. Annals of the South African Museum = Annale van die Suid-Afrikaanse Museum. Natural history. THE EARLY THERAPSIDS 41 Early therapsid history From the foregoing there is no doubt that on purely morphological grounds the therapsids must be derived from the captorhinomorphs by way of the sphenacodont pelycosaurs. Now, does this fit in with the known history of the early tetrapods ? We can begin the story with the primitive anthracosaurs which were the first tetrapods to successfully achieve an amphibious life. These are best known from the Lower Carboniferous of Scotland where the prevailing cl
. Annals of the South African Museum = Annale van die Suid-Afrikaanse Museum. Natural history. THE EARLY THERAPSIDS 41 Early therapsid history From the foregoing there is no doubt that on purely morphological grounds the therapsids must be derived from the captorhinomorphs by way of the sphenacodont pelycosaurs. Now, does this fit in with the known history of the early tetrapods ? We can begin the story with the primitive anthracosaurs which were the first tetrapods to successfully achieve an amphibious life. These are best known from the Lower Carboniferous of Scotland where the prevailing climate was warm and moist and eminently suitable for an existence partly in water and partly on land. At the close of the Lower Carboniferous times the Scottish climate changed radically. The elevation caused by the Hercynian Foldings made the climate arid and thus unsuitable for these amphibians. We now find the amphibian history continuing in central Europe and North America where during Upper Carboniferous times swampy conditions in a warmer climate prevailed. Swampy conditions continued into Lower Permian times in central Europe and North America, but slowly changed to drier conditions and this sparked off the explosive development of the earliest cotylosaurs especially in North America, closely followed by the rise of the pelycoasurs also mainly in North America but with representatives in central Europe. At the end of the Lower Permian the climate over North America became more and more arid and the cotylosaur—pelycosaur explosion came to an abrupt end. In parts of Europe, however, the Lower Permian climate remained cool and favourable for the continued existence of the sphenacodonts and during the Middle Permian this cool climate continued in Cisuralian Russia where the first therapsids made their appearance in deltaic conditions and from there spread to southern Africa where the favourable flood plain conditions existed in a fairly cool to warm climate. It would thus a
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