| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 4465803 | Palaeogeography, Palaeoclimatology, Palaeoecology | 2016 | 10 Pages |
•dextral and sinistral morphotypes of M. delrioensis are common during the OAE2•Several coiling direction changes among M. delrioensis are highlighted•δ18O and percentage of sinistral M. delrioensis variations are correlated•M. delrioensis coiling shift is a new proxy to estimate SST changes•M. delrioensis inner porosity is an additional SST index
Among some modern and recent fossil species of planktonic foraminifera, the proportion of left- to right-coiled shells in a population appears to be temperature-dependent; the relative abundance of each morphotype reflecting ecological preferences. A similar relationship is identified among Muricohedbergella delrioensis (Carsey, 1926) at the Cenomanian–Turonian stage boundary in mid-latitude sites of the Western Interior Seaway, including the Pueblo type section. The increase of sinistral M. delrioensis in the assemblage is related to higher δ18O carb values and decrease in inner porosity which suggests that changes in the coiling direction in this morphospecies could represent a new proxy for constraining Sea Surface Temperature (SST) variations. As surface dwellers, muricohedbergellids were not affected by Oceanic Anoxic Event (OAE2) and provide a continuous paleoclimatic signal throughout the Cenomanian–Turonian boundary interval. Furthermore, genetic evidence obtained from extant foraminifera indicates that shifts of coiling ratios in planktonic foraminifera species can express the signature of distinct genetic types, which are revealed through their opposite coiling directions. Coiling direction could be a genetic trait, implying that cryptic species may occur in the Mesozoic.
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