To obtain a better understanding of the locomotor abilities and potential aerial skills of these extinct dinosaur-bird transitional forms, I plan to first investigate functional signals in the bone tissues of extant birds and bats that reflect different capabilities of powered flight, secondary flightlessness, as well as the differences in ontogenetic timing of the first take-off. This will allow us to then get a more detailed insight into the paleobiology of bird-like dinosaurs, including hotly discussed questions like when, how many times, and in which dinosaur lineages powered flight might have evolved or disappeared secondarily.