Category Archives: Science

Living Miocene Bryozoans – #365papers – 2017 – 7

#365papers for January 7, 2017

Ziko, Eweda and El-Khawaga, 2016, Extant cheilostomatous bryozoans of teh Middle Miocene from the north Western Desert, Egypt: Journal of African Earth Sciences, v. 124, p. 12-31.

What’s it about?

This is a discussion of several species of bryozoan (tiny colonial animals) in Miocene aged rocks. These same species of bryozoans live today, but in different parts of the Mediterranean region.Continue reading “Living Miocene Bryozoans – #365papers – 2017 – 7”

Those Sponges Are Actually Bryozoans – #365papers – 2017 – 6

#365papers for January 6, 2017

Muricy, Domingos, Tavora, Ramalho, Pisera, and Taylor, 2016, Hexactinellid sponges reported from shallow waters in the Oligo-Miocene Pirabas Formation (N Brazil) are in fact cheilostome bryozoans: Journal of South American Earth Sciences, v. 72, p. 387-397.

What’s it about?

This paper is about some incorrectly identified fossils from Brazil. Sponges are animals that survive by filter feeding. Hexactinellid sponges have a skeleton made of glass and are only found at great depths, so it was interesting with previous authors found hexactinellid sponges in rocks deposited in shallow waters.

The authors of this paper took the sponge fossils and looked at them closely under a scanning electron microscope and realized that the earlier identification was incorrect and that these were in fact bryozoans, which are colonies of tiny filter-feeding organisms that can live in a structure that is shaped similar to that of sponges. Continue reading “Those Sponges Are Actually Bryozoans – #365papers – 2017 – 6”

Slow Growth of Dinosaur Embryos – #365papers – 2017 – 5

#365papers for January 5, 2017

Erickson, Zelenitsky, Kay, and Norell, 2016, Dinosaur incubation periods directly determined from growth-line counts in embryonic teeth show reptilian-grade development: Proceedings of the National Academy of Sciences.

What’s it about?

This paper discusses the use of growth lines in teeth to determine how long an animal was in its egg before hatching. We know already at what point during development that teeth begin to grow. All teeth preserve fine growth lines that form daily, and by counting the lines on teeth found in dinosaur eggs that appear ready to hatch, we can get a sense of how long the animal was in the egg from being laid to hatching.

The surprise was that dinosaur eggs were incubated for several months (estimates are 2.8 to 5.8 months), which is similar to modern reptiles. This is radically different than the incubation times of modern birds that range from 11-85 days (less than two weeks to about 2.5 months). Continue reading “Slow Growth of Dinosaur Embryos – #365papers – 2017 – 5”

Clumped Isotopes in Ethane – #365papers – 2017 – 3

#365papers – January 3, 2017

Webb, Wang, Braams, Bowman, and Miller, 2017. Equilibrium clumped-isotope effects in doubly substituted isotopologues of ethane: Geochimica et Cosmochimica Acta, v. 197, p. 14-16.

What’s it about?

Ethane is a molecule with two carbon atoms and six hydrogen atoms. Most carbon in the universe is carbon-12, having six protons and six neutrons in its nucleus. Some carbon is carbon-13, with an extra neutron to make seven. A very, very tiny bit of carbon is carbon-14, with two extra neutrons. Carbon-12 and carbon-14 can replace carbon-12 in ethane. Likewise, hydrogen, an element with one proton and neutrons, can also have a neutron (deuterium or hydrogen-2), or maybe two neutrons (tritium or hydrogen-3). Atoms that vary in the number of neutrons in the nucleus are called isotopes. Some are stable (like carbon-12 and hydrogen), and others are radioactive. This study ignores carbon-14 and tritium, as they are both radioactive. Carbon-13 and deuterium are both stable.

Ethane molecule

The focus of any clumped isotope analysis is molecules with two of the more uncommon forms of an element. For ethane, that could be two carbon-13 atoms, two deuterium atoms, and one carbon-13 with a deuterium atom. Continue reading “Clumped Isotopes in Ethane – #365papers – 2017 – 3”

The End-Guadalupian Mass Extinction, Pyrite, and Sulfur Isotopes – #365papers – 2017 – 2

#365papers – January 2, 2017

Wei, Wei, Qiu, Song, Shi, 2016, Redox conditions across the G-L boundary in South China: Evidence from pyrite morphology and sulfur isotopic compositions: Chemical Geology, v. 440, p. 1-14.

What’s it about?

This paper presents evidence that marine anoxia (lack of oxygen in ocean water) may be the cause of the end-Guadalupian (middle Permian) mass extinction, using the appearance of pyrite (a reduced-iron mineral, FeS2), the shape and structure of pyrite, and isotopic values of sulfur to show this.Continue reading “The End-Guadalupian Mass Extinction, Pyrite, and Sulfur Isotopes – #365papers – 2017 – 2”

Dinosaur Tail Feathers in Amber – #365papers – 2017 – 1

#365papers – January 1, 2017

Xing, McKellar, Xu, Li, Bai, Persons, Miyashita, Benton, Zhang, Wolfe, Yi, Tseng, Ran, and Currie, 2016, A Feathered Dinosaur Tail with Primitive Plumage Trapped in Mid-Cretaceous Amber: Current Biology, v. 26, p. 3352-3360.

What’s it about?

Part of a dinosaur tail was found in Burmese amber and had bones on the inside and feathers on the outside. This dinosaur was a small theropod, a group that also includes Tyrannosaurus rex.Continue reading “Dinosaur Tail Feathers in Amber – #365papers – 2017 – 1”