Category Archives: Paleontology

Back and Forth on the Oxygen Train – #365papers – 2017 – 19

#365papers for January 19, 2017

Kipp, Stueken, Bekker, and Buick, 2017, Selenium isotopes record extensive marine suboxia during the Great Oxidation Event: Proceedings of the National Academy of the Sciences.

What’s it about?

Sometime longabouts 2.3 and 2.1 billion years ago, Earth’s atmosphere became oxygenated and organisms came about that utilized oxygen extensively in their metabolic processes. However, these organisms did not come to dominate on the Earth until a billion years later. During this Great Oxidation Event, despite increases in oxygen overall in the atmosphere and the oceans, there were periods of more or less oxygen, which made it hard to oxygen-dependent organisms to proliferate.

Continue reading “Back and Forth on the Oxygen Train – #365papers – 2017 – 19”

Humans in North America Earlier than Thought! – #365papers – 2017 – 17

#365papers for January 17, 2016

Bourgeon, Burke, and Higham, 2017, Earliest Human Presence in North America Dated to the Last Glacial Maximum: New Radiocarbon Dates from Bluefish Caves, Canada: PLOS one.

What’s it about?

This paper discusses evidence of human working of fossils found in caves in north western Canada. These fossils were also dated at about 24,000 years old.Continue reading “Humans in North America Earlier than Thought! – #365papers – 2017 – 17”

When Skeletons Dissolve – #365papers – 2017 – 16

#365papers for January 16, 2017

Walker, Miller, Bowser, Furbish, Gualda, 2013, Dissolution of ophiuroid ossicles on the shallow Antarctic shelf: Implications for the fossil record and ocean acidification: Palaios, v. 28, p. 317-332.

What’s it about?

Ophiuroids are casually known as ‘brittle stars,’ sea stars with long, flexible arms. This paper discusses the skeletal structure of these arms (the ‘ossicles’ which are actually not bone but calcite) and how these structures dissolve on the ocean floor after the animal has died.Continue reading “When Skeletons Dissolve – #365papers – 2017 – 16”

What Controlled the Shape of Fenestrate Bryozoans? – #365papers – 2017 – 14

#365papers for January 14, 2017

Suarez Andres and Wyse Jackson, 2015, Feeding currents: a limiting factor for disparity of Paleozoic fenestrate bryozoans: Palaeogeography, Palaeoclimatology, Palaeoecology, v. 433, p. 219-232

What’s it about?

This paper discusses the various colony shapes available for a group of organisms called ‘fenestrate bryozoans.’ These colonies get their name because the structures are often shaped like window screen with tiny openings called ‘fenestra’ (which comes from the Latin word for window).

All bryozoans are filter feeders, so their colonies must optimize their ability to feed. The shapes of colonies possible are limited by the presence of fenestra in this group of bryozoans. This paper discusses these limitations and the range of shapes available (called ‘disparity’ in biology).Continue reading “What Controlled the Shape of Fenestrate Bryozoans? – #365papers – 2017 – 14”

Lucky Thirteen (Arms) – #365papers – 2017 – 13

#365papers for January 13, 2017 (A Friday, naturally)

Herringshaw, Smith, and Thomas, 2007, Evolutionary and ecological significance of Lepidaster grayi, the earliest multiradiate starfish: Zooliogical Jounal of the Linnean Society, v. 150, p. 743-754.

What’s it about?

This paper discusses a Silurian-aged sea star that had 13 arms, rather than the typical 5 of other sea stars. This is the earliest record of sea stars with more than 5 arms.Continue reading “Lucky Thirteen (Arms) – #365papers – 2017 – 13”

Hot Times in the Eocene – #365papers – 2017 – 12

#365papers for January 12, 2017

Methner, Mulch, Fiebig, Wacker, Gerdes, Graham, and Chamberlain, 2016, Rapid Middle Eocene temperature change in western North America: Earth and Planetary Science Letters, v. 450, p. 132-139.

What’s it about?

This paper discusses the use of multiple geochemical methods to study an episode of extreme warmth in Earth’s history. The authors were able to determine the magnitude of the warming and used multiple methods to assign ages to the rocks involved. Using other chemical and geological methods, the authors were also able to show how this warming and subsequent cooling changed the overall climate in the interior of North America.Continue reading “Hot Times in the Eocene – #365papers – 2017 – 12”

Soft Parts of Trilobites – #365papers – 2017 – 11

#365papers for January 11, 2017

Gutierrez-Marco, Garcia-Bellido, Rabano, and Sa, 2017, Digestive and appendicular soft-parts, with behavioural implications, in a large Ordovician trilobite from the Fezouata Lagerstatte, Morocco: Nature Scientific Reports.

What’s it about?

This paper discusses a the discovery of fossil trilobites that appear to preserve evidence of soft parts, in particular, part of the gut and of the legs.Continue reading “Soft Parts of Trilobites – #365papers – 2017 – 11”

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”