Acrotretida

Superregnum: Eukaryota
Regnum: Animalia
Phylum: Brachiopoda
Subphylum: Linguliformea

Classis: Lingulata

Ordo: †Acrotretida

Superfamilia: †Acrotretoidea

The Acrotretida are a group (order) of sessile, suspension-feeding brachiopods known from the Cambrian period and surviving until the present day.[2] Their shell has a round outline, and is usually phosphatic in recent specimens.

They contain the sole superfamily Acrotretoidea.[3]
References

WILLIAMS, A., CARLSON, S. J., BRUNTON, C. H. C., HOLMER, L. E., POPOV, L. E., MERGL, M., LAURIE, J. R., BASSETT, M. G., COCKS, L. R. M., RONG, J.-Y., LAZAREV, S. S., GRANT, R. E., RACHEBOEUF, P. R., JIN, Y.-G., WARDLAW, B. R., HARPER, D. A. T. and WRIGHT, A. D. 2000. Part H, Brachiopoda. Linguliformea, Craniiformea, and Rhynchonelliformea. Geological Society of America, .
Holmer, L. (1991). "Phyletic relationships within the Brachiopoda". GFF. 113: 84. doi:10.1080/11035899109453832.
WILLIAMS, A., CARLSON, S. J., BRUNTON, C. H. C., HOLMER, L. E., POPOV, L. E., MERGL, M., LAURIE, J. R., BASSETT, M. G., COCKS, L. R. M., RONG, J.-Y., LAZAREV, S. S., GRANT, R. E., RACHEBOEUF, P. R., JIN, Y.-G., WARDLAW, B. R., HARPER, D. A. T. and WRIGHT, A. D. 2000. Part H, Brachiopoda. Linguliformea, Craniiformea, and Rhynchonelliformea. Geological Society of America, .