Karoo Palaeontology Department


Organismal Response to Severe Environmental Perturbation

Permo-Triassic boundary site in the South African Karoo Basin

This research programme focuses on the response of extinct vertebrates - from the microscopic to macroscopic level - during severe environmental shifts that occur during mass extinctions. One of the greatest challenges in understanding the nature of past ecosystems is being able to accurately assess the biology and ecology of the extinct taxa living in these systems. This is particularly the case when attempting to understand how the life histories of extinct vertebrates varied through time, particularly during periods of extreme environmental fluctuation, such as those demonstrated by mass extinctions. Mass extinctions present an excellent opportunity for testing theories about differential survival in the face of dramatic environmental perturbation. The most catastrophic mass extinction event in Phanerozoic history is the Permo-Triassic Mass Extinction (PTME), which occurred approximately 252 million years ago. The South African Karoo Basin preserves the most complete terrestrial record of the Permo-Triassic sequence facilitating detailed studies on the effect of the extinction on vertebrate biology and ecology. Using the PTME as a model, a variety of techniques, including biostratigraphy, geochemistry, morphology and osteohistology, are used to test hypotheses regarding differential species survival.


Osteohistology of Fossil Vertebrates

Osteohistology of the therapsid Cynognathus
Life histories can be assessed based on the bone microanatomy and histology of vertebrates because these are known to reflect growth rates and patterns, ontogenetic stages, reproductive maturity, biomechanical adaptations, lifestyles and potentially the effects of significant environmental perturbation on growth. The osteohistology (bone microstructure) of fossil animals is thus one of the most powerful avenues for investigating the biology and ecology of extinct vertebrates. This research programme involves the study of extinct vertebrate life histories and aims to assess life history variation through time, partiularly during times of environmental stress, such as those caused by mass extinctions, and to identify osteohistological characteristics that may aid in survival.


Osteohistology of Living Vertebrates

Osteohistology of the aardvark
The aim of this programme is to develop a comparative modern vertebrate osteohistology database that can be used to study the osteohistology of extinct vertebrates. Various South African vertebrates have been collected for the purpose of developing this database. Research on this collection is currently focused on fossorial (burrowing) and semi-fossorial mammals. Numerous studies have shown that lifestyle preference affects the bone microstructure of an animal. Although much research has been done on the osteohistology of terrestrial and aquatic vertebrates, relatively little has been done on fossorial and semi-fossorial animals.