Micropalaeosoma

Micropalaeosoma balticus (formerly Palaeosoma balticus^{[lower-alpha 1]}) was reported as an extinct, fossil turbellarian flatworm known from Baltic amber of Kaliningrad, Russia, that lived approximately 40 million years ago. It measured approximately 1.5 mm in length. It was considered the oldest and most complete free-living flatworm body fossil.^[1][2] However, much older flatworm fossils have been reported ^[3][4] and it has been re-interpreted as a pseudo-inclusion (largely consisting of air bubbles).^[5]

Micropalaeosoma Temporal range: Eocene PreꞒ Ꞓ O S D C P T J K Pg N
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Platyhelminthes
Order:	Rhabdocoela
Suborder:	Dalytyphloplanida
Genus:	†Micropalaeosoma Poinar, 2004
Type species
†Micropalaeosoma balticus (Poinar, 2003)

References

1. The name Palaeosoma was preoccupied by a genus of fossil millipedes.

1. Poinar, George (2003). "A rhabdocoel turbellarian (Platyhelminthes, Typhloplanoida) in Baltic amber with a review of fossil and sub-fossil platyhelminths" (PDF). Invertebrate Biology. 122 (4): 308–312. doi:10.1111/j.1744-7410.2003.tb00095.x.
2. Poinar, George O. (2011). "Eggs, Oviposition, and Maternal Care in Amber". In Arthur J. Boucot; George O. Poinar, Jr. (eds.). Fossil Behavior Compendium. CRC Press. ISBN 9781439859230.
3. Knaust, D. (2010). Remarkably preserved benthic organisms and their traces from a Middle Triassic (Muschelkalk) mud flat. Lethaia, 43(3), 344-356.
4. De Baets, K., Dentzien-Dias, P., Harrison, G. W. M., Littlewood, D. T. J., & Parry, L. A. (2021). Fossil constraints on the timescale of parasitic helminth evolution. In The evolution and fossil record of parasitism: identification and macroevolution of parasites (pp. 231-271). Cham: Springer International Publishing.
5. Szadziewski, R., Szwedo, J., & Sontag, E. (2018). Fauna lasu bursztynowego/Fauna of the amber forest. Bursztyn Bałtycki—Skarb Zatoki Gdańskiej/Baltic Amber—Treasure of the Bay of Gdańsk, 216-217.