From edition 3.
Microfossils have been studied for a century or so yet not largely (pardon the pun) publicised. Even today it comes as a surprise to think such tiny creatures as these described here lived in the shadows of their, more glamorous titanic ‘cousins’. The minute remains pictured on these pages were once parts of small fish, amphibians, reptiles, and mammals and more – preserved over millennia, evoking a vision of swamp life in the Cretaceous period.
Charles Newman (Charlie!) became interested in this branch of fossil study a few years ago and is emerging as a local leading light in the field. He is in many respects following the footsteps of the late, great and sonorously named Samuel Husbands Beckles who, in 1857, oversaw the excavation of the eponymous Beckles Mammal Pit at Durlston Bay. Though his team was primarily concerned with retrieving more complete specimens, this retired lawyer was a pioneer of micro-fossil research, His finds were identified by the famous academic Sir Richard Owen, whose many achievements list first Superintendent (director) of what is now the Natural History Museum. The exact location of Beckles Pit is unremembered.
Charlie has only recently returned to his childhood haunt, The Zig Zag, where the fossiling bug bit at around age five. “Dad made it very apparent to me that this was a great place to go. Lots of early memories…” Over ensuing years the lad’s attention shifted closer to his Worth Matravers home; Chapman’s Pool and beyond, where they remained for many years. Inevitably, the fossil hunter in him couldn’t resist a fresh landslip. A major slide at the Zig Zag in 2010 “rekindled my incentive to go back and begin a systematic approach to collecting.”
The slip was probably the long delayed outcome of underground quarrying carried out generations ago beneath the Cinder Bed, a loosely packed deposit of the shells of the oyster Praeexogyra distorta. It’s not certain whether quarrs originally breached the cliff-face or if erosion wore it toward them but the slip they precipitated revealed a “particularly organic seam” of material. Charlie had already studied the lie of the land from Beckles’ work and others, most particularly the highly respected Paul Ensom, still kicking and who quite literally wrote the book. Several of them in fact; about the geology of Dorset and the Isle of Purbeck, and Yorkshire.
Paul Ensom explains; “The beauty of microfossils (often but not exclusively the shells of single celled organisms, or the pollen grains or spores of plants) is that the chance of finding examples in a few grams of clay, or other rock, is much greater than finding larger fossils. This ‘virtue’ has been exploited by geologists who extract microfossils from the small samples of rock brought to the surface when drilling for oil and gas. Distinctive varieties allow the age of the rock to be deduced and help in their search for the hydrocarbons to which our civilization has become addicted! When searching for the remains of microvertebrates (think of the tiny teeth and bones of our smallest amphibians, lizards, and shrews), if you are lucky, a sample of clay may contain many examples which can be picked from washed residues – just as Charlie Newman is doing. He is opening windows for us on what until comparatively recently has been a largely forgotten World.”
Images 1&2. Filtering; washing the mud though sieves until all clay and fine material is removed. Charlie’s parameter is between three hundred microns to around three millimetres. Smaller specimens are better observed through specialist equipment while larger pieces may be easily examined with a magnifying glass. Charlie first observed microfossils while cleaning macro-fossils under a mag. glass, sparking a deeper interest in that area.
Initial sieving through a large gauge mesh removes sticks, stones and larger bones. The result is a thickly viscous residue which is left to settle.
Image 3 Sieves. These sieves are not your common or garden variety. Charlie happened across the collection at the magnificent Dorset Steam Fair in 2011; two sets of laboratory-quality sieves with calibrations graduating from 4mm to 250 microns (a quarter of a millimetre), ten in all and each item worth thirty quid in the shade. Your man paid thirty quid – the lot! “I’m quite pleased about that.”
Image 4. Particles are segregated into three size categories: 300 – 600 microns, 600 – 1200 microns and 1200 microns – 2.5 millimetres.
For the sieving process, you will first need tolerant cohabitants or none at all. Charlie washes the mud through a series of sieves under the tap in the kitchen sink, drying the residue in the oven (not too hot!). Easily observable particles of turtle, crocodile and other species at around four to five millimeters or broader are revealed in the first sieving. Washing is repeated through the calibrations until the desired spectrum is obtained and the fine sediment of prehistory settles in the drain pipes.
Image 5. Separating fossilised material from organic and general mineral matter requires a steady hand, a practiced eye, a pointy twig and several years’ worth of rainy days.
Employing the time-honoured laboratory-researcher’s technique of dabbing cocktail-sticks to tongue, Charlie’s Guinness-laden saliva creates sufficient surface tension for the dried-thyme-like particles to adhere for removal to the ‘sorted residue’. It’s akin to removing five tonnes of pebble-dash, stone by stone, with a wet snooker queue; laborious but well worth the effort.
Charlie says he gets the same “in the zone” sensation he experiences when hunting fossils on the shore. Both environments induce a meditative state. “It’s just like walking the foreshore; my eyes are drawn to certain shapes and colours and tell-tale signs.” He estimates it takes anywhere between one to three hours to accumulate a matchbox-full of sorted material.
Image 6. Unsorted residue. Charlie approximates the ratio of debris to fossil at roughly 100:1
Image 7. Sorting the matrix. With a toothpick.
Image 8 Sorted residue. Among the fossils in this image, you will see; crocodile scute, the crushing tooth of a fish, Hybodus – shark tooth, the crown of a crocodile tooth, fih palate composed of teeth for crushing the shells of bivalves, skull – fish armour, fish teeth, Hybdont scales – shark and mandibles.
Charlie still finds things in the dirt he hasn’t seen before but typically the cache comprises limb bones including the ‘foot’ bones amongst which are unguals (claws), vertebrae, jaw bones with teeth in place and isolated teeth, also seeds and vestiges of plant material. As well as those listed below, the remains of frog and turtle are represented amongst the bone fragments. In addition, insects and ostracods (shrimp-like animals which still exist today, some of them bioluminescent). The oil industry has long used ostracods to determine the age of rock strata. ‘They lived in their own heads’ Charlie informs – he’s referring to the shrimp…
Image 9. Perhaps the jaw of a lizard, approximately 3.5 millimetres
Image 10. Lizard jaw, a toe bone – probably a metatarsal, a tooth fragment of Hybodus (shark)
Image 11. The word Selenite comes from the ancient Greek, meaning ‘moonstone’. It‘s a form of gypsum and is notable for its crystalline structure.
Image 12. Symmetrodont – ‘symmetry-tooth’. ‘Symmetrodonts’ are a group of mostly small mammals with a relatively simple pattern of molar design. This represents a stage in the evolution of mammals from those with teeth with lines of cusps on their biting surfaces to those with more complex arrangements of cusps and basins which allowed more effective interaction of upper and lower dentitions.
For more insight into Charlie’s fascinating world, visit www.squareandcompasspub.co.uk
To read the complete article you will first need a copy of edition 3, Spring/Summer 2012. Back copies are available though our shop where you can also subscribe!