Iridescent harvestmen (Arachnida: Opiliones: Sclerosomatidae) from the Eocene of Messel, Germany

Paleontologists have uncovered the first fossilized harvestmen (Arachnida: Opiliones) from the Messel Pit, Germany, dating back to the Eocene epoch (~47 million years ago). These specimens, belonging to the families ?Leiobunum messelense sp. nov. and ?Leiobunum schaali sp. nov., exhibit a remarkable iridescent, metallic coloration—a phenomenon previously unknown in arachnid fossils but common in insect fossils from Messel. The harvestmen display the characteristic 'daddy long legs' morphology, with small, rounded bodies and elongated legs, and their anatomical features suggest affiliation with the modern family Sclerosomatidae. The iridescence, typically associated with tropical sclerosomatids, hints at a possible link to subfamilies Gagrellinae or Leiobuninae, some of which also exhibit metallic lustre. This discovery suggests that warmer Eocene temperatures may have facilitated the exchange of early iridescent sclerosomatids between Eurasia and North America, contributing to their current global distribution and diversity.

Bartel, C., Dunlop, J. A., & Wedmann, S. (2024). Iridescent harvestmen (Arachnida: Opiliones: Sclerosomatidae) from the Eocene of Messel, Germany. Palaeobiodiversity and Palaeoenvironments, 104(4), 963–975. https://doi.org/10.1007/s12549-024-00607-4