Mass extinction events have far-reaching effects on Earth’s ecosystems. Understanding their effects on biodiversity is critical for understanding how organisms adapt to changing environments and how these adaptations play a role in the evolution of new species and traits after the extinction. Studies on past ecosystems have shown that changes in diversity, body shape, abundance, and/or resource availability may determine the success of a certain group during these events.
During the Late Carboniferous geological period, just over 300 million years ago, a group of animals called amniotes evolved from amphibians. These animals differed from amphibians in that they laid a different kind of egg, called the amniotic or cleidoic egg. This special egg allowed amniotes to colonize the land as it could survive out of water, allowing these animals to expand into drier areas.
Going back in time to 252 million years ago, before the evolution of dinosaurs, birds, and mammals,the South African Karoo (Figure 1) looked very different from how it does today. Mississippi-sized rivers bordered by massive floodplains and lush vegetation traversed the land.
Date: 9 April 2019, Bloemfontein
The National Museum, Bloemfontein today unveiled the complete skull and skeleton of Tapinocaninus, which was a 3-metre long dinocephalian, an ancient ancestor of mammals.
The specimen is the most complete dinocephalian yet discovered and has been beautifully prepared by the University of the Witwatersrand. The fossil was loaned to the University as several blocks of rocks 29 years ago. It has now been returned to the National Museum as a fully prepared specimen, which will soon be placed on exhibit. A month ago, Bruce Rubidge, Romalo Govender and Marco Romano published the full skeletal description of Tapinocaninus in the Journal of Systematic Palaeontology.
Figure 1. Browsers (e.g. giraffe) and grazers (e.g. zebra) by using different diet niches (photo courtesy J Codron).
Large mammal herbivores are among the most conspicuous elements of terrestrial landscapes. We South Africans all appreciate herbivores as flagships of our country’s natural heritage, enjoying them as food, for sport hunting, or simply for our holiday viewing pleasure. They are an exceptionally diverse animal group, represented by over 100 species on the African continent alone, ranging in size from the 3 kg rock dassie Procavia capensis to the African elephant Loxodonta africana with an average body mass around 4 000 kg (Codron 2013). How such a diversity of forms evolved, and still co-exist today, is nothing short of remarkable.