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Tommotiids from the early C ambrian ( S eries 2, S tage 3) of M orocco and the evolution of the tannuolinid scleritome and setigerous shell structures in stem group brachiopods
Author(s) -
Skovsted Christian B.,
Clausen Sébastien,
Álvaro Javier J.,
Ponlevé Deborah
Publication year - 2014
Publication title -
palaeontology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.69
H-Index - 63
eISSN - 1475-4983
pISSN - 0031-0239
DOI - 10.1111/pala.12060
Subject(s) - seta , basal (medicine) , biology , shell (structure) , anatomy , chemistry , zoology , genus , materials science , insulin , endocrinology , composite material
An assemblage of tannuolinid sclerites is described from the A mouslek Formation ( S ouss B asin) of the Anti‐Atlas Mountains in M orocco. The assemblage contains two species, T annuolina maroccana n. sp., which is represented by a small number of mitral and sellate sclerites, and M icrina sp., represented by a single mitral sclerite. T annuolina maroccana differs from other species of the genus in the presence of both bilaterally symmetrical and strongly asymmetrical sellate sclerites. This observation suggests that the scleritome of T annuolina was more complex than previously thought and that this tommotiid may have held a more basal position in the brachiopod stem group than previously assumed. The shell structure of both T . maroccana and M icrina sp. is well preserved and exhibits two fundamentally different sets of tubular structures, only one of which was likely to contain shell‐penetrating setae. Based on these observations, the structure of the tannuolinid shell is discussed and its implications for the evolution of tubular microstructures in stem and crown group brachiopods are analysed.