The West Coast Fossil Park is famous for its spectacular diversity of fossils, estimated to be over five million years old. Today, most species of mammals, birds, reptiles, and frogs whose remains adorn the fossil bed are extinct, residents of a bygone world. Visitors to the park can learn to appreciate these during guided tours and educational programmes well worth experiencing, even repeatedly, in your quest for learning.
The fossil bed may still harbour living witnesses, or at least their progeny, of that time five thousand millennia ago. They still nest in a large colony living beneath the dense layer of fossils on exhibit at the dig site. You can recognise them when they come to the surface to dispose of their rubbish or to rid themselves of unwelcome intruders.
These are termites, a kind called Southern Harvester Termite (Microhodotermes viator), widespread in the Western Cape. The termitaria of this species are enormous structures, low mounds of 1-2 m in height and 20-30 m in diameter, commonly referred to as heuweltjies.
At this time of year busy streams of workers can often be seen by day carrying leaves, sticks and seeds into their burrows, food for the colony. The regular patterning of heuweltjies, some 50-60 m apart across pastures, crop fields or hillsides is the basis for debate reminiscent of chicken-or-egg affirmations. The phosphate mine that used to operate at the West Coast Fossil Park site until 1993 had exposed a 5 m deep termite colony on the fossil bed. Exposure did not seem to bother the termites, which kept going almost as if they had not been disturbed.
After all, they can still get enough food by foraging for plants in the area surrounding the fossil dig site. Inside the fossil dig site, these termites pile their debris onto the fossils and parade their menagerie of pet beetles.
They also reveal what they are up against, namely many kinds of predators that pick them as soon as they show their heads above ground. Most conspicuous among these are Cape Robin-Chats.
These activities emphasise the fossil bed continues to be a living environment where moisture, temperature and conditions for mineral crystallisation change daily and seasonally, compounded by the bustling of termites and associated creatures.
The dynamics of these changes may ultimately cause the fossils, so well-preserved for aeons before excavation, to deteriorate gradually. A project was initiated to examine this, and visitors will soon see data loggers placed across the fossil bed. This study will inform how best to preserve this heritage for future generations of researchers, learners and tourists.
. Readers who expected to read about William Bond’s WCFP presentation on 22 July entitled “Spines and cages: enigmatic defences against (some) mammal herbivores” can read about it in next month’s column.
The next public talk at the WCFP is on fossil rabbits by Xavier Middleton on 19 August 2023. See you there!
