期刊
CRETACEOUS RESEARCH
卷 34, 期 -, 页码 200-207出版社
ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD
DOI: 10.1016/j.cretres.2011.10.018
关键词
Conoteuthis; Diplobelida; Sepiida; Coleoidea; Protoconch; Cretaceous
资金
- German Research Foundation [FU 762/1-1]
The phylogenetic origin of the Sepiida is still unclear. The presumed derivation from diplobelid belemnoids can be tested by comparison of their initial chambers (protoconchs). The first investigation of a juvenile phragmocone of the diplobelid Conoteuthis hayakawai from the Cenomanian of Hokkaido (northern Japan) yielded surprising insights into the internal protoconch morphology of the Diplobelida. The Conoteuthis protoconch exhibits in many aspects a mosaic of the belemnitid and the spirulid protoconch types. Whereas the sepiid protoconch represents most probably a modification of the spirulid type, the Conoteuthis protoconch is unique in having a closed (imperforated) proseptum. Apart from this, Conoteuthis differs in many other characters from the earliest sepiids (Ceratisepia, Belosepia), which makes a closer relationship unlikely. (C) 2011 Elsevier Ltd. All rights reserved.
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