Pterosaur Fossil Preservation
Fossils represent only the smallest amount of information about past life. They are only found where conditions are good for preserving organic remains. Most dead organisms are either eaten or they are decomposed by bacteria. Very few specimens survive to be fossils.
The best preserved fossils are those that are quickly buried where there are no bacteria. This occurs mostly in shallow water where sediment is being deposited quickly. It can also occur in very acid conditions, or very alkaline conditions where bacteria decomposers cannot survive.
This Rhamphorhynchus specimen is known as the Dark Wing. It has been preserved in very fine detail from rocks in Bavaria, Germany, called the Lithographic Limestone. The fossil is so good that the wing membrane structure can be seen.
Often, the fossils that are found will be small fragments of a pterosaur. This end of a lower jaw mandible was found in the Stonesfield Slate of the UK. It is very incomplete, but the preservation is still very good.
Here is a humerus from a large pterosaur found in the USA. The air cavity of this 20cm (10 inch) bone has collapsed, causing the structure of the bone to fragment and the overall shape of the has been altered to a flat, crushed structure. This bone is not in its original shape and needs to be reconstructed to show what it was really like.