IN Zimbabwe’s entire southern part lies two great Transfrontier Conservation Parks (Greater Limpopo and the Greater Mapungubwe Trans Frontier Conservation Areas), which the country shares with Botswana, South Africa and Mozambique.
They are rich in natural wonders and historical sites.
There is also the Limpopo River, which separates Zimbabwe from South Africa, and is dotted with several natural features on its course right down to the Indian Ocean.
All the Zimbabwean components of the mega-parks are found in Beitbridge District on the east and west.
An hour’s drive south west of Beitbridge town lies Sentinel Safaris where the Zimbabwean component of the Greater Mapungubwe TFCA begins.
This area has been home to the Bristow family for over five decades and has become a very significant feature since the discovery of the large dinosaur fossil beds, which the family says they have known since 1950.
The safari is also rich in flora and fauna with over 300 bird species.
Mrs Vanessa Bristow, the owner of the Safari (Sentinel), said, "The Bristow family has known of fossil beds on Sentinel Ranch since the early 1950s, and some work was done back then by Cran Cook of Bulawayo’s Natural History Museum.
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"There are at least 15 known sites, the best known of which is ‘Penny’, named after a member of the family who stumbled on the clearly visible vertebrae, ribs, pelvis and leg bones in their sandstone sarcophagus while walking on the farm with friends in 1994.
"Another site was discovered on Christmas Day in 2006 by our 12-year-old son, Adam Bristow, when he and his brother were kicked out of the kitchen by their mother busy with Christmas dinner, to look for fossils with their new folding pick-and-spade sets!
"Those fossils, a collection of large vertebrae and limb bones, were found tumbling out of a steep hillside where a deep gulley was being gouged by rain water.
"Therein lies the excitement of these discoveries — they are a coincidental meeting of circumstances extending over hundreds of millions of years."
Mrs Bristow said the most common species on Sentinel were Massospondylus carinatus owen.
"Massospondylus" means "massive spine" and is so named because of the heavy, robust vertebrae associated with this species.
One cannot easily tell from the available fossil material whether the animals are male or female, but Massospondylus was a "Prosauropod" [i.e. coming before the larger, better known "Sauropod" species such as "Brachiosaurus".
"In other words, it was an ancestor of the later Sauropods. This species is thought to have reached 5 metres in length (much smaller than the latter Jurassic period dinosaurs that have been popularised through films and books).
It had a small head with small leaf-blade-shaped serrated teeth, a long, strong neck and short front limbs armed with large claws.
"They are thought to have walked on muscular hind legs and used their long tails for balance and possibly defence, and may even have been covered in ‘thermo-plumes’ or feathers that protected them from the extreme day-time temperatures of the age," she said.
She added that Massospondylus lived in herds and probably fed mainly on reeds growing on the banks of annually flowing streams and swallowed stones (gastroliths) (like modern day crocodiles andostriches) to aid in the digestion of tough plant fibres.
Mrs Bristow said they believed that the creatures may also have been opportunistic carnivores that ate carrion when they could.
"Scientists are excited by Massospondylus because it marks the physiological divergence of lizard and bird forms in the fossil record of evolution," she added.
She also said they had a collection of numerous loose bones — ribs, vertebrae, shoulder blades, limbs, hand and feet bones, and claws that have been found, as well as a permanently articulated skeleton in sandstone displaying the spinal column, ribs, pelvis, legs, feet and tail bones, and another two specimens of pelvis.
"There are also ‘trace fossils’ — casts of ‘Erythrosuchus’ teeth in slabs of sandstone, where the teeth are no longer there, but minute details of their size and structure can still be seen, and a minute fragment of jawbone and teeth of a prehistoric animal the size of a mouse encased in a sandstone slab (which is extremely difficult to find)", said Mrs Bristow.
Mrs Bristow added that many of the fossils on Sentinel are found permanently frozen in situ in sandstone deposits on the property, while others lie scattered over hillsides on the property and left on site that has eroded down over millions of years, or in other areas where they spill out of softer ground in loose pieces like pebbles, or in fragile, shattered fragments found in shale areas.
"The state of preservation depends largely on what type of soil matrix surrounded the bones after the death of the animal, as fossils are a ‘print’ or ‘cast’ of bone material that has been replaced over tens or hundreds of millions of years by minerals seeping into the cellular structures of the bones from the surrounding matrix.
"An almost complete specimen of massospondylus was collected by Cran Cook in the 1950s and is now in the in the Natural History Museum in London," she said.
Mrs Bristow said plans were underway to display the fossils in a proposed site museum in the Greater Mapungubwe TFCA.
"Where fossils have been collected to protect them, it is hoped that they can one day be displayed in a proposed site museum in the Greater Mapungubwe Transfrontier Conservation Park of which Sentinel Ranch is part, for public enjoyment and where paleontologists can gather to further research on these fossil records.
"They are an important asset to this area, and will hopefully draw visitors to a formerly neglected and largely poverty stricken area through eco-tourism and research.
"For that reason, we feel it is important that they stay on site", she said.
She added that another rich fossil site had been identified for further research by a well-known American geologist/paleontologist husband-and-wife team, Kristi Curry and Ray Rogers.
The duo, she said, were still seeking National Geographic Society sponsorship for an expedition to Sentinel (hopefully in 2011) to further investigate their finds and hope to re-kindle a professional association with Zimbabwean-born Darlington Munikwa paleontologist, under the auspices of Zimbabwe’s National Museum and Monuments.
She said more dinosaur remains were found in the Elliot Formation of the Karoo fossil beds of the African sub-continent.
"There are numerous sites in Zimbabwe, the most well-known being in the Zambezi valley, which are represented in collections at the Museum of Natural History in Bulawayo," said Bristow.
According to Mrs Bristow more sites could be found in the area.
"In the last two decades, visiting paleontologists from South Africa and the USA have identified Massospondylus as well as Erythrosuchus fossils (a 240 million years old ancestor of the crocodile), and their preliminary research has shown that other rich fossil sites may yet yield unknown species of Therapod dinosaurs dating back to the cusp of the Triassic and Jurassic eras (approximately 210-190 million years ago:
"To put this in a chronological context, the animals that walked the earth at that time lived on the super-continent of Gondwanaland — made up of Africa, India and South America — before continental drift separated these continents to their present locations," she said.
She said research had shown that the super-continent of Gondwanaland that existed 200 million years ago was a massive trans-continental desert criss-crossed by annually flooding streams.
The African sub-continent at that time was rich in animal species, now extinct, that roamed vast tracts of land undemarcated by political boundaries.
Massospondylus fossils are not unique to Zimbabwe, but are also found in the Karoo fossil beds of South Africa, India and South America, and are therefore used to prove the theory of continental drift.
"Herds of these animals normally grazing on the edges of streams would drown during seasonal floods, and their bodies would collect in mud deposits and sand at the bends of rivers, or they would get stuck in mud at the edge of pools and waterholes, where their bodies would be covered by layer upon layer of silt and sand.
"Their flesh would rot away, but the bones would be held in position by tonnes of earth deposited over hundreds and thousands of years, during which time the cells of the bones would be ‘copied’ by minerals replacing the organic matter under huge geological pressures.
"Then, over time, natural forces of wind and water erosion would expose these fossils, now mineral casts of the original bones, to the surface where we find them today", added Mrs Bristow.
Co-Home Affairs Minister Kembo Mohadi, who is also in charge of the National Museums and Monuments, said the fossils could have been exposed after the Limpopo River changed its course at Bomba Mountains a long time ago.
The mountains are near Nottingham Estate.
"The river changed its course in many ways between Bomba Mountains and Nottingham thereby pushing the remains to the other side of the river (Sentinel) and exposing others.
"We believe that more sites could be found in the area as a result of soil erosion.
"Efforts are still underway to ascertain the age of fossils and the food the animals ate among other things," he said.
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