Dr. Michela Johnson

I work on body size, growth and ontogeny in Jurassic teleosauroids. My main objectives are: (1) examining palaeohistology (the study of biological tissues in fossils) to evaluate whether teleosauroids have microanatomical features similar to modern crocodiles; (2) determining whether teleosauroids grew quickly or slowly; and (3) how their growth rate was affected by the Toarcian Oceanic Anoxic Event (a time of great climatic upheaval). I will state-of-the-art thin sectioning, computed tomography and microanatomical techniques to examine teleosauroid histological samples, as well as sophisticated statistical software to calculate and graph teleosauroid growth rates for (1) the entire group and (2) individual species. Most of my work will focus on the taxon Macrospondylus bollensis. 

I will be working on the taphonomy of Jurassic teleosauroids, with particular interest in breakages/disarticulating of the jaws and necks, and evaluate how this might be happening. 

The proposed project aims to use a multi-isotope (C, O, N, Sr, and Ca) analytical approach, using both tooth enamel and bone bioapatite, from several thalattosuchian species from the Posidonia Shale to answer the following palaeoecological questions:
1. What are the similar/different changes in diet through ontogeny and/or species in Posidonia Shale thalattosuchians?
2. Are there distinct habitat differences within Posidonia Shale thalattosuchians?3. Is there any evidence of nearshore-offshore or yearly migration patterns in the common thalattosuchian teleosauroid Macrospondylus bollensis?