Darwin's "Warm little pond" revisited

Darwin’s “warm little pond” scenario for the origin of life on earth may not have been hot enough to do the work of chemosynthesis, combining the elements of life—CO2, methane, and water—into more complex biological compounds.

Some researchers suggest that hydrothermal vents like those found today in abyssal ocean depths are a more likely candidate for the environment in which life first evolved.

Water gushing from hydrothermal events tends to be alkaline from reaction with minerals in the earth’s crust. When an alkaline hydrothermal fluid (that is, a fluid with low Hydrogen ion levels) mixes with acidic seawater (which has a higher H ion concentration), the resulting pH gradient creates potential energy that can be used to power chemical reactions by the diffusion of hydrogen ions in a process called chemiosmosis. The oldest and simplest forms of life on Earth may have used chemiosomosis as an energy source.

Source: Nicole Branan writing in Earth, May 2010, based on research by Wm Martin and others in BioEssays

Photo credit: http://www.astrobio.net/exclusive/5/reflections-from-a-warm-little-pond

Footprint forensics

330 million years ago, during the Carboniferous Period, a marine-dwelling arthropod hoisted itself out of the water and dragged its tail-like telson across the wet mud.

The record of this early excursion is a 6-meter-long trackway preserved in sandstone from Scotland. The trackway is attributed to a euyrpterid or “sea scorpion” whose fossil remains are known from the area.

The trackway consists of two parallel rows of footprints and a continuous groove in the middle marking the telson dragmark. The width of the trackway, indicates that the animal was 1 meter wide, and perhaps 2 meters long. The telson drag mark suggests that the animal was moving out of water, because underwater the eurypterid would not have dragged its telson.

The trackway confirms suspicions that some eurypterid could leave their aquatic habitat and venture onto land. These footprints also have the distinction of being the largest known tracks of an invertebrate.

http://news.bbc.co.uk/2/hi/uk_news/scotland/edinburgh_and_east/8632427.stm

How much wood would a woodchuck chuck...

The tongue-twister about woodchucks could be asked of Castoroides ohioensis, the so-called giant beaver that inhabited North America during the last ice age, about 14,000 years ago.

The ice age animal was about twice the size of modern beavers, but, surprisingly, there is no evidence that the ice age beaver ate wood.

We are what we eat, and researchers from Michigan State University and the University of Wisconsin studied the isotopic composition of a jawbone of the ice age beaver and found that the ratio of carbon 13 to carbon 12 did not match that expected for an animal that ingested wood, but was closer to that of an animals that dined on aquatic plants.

The scientists compared the giant beaver to be, ecologically, “like little hippos.”

Source: Catherine Yansa, Geological Society of America Meeting, October 19, 2010

Geological Society of America Abstracts with Programs, Vol. 41, No. 7, p. 257

Reported by Perkins, S., Science News, November 21, 2009

Illustration (inset): giant beaver compared to modern beaver. From www.nature.ca

Before "Jaws"

Ichythosaurs, the dolphin-shaped, marine-dwelling reptiles of the Mesozoic Era, shared the Mesozoic seas with other reptile predators, like mosasaurs and plesiosaurs, but the discovery of a 10-meter long ichthyosaur from 240 million year old rocks in Nevada lays claim to top carnivore in Early Mesozoic marine ecosystems.

The Nevada ichythosaur has serrated teeth, previously unknown in ichythosaurs from this age. Other ichythosaurs of this time had conical teeth fit for grabbing fish and swallowing them whole, or blunt teeth suited for crushing shelly invertebrates like ammonites.

Later ichthyosaurs had serrated teeth, but did not reach the size of the Nevada specimen. This new find indicates that ichythosaurs were ecologically more diverse early in their evolutionary history than previously suspected.

Source: Nadia Frobisch, September 23, 2010, Society of Vertebrate Paleontology meeting.

Illustration from : http://www.marshalls-art.com/images/ipaleo/paleopg17/Ichthyosaurs_final.jpg

The pitter-patter of thunder lizard feet

A dozen tiny, three-toed footprints were discovered in rocks about 120 million years old in coastal South Korea.

The tracks, no bigger than one and a half centimeters long, were originally made in mud, now hardened to shale, along a Jurassic riverbank. The tracks resemble those of therapod dinosaurs, the bipedal carnivores.

These tracks are not necessarily evidence of a new species of diminuative dinosaur; paleontologists previously found larger fossil footprints in the area and so these miniature tracks were probably made by a hatchling.

The size of the tracks can be used to estimate the size of the hatchling, which was probably no more than 4 centimeters at the hip. For now, these are the smallest dinosaur tracks known.

Photo credit: Kyung Soo Kim of Chinju National University of Education in Jinju, South Korea

A new fossil spider

New fossil finds seem to come out of China on a weekly basis, fostered by international collaborations between Chinese and western scientists. Most famous among the Chinese discoveries are the feathered dinosaurs and rare early mammals, but there are also significant finds of humble invertebrates.

Incredibly well preserved spiders (click on the photo for an enlarged view for details) were discovered in Mongolia from rocks 120 million years old. Even though the fossil spiders are barely 5 mm long, their exceptional preservation permits paleoarachnologists to identify them as members of a modern family of spiders that previous has only been known from the USA, Mexico, Cuba, and Costa Rica.

The discovery extends the geologic range of the family 120 million years to the Middle Jurassic, and indicates that these spiders were much more widely distributed in the past.

Photo and source: Paul Selden and Diying Huang, 2010, The oldest haplogyne spider (Araneae: Plectreuridae), from the Middle Jurassic of China. Naturwissenschaften 97:

See also: Paul Selden and David Penny, 2010. Fossil Spiders. Biological Reviews 85:171-206

Going nuclear

It’s clean and efficient, but reservations to using nuclear power have kept this energy alternative from growing.

Nuclear plant accidents, the accidental release of radiation into the environment, although rare, make headline news, as in the 1979 accident at Pennsylvanian's Three-Mile Island reactor and the 1986 accident at the Chernobyl reactor in the former Soviet Union.

A larger concern is how to dispose of the radioactive waste produced by nuclear power plants. This waste will remain radioactive for hundreds or thousands of years. Improved technologies and new materials can help to minimize these concerns, still, our generation faces the considerable challenge of designing a radioactive waste disposal plan that will endure for many generations to come.

Illustration: schematic diagram of a nuclear power plant. From http://www.hk-phy.org/energy/power/print/nuclear_phy_print_e.html

Blowin' in the wind

Energy from the sun can be harnessed directly, by solar panels, but the sun is also the source for another form of energy.

Heat from the sun sets wind into motion. Wind energy has been harnessed for hundreds of years to power sailing ships and windmills. Sleek, modern wind turbines convert wind energy to electricity, and “wind farms” are cropping up atop ridges and wherever there is a strong, steady wind.

Large-scale production of wind energy requires a lot of wind turbines and therefore a lot of land and some people find the large wind generators noisy or unsightly. We cannot fill our gas tanks directly with wind or sunshine, but these alternative energy sources hold promise for future development.

Photo: a wind turbine from http://www-personal.umich.edu/~dopila/files/wind-turbine.jpg

Let the sunshine in

Why use fossil fuels when you can tap the sun’s energy directly?

Photovoltaic cells convert sunlight into electricity, and are already widely used to power small electronic devices, like calculators. Solar panels are added to roofs in certain parts of the country, for heating homes or providing hot water.

Solar energy is relatively cheap and clean, and it’s renewable as long as the sun shines, which should be for billions of years to come.

The downside to solar energy is that it is most effectively used in sunny areas, and large-scale use of solar power requires many acres of land for the solar collectors. Still, advances in solar cell research and technology forecast a (ahem) bright future for solar power.

Photo: array of solar panels, from http://is.njit.edu/competition/2009/Cat2_2_Winner_Group142/

Dam it

We’ve come a long way from the first water-powered mills that were located along rushing streams; today’s hydroelectric plants have been carved out of landscapes that are dramatically changed as a result.

Damming a river and creating a reservoir results in the loss of land and habitats upstream of the dam, and changes the dynamics of the entire river system. Dams and reservoirs have a finite lifespan, on the order of 20 -200 years, and maintaining them can be costly.

But dams bring life to the desert and reservoirs provide recreational opportunities not otherwise possible in arid regions. As with all decisions regarding potential energy sources, there are trade-offs and consequences.

Photo credit: View of Hoover Dam, http://geochange.er.usgs.gov/sw/changes/natural/codrought/

Alternative Energy: Water

This week: Alternative energy

Fossil fuels are relative newcomers as energy sources. For as long as water has been running downhill, there has been a cheap, renewable, readily available energy source.

The energy created by water flowing downhill under the influence of gravity has been harnessed for hundreds of years. Factories in the 19th century were built at waterfalls or along rivers where the energy of flowing water could directly turn the waterwheel that drove their machinery.

In modern times, this energy is used to turn turbines that create electricity for distribution over power lines to large areas. Hydroelectric power is relatively inexpensive, clean, it produces no greenhouse gasses or smog, and it is renewable for as long as water can be made to run downhill.

Tomorrow: is there a downside to hydroelectric power?

Photo credit: http://www.top-alternative-energy-sources.com/images/water-wheel.jpg