''Cardiograptus'' is a genus of

graptolite Graptolites are a group of colonial animals, members of the subclass Graptolithina within the class Pterobranchia. These filter-feeding organisms are known chiefly from fossils found from the Middle Cambrian ( Miaolingian, Wuliuan) through t ...

, which is easily recognised even when poorly preserved by the form of the

theca In biology, a theca (: thecae) is a sheath or a covering. Botany In botany, the theca is related to plant's flower anatomy. The theca of an angiosperm consists of a pair of microsporangia that are adjacent to each other and share a common ar ...

References

Graptolite genera Glossograptidae Paleozoic life of Newfoundland and Labrador Paleozoic life of Yukon {{paleo-invertebrate-stub