Rare Crab Fossils Discovered Upside Down in AlUla Nature Reserve

The Royal Commission for AlUla announced the discovery of rare horseshoe crab fossils dating back nearly 465 million years, uncovered in the AlGharameel Nature Reserve in AlUla.

According to the study, the fossils date to the Middle Ordovician period and are considered among the oldest known horseshoe crab specimens worldwide. The findings were published in peer‑reviewed journal Gondwana Research, where researchers noted the crabs’ unusually large size and the fact that all were preserved upside down, a preservation pattern not previously recorded.

Geological analysis suggests the organisms were pushed into shallow coastal areas by intense seasonal storms before being rapidly buried in sediment. The discovery included a previously unclassified species, which is currently being investigated further in collaboration with an international research team. The fossils have been added to the Royal Commission for AlUla’s museum collections.