Graptolites have been discovered growing on algae

For the first time, the unusual phenomenon of graptolites growing on algae is observed. Sessile green algae belonging to the Dasycladales were found in the Silurian (about 427 million years ago) sediments of a shallow shelf sea, in Podolia, western Ukraine. Graptolites belonging to the Dendroidea were epiphytes growing on the alga. Both forms, Voronocladus dryganti (alga) and Podoliagraptus algaeoides (graptolite), were unknown until now. The exceptional state of preservation of both forms allows treating the outcrop as a ‘Konservat Lagerstätte’.

Figure: Reconstruction of the dasycladalean green alga Voronocladus dryganti gen. et sp. nov. (drawing by Bogusław Waksmundzki)