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

Rock Weathering and its Influence on Climate – #365papers – 2017 – 125

#365papers for May 5, 2017

Godderis, Donnadieu, Carretier, Aretz, Dera, Macouin, and Regard, 2017 Onset and ending of the late Palaeozoic ice age triggered by tehtonically paced rock weathering: Nature Geoscience, doi:10.1038/ngeo2931

What’s it about?

Many hypotheses have been put forward to explain global glaciation that happened toward the end of the Paleozoic (started around 340-330 million years ago and ended around 290 million years ago). This paper explores the hypothesis that uplift and subsequent erosion of the ancient Hercynian orogeny (mountain belt) which once straddled the equator may have played an important role. Continue reading

What Happens to Make Fish Muscle Turn to Pyrite? – #365papers – 2017 – 124

#365papers for May 4, 2017

Oses, Petri, Boltani, Prado, Galante, Tizzutto, Rudnitzki, da Silva, Rodrigues, Rangel, Sucerquia, and Pacheco, 2017, Deciphering pyritization-kerogenization gradient for fish soft-tissue preservation: Nature Scientific Reports, v. 7, doi:10.1038/s41598-017-01563-0

What’s it about?

Fish fossils from the Santana Formation in northeastern Brazil are often exquisitely preserved, with soft-tissues (muscles, eyes, etc) often evident and available for study. The authors here are less concerned with what specifically was preserved, but how it was preserved. In some cases, the fossils were altered to pyrite; in others to kerogen. The path for alteration and preservation depended on minute details of the rocks and the geochemical environment in which the dead organisms were deposited. Continue reading

Highs and Lows of the Rocky Mountains in the Middle to Late Eocene – #365papers – 2017 – 97

#365papers for April 7, 2017

Fan, Constensius, and Dettman, 2017, Prolonged high relief in the northern Cordilleran orogenic front during middle and late Eocene extension based on stable isotope paleoaltimetry: Earth and Plantery Science Letters, v. 457, p. 376-384.

What’s it about?

The Rocky Mountains have been around for a long, long time. This study focuses on a part of the Rockies that was still growing between about 46 to about 34 million years ago. Through the study of fossil soils and fossil snails, the authors show that the difference between the lowest basins and the highest mountain peaks was around 4 km – which is a lot! Continue reading

Tall Teeth and Grazing Diets – #365papers – 2017 – 94

#365papers for April 4, 2017

Feranec and Pagnac, 2017, Hypsodonty, horses, and the spread of C4 grasses during the middle Miocene in southern California: Evolutionary Ecology Research, v. 18, p. 201-223.

What’s it about?

Modern horses have very tall (hypsodont) teeth. This is thought to be an adaptation for grazing, because chewing grass wears down teeth faster than chewing the leaves off a tree.

A fossil horse tooth from Natural Trap Cave. The grinding surface is on the left. Only about 1/5 of this tooth stuck above the gum line.

Paleontologists use the height of the tooth (its hypsodonty) to distinguish animals that grazed from those that ate bushes, shrubs, and trees (called browsing).

Isotopically, grasses look different from leaves from bushes. This chemical difference gets recorded into teeth.

The authors use isotopes from early horses that are hypsodont to show that tall teeth are related to doing more grazing. Continue reading

Birth of the Amazon River – #365papers – 2017 – 80

#365papers for March 21, 2017

Hoorn, Bogota-A, Romero-Baez, Lammertsma, Flantua, Dantas, Dino, Carmo, and Chemale, 2017, The Amazon at sea: Onset and stages of the Amazon River from a marine record, with special reference to Neogene plant turnover in the drainage basin: Global and Planetary Change.

What’s it about?

The authors of this paper use data from an ocean core collected in the delta of the Amazon River to determine when the Amazon River began to deposit sediments into the ocean and also when it began to carry sediments all the way from the Andes Mountains. Continue reading

Putting All the Data Together Makes a More Complete History – #365papers – 2017 – 77

#365papers for March 18, 2017

Feakins, Levin, Liddy, Sieracki, Eglinton, and Bonnefille, 2017, Northeast African vegetation change over 12 m.y.: Geology, v. 41, p. 295-298.

What’s it about?

The authors combine pollen and isotopic data from fossil leaf waxes from an ocean core with soil carbonate data from northeast Africa to better understand the origin and composition of grasslands in northeast Africa over the last 12 million years. Continue reading

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