Post-doctoral Researcher. Advisor: Zhonghe Zhou, Institute of Vertebrate Paleontology and Paleoanthroplogy.
Current research includes a wide range of topics, mostly dealing with Mesozoic birds and the transition from non-avian dinosaurs. My interests lie primarily in morphology and what this can tell us about the closest avian out-group, avian diversity in the Mesozoic, relationships between basasl lineages of birds, growth and ontogenetic strategies in extinct groups, ecology, diet, and much more. My research includes: taxonomic revisions of old fragmentary taxa; redescriptions of poorly known species; cladistic analysis of the largest dataset of Mesozoic avian taxa; descriptions of new specimens and species. Interests include ontogenetic differences within a species as well as differences between the development of different lineages of Mesozoic birds; basal bird feathers; the origin of birds; biological differences between Enantiornithes and Ornithuromorpha; the extinction of the Enantiornithes; taxonomy of purported non-avian dinosaurs or basal birds; relationships of basal lineages of birds; origin of the modern avian growth strategy; and the evolution of 'avian' features such as the pygostyle and the nature of their homology between different clades of Mesozoic birds.
Dissertation: A systematic review of Enantiornithes (Aves: Ornithothoraces)
Advisors: Luis Chiappe and David Bottjer, University of Southern California, Dept. of Geological Sciences.
My project dealt with the enantiornithines, or ‘opposite birds,’ a group of Mesozoic birds with a relatively short scientific history. Since the group was first recognized as the fourth known “subclass” of birds in the 1980’s (Walker 1981), more than 60 species have been named, making it the most taxonomically diverse clade of Mesozoic birds, with specimens collected from every continent with the exception of Antarctica (Chiappe and Walker 2002). These primitive birds formed a major component of Cretaceous avifaunas, coexisting with other groups of birds both more primitive and advanced, lived in a variety of environments ranging from lacustrine, desert, and near shore (Chiappe and Walker 2002), and occupied a considerable size range, from very small, sparrow-sized taxa to taxa the size of a turkey vulture (Chiappe and Walker 2002). The diversity of the group is reflected by the development of numerous diverse feeding and locomotor specializations (Hou et al. 2004). Enantiornithines are the first group of birds to undergo a large-scale radiation, the details of which are poorly understood. They dominated the avian component of most Cretaceous faunas making their subsequent extinction at the end of the Cretaceous perplexing. My thesis sought to better understand this clade in several parts, primarily: a taxonomic review of the clade, which led to the recommendation that approximately half of the named species are nomina dubia; a morphological review of the skull and post-cranial; a review of enantiornithine integument including possibly molecular pathways for the development of primitive feather morphologies; a review of our understanding of enantiornithine ontogeny; and the largest cladistic analysis ever conducted on the clade. The results, when all taxa are included, are largely polytomous as in other published studies. With the removal of three very fragmentary taxa (Nanantius, Gurilynia and Otogornis), relationships emerge. Among interesting results, the enantiornithine Lectavis is resolved as a basal ornithuromorph and Liaoningornis is resolved as an enantiornithine.