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Lack of oxygen delayed the appearance of animals on Earth

By Guest PostNovember 23, 2014Scienceappearance of animals, boring billion period, chromium oxidation, earth, origins of animals, oxygen levels, rise of animals

Geologists are letting the air out of a nagging mystery about the development of animal life on Earth.

Scientists have long speculated as to why animal species didn’t flourish sooner, once sufficient oxygen covered the Earth’s surface. Animals began to prosper at the end of the Proterozoic period, about 800 million years ago — but what about the billion-year stretch before that, when most researchers think there also was plenty of oxygen?

Well, it seems the air wasn’t so great then, after all. (more…)

Evolution of Earliest Horses Driven by Climate Change

By Guest PostFebruary 24, 2012Environment, Nature, Scienceaaron wood, atmosphere, bighorn basin, body size, cabin fork area, carbon, carbon dioxide, cause and effect, climate model, clydesdale, concentration, doug boyer, dwarfing phenomenon, earliest horse, evolution, florida museum of natural history, fossil, geochemical analysis, global temperature, h richard lane, horse teeth, industrial revolution, jonathan bloch, mammal, national science foundation, natural selection, North America, nsf, ocean, ornithologist, oxygen levels, paleocene-eocene thermal maximum, petm, prediction, ross secord, sifrhippus sandae, stephen chester, temperature, university of florida, university of nebraska lincoln, worland, yale

*The hotter it gets, the smaller the animal?*

When Sifrhippus sandae, the earliest known horse, first appeared in the forests of North America more than 50 million years ago, it would not have been mistaken for a Clydesdale.

It weighed in at around 12 pounds–and it was destined to get much smaller over the ensuing millennia.

Sifrhippus lived during the Paleocene-Eocene Thermal Maximum (PETM), a 175,000-year interval of time some 56 million years ago in which average global temperatures rose by about 10 degrees Fahrenheit. (more…)

Gulf of Mexico Dead Zone Severely Impairs Reproduction in Atlantic Croaker, Researchers Find

By Guest PostJune 16, 2011Environment, Scienceandrogens, aromatase, atlantic croaker, coast of louisiana, coastal regions, dead zone, enzyme, estrogens, female sex hormones, fish population, gulf of mexico, hypoxic area, hypoxic coastal zone, hypoxic dead zone, impairment of reproductive output, low oxygen waters, male sex hormones, marine animals, marine science, marine scientist, masculinized, neuroendocrine function, ovarian masculinization, oxygen levels, peter thomas, reproductive impairment, saydur rahman, second largest seasonal hypoxic zone, sperm and eggs, the university of texas at austin, thomas and rahman, world

AUSTIN, Texas — Atlantic croaker living in the large Gulf of Mexico “Dead Zone” exhibit severe reproductive impairment with potential long-term impacts on the fish’s population abundance, researchers from The University of Texas at Austin’s Marine Science Institute have found.

Males and females were found to produce dramatically fewer sperm and eggs. In addition, females in the hypoxic Dead Zone waters were masculinized — some 20 percent actually produced sperm in their ovaries. The sex ratio was also heavily skewed toward males in the hypoxic area. (more…)

Tag Archives: oxygen levels

Lack of oxygen delayed the appearance of animals on Earth

Evolution of Earliest Horses Driven by Climate Change

Gulf of Mexico Dead Zone Severely Impairs Reproduction in Atlantic Croaker, Researchers Find