Global Warming; Shrinking Mammals – #365papers – 2017 – 76

#365papers for March 17, 2017

D’Ambrosia, Clyde, Fricke, Gringerich, Abels, 2017, Repetitive mammalian dwarfing during ancient greenhouse warming events: Science Advances, v. 3, e1601430.

What’s it about?

Rapid global warming in Earth’s past had occurred more than once. The most commonly studied episode occurred 55 million years ago, at the boundary between the Paleocene and Eocene epochs (Paleocene Eocene Thermal Maximum, PETM). Several other episodes have happened, including the ETM2 and H2 episodes which are discussed in this paper.

Dwarfing of mammalian species has been documented at the PETM. This paper shows dwarfing of mammals also occurred at the ETM2. Continue reading

Rocks and Fossils in the Uinta Basin, Getting it in Order – #365papers – 2017 – 74

#365papers for March 15, 2017

Townsend, Friscia, and Rasmussen, 2006, Stratigraphic distribution of upper middle Eocene fossil vertebrate localities in the eastern Uinta Basin, Utah, with comments on Uintan biostratigraphy: The Mountain Geologist, v. 43, p. 115-134.

What’s it about?

This paper is a synthesis of over 100 years worth of research in the Uinta Basin, making a huge effort to sort out how the rocks and fossils correlate and to get everything in the correct chronologic order. Continue reading

Appearance and Spread of Modern Forests in Asia and North America – #365papers – 2017 – 72

#365papers for March 13, 2017

Baskin and Baskin, 2016. Origins and relationships of the mixed mesophytic forest of Oregon-Idaho, China, and Kentucky: Review and synthesis: Annals of the Missouri Botanical Gardens, v. 101, p. 525-552.

What’s it about?

Modern forests of North America and Asia are remarkably similar in the species of trees present, but there is no obvious connection between the two. This paper discusses the lead hypotheses to explain the similarities Continue reading

Lakes Come and Go, 50 Million Years Ago – #365papers – 2017 – 69

#365papers for March 10, 2017

Davis, Wiegand, Carroll, and Chamberlain, 2008, The effect of dreainage reorganization on paleoaltimetry studies: An example from the Paleogene Laramide foreland: Earth and Planetary Science Letters, v. 275, p. 258-268.

What’s it about?

The authors use isotopes of carbon, oxygen, and strontium, plus relative abundances of strontium and calcium in lake deposits to interpret water sources, connectivity of lakes, and general environmental parameters for the Uinta Basin during the Eocene (~55-~43 million years ago). Continue reading

The Middle Eocene Climatic Optimum in the Northern Hemisphere – #365papers – 2017 – 67

#365papers for March 8, 2017

Jovane, Florindo Coccioni, Dianares-Turell, Marsili, Monechi, Roberts, Sprovieri, 2007, The middle Eocene climatic optimum event in the Contessa Highway section, Umbrian Apennines, Italy: GSA Bulletin, v. 119, p. 413-427.

What’s it about?

This paper like others I’ve read recently discusses the abundance of single-celled organisms in the ocean called foraminifera (forams). The overall abundance of different species plus isotopic analysis of the fossils themselves can provide insights about climate during the middle Eocene. Continue reading

Paleogene Antarctic ocean circulation from isotopes – #365papers – 2017 – 66

#365papers for March 7, 2017

Kennett and Stott, 1990 Proteus and Proto-Oceanus: ancestral paleogene oceans as revealed from Antarctic stable isotopic results; ODP Leg 113: Proceedings of the Ocean Drilling Programs, Scientific Results, v. 113, p. 865-880.

What’s it about?

These are the published results of an ocean drilling cruise that took place in Antarctica in the late 1980’s. A core from the ocean floor was drilled and various parts of it were studied. This paper discusses geochemical results from the skeletons (tests) of single-celled organisms called foraminifera (forams) found throughout the core. From these results, the authors discuss deep ocean currents from millions of years ago. Continue reading

The Paleocene-Eocene boundary in deep ocean foraminifera – #365papers – 2017 – 65

#365papers for March 6, 2017

Thomas and Shackleton, 1996, The Paleocene-Eocene benthic forminiferal extinction and stable isotope anomalies, in Knox, Corfield, Dunay, eds., Correlation of the Early Paleogene in Northwest Europe: Geological Society Special Publication n. 101, p. 401-441.

What’s it about?

This paper examines the abundance and geochemistry of single-celled organisms called foraminiferans (forams) that were living in the oceans around 55 million years ago. Forams are still present today worldwide. They make little tiny calcite skeletons (called tests) that can be used to identify the species and then can be analyzed.

Using these foram skeletons, the authors identified the many species that lived in the ocean before and after the Paleocene-Eocene boundary and recognized some extinctions associated with the boundary. With geochemical analysis, they showed that there are some significant anomalies (rapid, unexpected changes) at the Paleocene-Eocene boundary. Continue reading

Knowing a Snail’s Diet from the Chemistry of its Shell – #3650papers – 2017 – 62

#365papers for March 3, 2017

Prendergast, Stevens, Hill, Hunt, O’Connell, and Barker, 2015, Carbon isotope signatures from land snail shells: Implications for palaeovegetation reconstruction in the eastern Mediterranean: Quaternary International, in press.

What’s it about?

This paper discusses the use of carbon isotopes in the shells of land snails to interpret what the snails were eating. To do this, they studied wild snails for which they could also measure the carbon isotopes of potential food sources. Continue reading

Recognizing What Was Once a Safe Space Using Fossil Snails – #365papers – 2017 – 59

#365papers for February 28, 2017

Prendergast, Stevens, O’Connell, Hill, Hunt and Barker, 2016, A late Pleistocene refugium in Mediterranean North Africa? Palaeoenvironmental reconstruction from stable isotope analyses of land snail shells (Haua Fteah, Libya): Quaternary Science Reviews, v. 139, p. 94-109.

What’s it about?

There was a time in early human history when northern Africa grew arid, making life rather challenging for people. This paper is about an area where the aridity did not have such an impact, making a safe refugium for people to wait it out. The evidence that there was, in fact, a ‘safe space’ comes from isotopic analysis of fossil snails. Continue reading

Interpreting Eocene Habitat Change from Adaptive Profiles – #365papers – 2017 – 58

#365papers for February 27, 2017

Townsend, Rasmussen, Murphey, Evanoff, 2010, Middle Eocene habitat shifts in the North American western interior: A case study: Palaeogeography, Palaeoclimatology, Palaeoecology, v. 297, p. 144-158.

What’s it about?

The middle Eocene represents the warmest times in the Earth’s last 65 or so million years. Temperatures peaked, then began to drop. There is some debate over when the drop in temperatures actually began and how it affected mid-continental environments. This study looks at mammal fossils in the Rocky Mountains of North America to find out. Continue reading