It has long been known that the Zambezi Valley contains a rich treasure-trove of fossil remains hundreds of millions of years old, gradually being revealed by the erosive powers of water and weathering.
In the area now flooded by Lake Kariba, the first really exciting find was in 1969, when the fossil remains of a large, sauropod dinosaur was discovered on "Island126/127" west of Bumi Hills.
New to science, this creature was subsequently named Vulcanodon karibaensis. It was a four-legged, ground-dwelling herbivore, with column-like legs and a long neck and tail. It was much smaller than most other sauropods, measuring approximately 6.5 metres (20 ft) in length.
It lived during the Early Jurassic era (around 150 million years ago), and was so named because this was a time when vast outpourings of basalt lava had created a volcanic landscape.
In more recent years, amateur fossil hunter and veteran safari guide, Steve Edwards of Musango Safari Camp
on Lake Kariba, has been enthusiastically collecting fossils in the area. Almost all of his finds are older than the Vulcanadon - and are from the Triassic period, dating back 150 to 250 million years. They consist of bits of limb bones, ribs, jaws, teeth and other unidentified fossil bones.
The finds have been analysed by world-renowned paleaontologists and early in 2017, a specialist group from the Natural History Museum in London, UK, from South Africa and from Zimbabwe, visited the area to have a look for themselves.
They are pictured here (photo by Lucy Broderick) perched on a few excellent examples of the massive fossil tree trunks dating from the Late Triassic era (around 220 million years ago) which are quite commonly found in the Matusadona National Park (on the shores of Lake Kariba) and show that the region must have been densely wooded at that time
Ironically, the recent drop in the water levels of Lake Kariba have allowed for the discovery of several more dinosaur fossil bed sites on the shores of the lake in recent years.
The interest sparked by these fossils has inspired professional safari guides from other safari camps in the area (Rhino Safari Camp and Spurwing Island Lodge) to enthusiastically join the search.
In March 2017, Wild Zambezi was lucky enough to see some of the fossil finds for ourselves on a visit to Rhino Safari Camp.
We set off on a walk in the Matusadona National Park accompanied by pro-guide Steve Chinhoi.
On a gentle slope leading down to the lake, we came across a "field" of fossil wood (of the same era as described above) with some quite large sections of ancient, fossilised tree trunks (see above left) scattered amidst a mass of rocky "twigs". It is believed that the trees of that period were coniferous and grew in swampy conditions.
We then descended into a river valley filled with large conglomerate boulders (a coarse-grained sedimentary rock which includes a mix of rounded pebbles, granules and cobbles).
Embedded in these rocks, are the extraordinary remains of ancient creatures known as Phytosaurs. Fossils of these have previously been dated by paleaontologists to the same Late Triassic era as the fossil wood (some 220 million years ago)
Phytosaurs were not dinosaurs, but semi-aquatic reptiles - long-snouted and heavily armoured, bearing a remarkable resemblance to modern crocodilians in size, appearance, and lifestyle. .
The name "phytosaur" is misleading. It means "plant reptile", and was chosen because the first fossils of phytosaurs were mistakenly thought to belong to plant eaters. However, the sharp teeth in phytosaur jaws clearly show that they were predators, and the more accurate name of "Parasuchia" meaning 'alongside crocodiles' has now been applied, but is seldom used.
With their heavily armoured bodies measuring nearly 5 metres (up to 16 ft) in length and brandishing a slender snout, full of razor sharp teeth, these creatures were the dominant predators in the lakes, rivers and swamps during their time. Two Phytosaur families occurred: those with long snouts (pictured below) were predominantly fish eaters, while the short-snouted variety (above) had much stronger jaws capable of attacking and holding struggling prey such as terrestrial animals that came to the water to drink.
Phytosaurs were very similar to modern day crocodiles with the exception of a few features. The most obvious difference is that phytosaurs had their nostrils very high up on the head just in front of their eyes. Crocodiles have theirs at the tip of their snout. Unlike crocodiles that possess a double palate to enable them to breath despite a mouth full of water, phytosaurs lacked this feature. Nevertheless, the higher level nostrils up near the eyes would have enabled them to accomplish this same breathing ability like modern day crocodiles.
The body armour of phytosaurs was much heavier than crocodiles. They had very thick bony scutes (armour plates) on the back and even covering the throat. These are often found as fossils, and indeed were present at the Matusadona site (see images above). The belly was also supported by a separate set of abdominal ribs called gastralia later to become a common feature in many dinosaurs.
Phytosaur remains have been found in North America, India, North Africa and Europe. So.... is this a first for Southern Africa?!
If so, it's very exciting news for Lake Kariba and the Zambezi Valley. We wait, with bated breath, for the paleaontologists to give their official verdict!