South African Eden
The sixth chapter in “Extinction” by Douglas H. Erwin is entitled, “South African Eden”. The chapter focuses on the land in contrast to the previous few chapters which talked about the sea. Towards the end of the Permian era, the first stubby plants which had begun to develop during the Silurian and Devonian had developed into a various mix of groups of plants that included conifers and seed ferns. However, flowering plants had not yet evolved.
When considering the Permian, it is important to understand that the events of the mass extinction relate to where the extinction occurred, on land or water. In previous decades, paleontologists had assumed that the extinction had occurred in a marine setting and that it had little to no impact on terrestrial organisms. However, just as there were significant extinctions realized in the oceans, there were also significant extinctions among vertebrates, plants, and insects. It is believed that this was the first and only mass extinction for insects ever.
The Late Permian therapsids include the ancestors of mammals and are characterized for having mammal-like reptiles. Therapsids include a wide variety of animals than just pareiasaurs. They also include both carnivores as well as herbivores.
It is clear that neither dicynodonts nor the gorgonopsids gave rise to the mammals. Instead, it was a different group of therapsids known as therocephalians. These creatures first appeared in the Early Permian as did other therapsid groups By the Late Permian, these included some small insect-eaters with small incipient cusps on their back teeth. This previewed later...
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