Colymbosathon

Colymbosathon
Scientific classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Arthropoda
Class: Ostracoda
Order: Myodocopida
Family: Cylindroleberididae
Genus: Colymbosathon
Siveter, Sutton, Briggs & Siveter, 2003
Species:
C. ecplecticos
Binomial name
Colymbosathon ecplecticos
Siveter, Sutton, Briggs & Siveter, 2003

Colymbosathon ecplecticos is a fossil ostracod described from a specimen obtained from Herefordshire which is dated to the Silurian (425 Ma). It was given a binomial name in 2003 and is the only species within the genus Colymbosathon. The generic name is from Greek Kolymbos (swimmer) and sathon (having a large penis) while the species epithet is from ekplektikos meaning "astounding".

Imaging and virtual reconstruction of the fossil showed that the soft parts were well-preserved. The specimen was placed in the Cylindroleberididiae based on its having six pairs of gills. The bivalved carapace is about 5210 μm long. The specimen, a male, was found to have a large copulatory organ. The find was popularized as being the oldest known penis. It is the oldest known specimen with gills among fossil ostracods.