Messel Fossils

The Middle Eocene (50 million year old) oil shales of Messel near Frankfurt, Germany are world-reknowned for the unusually complete and detailed picture they present of life of the past. The abundant remains of both animals and plants represent essentially a complete ecosystem in an exceptional state of preservation. Not only are the skeletons and other hard parts preserved, but the soft tissues and even stomach contents that are usually lost can be often seen. The fantastic exhibit of Messel fossils at the Senckenberg Museum in Frankfurt can leave an indelible impression on the fossil collecor. There are 50 million year old beetles with their original metallic green colors, any number of fish and turtles in a remarkable state of preservation, as well as the early horse Propaleotherium complete with stomach contents which clearly show which individual species of plants this early horse ate. The Messel area climate was dramatically different from that of modern-day Germany as shown by the anteaters, tapirs, crocodiles and many other animal species that have been found. Palm fronds also point to the climate as having been tropical to sub-tropical in nature. The Messel Formation consists at its base of gravel and sand, followed by a flaky claystone referred to as "oil shale", and topped by sands and clays. These are lacustrine (lake) deposits which at the time of deposition were packed tightly together. Pores filled with water made up a large part of the volume. Over time, the sheer weight of deposits from above compressed the materials until solid rock was formed. Even today Messel rock has a water content of 40%. The high organic content of the shale can be traced back to the cell walls of the green alga Tretraedon. They grew in large numbers in annual blooms, died off, and sank to the bottom mud. The fineness of the layers indicates that a fairly deep lake was present at the site. It is the presence of this oil shale deposit to which we owe the discovery of this magnificent site. Chance finds of limonite in the area in 1859 led to the mining of "brown coal" (oil shale) in 1875 and the discovery of the first fossil (a crocodile) late that year. Under normal circumstances, fossils are found during the splitting of the shale. Due to the high water content of the rock, it is very fragile, and care must be taken to keep the specimens moist during removal. Because of this fagility, the best method for preservation is the transfer process: Half the fossil is freed from the shale using needles and scrapers. A frame of clay is placed around the specimen, which is then dried briefly with a blast of air. A thin layer of resin is applied, then dried. Further resin is then added in thin layers. Once the block has hardened it can be inverted, and the process repeated on the other side. The surface of the fossil is then coated with a colorless layer to stabilize it. The end result is a specimen essentially free of matrix in a resin support.