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Zootaxa. 2018 Jul 6;4444(1):1-24. doi: 10.11646/zootaxa.4444.1.1.

Extreme reduction of morphological characters: a type of brachidial development found in several Late Cretaceous and Recent brachiopod species-new relationships between taxa previously listed as incertae sedis.

Author information

1
Royal Belgian Institute of Natural Sciences, O.D. Earth and History of Life, Vautier Street, 29, 1000 Brussels, Belgium.. user@example.com.

Abstract

Size reduction and development of a simplified brachidial structure occurred several times during the long evolution of the Phylum Brachiopoda. Even Recent forms may be micromorphic and paedomorphic with reduced brachidia or none at all. A revision of the Maastrichtian (Late Cretaceous) Terebratella (Morrisia?) suessi Bosquet, 1859 has allowed us to erect a new genus, Jagtithyris gen. nov., because its singular brachidium development does not match any platidiid structure. Such a brachidium has also been observed in another European Late Cretaceous brachiopod, which indicates that this type was not a unique morphological curiosity. This species is the micromorphic Campanian-Maastrichtian Leptothyrellopsis polonicus Bitner Pisera, 1979, which has brachidial structures in common with Jagtithyris suessi comb. nov., although a number of differences have been observed. The genera Leptothyrellopsis and Jagtithyris gen. nov., are included in a new family, Jagtithyrididae fam. nov. During an ongoing revision of extant brachiopod faunas we have been led to recognize a link between this family and representatives of the genus Simplicithyris Zezina, 1976. The taxonomic position of this peculiar group is also discussed.

KEYWORDS:

Mollusca, Rhynchonelliformea, Jagtithyrididae fam. nov., Cretaceous, Holocene, brachidial simplification, new taxa

PMID:
30313939
DOI:
10.11646/zootaxa.4444.1.1
[Indexed for MEDLINE]

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