Evaluating the responses of three closely related small mammal lineages to climate change across the Paleocene–Eocene thermal maximum (original) (raw)
Related papers
Special Paper 369: Causes and consequences of globally warm climates in the early Paleogene, 2003
The Paleocene-Eocene transition in North American land-mammal faunas is well documented on the south side of Polecat Bench and in surrounding badlands of northwestern Wyoming. Here a rich fossil record is known from a stratigraphic section with an established geomagnetic polarity time scale and medium-to high-resolution carbon and oxygen isotope records. The Paleocene-Eocene carbon isotope excursion (CIE) and temperature maximum (PETM) associated with greenhouse warming are both represented, starting at ca. 55 Ma and lasting ∼ ∼86 k.y., during the transition from Paleocene to Eocene epochs and from Clarkforkian to Wasatchian land-mammal ages.
Climate directly influences Eocene mammal faunal dynamics in North America
Proceedings of the National Academy of Sciences, 2009
The modern effect of climate on plants and animals is well documented. Some have cautioned against assigning climate a direct role in Cenozoic land mammal faunal changes. We illustrate 3 episodes of significant mammalian reorganization in the Eocene of North America that are considered direct responses to dramatic climatic events. The first episode occurred during the Paleocene–Eocene Thermal Maximum (PETM), beginning the Eocene (55.8 Ma), and earliest Wasatchian North American Land Mammal Age (NALMA). The PETM documents a short (<170 k.y.) global temperature increase of ≈5 °C and a substantial increase in first appearances of mammals traced to climate-induced immigration. A 4-m.y. period of climatic and evolutionary stasis then ensued. The second climate episode, the late early Eocene Climatic Optimum (EECO, 53–50 Ma), is marked by a temperature increase to the highest prolonged Cenozoic ocean temperature and a similarly distinctive continental interior mean annual temperature (...
Evolution of the earliest horses driven by climate change in the Paleocene-Eocene Thermal Maximum
Science (New York, N.Y.), 2012
Body size plays a critical role in mammalian ecology and physiology. Previous research has shown that many mammals became smaller during the Paleocene-Eocene Thermal Maximum (PETM), but the timing and magnitude of that change relative to climate change have been unclear. A high-resolution record of continental climate and equid body size change shows a directional size decrease of ~30% over the first ~130,000 years of the PETM, followed by a ~76% increase in the recovery phase of the PETM. These size changes are negatively correlated with temperature inferred from oxygen isotopes in mammal teeth and were probably driven by shifts in temperature and possibly high atmospheric CO(2) concentrations. These findings could be important for understanding mammalian evolutionary responses to future global warming.
Geology, 1998
New stratigraphic and paleontological information from the McCullough Peaks, northern Bighorn Basin, Wyoming, is incorporated into an isotaphonomic faunal database and used to investigate the impact of the latest Paleocene thermal maximum and coincident earliest Wasatchian immigration event on local mammalian community structure. Surface collections from Willwood Formation overbank deposits provide taphonomically consistent and stratigraphically resolved samples of the medium-to large-sized components of underlying mammalian communities. Rarefaction shows that the immigration event caused an abrupt and dramatic increase in species richness and evenness. After this initial increase, diversity tapered off to more typical Wasatchian levels that were still higher than those in the preceding Clarkforkian. Wasatchian immigrants were rapidly incorporated into the new community organization, representing ~20% of the taxa and ~50% of the individuals. Immigrant taxa generally had larger body sizes and more herbivorous and frugivorous dietary habits compared to endemic taxa, causing significant turnover in body-size structure and trophic structure. There was a significant short-term body-size decrease in many lineages that may have been prompted by the elevated temperatures and/or decreased latitudinal thermal gradients during the latest Paleocene thermal maximum. Rapid short-term climatic change (transient climates) and associated biotic dispersal can have abrupt and long-lasting effects on mammalian community evolution. 1012 GEOLOGY, November 1998 Figure 2. Graph showing changes in Bighorn Basin mammalian community structure coincident with latest Paleocene thermal maximum (LPTM). Carbon isotopic record (Koch et al., 1995) shows characteristic negative excursion at LPTM (PDB-Pedee belemnite standard). Coincident with isotopic excursion is a peak in first appearances (FAD-first appearance datum) representing influx of Wasatchian immigrants but few last appearances (LAD-last appearance datum). At species level, immigrant taxa represent ~20% of entire fauna (shaded area) upon immigration yet come to represent ~50% of all individuals (white area) soon after first appearance. Rarefied species richness rises dramatically in response to immigration event and then tapers to levels in Wasatchian that are still higher than during preceding Clarkforkian (Clarkf.) time. Mean species size increases dramatically at LPTM due to influx of larger bodied immigrants. Mean individual size decreases temporarily during brief warming of LPTM.Trophic structure also undergoes significant turnover across LPTM; herbivores and frugivores become more important in new Wasatchian community structure (PC-1-score on first principal component). Shaded area on time scale represents uncertainty pending designation of a new global stratotype for Paleocene-Eocene boundary. Dashed lines represent 95% confidence intervals.
Proceedings of the National Academy of Sciences, 2004
Mid-Pleistocene vertebrates in North America are scarce but important for recognizing the ecological effects of climatic change in the absence of humans. We report on a uniquely rich mid-Pleistocene vertebrate sequence from Porcupine Cave, Colorado, which records at least 127 species and the earliest appearances of 30 mammals and birds. By analyzing >20,000 mammal fossils in relation to modern species and independent climatic proxies, we determined how mammal communities reacted to presumed glacial–interglacial transitions between 1,000,000 and 600,000 years ago. We conclude that climatic warming primarily affected mammals of lower trophic and size categories, in contrast to documented human impacts on higher trophic and size categories historically. Despite changes in species composition and minor changes in small-mammal species richness evident at times of climatic change, overall structural stability of mammal communities persisted >600,000 years before human impacts.
Marine records show major cooling during the Eocene-Oligocene Climate Transition (EOCT). Most proxy studies in the White River Group suggest drying across the EOCT, and some suggest cooling. The lower resolution continental record has hindered a direct correlation of the marine climate record to Nebraska. I explore various correlation schemes and what they imply for faunal changes. This study compiles and analyzes data from 4,875 specimens in the University of Nebraska State Museum (UNSM) collection to test the hypothesis that climate change across the Eocene-Oligocene (E-O) boundary caused significant abundance changes in mammals. A series of binning schemes was created. One binning scheme followed previously established lithological zones, two schemes were based on average sediment accumulation rates, and three more were created by applying a cubic spline curve to published 206 Pb/ 238 U zircon ash dates. For the purpose of correlating the marine and Toadstool sections, I constructed a high-resolution (±0.5 m) carbon isotope stratigraphy across the E-O boundary using fossil enamel from the oreodont Merycoidodon. Results show that turnover in taxonomic abundance occurs throughout the study interval and is not concentrated across the EOCT. The largest pulse of faunal change and largest abundance changes for the most common taxa, Merycoidodon and the horse Mesohippus, slightly predate the EOCT. This raises the possibility that climate change began earlier in the continental interior than indicated by the marine benthic oxygen isotope record. Chord distance analyses reveal that the faunal composition of Orellan zones are more similar to one another than they are to the faunas of Chadron zones. This similarity is likely caused by the extinction, or near extinction, of Chadron taxa like Megacerops around the EOCT. Despite the lack of significant change in evenness, numerous taxa underwent extended changes in relative abundance through time. Archaeotherium, a water-dependent artiodactyl, decreased in relative abundance through time just as Poebrotherium, a water-independent camelid, increased in abundance through time. Changes in the relative abundances of Poebrotherium and Archaeotherium are consistent with a drier environment beginning in EOCT. The level of waterdependence in other taxa is less clear, and their changes in abundance cannot be confidently explained through diet, dentition, body mass, or locomotion.
The impact of regional climate on the evolution of mammals: A case study using fossil horses
Evolution, 2010
horses with low-crowned molar teeth to faunas with hipparionine horses characterized by high-crowned teeth. The spread of hipparionine horses is associated with increased seasonality and the expansion of open habitats. It is generally accepted that anchitheriine horses did not display an evolutionary increase in tooth crown height prior to their extinction. Nevertheless, to test whether anchitheriines showed any changes interpretable as adaptation to local conditions, we analyzed molar teeth from multiple populations of Anchitherium in three dimensions. Our results show differences in tooth morphology that suggest incipient hypsodonty in Spain, the first region experiencing increasingly arid conditions in the early Miocene of Europe. Furthermore, analyses of tooth wear show that Spanish specimens cluster with present ungulates that eat foliage together with grasses and shrubs, whereas German specimens cluster with present-day ungulates that eat mostly foliage. Taken together, even a taxon such as Anchitherium, with a long and successful history of forest adaptation, did respond to regional environmental changes in an adaptive manner.
Influence of Late-Holocene Climate on Northern Rocky Mountain Mammals
Quaternary Research, 1996
An exceptionally rich paleontological site containing thousands of mammalian fossils and well-dated with 18 radiocarbon samples provides evidence of late-Holocene ecological response to climatic change in northern Yellowstone National Park, Wyoming. The mammalian fauna, composed of 10,597 identified specimens, shows surprising affinity to the local habitat with little evidence of long-distance transport of faunal elements, thus revealing the faithfulness of a fossil site to the community from which it is derived. The mammals illustrate ecological sensitivity to a series of mesic to xeric climatic excursions in the sagebrush-grassland ecotone during the past 3200 yr. From 3200 cal yr B.P. to a maximum of 1100 cal yr B.P., the species composition of mammals indicates wetter conditions than today. Beginning about 1200 cal yr B.P., the fauna becomes more representative of xeric conditions with maxima in xeric-indicator taxa and minima in mesic-indicator taxa, concordant with the Medieva...
Rapid range shifts and megafaunal extinctions associated with late Pleistocene climate change
Nature Communications, 2020
Large-scale changes in global climate at the end of the Pleistocene significantly impacted ecosystems across North America. However, the pace and scale of biotic turnover in response to both the Younger Dryas cold period and subsequent Holocene rapid warming have been challenging to assess because of the scarcity of well dated fossil and pollen records that covers this period. Here we present an ancient DNA record from Hall's Cave, Texas, that documents 100 vertebrate and 45 plant taxa from bulk fossils and sediment. We show that local plant and animal diversity dropped markedly during Younger Dryas cooling, but while plant diversity recovered in the early Holocene, animal diversity did not. Instead, five extant and nine extinct large bodied animals disappeared from the region at the end of the Pleistocene. Our findings suggest that climate change affected the local ecosystem in Texas over the Pleistocene-Holocene boundary, but climate change on its own may not explain the disappearance of the megafauna at the end of the Pleistocene.