Browsing by Author "Botha, Jennifer"

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    Growth and life habits of the Triassic cynodont Trirachodon, inferred from bone histology
    (2004) Botha, Jennifer; Chinsamy, Anusuya
    Growth pattern and lifestyle habits of the Triassic non−mammalian cynodont Trirachodon are deduced from bone histol−ogy and cross−sectional geometry. Several skeletal elements of Trirachodon were examined in order to document histological changes during ontogeny, as well as histovariability in the skeleton. The bone histology of all the elements consists of a moderately vascularized, periodically interrupted, fibro−lamellar bone tissue. This suggests that the overall growth of Trirachodon was probably rapid during the favourable season, but decreased or ceased during the unfavourable season. As the environment is thought to have been semi−arid with seasonal rainfall, it is possible that Trirachodon was sensitive to such environmental fluctuations. Some inter−elemental histovariability was noted where the number and prominence of growth rings varied. Limb bone cross−sectional geometry revealed a relatively thick bone wall and sup−ports earlier proposals that Trirachodon was fossorial.
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    The palaeobiology of the non-mammalian cynodonts deduced from bone microstructure and stable isotopes
    (2002) Botha, Jennifer; Chinsamy-Turan, Anusuya
    The biology of six non-mammalian cynodont genera, from basal to more derived forms was examined using bone cross-sectional geometry and histology, as well as isotope analyses. The bone histology of multiple postcrania revealed distinct variations in growth pattern between the genera studied. The bone histology of the basal Procynosuchus indicates that this animal had a slow, cyclical growth strategy and was probably sensitive to enviromental fluctuations. In contrast, the initial growth of more derived Thrinaxodon was rapid and only shows a marked decrease in growth rate with the onset of sexual maturity. The bone histology of the derived Cynognathus indicates rapid, sustained growth, whereas the bones of the contemporary Diademodon reveal a cyclical growth strategy that alternated between rapid growth during the favourable season and slow or arrests of growth during the unfavourable season.