21. Climatic, Floristic, and Vegetational Changes near the Eocene/Oligocene Boundary in North America

Wolfe, Jack A.

doi:10.1515/9781400862924.421

Cited by 91 publications

(89 citation statements)

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“…Similarly, Evanoff et al (1992) concluded that there was a minor drop in MAT in the early Oligocene (from 16.5°C in the late Eocene) based on the terrestrial gastropod fauna near Douglas, Wyoming. Contrariwise, Wolfe (1992) found that, between the late Eocene and early Oligocene in Colorado, MAT decreased from ~12.5 to ~4.5°C; the magnitude of this drop (8°C) is comparable to what he found in the Pacific Northwest and elsewhere in North America (Wolfe 1978). The late Chadronian Ruby flora of Montana had a great many conifers and indicates a MAT of ~12°C and a probable MART of <16°C (Wolfe 1992).…”

Section: Introductionsupporting

confidence: 59%

Late Paleocene glyptosaur (Reptilia: Anguidae) osteoderms from South Carolina, USA

Cicimurri¹,

Knight²,

Self‐Trail³

et al. 2016

J. Paleontol.

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The current fossil record of squamates across the Eocene/Oligocene boundary in central North America is perplexing in that it shows a marked increase in species richness in response to climatic cooling and drying, which is contrary to both the European record and expectation. A diverse, new squamate assemblage from the late Eocene Chadron Formation of the Medicine Pole Hills, North Dakota, provides new insight into these changes. Nineteen squamate species are described, fourteen of which were previously unknown. The acrodontan, varanid, and diploglossine anguid are previously unreported holdovers from the early Eocene. The Medicine Pole Hills local fauna is one of the most species-rich squamate assemblages yet reported from the fossil record.Late Eocene iguanids are remarkable for both their species-level and higher taxonomic diversity: among their numbers are a phrynosomatine (fence lizards and relatives), a polychrotine (anoles and relatives), and a crotaphytine (collared and leopard lizards). The polychrotine, interpreted as the earliest-known representative of the Polychrus lineage, indicates that at least one subgroup of Iguanidae shows a historical biogeographic pattern similar to that of North American scincomorph and anguimorph lizards. The increasing numerical dominance of iguanid species has been considered a hallmark of herpetofaunal modernization in central North America, but this measure appears inadequate in light of these data.Including the new fauna, the record of central North American squamates, like the European record, shows a decrease in richness across the Eocene/Oligocene boundary. However, many uncorrected sampling biases remain that may distort our picture of the squamate response to Eocene/Oligocene climate change. Sampling-standardized studies are indicated.Krister T. Smith.

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Section: Introductionsupporting

confidence: 59%

Late Paleocene glyptosaur (Reptilia: Anguidae) osteoderms from South Carolina, USA

Cicimurri¹,

Knight²,

Self‐Trail³

et al. 2016

J. Paleontol.

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“…The distribution of global vegetation changed significantly during the early Oligocene, with retreat of the tropical and paratropical biomes to the lower latitudes and an equatorward expansion of temperate vegetation (e.g. Wolfe, 1992, Leopold et al, 1992, Janis, 1993, Willis and McElwain, 2002. In the Northern Hemisphere, including North America, broad-leaved forests declined, and conifer forests migrated southwards (Janis, 1993).…”

Section: U Kotthoff Et Al: Late Eocene To Middle Miocene Vegetationmentioning

confidence: 99%

Late Eocene to middle Miocene (33 to 13 million years ago) vegetation and climate development on the North American Atlantic Coastal Plain (IODP Expedition 313, Site M0027)

Kotthoff¹,

Greenwood

McCarthy

et al. 2014

Clim. Past

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Abstract.We investigated the palynology of sediment cores from Site M0027 of IODP (Integrated Ocean Drilling Program) Expedition 313 on the New Jersey shallow shelf to examine vegetation and climate dynamics on the east coast of North America between 33 and 13 million years ago and to assess the impact of over-regional climate events on the region. Palynological results are complemented with pollenbased quantitative climate reconstructions. Our results indicate that the hinterland vegetation of the New Jersey shelf was characterized by oak-hickory forests in the lowlands and conifer-dominated vegetation in the highlands from the early Oligocene to the middle Miocene. The Oligocene witnessed several expansions of conifer forest, probably related to cooling events. The pollen-based climate data imply an increase in annual temperatures from ∼ 11.5 • C to more than 16 • C during the Oligocene.The Mi-1 cooling event at the onset of the Miocene is reflected by an expansion of conifers and mean annual temperature decrease of ∼ 4 • C, from ∼ 16 • C to ∼ 12 • C around 23 million years before present. Relatively low annual temperatures are also recorded for several samples during an interval around ∼ 20 million years before present, which may reflect the Mi-1a and the Mi-1aa cooling events. Generally, the Miocene ecosystem and climate conditions were very similar to those of the Oligocene. Miocene grasslands, as known from other areas in the USA during that time period, are not evident for the hinterland of the New Jersey shelf, possibly reflecting moisture from the proto-Gulf Stream.The palaeovegetation data reveal stable conditions during the mid-Miocene climatic optimum at ∼ 15 million years before present, with only a minor increase in deciduousevergreen mixed forest taxa and a decrease in swamp forest taxa. Pollen-based annual temperature reconstructions show average annual temperatures of ∼ 14 • C during the midMiocene climatic optimum, ∼ 2 • C higher than today, but ∼ 1.5 • C lower than preceding and following phases of the Miocene. We conclude that vegetation and regional climate in the hinterland of the New Jersey shelf did not react as sensitively to Oligocene and Miocene climate changes as other regions in North America or Europe due to the moderating effects of the North Atlantic. An additional explanation for the relatively low regional temperatures reconstructed for the mid-Miocene climatic optimum could be an uplift of the Appalachian Mountains during the Miocene, which would also have influenced the catchment area of our pollen record.

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“…Following the Eocene thermal maximum, a long period of cooling in the middle and late Eocene culminated with the "Terminal Eocene Event" (TEE; Wolfe, 1978), now known to be early Oligocene. The TEE is the most abrupt climate shift in the Paleogene and represents the final transition from the warmer climates of the Eocene to the cooler climates of the Oligocene, reflected globally in marine and continental climate archives (e.g., Wolfe, 1978Wolfe, , 1992Miller, 1992;Zachos et al, 1993). The TEE was first defined by Wolfe (1978) on the basis of fossil leaf assemblages from the western U.S., and is interpreted to be a 7-8°C cooling in mean annual temperature (Wolfe, 1992(Wolfe, , 1994.…”

Section: Introductionmentioning

confidence: 99%

“…The TEE is the most abrupt climate shift in the Paleogene and represents the final transition from the warmer climates of the Eocene to the cooler climates of the Oligocene, reflected globally in marine and continental climate archives (e.g., Wolfe, 1978Wolfe, , 1992Miller, 1992;Zachos et al, 1993). The TEE was first defined by Wolfe (1978) on the basis of fossil leaf assemblages from the western U.S., and is interpreted to be a 7-8°C cooling in mean annual temperature (Wolfe, 1992(Wolfe, , 1994. Climate deterioration in the late Eocene early Oligocene associated with the TEE is reflected in the White River Group in paleosol morphology (Retallack, 1983(Retallack, ,1992, other detailed aspects of sedimentology (Clark et al, 1967), and fossil land snail, amphibian, and reptile faunas (Evanoff et al, 1992;Hutchison, 1992), all of which record progressively more arid environments during the late Eocene and early Oligocene.…”

Section: Introductionmentioning

confidence: 99%

Biologic and climatic signals in the oxygen isotopic composition of Eocene-Oligocene equid enamel phosphate

Bryant

Froelich

Showers

et al. 1996

Palaeogeography, Palaeoclimatology, Palaeoecology

138

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Oxygen isotope results for tooth enamel-phosphate (6p) from late Eocene-early Oligocene fossil horses are presented to determine if paleobiologic and paleoclimatologic information is recorded in fossil tooth enamel chemistry. Teeth from jaws of Mesohippus and Miohippus from the White River Formation (or Group) in the western Great Plains are well preserved and have excellent geochronologic control. Although there is clear evidence for post-depositional alteration of the enamel, a hydroxylapatite mineralogy is preserved and isotopic exchange of oxygen does not appear to be significant. There are distinctive patterns of 6p variation among individual teeth from the same jaw. These patterns reflect season of birth and timing of enamel mineralization. Most of the horses were born in the spring, and mineralization of the enamel is complete after 1-1.5 years. These results show that paleoclimate reconstruction from enamel 6p must account for tooth position and timing of mineralization. The observation that there are different intrajaw patterns of 6p variation among Mesohippus and Miohippus may provide a basis to reconstruct changes in climate seasonality in ancient environments.

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21. Climatic, Floristic, and Vegetational Changes near the Eocene/Oligocene Boundary in North America

Cited by 91 publications

References 0 publications

Late Paleocene glyptosaur (Reptilia: Anguidae) osteoderms from South Carolina, USA

Late Paleocene glyptosaur (Reptilia: Anguidae) osteoderms from South Carolina, USA

Late Eocene to middle Miocene (33 to 13 million years ago) vegetation and climate development on the North American Atlantic Coastal Plain (IODP Expedition 313, Site M0027)

Biologic and climatic signals in the oxygen isotopic composition of Eocene-Oligocene equid enamel phosphate

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