Courtesy Mark RyanA new study appearing in Biology Letters shows that trilobites - everyone's favorite prehistoric water bug - developed an effective survival strategy much earlier than previously thought.
Trilobite fossils from Early Cambrian rock formations in the Canadian Rockies and elsewhere lend evidence that some of the earliest trilobites used enrollment (i.e rolling themselves up into a ball like an armadillo) to protect themselves from predators or the environment. Trilobite fossils found here in Minnesota are several million years younger dating back to the Late Cambrian through Late Ordovician Periods (500 - 430 mya) and are often found enrolled. It was an effective survival strategy.
Trilobites were arthropods, which meant they possessed exoskeletons, segmented bodies and jointed appendages. Their closest extant relative is the horseshoe crab. Trilobite bodies - for the most part - were comprised of a head (cephalon) positioned on a body (thorax) that was divided into three lobes: essentially an axial dividing a left and right pleura, and a tail (pygidium). The mouth (hypostome) was located on the underside. It's thought that most early trilobites were predators and/or scavengers who spent their lives roaming the sea floors looking carcasses, detritus or living prey to feed upon. Most trilobites possessed complex eyes (although some were eyeless). Like other arthropods (e.g. today's lobsters), trilobites would outgrow their exoskeletons, discarding them (molting) as they grew in size or changed shape. Their newly exposed soft skin soon hardened into a new, tough, outer casing. Once hardened, their segmented exoskeletons (composed of calcium carbonate) were ventrally flexible, giving them the ability to roll up into a ball should they need sudden protection from whatever threatened them.
Some early trilobite forms from Middle Cambrian-aged fossils had been viewed as incapable of enrolling but the new research based on much older fossils found in mudstones in the Canadian Rockies in Jasper Park pushes back the origins of the strategy to some of the earliest trilobites to appear in the fossil record (Suborder Olenellus). These appeared 10-20 million years earlier at the very beginnings of the Cambrian Period and show evidence of having already developed the ability to enroll.
Trilobites in some form or another existed across a span of more than 270 million years, a very successful run by any measure. The enrollment strategy certainly contributed to their longevity. Although trilobites were already in decline, the last of their kind were wiped out in the great extinction event that marked the end of the Permian Period and the start of the Triassic. They weren't the only casualty of the extinction: nearly 90 percent of Earth's species were terminated along with them.
Even though trilobites are extinct (they died out in the Permian Mass Extinction along with around 90 percent of Earth's species) they were an extremely successful and adaptable life form. No wonder they remain today a favorite among fossil collectors.
Courtesy WikipediaFilm goers will have the chance to travel through space this weekend with the blockbuster movie "Gravity" hitting the theaters. Its a ficticious story about two American astronauts dealing with disaster during a space shuttle mission.
I've come to expect Hollywood to place loose and easy with actual science when it comes to movies with scientific themes. And then today I stumbled upon this article in Time by Jeffrey Kluger, the co-author, with astronaut Jim Lovell, of Lost Moon: The Perilous Voyage of Apollo 13, which was the basis of the Apollo 13 movie released in 1995.
He applies his extensive space knowledge to fact check what's depicted in the new George Clooney/Sandra Bullock film. Here's his analytical summary: "So, that’s a lot that Gravity gets wrong. But you know what? So what? The shuttle, space station and spacesuits are painstakingly recreated; the physics of moving about in space—thrusts requiring counterthrusts, spins requiring counterspins, the hideous reality that if you do go spiraling off into the void your rotation never, never stops—are all simulated beautifully, scarily and accurately."
Click on the link above to get detailed analysis of what's scientifically right and wrong with Gravity.
Have you seen the film? What do you think about its accuracy in portraying the science of living and traveling in space?
Courtesy Mark RyanOver the past couple years, Science Buzz has posted several stories (here and here) about the humongous patches of garbage and plastic debris found floating in the world's oceans. It's a serious problem and one that should raise red flags for anyone concerned with the Earth's environment. But even more troubling is the recent news that plastic particles have now been found in all five of the Great Lakes lining the border of the USA and Canada. Unlike the large globs of plastic clogging areas of the ocean, the plastics polluting the Great Lakes are microscopic particles detectable only in a microscope. But they're no less disturbing.
A team of researchers led by Dr. Sherri “Sam” Mason, professor of chemistry at SUNY-Fredonia has been gathering water samples and reported finding high concentrations of plastic particles in the chain of freshwater lakes. One of the researchers involved is environmental chemist Lorena Rios-Mendoza from University of Wisconsin-Superior. Both she and Mason have studied the Great Trash Island (aka Trashlantis) in the Pacific Ocean but has now turned their attention to the Great Lakes.
Most of the plastic found in the water is visible only under a microscope, but has been found in all five of the Great Lakes, both in the water column, and in lake sediment. The amount of micro-plastic varies between lakes with Lake Erie - the shallowest and smallest by water volume - containing the largest ratio and Lake Superior - the largest and most voluminous - a much smaller ratio. But it doesn't matter; the point is that we're polluting some of our important sources of fresh water with plastic.
It's thought that cosmetics with could one of the sources, since the industry relies heavily on using micro-beads in its products. These tiny plastic particles used on our faces, skin, and teeth, eventually get washed off into the water supply where they're too small to get filtered out. But cosmetics certainly aren't the only source.
Courtesy tedxgp2Think of the ungodly amount of plastic material we use and discard every year. Surprisingly, only about five percent of the bags, bottles, cups, electronics, etc. get recycled; most plastic trash ends up in landfills where it slowly degrades and eventually finds its way into the world's favorite garbage dump: the oceans.
“We have no idea how long some of these plastics stay in the ocean, could be more than 40 years,” Rios-Mendoza said. She also worries if organic toxins in the water can attach themselves to the tiny plastic particles, and end up in the food chain. In this regard, Rios-Mendoza has been sampling Great Lake fish to see if such toxic particles are present in their guts.
It's important to remember that only 3 percent of the world's water is freshwater and the five Great Lakes - Superior, Huron, Michigan, Ontario, and Erie - together contain 20 percent of that freshwater. That's a large portion of a relatively scarce and essential life ingredient. Last fall, I posted an interesting graphic that illustrates nicely Earth's total water supply versus fresh water and puts things in perspective.
Courtesy Mark RyanRios-Mendoza and Mason have been collaborating with a research and education group called 5Gyres Institute that monitors and studies garbage patches found in five subtropical gyres in the world's oceans. Rio-Mendoza presented a preliminary study of their work on the Great Lakes at a recent meeting of the American Chemical Society. The team's future studies involve pinpointing the sources of plastic pollution and acquiring a better understanding of how plastics degrade in the environment.
"We all need to become aware of how much plastic we use in our lives and avoid using single-use products. Don’t buy water in plastic bottles or cosmetic products with micro beads. Bring re-usable bags to the store with you. Simple things like this make a big difference, but it’s also important to keep talking about this issue and raising awareness about how it affects the Great Lakes and the world’s oceans.” --- Dr. Sherri Mason“
By the way, here in Minnesota, and situated at the western tip of Lake Superior, the city of Duluth was recently proclaimed to have the best tasting drinking water in the state. By best-tasting, I'm assuming they mean it has no taste whatsoever since water is described as a colorless, tasteless liquid. Whatever the case, I always thought Duluth's drinking water was the best while growing up there (my grandparents lived in a Twin Cities' suburb and I never liked the taste of their softener-treated water).
In another water-related story, it's estimated that life on Earth can survive for at least another 1.75 billion years until we move out of the habitable zone and our oceans (and other water sources) will evaporate in the increased heat. So it's probably best that we take care of what water we have - it needs to sustain us for a long time.
Courtesy ap2il via FlickrOne of the strangest creatures to emerge from the famed Burgess Shale in the mountains of British Columbia, is the rightly named Hallucigenia, a strange spiky, wormlike creature that once scuttled across the Cambrian sea bottom more than 500 million years ago. Originally considered a totally unique (and baffling) creature, Hallucigenia has now been linked to other similar-aged wormlike creatures found around the world.
Hallucigenia first came to light in 1909 after Charles Doolitle Walcott, an expert in trilobites and secretary of the Smithsonian Institute, discovered a Lagerstätte in the mountains of British Columbia that was unlike any other found before.
Courtesy Mark RyanLocated in Yoho National Park on a steep slope between Mount Field and Wapta peak above the railroad town of Field, B.C., Walcott's quarry produced some of the strangest creatures - many of them soft-bodied and rarely found in the fossil record. The rock section, previously known as the Stephens Formation became known as the Burgess Shale, after nearby Burgess Pass. In the years following the discovery, Walcott and other scientists studied the strange fossils in an effort to decipher them and the environment in which they had lived and died.
Because of the high degree of preservation, the creatures that made the fossils were most likely buried suddenly in some sort of giant underwater mudslide that quickly entombed an entire marine community in an anoxic environment where decomposition was stifled. A perfect environment for preserving the soft-bodied tissue.
Courtesy Mark RyanSome of the Burgess Shale denizens appeared to be of completely new and unknown phyla with bizarre and unfamiliar body plans and no known descendents in the modern age. Hallucigenia certainly led the pack in this department. The tiny strangely constructed worm was only about an inch in length and confounded Walcott and other scientists for more than a century. They couldn''t even say for sure which side was up or down. Early Hallucigenia fossils showed a row of seven tentacles along one side. The opposite side contained seven sets of stiff spikes that were interpreted to be legs. A truly bizarre, aptly named freak-show creature that would be right at home in your average nightmare.
New evidence can often turn an old idea on its ear - or in this case, on its back. Recent scrutiny of newer, better-defined Hallucigenia fossils has revealed another set of "tentacles", leading scientist to realize they had Hallucigenia all flipped around. What they once thought was its top side was actually its bottom. Its dorsal "tentacles" were actually its legs. And its spiky "legs" belonged on its back, probably to serve as protection against predators.
This information along with a new study published in Proceedings of the Royal Society B now places Hallucigenia within a group of other worm-like creatures whose fossils are found around the world, including China, Canada, Great Britain, and Australia. It also links it to a living group - Onychophora - the velvet worms that mostly inhabit the tropical forests of the Southern Hemisphere.
"They may not be exactly the same species, but they are all probably related to the same group of worm-like creature that we call lobopods," said Dr. Jean-Bernard Caron, curator of invertebrate paleontology at the Royal Ontario Museum and the study's lead researcher. Caron is an expert in Burgess Shale fossils and his study of Hallucigenia and other fossils from the formation continues to glean new knowledge about the strange creatures that existed in the so-called Cambrian Explosion. Check out Caron's Burgess Shale website. It's full of great information about the quarry and the incredible fossils found there.
Courtesy Mark RyanWalcott's Burgess Shale quarry has been designated a World Heritage site. The only way to visit it (or the fossil fields on nearby Mt. Stephen) is through guided hikes led by either Parks Canada or The Burgess Shale Geoscience Foundation. The 10 hour round-trip hike (rated moderate to difficult) takes participants up 2500 feet in elevation to Mt. Fields and requires reservations and a deposit. Fossil collecting is prohibited but the views are said to be spectacular.
SOURCE and LINKS
The Province story
The Burgess Shale at Smithsonian website
Dr. Caron's Burgess Shale website
Parks Canada Burgess Shale info
A long-buried, underwater forest of Cypress trees was recently discovered in the Gulf of Mexico. The forest, estimated to be about 50,000 years old, was once buried under tons of sediment, heading toward possible fossilization, until the natural forces (most likely 2005's Hurricane Katrina) riled up the Gulf Coast waters and uncovered it again. Hundreds of stumps and fallen logs - some huge - covering 1.3 square kilometers can now be seen in 60 feet of water, 10 miles off the coast of Alabama. The Cypress forest once populated the area around the Mobile-Tensaw Delta when the Gulf's coastline was farther south, and the water level was 120 feet lower than it is today. As the climate began to warm, rising sea levels eventually drowned the forest. The trees all died but oxidation and decomposition were halted as a constant rain of delta silt covered the forest for thousands of years. When cut, the well-preserved wood still smells as fresh as living Cypress, but now that the forest has been uncovered again, wood-boring marine animals are back at work tearing it down.
Courtesy Mark RyanI've had the great fortune of being able to volunteer in the paleontology lab at the Science Museum of Minnesota. I'm in my fourth month there and it's been a real blast. My first project was preparing (cleaning) the skull of a small oreodont collected from the White River Formation in Wyoming. This is the same formation exposed in the fossil-rich South Dakota Badlands. By cleaning, I mean removing all the rock (matrix) in which the skull is encased. I've also helped patch up the casts of a couple of lambeosaurus skulls, and spent a few days puzzling over a crocodile skull reduced to about 1000 pieces.
Courtesy Mark RyanAt the moment, preparators been working on the remains of a 52 million year-old gar collected from the Green River Formation in southwestern Wyoming. Most of the work is being done by the more experienced volunteers in the lab but I've been able to help a little, taking my turn with the air scribe to reveal some caudal scales in their rocky grave. This particular specimen, an ancient member of Lepisosteus, was collected in Lincoln County, Wyoming. It's fascinating work uncovering something that last saw sunlight more than 50 million years ago. Now, at least, its remains can bask in the glare of the paleo lab's artificial lights.
Courtesy Mark RyanFifty some million years ago, the gar lived in a large body of water known as Fossil Lake, one of three intermountain lakes that existed at different times in a sub-tropical environment in that part of Wyoming. The intermountain basin in and around the lake teemed with both floral and faunal life that over about 4000 years lived and died and were fossilized forming one of the great Lagerstätten in the world. The surrounding mountains were composed mainly of limestone, and the rivers and streams eroding those mountains carried high levels of calcite (CaC3) into the lake, resulting in a high sedimentation rate that added to the ideal fossilization environment.
Most of the fossils coming out of the Fossil Lake strata have been fossilized by a process called permineralization, where mineral-rich water permeates all the spaces and pores in the skeleton and the minerals (in this case calcite) crystallize out of the water replacing bone material down to the cellular level. Some carbonization is also involved. This process depletes the remains of volatiles and is caused by the heat and pressure of sediment compression, which also crushes and flattens the fossils, and tends to color them either brown or black.
Courtesy Mark RyanThat's very apparent with our gar. Although only portions of the fish's remains have been exhumed (its head and tail) the fossil is already providing some information about what followed the gar's death (taphonomy). Lepisosteus favored the shallow, swampy edges of Fossil Lake and when it died it probably floated on the surface for a while giving bacteria time to enter its mouth and gills and begin their decomposition work before the corpse was buried beneath sediments.
We can deduce this scenario by the manner the remains are preserved. The bones of the gar's skull and jaws are scattered and jumbled in a mish-mash of bones and scales. The head appears to have been blown apart, and that's probably what happened. As the microbes feasted on the fish's head, they released gases inside the corpse which built up, and bloated the gar to a point where it burst from the internal pressure. The mandibles, the cranium, and other bones broke apart before settling to the bottom and are disarticulated. The very end of the tail, however, shows no such disruption. The rays of the caudal fins looking almost as fresh as they did when the gar died half a million centuries ago.
Courtesy Mark RyanThe scales of its mid-section are beginning to come to light. These diamond-shaped structures were covered with ganoin, an enamel-like tissue containing less than five percent organic material. The mineralized tissue gave Lepisosteus a very tough, predator-resistant exterior when it was alive but not so resistant to the bacteria that attacked the gar from the inside after it died. Preliminary work of the mid-section is showing signs of decomposition there but further work required.
One of the major experts on the fossils found in the Green River Formation is Lance Grande, a graduate of the University of Minnesota (and elsewhere) who has been working at Chicago's Field Museum for the past few decades. In the early '80s, Dr. Grande wrote a hefty bulletin titled Paleontology of the Green River Formation for the Wyoming Geological Survey, and has now come out with a new book titled The Lost World of Fossil Lake: Snapshots from Deep Time. In a recent television interview, Dr. Grande talked about his book and about the fossils found in the Green River Formation.
Hundreds of thousands of finely preserved fossils from Fossil Lake deposits can be found in museum displays and on rock shop shelves world-wide. The best fossils were buried quickly and preserved in near pristine condition. Many of these come from what used to be the deep center of the lake where conditions were probably anoxic and burial fairly swift. At times during Fossil Lake's history events like seasonal algal blooms or rapid turnovers of the water column occurred and caused massive die-offs of fishes. Other fish, like our gar, probably just died a regular death.
Courtesy Mark RyanEvery fossil tells a story, and our gar is no exception. Back in the Eocene epoch it lived for a short time in the then subtropic environment of southwest Wyoming, doing what gars do before it finally died along the shores of Fossil Lake. After it was buried, it was fossilized, dug up, and transferred to the collections vault of the Science Museum of Minnesota. A few months ago, it was retrieved from the vault and brought into the paleo lab where it's been worked on each week by several people. Whatever the gar was thinking when it was alive back in the late Eocene, you can be sure it was unaware that its post-mortem life would provide hours of detailed work, study and fascination for another curious life-form 52 million years later.
SOURCES AND LINKS
I had an interesting discussion related to the many and dramatic ways a person would perish when exposed to the vacuum of space recently. We discussed the many dramatic and horrific things that would happen. Blood boiling, eyes popping out... Turns out to be a lot less dramatic. Here is what NASA has to say about what happens to the body when exposed to the vacuum of space.
If you don't try to hold your breath, exposure to space for half a minute or so is unlikely to produce permanent injury. Holding your breath is likely to damage your lungs, something scuba divers have to watch out for when ascending, and you'll have eardrum trouble if your Eustachian tubes are badly plugged up, but theory predicts -- and experiments confirm -- that otherwise, exposure to vacuum causes no immediate injury. You do not explode. Your blood does not boil. You do not freeze. You do not instantly lose consciousness.
Various minor problems (sunburn, possibly "the bends", certainly some [mild, reversible, painless] swelling of skin and underlying tissue) start after ten seconds or so. At some point you lose consciousness from lack of oxygen. Injuries accumulate. After perhaps one or two minutes, you're dying. The limits are not really known.
You do not explode and your blood does not boil because of the containing effect of your skin and circulatory system. You do not instantly freeze because, although the space environment is typically very cold, heat does not transfer away from a body quickly. Loss of consciousness occurs only after the body has depleted the supply of oxygen in the blood. If your skin is exposed to direct sunlight without any protection from its intense ultraviolet radiation, you can get a very bad sunburn.
At NASA's Manned Spacecraft Center (now renamed Johnson Space Center) we had a test subject accidentally exposed to a near vacuum (less than 1 psi) in an incident involving a leaking space suit in a vacuum chamber back in '65. He remained conscious for about 14 seconds, which is about the time it takes for O2 deprived blood to go from the lungs to the brain. The suit probably did not reach a hard vacuum, and we began repressurizing the chamber within 15 seconds. The subject regained consciousness at around 15,000 feet equivalent altitude. The subject later reported that he could feel and hear the air leaking out, and his last conscious memory was of the water on his tongue beginning to boil.
So, bad things clearly happen. Just not the very dramatic bad things I, and lots of others, had previously imagined.
How much of terrestrial plant and animal life can humanity safely consume without seriously damaging the live-support systems of our planet? It has been challenging to answer that question because of the difficulty of measuring how much biomass is produced annually on land and how much of this yearly production humans co-opt.
Huge regional variability exists in terrestrial productivity from year to year because of heat, cold, floods and droughts but what is striking from recent reviews of more than 30 years of satellite imagery is how little global variability there is annually. Each year, terrestrial plants fix about 53.6 petagrams of biomass – a gigantic quantity but what matters is not so much the size of annual biomass production but rather that it seems to vary by only about two percent per year.
Recent estimates from satellite imagery indicate that humans now appropriate 38 percent of all terrestrial biomass generated annually. That would seem to leave 62 percent on the table for expanded human consumption but the vast majority of this biomass appears to be not harvestable because it includes root growth below ground and biomass production on lands in parks or wilderness areas that are either protected or inaccessible.
It appears likely that the upper limit for how much of terrestrial biomass that humans can co-opt annually is only about ten percent more for a total of 48 percent. Current land use patterns and projections that the global human population may reach nine billion by 2050 suggest that this 48 percent of all available terrestrial biomass may be reached within the next few decades.
Courtesy NASA (via Zonu.com)Back in 1969, when Neil Armstrong and Buzz Aldrin were making their historic moonwalk, I remember thinking to myself, what would happen if some kind of malfunction on the Lunar Module prevented them from blasting off the Moon's surface back to the Command and Service Module? They would most certainly die, there's no doubt about that, because NASA had no rescue plan in place. But what about Michael Collins, the Command Module pilot who was orbiting the Moon in the mother ship? He was waiting to take his fellow crew members home to Earth. If they didn't show up, he'd be in for a pretty lonely and agonizing three-day trip across the quarter-million miles of empty space back to Earth. I wondered what that would have been like.
Fortunately, Apollo 11 was a tremendous success and all three astronauts made it back safely, as did the 18 Apollo astronauts who followed in their footsteps (including the ill-fated Apollo 13 astronauts), so the tragic scenario never played out.
Courtesy NASABut what would that have been like? Astronaut Al Worden probably came closest to experiencing the profound loneliness of isolation in ourter space, when he was piloting the Command Module for the Apollo 15 mission. While his crew mates were busy walking (and driving!) on the Moon's surface, Worden was circling overhead - all by himself - for 3 days. At times, when his craft disappeared behind the far side of the Moon, he had no communications with anyone - not even Mission Control - and was thousands of miles away from his colleagues, and hundreds of thousands of miles away from any other human beings. He holds the record for being the "most isolated human being" ever.
You might think it must have been an anxious time for the solo astronaut, but his story, which can be found here, might just surprise you.