Most living organisms are never preserved, in fact only a small number of species are preserved as fossils. Many are preserved due to the presence of hard body parts but few are preserved with only soft parts.
Fossils which have been preserved in certain conditions may have both the hard parts such as bones preserved along with their soft tissues such as organs and skin. The location at which these exceptionally well preserved fossils are preserved is known as a lagerstätten.
One of the most famous lagerstätten is the Burgess Shale in Canada which was first discovered in 1909. The fossils here are Cambrian (505 million years old) in age. The Silurian (425 million years old) Wenlock Series in the UK is also a noted lagerstätten in the Herefordshire section of the unit. Here three dimensional body fossils have been found. Within the collection at Dudley Museum & Art Gallery there is a soft bodied worm which was preserved within the Much Wenlock Limestone Formation from the Wrens Nest, Dudley. Another local site is the Coseley lagerstätten, containing Carboniferous plant remains. Other internationally important sites include the Chengjiang Shale’s in China which are 525 million years old (Early Cambrian) and Mazon Creek in Illinois, USA which is 300 million years old (Carboniferous). They are found all over the world with these few sites been the most famous.
There are two types of lagerstätten, concentration and conservation. Concentration lagerstätten are when large quantities of hard parts have been preserved. A good example of this is a bone bed. Conservation lagerstätten are exceptionally well preserved organisms which have had their soft and hard parts preserved, they usually form a mould or a cast. The conservation lagerstätten have been very useful in the study of evolution.