Tuesday, August 19, 2008

My PhD thesis

With 42 days to go until I have to submit my PhD thesis, I haven't really had much time to blog...let alone draw dinosaurs! All I have time for is to get stressed out.

Anyway, in the midst of all this, I've finally decided on a thesis title:

Bite force, and the evolution of feeding function in birds, dinosaurs and cats.

The perfect title to show just how much unfocused my thesis is when it comes to a taxonomic group of interest, but extremely obsessed with bite force...ha! Of course it may be subject to change.

The actual thesis consists of five chapters:

Chapter 1: Introduction
Chapter 2: Myology and functional morphology of extant archosaurs
Chapter 3: Reconstruction of the jaw adductor muscles and jaw biomechanics in dinosaurs
Chapter 4: Dry skull bite force estimation in felids
Chapter 5: Tracing the evolution of bite force in Darwin’s finches and felids

Chapter 1 introduces biomechanical concepts regarding bite force and also introduces bite force as a useful single-value indicator of feeding function. So Chapter 1 is theory-heavy.

Chapter 2 is pretty much a preparation chapter for Chapter 3 and is dominated by straightforward muscle descriptions in extant archosaurs but primarily birds. Special focus is given to the Herring Gull/Lesser Black-backed Gull complex (Larus argentatus/L. fuscus), Common Buzzard (Buteo buteo) and Domestic Chicken (Gallus domesticus) but also feature the Ostrich (Struthio camelus) and other assorted birds. But perhaps the most important thing about this chapter is the data collection of cross-sectional areas of muscles for muscle force estimation.

Chapter 3 deals with jaw muscle reconstructions and bite force estimations in dinosaurs, in particular theropods. A simple method of bite force estimation is discussed and bite force is then predicted in a wide range of theropod taxa which is then used to test evolutionary hypotheses regarding feeding adaptations...

Chapter 4 is a critical reinvestigation into the Dry Skull method using extant and extinct cats. Bite force is estimated in 38 extant species of felids plus 3 extinct cats (Miracinonyx trumani, Panthera atrox, and Smilodon fatalis).

Chapter 5 takes the bite forces estimated for cats in Chapter 4 and uses a phylogenetic comparative method to test evolutionary hypotheses. Data in Darwin's finches are also analysed in the same way, mostly for the historical significance of finches in the development of evolutionary theories but also because there are plenty of data available for Darwin't finches in the literature. I gave a talk at PalAss last December on a priliminary version of this chapter.

There is also a summary and conclusions section at the end to wrap it all up.

So in summary, my thesis is really about bite force estimation methods and practical uses of bite force in evolutionary analyses...the evolution of functional adaptations intrigues me to no end and I believe that bite force is a strong tool in analysing functional adaptations regarding feeding.