Boundary conditions for the Middle Miocene Climate Transition
(MMCT v1.0)

Frigola, Amanda; Prange, Matthias; Schulz, Michael

doi:10.5194/gmd-2017-171

Cited by 21 publications

(39 citation statements)

References 25 publications

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“…The causes for the MMCT still are a matter of debate; suggested driving mechanisms for this transition include declining atmospheric pCO 2 , changes in ocean gateways and oceanic circulation, and/or orbital triggering causing changes in atmospheric heat and moisture transport (Flower & Kennett, 1994; Holbourn et al, 2005; Holbourn, Kuhnt, Schulz, Flores, & Andersen, 2007). Recent modelling studies carried out for two sets of boundary conditions characterizing the periods of the MCO and of the middle Miocene Glaciation (MMG), indicate moderate cooling of the surface temperature in the order of 2°C for the mid‐latitudes of Europe (Frigola, Prange, & Schulz, 2018), a value that is in the order of proxy‐based estimates, although surfaces temperatures obtained in the model scenarios for the mid‐latitudes of Europe are significantly cooler compared to proxy‐based reconstructions (Henrot et al, 2017). In addition, the very moderate temperature decline and stable precipitation throughout the studied time‐span, as suggested by proxy data and modelling (Bruch, Utescher, Mosbrugger, & NECLIME members, 2011; Frigola et al, 2018; Mosbrugger et al, 2005) are in line with the observed relative stability of plant diversity and the persistence of the peat forming vegetation of the LRB at that time.…”

Section: Discussionmentioning

confidence: 99%

Diversity patterns in microfloras recovered from Miocene brown coals of the lower Rhine Basin reveal distinct coupling of the structure of the peat‐forming vegetation and continental climate variability

et al. 2020

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Brown coal deposits of the Lower Rhine Basin, northwest Germany, cover the late Burdigalian to Serravallian and most of the Tortonian enabling access to observations of vegetation dynamics during the Miocene Climatic Optimum and Late Miocene Cooling. Based on a total of 500 microfloras sampled from brown coal seams in the Bergheim and Inden open cast mines, structural changes in the vegetation are studied in comparatively stable environments of persisting coastal mires. In order to minimize the impact of local edaphic conditions in the peat bog, the palynomorph record is characterized as diversity using plant functional types (PFTs). In total, 41 herbaceous and arboreal PFTs are assigned to pollen and spores types based on their botanical affinity.The diversity spectra reveal a variable proportion of herbaceous and shrubby PFTs attaining a mean of 30%, in both the middle and late Miocene sample sets. With ca. 70% of the total diversity attributable to arboreal functional types, the peat‐forming vegetation of the studied Miocene strata classifies as a swamp forest. The composition of the arboreal fraction shows a long‐term declining trend in the proportions of thermophilous evergreen types among broadleaved PFTs following the overall climate cooling throughout the studied time. Conifers became more diverse during the Langhian (ca. 15%, at a mean) and attained a high diversity level of ca. 20% of the total PFT diversity in the Tortonian. The diversity proportions of conifer PFTs among other arboreal components and the composition of the broadleaved angiosperm PFT fraction display a pointed short‐term variability that could probably be related to eccentricity cycles when considering the available independent stratigraphic framework. Our results suggest a distinct coupling of the structure of the peat‐forming vegetation and continental climate variability in the study area.

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Section: Discussionmentioning

confidence: 99%

Diversity patterns in microfloras recovered from Miocene brown coals of the lower Rhine Basin reveal distinct coupling of the structure of the peat‐forming vegetation and continental climate variability

et al. 2020

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“…Site locations on Figure . (a) For four different locations in the North Atlantic, comparison of annual average sea surface temperature (SST) modeled by the CCSM3 model for the Middle Miocene Climatic Optimum assuming Miocene paleogeography and 400 ppmv CO 2 by Frigola et al () and average SST proxy data for the broad MCO interval from 18 to 14.5 Ma. The color of each bar matches the color of the symbol for proxy locations whose SST is shown in the compilation of (b) Ocean Drilling Program (ODP) 925 (4°N, 43°W; orange); Integrated Ocean Drilling Program (IODP) 1406 (40N, 50°W; blue); ODP 608 (42°N, 23°W;green); ODP 982 (58°N, 16°W; purple).…”

Section: Discussionmentioning

confidence: 99%

“…Paleoclimate model simulations with relevant paleogeography for the MMCO and 400 ppmv CO 2 do not reproduce the extremely warm temperatures in the extra‐tropical North Atlantic sites, and simulate a much stronger latitudinal gradient between the equatorial site and the locations of extratropical records (Frigola et al, ; Herold et al, ). Simulations of Paleocene Eocene Thermal Maximum, which feature different paleogeography, using 2250 ppmv CO 2 and altered cloud feedbacks, simulate extreme midlatitude temperatures of 30°C at 42°N in the western Atlantic.…”

Section: Discussionmentioning

confidence: 99%

Midlatitude Temperature Variations in the Oligocene to Early Miocene

Guitián

Phelps

Polissar

et al. 2019

Paleoceanog and Paleoclimatol

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Antarctic ice sheet margin extent and the sensitivity of benthic δ18O to orbital forcing have varied on million‐year timescales during the Oligocene to Early Miocene. However, few sea surface temperature (SST) records for this time interval exist to evaluate links between polar processes and mean temperature outside polar regions. Here, we present a new record of SST for the time interval 30 to 17 Ma derived from the long‐chain alkenone unsaturation ratio ( U37k′) at Integrated Ocean Drilling Program Site 1406A in the midlatitude North Atlantic. Results confirm that warm temperatures from 24°C to over 30°C prevailed in midlatitudes in this time and suggest a transition from colder early‐middle Oligocene to warmer average conditions after 24.5 Ma. The global significance of this transition is highlighted by the coincidence with changes in the dominance from marine‐ to terrestrial‐terminating ice sheets in the Ross Sea around Antarctica. The longest continuous section of the record (20.6 to 26.6 Ma) contains multiple 2 million‐year cycles in SST, potentially paced by long obliquity modulation. Complex and temporally varying relationships are observed between North Atlantic SST and benthic δ18O in paired samples; significant covariation is only observed around the Oligocene‐Miocene transition, coincident with a lower average marine ice extent. These North Atlantic U37k′ temperature records provide a new context in which to examine the stability of climate and the Antarctic ice sheet during the Oligocene and early Miocene.

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“…For example, this causal link has been inferred for the Paleocene fauna of Cerrejón, Colombia, which includes the largest snake ever, Titanoboa cerrejonensis (2), and the largest Paleogene pelomedusoid turtles and crocodylians (12,45). Although less warm than the Paleocene and the Eocene, the Miocene was also an epoch with notable climatic events that could have affected the body size of neotropical animal species, for example, the warm middle Miocene climatic optimum (MMCO) (46,47), the global cooling between ~15 and 13 Ma known as middle Miocene climatic transition (MMCT), and continuous decreasing of global temperature during the late Miocene (48). The time range so far known for S. geographicus (middle Miocene to late Miocene) (this study) indicates that this taxon overcame the MMCT event.…”

Section: Paleoecologymentioning

confidence: 99%

The anatomy, paleobiology, and evolutionary relationships of the largest extinct side-necked turtle

et al. 2020

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Despite being among the largest turtles that ever lived, the biology and systematics of Stupendemys geographicus remain largely unknown because of scant, fragmentary finds. We describe exceptional specimens and new localities of S. geographicus from the Miocene of Venezuela and Colombia. We document the largest shell reported for any extant or extinct turtle, with a carapace length of 2.40 m and estimated mass of 1.145 kg, almost 100 times the size of its closest living relative, the Amazon river turtle Peltocephalus dumerilianus, and twice that of the largest extant turtle, the marine leatherback Dermochelys coriacea. The new specimens greatly increase knowledge of the biology and evolution of this iconic species. Our findings suggest the existence of a single giant turtle species across the northern Neotropics, but with two shell morphotypes, suggestive of sexual dimorphism. Bite marks and punctured bones indicate interactions with large caimans that also inhabited the northern Neotropics.

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Boundary conditions for the Middle Miocene Climate Transition (MMCT v1.0)

Cited by 21 publications

References 25 publications

Diversity patterns in microfloras recovered from Miocene brown coals of the lower Rhine Basin reveal distinct coupling of the structure of the peat‐forming vegetation and continental climate variability

Diversity patterns in microfloras recovered from Miocene brown coals of the lower Rhine Basin reveal distinct coupling of the structure of the peat‐forming vegetation and continental climate variability

Midlatitude Temperature Variations in the Oligocene to Early Miocene

The anatomy, paleobiology, and evolutionary relationships of the largest extinct side-necked turtle

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