Research Interests
I am interested in the evolution of skull morphology and how phylogenetic patterns, and developmental and functional constraints underlie the origin of morphological diversity. I take a broadly comparative approach and apply integrative techniques by combining the fields of comparative anatomy, developmental biology, experimental genetics, functional morphology, systematics and paleontology to characterize instances of morphological diversification in major lineages of tetrapods. Currently I employ extinct and extant amphibians to work towards these goals.

Experimental evolutionary developmental morphology
The evolutionary morphology of the skull is shaped, in part, by heritable genetic and developmental factors. I am interested in the role of developmental evolution as a source of morphological diversity. My goals in this area involve characterizing skull morphogenesis, and to use a phylogenetic context to understand how changes produce variation in adult morphology. I am currently investigating the evolutionary development of the skull in amphibians. I utilize GFP-mutant strains and injection methods to trace developing cell lineages and observe structural morphogenesis. This is followed by examining the expression of patterning genes (e.g., Hox, Pax) and by, finally, taking an experimental approach to determining the function of genes, through controlled perturbation. This work identifies pathways that may be more or less labile/plastic, as well as instances of the evolution of novel morphogenetic pathways.

Morphological evolution in deep time
I utilize the fossil record to document the consequences of large-scale morphological evolutionary events, such as those produced by heterochrony. It has been hypothesized that modern amphibians diverged from Paleozoic amphibians via heterochronic events producing a paedomorphic morphology. However, the details of this process remain inadequately understood. My goal in this area of research is to document (qualitatively and quantitatively) the patterns of morphological change that characterize transitions in the stem of modern amphibians. My research works towards synthesizing previous work with new data from other regions, such as the braincase, treating the skull as an integrated whole. These data can be used to generate hypotheses of the types of heterochrony operating, thereby refining morphological models associated with specific types of developmental perturbations. These refined models provide a means for making comparisons with transitions in other lineages to test competing hypotheses that certain processes are expressed as universal patterns in the evolution of morphological diversity, or not.
research fig

Environmental and functional influences on morphology
In addition to molecular and development constraints, functional factors have a strong influence on morphology, and can be powerful sources of morphological diversity. Fossoriality (burrow excavation) is an example of a behaviour that has strongly influenced morphology in vertebrates. In fact, it is a rare example of a behaviour that has evolved convergently in every major tetrapod lineage, making it a unique system for exploring functional influence on morphological evolution in a broad phylogenetic context. My goal in this area includes documenting instances of convergent as well as novel strategies for coping with functional constraints. Recent work employing Finite Element Analysis (FEA) has revealed how stress and strain are distributed throughout the skull in caecilians, which will be used as a point of comparison to test whether tetrapod skulls respond in morphologically similar ways to similar functional pressures. This research sheds light on the ability of the skull to adapt to complex behaviours and to diversify to fill specialist niches in ecosystems.
research 2

Phylogenetic implications of the morphology and development of the braincase of caecilian amphibians (Gymnophiona)


Cranial Anatomy of
Ennatosaurus tecton (Synapsida: Casiedae) from the Permian of Russia and the evolutionary relationships of Caseidae

BSc. (Honours theses)
1) The evolution of the process of keratinization: comparative histology of amphibian and reptile claws

2) The evolution of morphology in the terminal phalanges of non-therapsid synapsids