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Abstract

Shell intracrystalline proteinaceous macromolecules isolated from forty four Recent terebratulide brachiopod species, covering all living superfamilies and two thirds of living families, have been compared using immunological techniques. Immunological data indicate that the examined species belong to one of the following four groups, which are also morphologically distinct: (1) Cancellothyridoidea, (2) 'Terebratelloidea' (Dallinidae, Terebratellidae, Laqueidae), (3) Terebratuloidea, and (4) a newly identified category (Kraussinidae, Megathyrididae, Macandreviidae, Ecnomiosidae). Immunological data clearly indicate that groups (3) and (4) form a coherent cluster, and that this cluster has a trichotomous relationship with the remaining two groups. This pattern was not predicted by traditional taxonomies, but reinforced previous immunological studies. The discovery that Ecnomiosa groups with kraussinids, along with megathyridids and Macandrevia, allows the presentation of a revised interpretation of terebratulide phylogeny, in which the extinct zeilleriids and kingenids are considered as a possible link between the Terebratuloidea and the newly recognized group which includes the Kraussinidae.