Where Did the Bony Fishes Come From? – #UREES270 – 2018

Friedman and Brazeau, 2018, A reappraisal of the origin and basal radiation of the Osteichthyes: Journal of Vertebrate Paleontology, v. 30, p. 36-56

What’s it about?

The authors look closely at the characteristics that distinguish osteichthians from other jawed fishes. They then review materials from fossil groups of fishes, in particular the Acathodii, and score them for the same characters. The result of their analysis is that they place the Acathodii as basal osteichthians, a sister group to the crown osteichthian groups, the Actinopterygii and the Sarcopterygii. Continue reading

When Two Species Merge into One – #365papers – 2018 – 60

Kearns, Restani, Szabo, Schoder-Nielsen, Kim, Richardson, Marzluff, Fleisher, Johnsen, and Omland, 2018, Genomic evidence of speciation reversals in ravens: Nature Communications, v. 9, 906

What’s it about?

The authors describe how what were once two distinct lineages of ravens (the Californian and the holarctic) have merged into what we now refer to as the common raven in the western United States. Using evidence from mitochondrial DNA, the authors show that not only is the common raven the result of the fusion of two lineages, but that the Chihuahuan raven, that lives alongside the common raven, is a descendant of the Californian raven. Continue reading

Bringing Up Baby (Mountains) in Western North America – #365papers – 2018 – 59

Yonkee and Weil, 2015, Tectonic evolution of the Sevier and Laramide belts within the North American Cordillera orogenic system: Earth-Science Reviews: v. 150, p. 531-593

What’s it about?

This paper is a wonderful, yet highly technical, summary of the tectonic events leading to the Rocky Mountains as we know them today. Continue reading

Pharyngeal Denticles and the Placoderms – #365papers – 2018 – 58

Johanson and Smith, 2005, Origin and evolution of gnathostome dentitions: a question of teeth and pharyngeal denticles in placoderms: Biological Reviews, v. 80, p. 303-345

What’s it about?

This paper presents a detailed discussion of tooth development in fishes. In particular, the authors review the state of knowledge of tooth development in placoderms, among the first of the jawed fishes and now extinct. They also make observations about denticles, tooth-like bumps, on the gill arches of many fishes, including jawless forms, and how the development of these relate the development of teeth and external scales in early fishes. With these details, the authors propose a hypothesis for the origins and development of teeth in placoderms and in modern fishes. Continue reading

What if We’re Wrong About Placoderms? – #365papers – 2018 – 57

Zhu, Yu, Ahlberg, Choo, Lu, Qiao, Qu, Zhao, Jia, Blom, and Zhu, 2013, A Silurian placoderm with osteichthyan-like marginal jaw bones: Nature, v. 502, p. 188-193

What’s it about?

I reported on another paper with Zhu as lead author sometime last week. That paper provided evidence that certain dermal bones (the dentary and maxilla), traditionally viewed as synapomorphies for the crown osteichthyes may also be present in placoderms. This is the first paper in which Zhu reported this observation. Continue reading

Clay Keeps Records of Ancient Water – #365papers – 2018 – 56

Mix and Chamberlain, 2014, Stable isotope records of hydrologic change and paleotemperature from smectite in Cenozoic western North America: Geochimica et Cosmochimica Acta, v. 141, p. 532-546

What’s it about?

Smectite is a specific kind of clay mineral, common in volcanic ash. This kind of clay incorporates water during its formation, which, as the authors show, can provide a record of what surface water was like when the clay formed. Continue reading

Is Your Beer Making You Sick? – #365papers – 2018 – 55

Pradenas, Galarce-Bustos, Henriquez-Aedo, Mundaca-Uribe, and Aranda, 2016, Occurrence of biogenic amines in beers from Chilean market: Food Control, v. 70, 138-144

What’s it about?

Brewing beer is serious organic chemistry, and beer can have some not-really-healthy chemicals in them from various sources. The authors of this paper discuss the occurrence of amines (a type of biologically produced chemical) in beers produced in Chile that can, at high concentrations, have negative effects on the health of the beer drinker.

There are two general sources of these amines, either from microbial contamination (like small quantities of bacteria in the beer) or could have been present in the raw materials used to make the beer (barley, yeast, and hops). Continue reading

Plants and Animals Don’t Respond to Climate Change the Same Way – #365papers – 2018 – 54

Wing and Harrington, 2001, Floral response to rapid warming in the earliest Eocene and implications for concurrent faunal change: Paleobiology, v. 27, p. 539-563

What’s it about?

The Paleocene-Eocene boundary is marked by a period of rapid global warming and co-occuring changes in mammals in response to the warming, including the appearance of seemingly dwarfed species and the rise of important mammal groups like the hoofed mammals and primates. The authors here use fossilized pollen from rocks known to bracket the Paleocene-Eocene boundary and discuss the changes in plants during this important episode of climate change. Continue reading

The Value of Fossils from the Margins of Basins – #365papers – 2018 – 53

Muldoon and Gunnell, 2012, Omomyid primates (Tarsiiformes) from the Early Middle Eocene at South Pass, Greater Green River Basin, Wyoming: Journal of Human Evolution, v. 43, p. 479-511

What’s it about?

Much of this paper is a description of a new species of early primate, along with a description of the primate fauna from South Pass, Wyoming, which is on the edge of the Green River Basin. This particular fauna is important because it is on the edge of a geographical basin, so it includes a mixture of animals that prefer flat plains and those that prefer upland areas. Continue reading

How Do Teeth and Jaws in Placoderms Grow? – #365papers – 2018 – 52

Rucklin, Donoghue, Johanson, Trinajstic, Marone, and Stamponi, 2012, Development of teeth and jaws in the earliest jawed vertebrates: Nature, v. 491, p 748-752

What’s it about?

Using tomographic data, the authors tease the different growth stages of the lower jaws of placoderms apart and show that the development of teeth are separate from the development of the jaw bone itself. Continue reading