Type species of the genus: Thalassocrinus pontifer A.H. Clark, 1911.
Synonymy: A.H. Clark, 1911: 174; 1915: 160; Gislén, 1939: 13; Roux, 1980: 40–42; Mironov & Sorokina, 1998: 34; Roux, 2002: 174; Roux & Lambert, 2011: 48, 51.
Remarks. Roux & Lambert (2011) suspected Thalassocrinus to be a polyphyletic genus. They pointed out significant differences in anal sac features that suggested close affinities between (1) T. pontifer and Hyocrinus bethellianus Thomson, 1876, (2) T. alvinae Roux, 2002, and T. clausus Mironov & Sorokina, 1998, and (3) T. mironovi Roux, 2002, and Laubiericrinus pentagonalis Roux, 2004. Molecular phylogeny (Roux et al. 2013) confirmed that T. pontifer and H. bethellianus are closely related. DNA sequences from the four other species need to be added to get a better understanding of the interrelationships between these species. The genus Thalassocrinus sensu lato is therefore provisionally maintained.