Hederellids are

extinct Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...

colonial

animal Animals are multicellular, eukaryotic organisms in the biological kingdom Animalia. With few exceptions, animals consume organic material, breathe oxygen, are able to move, can reproduce sexually, and go through an ontogenetic stage ...

s with calcitic tubular branching

exoskeleton An exoskeleton (from Greek ''éxō'' "outer" and ''skeletós'' "skeleton") is an external skeleton that supports and protects an animal's body, in contrast to an internal skeleton ( endoskeleton) in for example, a human. In usage, some of the ...

s. They range from the

Silurian The Silurian ( ) is a geologic period and system spanning 24.6 million years from the end of the Ordovician Period, at million years ago ( Mya), to the beginning of the Devonian Period, Mya. The Silurian is the shortest period of the Paleoz ...

to the

Permian The Permian ( ) is a geologic period and stratigraphic system which spans 47 million years from the end of the Carboniferous Period million years ago (Mya), to the beginning of the Triassic Period 251.9 Mya. It is the last period of the Paleo ...

and were most common in the

Devonian The Devonian ( ) is a geologic period and system of the Paleozoic era, spanning 60.3 million years from the end of the Silurian, million years ago (Mya), to the beginning of the Carboniferous, Mya. It is named after Devon, England, wh ...

period. They are more properly known as "hederelloids" because they were originally defined as a suborder by Bassler (1939), who described about 130 species. Although they have traditionally been considered

bryozoans Bryozoa (also known as the Polyzoa, Ectoprocta or commonly as moss animals) are a phylum of simple, aquatic invertebrate animals, nearly all living in sedentary colonies. Typically about long, they have a special feeding structure called a l ...

, they are clearly not because of their branching patterns, lack of an astogenetic gradient, skeletal microstructure, and wide range in tube diameters (Wilson and Taylor, 2001). Work continues on assessing the true affinities of hederelloids, but they appear to be most closely related to phoronids and other

lophophorate The Lophophorata are a Lophotrochozoan clade consisting of the Brachiozoa and the Bryozoa. They have a lophophore. Molecular phylogenetic analyses suggest that lophophorates are protostomes Protostomia () is the clade of animals once though ...

s (Taylor and Wilson, 2008; Taylor et al., 2010).

Classification

*Family Hederellidae **Genus '' Diversipora'' **Genus '' Hederella'' *Family Reptariidae **Genus '' Cystoporella'' **Genus '' Hederopsis'' **Genus '' Hernodia'' File:HedCloseUp.JPG, Three hederelloid species on a Devonian rugose

coral Corals are marine invertebrates within the class Anthozoa of the phylum Cnidaria. They typically form compact colonies of many identical individual polyps. Coral species include the important reef builders that inhabit tropical oceans and se ...

File:HederellaOH3.jpg, Hederelloids encrusting a

brachiopod Brachiopods (), phylum Brachiopoda, are a phylum of trochozoan animals that have hard "valves" (shells) on the upper and lower surfaces, unlike the left and right arrangement in bivalve molluscs. Brachiopod valves are hinged at the rear end, w ...

from the Devonian of Ohio File:HederelloidSEM.jpg, SEM image of a hederelloid from the Devonian of Michigan (largest tube diameter is 0.75 mm)

References

*Bassler, R.S. (1939) The Hederelloidea. A suborder of Paleozoic cyclostomatous Bryozoa. Proceedings of the United States National Museum, 87:25-91. * *Taylor, P.D. and Wilson, M.A. (2008) Morphology and affinities of hederelloid "bryozoans", p. 301-309. In: Hageman, S.J., Key, M.M. Jr., and Winston, J.E. (eds.), Bryozoan Studies 2007: Proceedings of the 14th International Bryozoology Conference, Boone, North Carolina, July 1–8, 2007. Virginia Museum of Natural History Special Publication 1

*Wilson, M.A. and Taylor, P.D. (2001) "Pseudobryozoans" and the problem of encruster diversity in the Paleozoic. PaleoBios, 21 (supplement to no. 2):134-135. *

Enigmatic animal taxa Carboniferous invertebrates Devonian animals Late Devonian animals Permian animals Permian extinctions Protostome enigmatic taxa Silurian animals Silurian first appearances {{Permian-animal-stub