THE LATE DEVONIAN: IN THE TIME THAT WE FIRST GREW LEGS
Dr Robert Gess, palaeontologist, Albany Museum and Rhodes University Geology Department
During the Devonian period (359–420 million years ago) vertebrates reached their greatest ordinal diversity. Most were ‘fishes’, though generally unlike modern groups. Towards the end of the period the first tetrapods evolved from lobe-finned-fish. These were aquatic, but in the subsequent Carboniferous period their descendants became terrestrial. An extinction event at the end of the period severely reduced vertebrate diversity. In parallel plants evolved during the Devonian from small simple taxa to early representatives of most surviving groups, including woody trees. These spread around the world to create diverse lowland forests inhabited by pioneering terrestrial invertebrates: habitats conducive to the transition of vertebrates to life on land. Excavation of the Waterloo Farm locality near Makhanda, formerly Grahamstown, has opened a globally unique window into antarctic latitude palaeoenvironments during the Late Devonian and overturned many conventional scientific assumptions. These topics will be discussed in this course.
1. A 360 million year old estuarine lagoon from the Eastern Cape
2. The searches for Africa’s oldest and youngest coelacanths
3. The earliest four-legged creatures from Africa
Clack, J.A. 2012 Gaining Ground: the origin and early evolution of tetrapods, second edition: Indiana University Press.
Schultze, H-P. and Cloutier, R. (eds) 1996. Devonian Fishes and Plants of Miguasha, Quebec, Canada. 227-247, Verlag Dr Friedrich Pfeil. Munchen.
Janvier, P. (1996). Early Vertebrates. Oxford University Press, Oxford.