Marsupites is an extinct genus of crinoids from the Santonian stage of the Late Cretaceous.^[1]

The International Commission on Stratigraphy (ICS) had provisionally assigned the extinction of Marsupites testudinarius as the defining biological marker for the start of the Campanian stage of the Late Cretaceous, 83.6 ± 0.2 million years ago, until a new final definition was eventually ratified in 2022, based instead primarily on magnetostratigraphy.

Fossils of the genus have been found in:^[1]

• Lipnik, Poland^[2]
• Haslam Formation, British Columbia, Canada^[3]

• Haggart, J. W.; Graham, R. (2018), "The crinoid Marsupites in the Upper Cretaceous Nanaimo Group, British Columbia: resolution of the Santonian-Campanian boundary in the North Pacific Province", Cretaceous Research, 87: 277–295, Bibcode:2018CrRes..87..277H, doi:10.1016/j.cretres.2017.05.029
• Lach, R.; Salamon, M. A. (2016), "Late Cretaceous crinoids (Echinodermata) from the southwestern margin of the Holy Cross Mts. (southern Poland) and phylogenetic relationships among bourgueticrinids", Paläontologische Zeitschrift, 90 (3): 503–520, Bibcode:2016PalZ...90..503L, doi:10.1007/s12542-016-0313-9, PMC 5448076, PMID 28596624
• Fossils (Smithsonian Handbooks) by David Ward (Page 173)