Echinoderm faunas from the lower Cretaceous (Aptian–Albian) of Alexander Island, Antarctica
Strata assigned to the Fossil Bluff Group on
Alexander Island, Antarctica, contain Aptian to Albian highlatitude echinoderm faunas that lived at palaeolatitudes
greater than 60 degrees south. The Pluto Glacier Formation,
of essentially Aptian age, yields a deep-water assemblage that includes two ophiuroids, an ophiacanthid and a representative of the ophiolepidid genus Mesophiomusium, both represented by partially articulated specimens. The echinoid fauna includes a new genus of diadematoid, Australidiadema, and a new genus of disasteroid, Notidisaster, which extend the record of both groups into the southern hemisphere. The overlying Neptune Glacier Formation, of late Albian age, yields only spatangoids which are common but rarely well enough preserved to be identified even to genus level, although at least some belong to the genus Hemiaster.