A new proxy for Cretaceous paleoceanographic and paleoclimatic reconstructions: Coiling direction changes in the planktonic foraminifera Muricohedbergella delrioensis

作者：Desmares Delphine^*; Crognier Nemo; Bardin Jeremie; Teste Marc; Beaudoin Bernard; Grosheny Daniele

来源：Palaeogeography, Palaeoclimatology, Palaeoecology, 2016, 445: 8-17.

DOI：10.1016/j.palaeo.2015.12.021

• Planktonic foraminifera
• Coiling direction
• Oceanic Anoxic Event 2
• Western Interior Seaway
• Sea surface temperature

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 delta O-18 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.

• 出版日期2016-3-1
• 单位Mines Paristech