The sponge genus Ephydatia from the high-latitude middle Eocene: environmental and evolutionary significance

The freshwater sponge species Ephydatia cf.
facunda Weltner, 1895 (Spongillida, Spongillidae) is
reported for the first time as a fossil from middle Eocene
lake sediments of the Giraffe kimberlite maar in northern
Canada. The sponge is represented by birotule gemmuloscleres
as well as oxea megascleres. Today, E. facunda
inhabits warm-water bodies, so its presence in the Giraffe
locality provides evidence of a warm climate at high latitudes
during the middle Eocene. The morphological similarity
of the birotules to modern conspecific forms suggests
protracted morphological stasis, comparable to that reported
for other siliceous microfossils from the same locality.