Isotopes and Interpretations: Are We Getting it Right? – #365papers – 2018 – 15

Kohn and McKay, 2012, Paleoecology of late Pleistocene-Holocene faunas of eastern and central Wyoming, USA, with implications for LGM climate models: Palaeogeography, Palaeoclimatology, Palaeoecology, v. 326-328, 42-53.

What’s it about?

Here, the authors compare values of carbon and oxygen isotopes from multiple species (herbivores and carnivores) from a single site to understand how these isotopes reflect environmental variables like annual precipitation and temperature, and how all the animals interacted with each other and the environment. Understandings gathered from the isotopic results were compared to what is known from modern, living animals and to the results from climate models. Continue reading

Oxygenating the Oceans in the Early Cambrian – #365papers – 2018 – 8

Zhang, Chang, Khan, Feng, Denelian, Clausen, Tribovillard, and Steiner, 2017, The link between metazoan diversity and paleo-oxygneation in the early Cambrian: An integrated palaeontological and geochemical record from the eastern Three Gorges Region of South China: Palaeogeography, Palaeoclimatology, Palaeoecology.

What’s it about?

The Cambrian is the period of Earth’s history in which many of the modern groups of multicelluar organisms appeared in the fossil record for the first time. Some have argues that this also when these groups first appeared (the so-called “Cambrian Explosion”), but that’s not necessarily the case and is a good topic for another blog post. Rocks in South China provide a good record of this period of time and the authors show that the amount of oxygen in the ocean (and therefore in the atmosphere) fluctuated frequently during this important period of time. Continue reading

Geochemistry Shows Oldest “Fossils” Really Are Fossils – #365papers – 2018 – 6

Schopf, Kitajima, Spicuzza, Kudryavtsev, Valley, 2018, SIMS analyses of the oldest known assemblage of microfossils document their taxon-correlated carbon isotope compositions: Proceedings of the National Academy of Sciences, v. 115, p. 53-58.

What’s it about?

The best evidence for the origins of life on this planet are geochemical signatures in rocks representing the metabolism of living organisms. Here, the authors show that the geochemical (isotopic) signatures directly correlate with what have been interpreted at the body fossils of primitive life forms, mostly bacteria. Continue reading

How Aluminum in Zircon Can Tell Us What Happened Billions of Years Ago – #365papers – 2017 – 150

#365papers for May 30, 2017

Trail, Tailby, Wang, Harrison, and Boehnke, 2017, Aluminum in zircon as evidence for peraluminous and metaluminous melts from the Hadean to present: Geochemistry, Geophysics, Geosystems, v. 18, p. 1580-1593.

What’s it about?

Zircon is a mineral that forms in igneous rocks. As the rocks erode away, the zircons often survive and can be mixed into younger rocks, including new igneous rocks. Here, the authors use the concentration of aluminum in the zircons to determine the type of igneous rock the zircon originally formed in. Continue reading

Calcium Can Tell Us About Ancient Ecosystem Structure – #365papers – 2017 – 147

#365papers for May 27, 2017

Martin, Vincent, Tacail, Khaldoune, Jourani, Bardet, Balter, 2017, Calcium isotopic evidence for vulnerable marine ecosystem structure prior to the K/Pg extinction: Current Biology, v. 27

What’s it about?

The variations of the amounts of stable isotopes (that is non-radioactive) found in rocks and fossils can be used to help us understand patterns of weather, of vegetation, and of who’s eating whom in modern and fossil rocks, bones, teeth, and shells. Most of the time carbon, oxygen, and nitrogen are used for this.

The authors here show that calcium isotopes can be used to understand tropic level (where organisms are on the food chain) in modern and fossil animals. Their work shows that large marine reptiles likely went extinct at the end of the Permian Period because they all lived at the same trophic level. There was some sort of ecological change that eradicated their food supply and the marine reptiles could not recover. Continue reading

Because Isotopes of Carbon and Oxygen Are So Last Century… – #365papers – 2017 – 141

#365papers for May 21, 2017

Martin, Tacail, and Balter, 2017, Non-traditional isotope perspective in vertebrate palaeobiology: Palaeontology, p. 1-18.

What’s it about?

The authors discuss the utility of isotopes of calcium, magnesium, copper, iron, and zinc for study of ancient environments, dietary preferences, and food chains. Continue reading

Volcanoes and the Late Ordovician Extinction – #365papers – 2017 – 139

#365papers for May 19, 2017

Jones, Martini, Fike, and Kaiho, 2017, A volcanic trigger for the Late Ordovician mass extinction? Mercury data from south China and Laurentia: Geology,

What’s it about?

One of the “Big Five” mass extinctions that has affected life on this planet is the Late Ordovician mass extinction or LOME. The causes of such extinctions are topics of focused research efforts. Here, the authors show that pulses of volcanic activity may be related to the extinction events. Continue reading

Dinosaur Fossils: Dating the Rock to Date the Bones – #365papers – 2017 – 137

#365papers for May 17, 2017

An, Kuang, Liu, Peng, Xu, Xu, Zhang, Wang, Chen, and Zhang, 2016, Detrital zircon dating and tracing the provenance of dinosaur bone beds from the Late Cretaceous Wangshi Group in Zhucheng, Shandong, East China: Journal of Palaeogeography, v. 5, 72-99.

What’s it about?

Geochemical and sedimentological methods are used to determine the age and provenance (i.e. where did the sediments come from) of dinosaur-bearing rocks. The bones themselves could not be directly dated, but cannot be younger than the rocks they’re found in. Continue reading

How Did the Earth’s Crust Grow – #365papers – 2017 – 133

#365papers for May 13, 2017

Rozel, Golabek, Jain, Tackley, and Gerya, 2017, Continental crust formation on early Earth controlled by intrusive magmatism: Nature.

What’s it about?

The Earth didn’t always have continents. This paper explores how the planet’s first continents probably formed. The major hypotheses were that the continents formed by volcanic eruptions primarily, or by upwellings of magma that never erupted on the surface. It seems that the latter is most likely. Continue reading

Keratin Ain’t Gonna Make It – #365papers – 2017 – 132

#365papers for May 12, 2017

Saitta, Rogers, Brooker, Abbott, Kumar, O’Reilly, Donohoe, Dutta, Summons, and Vinther, 2017, Low fossilization potential for keratin protein revealed by experimental taphonomy: Palaeontology, p. 1-10.

What’s it about?

Keratin is a major protein making up hair and nails. The authors conduct experiments on modern keratin to emulate fossilization to test whether or not keratin is likely to fossilize. Based on these experiments, keratin should not survive the process of fossilization, though calcium phosphate and pigments might. Continue reading