期刊
CRETACEOUS RESEARCH
卷 132, 期 -, 页码 -出版社
ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD
DOI: 10.1016/j.cretres.2021.105110
关键词
Large heteromorph ammonites; Systematic palaeontology; New species; Aptian; Phylogeny; Tropaeum species
Tropaeum (Tropaeum) evolutum is a new species characterized by remarkably evolute coiling, with a body-chamber of rather more than half a whorl and fourteen widely spaced primaries.
Tropaeum is a genus of large to very large heteromorph ammonites, typical of the Aptian and among the dominant invertebrate organisms of its time. Here we describe a new species, Tropaeum (Tropaeum) evolutum sp. nov., from the basal upper Aptian Epicheloniceras martinioides Zone of the now back-filled Coombe Quarry at Maidstone, Kent, southern England. The new species is characterised by remarkably evolute coiling, the umbilical diameter exceeding 56% of the total, and by a body-chamber of rather more than half a whorl, which is boldly sculpted throughout with fourteen widely, but equally spaced single primaries. Unlike many early (lower Aptian) Tropaeum species, where the adult body-chamber is un-coiled, it appears that in the upper Aptian T. (T.) evolutum sp. nov., the whorls remained just in contact to the end. This follows the general trend exhibited by other late examples of the genus. (c) 2021 Elsevier Ltd. All rights reserved.
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