Age: Upper Jurassic, Tithonian, 145 million years old
Size: 270cm / 106.29" x 74cm / 29.13" x 1cm / 0.39"
Length of the fossil: 17.5cm / 6.88"
Track length: 220cm / 86.61"
Description: The lagoon in which the animal was located was anoxic, meaning that there was no oxygen and nothing living at the bottom of these lagoons. This horseshoe crab, Mesolimulus walchi, found itself on the bottom of the lagoon and you can see from the tracks that the animal sat up, got on its feet and started to walk. However, the anoxic conditions of the lagoon floor quickly became the arthropod's undoing, and it soon began to struggle. We began to examine the specimen more closely and noticed that the animal's walking patterns and behavior began to change. The leg prints became deeper and more irregular, the telson (the long spiky tail) began to rise up and down, up and down, showing that the animal was truly affected by the conditions.
Additional information: Solnhofen Limestone, famous Jurassic period limestone unit near the town of Solnhofen, southern Germany, which contains exceptionally well-preserved fossils from the Tithonian (150.8 million to 145.5 million years ago) of the Jurassic period. The Solnhofen limestone consists of thin layers of fine-grained limestone interspersed with thin layers of slate; they were originally deposited in small, stagnant ocean basins (possibly with very high salt and low oxygen) surrounded by reefs.
