Patricia Vickers-Rich , Peter Trusler, Steve Morton, Peter Swinkels, Thomas H Rich, Mike Hall and Steve Pritchard (Australia)
The “road map” allowing (time) travellers to move across more than 1,000 million years in Namibia is recorded in the rocks of this land. And, it is on display in several museums in Namibia – in Swakopmund, Windhoek, Rosh Pinah and Farm Aar.
The old part of the road
In drafting the early section of this map, Southern Namibia has been a key region for understanding some of the sights our time traveller will come into contact with, some being the weird organisms called Ediacarans. Since the early days of the twentieth century, when geologists, such as Paul Range, and German soldiers occupying isolated outposts in the Aus region of Southern Namibia, some of these strange fossils were reported.
These were the first ‘large’ multicellular organisms that prospered on planet Earth before the development of true animals, and amongst them were the tiny cloudinids. Their fossils are preserved in the thick rock sequences that can be seen along the “time road” in Southern Namibia. These showcase a time in the history of life when there were fundamental and pivotal changes in life occurring, with life transitioning from an enigmatic biota to what we consider normal today.
And, at a number of museums in Namibia, including the Swakopmund Museum and the Namibian Geological Survey in Windhoek, several of these intriguing organisms are on show – such as the soft-bodied Ernietta, Pteridinium and Rangea,and the tiny hard shelled cloudinids.
The “time road” travelled showcases the fossil record that helps humans understand the progress of life on Earth. This allows for the examination of rocks that host an abundance of the world’s first skeletal fossils, preserved in a number of carbonate rocks exposed throughout the Nama Group in southern Namibia.
Some of these early, hard-skeletoned forms played a major role in building some of the world’s first reefs (Germs, 1972; Grotzinger et al., 2000, 2005; Wood et al., 2002; Wood, 2015; Penny et al., 2014). Cloudina Germs, 1972, the first pre-Cambrian shelly fossil named anywhere in the world, consists of millimetre-scale diameter calcified tubes, with a distinctive pattern of stacked, funnel-shaped transverse partitions inside the tube. Most researchers consider it likely that Cloudina was a true animal.
The road takes a turn (the Early Palaeozoic) and “crosses the line” of the biodiversity landscape – 538.8 million years ago
At the end of the Precambrian (the Neoproterozoic) over a few million years, life took a path that changed the landscape forever. Some organisms began to lay down hard parts – skeletons like the cloudinids. And, at around the same time, true predators first appeared, so there was a push to develop some sort of protection – thus skeletons appeared and digging into the sediments to escape developed.
This changed the landscape – there were burrows dug and skeletons became a common part of the fossil landscape. And for our traveller, this helps in understanding these changes, because the skeletons are better preserved than just soft parts. As a result, a range of new life forms start to appear on the horizon – snails (gastropods), a variety of arthropods (trilobites), nautiloids and ammonites (relatives of the squid and octopus – but with shells), corals, starfish and their relatives (crinoids, or sea lilies, for example) and then, a bit later, animals with backbones, first in the water and then on land.
The road comes out of the water and onto land (the Late Palaeozoic and Mesozoic) – 270-66 million years ago
Driving might have become very difficult, and dangerous, as one neared the road section for the Late Palaeozoic – during times called the Carboniferous and Permian. And the driver would have to transition from a boat to a terrestrial vehicle most of the time.
Not only had the fauna and flora changed, for example, there were great coal swamps in the Carboniferous that were “treed” by non-flowering plants (unlike the sorts that make up so much of our modern forests), but that was followed by a time of huge glaciations in turn followed by mass extinctions on an horrific scale at the end of the Palaeozoic – at the end of the Permian around 251 million years ago.
Thus, at the end of the Palaeozoic, the landscape changed. If you could have a break from your “driving down the time road” and stopped for a little fishing in one of the freshwater ponds, you could well have landed one of the many primitive palaeoniscoid fish, as well as a little carnivorous Mesosaurus freshwater reptile that also lived there, fossils of which have been found in abundance near Keetmanshoop in the Permian rocks there. This little reptile was very closely related to another that lived in the freshwaters of South America, when it lay close to Africa and was not separated by an ocean differing from the geography of today.
And now into dinosaur territory – middle of the road trip (the Mesozoic)
As the traveller moves across the time boundary into the Mesozoic, around 240 million years ago, and into the Triassic and down the road to the Jurassic and Cretaceous, he or she will find the rocks of the Erni Formation (Triassic). The Etjo Formation (late Triassic or Early Jurassic) and finally into Twyfelfontein (of Cretaceous age) dinosaurs make their appearance in the Namibian landscape – so watch out!
Most of the remains are those of plant-eaters, such as the little, bipedal ornithopods, so far only known from fragmentary remains, and perhaps even the Massospondylus, which left only footprints. Along with these water-dwelling and terrestrial fauna, there are also actinopterygian fish fossils, trace fossils of such forms as Planolites (whatever those might represent), ammonites and a variety of fossil plants, including conifers, horsetails and an expanding number of flowering plants (angiosperms).
And the road wanders into the present (the Cenozoic) – 66 million years to now
The remainder of the museum exhibitions deal with a fauna and flora that moves into the modern – during the last 66 million years. Specimens include the teeth of a variety of fossil sharks that inhabited a growing ocean between Africa and South America, along with the bones and teeth of the land fauna of Namibia – fossils such as ostrich eggs and bones of both mammals and birds that are clearly related to the fauna that graces Namibian lands today.
Undoubtedly as exploration continues, there will be new discoveries that will appear in these cases in the Namibian museums, so stay tuned and keep exploring.
About the authors
Patricia Vickers-Rich and Peter Trusler are based at Monash and Swinburne Universities; Steve Morton and Peter Swinkels at Monash University, and Tom Rich at Museum Victoria, all in Melbourne.
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