- journal_title：Journal of Paleontology
- Contributor：Christina Ifrim ; Francisco J. Vega ; Wolfgang Stinnesbeck
- Publisher：Paleontological Society
- Date：2011-
- Format：text/html
- Language：en
- Identifier：10.1666/10-052.1
- journal_abbrev：Journal of Paleontology
- issn：0022-3360
- volume：85
- issue：3
- firstpage：524
The discovery of platy limestone deposits in northeastern Mexico has led to the collection of well-preserved stramentids of early Turonian age from Vallecillo, state of Nuevo León, and of early Coniacian age from El Carranza, state of Coahuila. med-content genus-species" id="named-content-1">Stramentum (med-content genus-species" id="named-content-2">Stramentum) med-content genus-species" id="named-content-3">pulchellum (Sowerby, 1843) colonized the ammonite shells during the lifetime of the animals, occasionally in two subsequent generations. Colonization of the ammonite shell by med-content genus-species" id="named-content-4">Stramentum (med-content genus-species" id="named-content-5">S.) med-content genus-species" id="named-content-6">pulchellum was hindered by strong ornamentation only. The ammonites did not interfere with their epizoans. Colonization during lifetime shows that these ammonites dwelled in well-oxygenated water levels near the surface, and most stramentids were embedded alive. The known paleobiogeographic occurrence of med-content genus-species" id="named-content-7">Stramentum (med-content genus-species" id="named-content-8">S.) med-content genus-species" id="named-content-9">pulchellum and its long stratigraphic occurrence are considerably enlarged by our findings. The pseudoplanktonic mode of life of med-content genus-species" id="named-content-10">Stramentum, and attachment to ammonite shells, may have been a response of a once benthic organism to repeated oxygen-deficient conditions on the seafloor of mid-Cretaceous oceans, i.e., to oceanic anoxic events (OAEs).