A New Feathered Troodontid Dinosaur with Asymmetrical Feathers – #365papers – 2017 – 127

#365papers for May 7, 2017

Xu, Currie, Pittman, Xing, Meng, Lu, Hu, and Yu, 2017, Mosaic evolution in an asymmetrically feathered troodontid dinosaur with transitional features: Nature Communications, doi:10.1038/ncomms14972

What’s it about?

This paper is a description of a new species of dinosaur, Jianianhualong tengi, from the famous Jehol Group of China. This new species shows a mixture of traits, some that are characteristic of non-flying dinosaurs and others characteristic of flying dinosaurs like Archaeopteryx. This includes asymmetrical feathers, stiff feathers that are thicker on one side of the central vein than on the other, which are a necessary adaptation for flight. Continue reading

How Necks Become Backs in Diplodocid Dinosaurs – #365papers – 2017 – 126

#365papers for May 6, 2017

Tschopp and Mateus, 2017, Osteology of Galeamopus pabsti sp. nov. (Sauropoda: Diplodocidae), with implications for the neurocentral closure timing, and the cervico-dorsal transition in diplodocids: PeerJ, doi:10.7717/peerj.3179

What’s it about?

Most of this paper is a description of a new species of dinosaur, Galeamopus pabsti. This individual is quite well preserved and allowd the authors to examine two important aspects of diplodocid growth and development: the fusion of certain parts of the vertebrae (‘neurocentral closure’) previously associated with adulthood, and the transition from neck vertebrate to back vertebrae (which bear ribs). 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

Whence Come Mandibulate Arthropods? – #365papers – 2017 – 123

#365papers for May 3, 2017

Aria and Caron, 2017, Burgess Shale fossils illustrate the origin of the mandibulate body plan: Nature, doi:10.1038/nature22080

What’s it about?

The authors describe a fossil from the Burgess Shale that is likely a primitive member of the ‘mandibulate’ arthropods, those exoskeleton-bearing organisms that possess mouth structures called mandibles. Using this new description, they are able to better understand the relationship between mandibulates and other important arthropod groups. Continue reading

2.4-billion-year-old Fossils of Fungus – #365papers – 2017 – 122

#365papers for May 2, 2017

Bengtson, Rasmussen, Ivarsson, Muhling, Broman, Marone, Stampanoni, and Beckker, 2017, Fungus-like mycelial fossil in 2.4-billion-year-old vesicular basalt: Nature Ecology & Evolution, v. 1, 0141.

What’s it about?

Basalt is a common resulting rock from volcanic eruptions. Bubbles (technically called vesicles) are common in basalt, and simple organisms often move into these openings once the rock has cooled sufficiently.  Here, the authors show what appears to be fungal filaments in vesicles formed 2.4 billion years ago. Continue reading

Distinct Species of Horses, and Illusions from Tooth Wear – #365papers – 2017 – 121

#365papers for May 1, 2017

Li, Deng, Hua, Ki, and Zhang, 2017, Assessment of dental ontogeny in late Miocene hipparionines from the Lamagou fauna of Fugu, Shaanxi Province, China: PLoSONE v. 12, e0175460.

What’s it about?

Hipparionines are a branch of fossil horses that include the genus Hipparion. Horse molars have complex ridges, basins, and swirly walls of enamel. The relationships, sizes, and shapes of these structures are used to distinguish among the various species of horses. The authors here examine the teeth of two ‘different’ species of Hipparion, using observation of complete specimens at various stages of wear, looking at whole jaws in cross-section using spiral computed tomography (CT), and by selecting several teeth to literally slice up to examine the changes in tooth enamel shapes over the height of the tooth. Continue reading

Humans in Southern California 130,000 years ago? – #365papers – 2017 – 120

#365papers for April 30, 2017

Holen, Demere, Fisher, Fullagar, Paces, Jefferson, Beeton, Cerutti, Rountrey, Vescera and Holen, 2017, A 130,000-year-old archaeological site in southern California, USA: Nature, v. 544, p. 479-483.

What’s it about?

Herein is described an archaeological site from southern California dates at 130,000 years old. The age is based on a radiometric technique called Thorium/Uranium. The influence of humans is based upon apparent working and tooling of bones and of stones in the site. Continue reading

How Old Is the Wasatch Formation at Fossil Butte? – #365papers – 2017 – 119

#365papers for April 29, 2017

Gunnell, Zonneveld, and Bartels, 2016, Stratigraphy, mammalian paleontology, paleoecology, and age correlation of the Wasatch Formation, Fossil Butte National Monument, Wyoming: Journal of Paleontology, v. 90, p. 981-1011.

What’s it about?

Here is a nice description of all the mammalian species found from early Eocene rocks in Fossil Butte National Monument. Not only is there a list of fossil species, but they’re also put in chronological order, so that changes over time can be discussed. Continue reading