Helicoplacus (often misspelled Helioplacus) is the earliest well-studied fossil echinoderm. Fossil plates are known from several regions. Complete specimens...

†Helicoplacidae †Helicoplacus Durham & Caster, 1963 †Polyplacus Durham, 1967 †Waucobella Durham, 1967 Helicoplacus guthi, one of two species of Helicoplacus, was...

Helicoplacus...

3 of the Cambrian, 521 million years ago starting with forms such as Helicoplacus. Two other Cambrian Stage 3 (521-514 mya) species, Haikouichthys and...

not, in fact, be such structures. No known orders, 2 known species, Helicoplacus curtisi and H. guthi Order Coronata † Order Fissiculata † Order Spiraculata...

Helicoplacus...

applegatei – type locality for species †Heintzella playfordi †Helicoplacus †Helicoplacus gilberti †Helicoprion †Helicoprion davisii †Helicotoma †Helicotoma...

report †Euomphalus †Fallotaspis †Favosites †Fenestella †Gogia †Halysites †Helicoplacus †Helicoprion †Helicoprion davisii †Heliomeroides †Hercynella †Holopea...

†Helfriedella †Helianthaster †Heliaster †Helicocrinus †Helicocystis †Helicoplacus †Heliocidaris †Heliocrinites †Heliophora †Heliosocrinus †Helodiadema...