Volume 43 April 2008

Permanent URI for this collectionhttps://wiredspace.wits.ac.za/handle/10539/13289

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    Re-evaluation of the postcranial skeleton of the Triassic dicynodont Kannemeyria simocephalus from the Cynognathus Assemblage Zone (Subzone B) of South Africa
    (Bernard Price Institute for Palaeontological Research, University of the Witwatersrand, 2008-04) Govender, Romala; Hancox, Phillip John; Yates, Adam M.
    Kannemeyeria simocephalus is probably the best known Middle Triassic dicynodont from South Africa and has been the standard against which other Triassic dicynodonts are compared. In the past studies have concentrated on the cranial morphology of K. simocephalus and its implications for Triassic dicynodont taxonomy and phylogeny. There has been little work on the postcranial anatomy of K. simocephalus, which remains poorly understood. An analysis of the postcranial skeleton of K. simocephalus has identified characters that diagnose the postcranial skeleton. These include a tubercle on the proximo-posterior corner of the medial surface of the acromion; almost straight lateral border of the femur. Material previously described as K. simocephalus by Pearson (1924) and Cruickshank (1975) was also included in this study. Some of the material was found to be significantly different from what is understood to be K. simocephalus and as a result has been included a separate study. It was therefore concluded that the referred specimen BP/1/5624 is currently the most complete and positively identified as K. simocephalus.
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    A new cynodont record from the Tropidostoma Assemblage Zone of the Beaufort Group: implications for the early evolution of cynodonts in South Africa
    (Bernard Price Institute for Palaeontological Research, University of the Witwatersrand, 2008-04) Botha-Brink, J.; Abdala, F.
    A new specimen of cynodont has been recovered from the lower Upper Permian levels of the Tropidostoma Assemblage Zone of the South African Karoo Basin. A series of characters, including the presence of an interpterygoid opening, triconodont postcanine teeth, which are circular in crown view, a probable lingual cingulum, and most significantly, the presence of a masseteric fossa high on the coronoid process, allows this specimen to be assigned to the Procynosuchidae. However, unlike most procynosuchids, precanine teeth are absent and the incisors are represented by four left and five right upper and probably, three lower teeth. Considering the small size of the new specimen from the Tropidostoma Assemblage Zone we identify it as a juvenile Procynosuchus delaharpeae, the only species currently recognized in the genus. The low number of incisors and absence of precanines in this specimen are interpreted as ontogenetic variation (i.e. juvenile characters). This discovery extends the biostratigraphic range of Procynosuchus, as it is now recorded in three assemblage zones, indicating that this taxon is the longest-lived cynodont in the Karoo Basin. The new specimen of Procynosuchus and the recently described Charassognathus gracilis, are the oldest global records of cynodonts, and indicate an earlier initial radiation of this lineage than was previously thought.