Modelling the skeletal taphonomy of marine reptiles using Serpianosaurus

2007. UREKA Internship, University College Dublin, Ireland.

Taphonomic models reconstruct the processes that affect carcasses during the transition from biosphere to geosphere; particularly, from death and burial. We (Beardman et al. 2012 [see publications]) developed a new taphonomic method by independently scoring nine anatomical units (the head, neck, dorsal, tail, ribs and four limbs) for articulation and completeness. We demonstrated the method using the Triassic marine reptile Serpianosaurus from Monte San Giorgio, Switzerland. Working with Dr. Patrick Orr through the UREKA program, I analyzed fossils for patterns of disarticulation (i.e. completeness and orientation of skeletal elements). We found that individuals reached the sediment-water relatively soon after death and remained largely intact. After decay, weak bottom currents removed minor elements. Episodic deposition then rapidly buried individuals at various stages of decay, which inhibited further disarticulation and loss of completeness.                                     Photo by Patrick Orr

 

The unprecedented warming of Lake Tanganyika, East Africa

2008. Undergraduate Research, University of Arizona.

Evidence suggests that Lake Tanganyika in East Africa has become warmer and less productive over the past 90 years; however, it is unclear whether these trends are due to climate change or anomalies within long-term variation. We (Tierney et al. 2010 [see publications]) used sediment cores to re-construct lake-surface temperature, productivity, and regional wildfire frequency over the past 1,500 year. In the Paleolimnology Lab at the University of Arizona, I re-constructed the regional wildfire record. Wildfires within the watershed of Lake Tanganyika burn plant materials, producing charcoal that is deposited in the lake sediment. We determined charcoal concentrations vs core depth, which was correlated with age estimates from Pb-210 analysis. Our record shows that recent warming trends are unprecedented since AD 500 and suggest that climate warming has led to warmer lake temperatures, decreased productivity, and drier regional climate conditions that has led to increased wildfire frequency.                                Photo by Andrew Cohen