Courtesy Fancy Horse (underwater background)The genome of the coelacanth, the world's best known living fossil, has been sequenced by an international team of researchers and is revealing something scientists already suspected: that the primitive-looking fish has evolved more slowly than most other organisms. The coelacanth is related to the lungfish and several extinct Devonian fish species that are considered precursors to land dwelling tetrapods. Kerstin Lindblad-Toh is senior author of the study which appeared recently in the science journal Nature.
"We often talk about how species have changed over time, but there are still a few places on Earth where organisms don't have to change, and this is one of them," Lindblad-Toh said. "Coelacanths are likely very specialized to such a specific, non-changing, extreme environment -- it is ideally suited to the deep sea just the way it is."
Lindblad-Toh is scientific director of the Broad Institute's vertebrate genome biology group in Cambridge, Massachusetts, which did the genome research. The institute is linked to both MIT and Harvard.
The genetic map, which involved sequencing some 3 billion letters of DNA, also showed (via RNA content) that tetrapods - four-legged land dwelling animals - though related to both coelacanths and lungfish, are more closely related to lungfish and followed that line rather than that of the coelacanth. We humans also branched off that same line. The genome of a lungfish is composed of over 100 billion DNA letters, making it a much more difficult task to sequence, so for the time being, the coelacanth's DNA makes for a reasonable alternative for study.
"This is just the beginning of many analyses on what the coelacanth can teach us about the emergence of land vertebrates, including humans, and, combined with modern empirical approaches, can lend insights into the mechanisms that have contributed to major evolutionary innovations," said professor Chris Amemiya at the University of Washington, and the paper's co-author.
Courtesy photo by Haplochromis via Wikipedia Creative CommonsWhen Louis Agassiz named the first fossil coelacanth back in 1836, the Swiss paleontologist probably never imagined that a nearly identical descendent of the primitively constructed Devonian-aged fish would one day be found still inhabiting the world's oceans. The coelacanth was thought to have gone extinct along with the non-avian dinosaurs at the end of the Cretaceous period. None have been found in the fossil record after that time, but two extant species are known today. The first specimen Latimeria chalumnae was netted off the coast of South Africa in 1938, near the Chalumnae river and retrieved by East London Museum curator Marjorie Courtenay-Latimer who discovered what she called "the most beautiful fish I'd ever seen" in the catch of local fisherman, Henrik Goosen. Since then several more coelacanths have been caught, including the Indonesian species, Latimeria menadoensis, from the Indian Ocean.
The remarkable prehistoric throw-back, sometimes referred to as "old four legs" because of its leg-like fins, hasn't changed much in its 350 million year history. A member of the clade of lobe-finned fishes called Sarcopterygii, coelacanths retain primitive characteristics such a notochord, a hollow fluid-filled tube made of cartilage that underlies the spine over the length of its body. In all other vertebrates, the notochord is an anatomical structure that appears briefly only during the embryonic stage but not in adults. Not so with the coelacanth. It also possesses, primitive shark-like intestines, a linear heart, and tightly-woven armor-like scales (known as cosmoid) that are only found on extinct species of fish. The coelacanth's brain case contains only 1.5 percent gray matter - the other 98.5 percent of space is filled with fat. The other end of the coelacanth body begins to taper before expanding into a strange, three-lobed tail. Its most notable features are its lobed pectoral and pelvic fins that are structured with bones that look like toes, and move in an alternating tetrapod manner. An electroreceptive rostal organ located in its snout is used to detect prey, and the coelacanth is the only living animal that can unhinge a section of the its cranium to increase the gape of its mouth, enabling it to consume larger prey.
The blue or brown, white-speckled coelacanths prefer deep-water environments, and can reach six and a half feet in length and weigh upwards to 175 pounds. For some reason no living coelacanth has managed to survive more than a single day in captivity. With a dwindling population estimated at only 500-1000 individuals, the coelacanth was declared an endangered species in 1989.
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Courtesy The Theater of Public PolicyPreliminary information from a study of river water DNA samples done two years ago cranked up concerns about the presence of Asian carp in Minnesota sections of the Mississippi River and also the St. Croix River. But new and deeper analysis of the data shows that the menacing fish haven't been regular residents of those waters, and that local authorities have plenty of time to plan ways of keeping the invasive species away.
What changed? Last year researchers used more precise methods of identifying the DNA, they found that the earlier DNA samples were most likely not from Asian carp.
It's all good news in the short term. The Asian carp have been slowly migrating up the Mississippi River, upsetting the eco-balance of those waters for many years. The fish are aggressive and actually can "jump" out of the water and into anglers' boats. They also are aggressively eating foods that are the diets of native fish.
This new information isn't slowing down plans to try to halt the spread of the fish upstream, authorities added. Among the plans are to install underwater noise and bubble barriers at the Ford Dam on the Mississippi River in the heart of the Twin Cities.
Courtesy Peabody Museum of Natural History, Yale UniversityOn this day in 1877, railroad worker William Harlow Reed came over a ridge-top with the remains of a freshly killed antelope slung over his shoulder, and spotted huge fossilized bones exposed on the side of the steep bluff located a half-mile south of Como Station, a desolate railroad stop on the High Plains of Wyoming. It was a discovery that would forever change his life.
Reed and station master, William Carlin, began collecting up as much as they could, dreaming of money and employment other than railroad work. They waited several months before announcing the discovery in a letter to Yale professor Othniel C. Marsh, at the time one of America's prominent paleontologists. When a crate of bones - along with the guarantee of many more - arrived at Yale, Marsh realized they were dinosaur remains and hired both men to excavate and send him as much as they could, and to keep out any interlopers to his claim. Marsh knew if he could keep it secret - at least for a short time - the fossils at Como Bluff could give him a huge advantage in his rivalry with Philadelphia paleontologist, Edward Drinker Cope, and their notorious Bone Wars.
Courtesy Mark RyanThe dinosaur-rich strata at Como Bluff (the Morrison Formation) are found in the exposed flanks of an anticline (an upward fold), the center of which has been carved out by erosion [see diagram]. All three periods of the Mesozoic Era (Triassic, Jurassic, Cretaceous) are represented in the rock layers found there. Besides dinosaurs, fossils of fish, crocodiles, flying and swimming reptiles have also been found there. A significant number of important Late Jurassic mammalian fossils were discovered and collected by William Reed from Quarry 9 on the east end of Como. Reed also discovered and removed the great Brontosaurus excelsus skeleton that stands today in Yale's Peabody Museum.
Courtesy Peabody Museum of Natural History, Yale UniversityIn the years following its discovery hundreds of tons of dinosaur remains quarried at Como Bluff were shipped to Yale and other institutions pushing America into the forefront of vertebrate paleontology, and heavily influencing how museums would be constructed throughout the world.
Courtesy Mark RyanThe dinosaur halls at the American Museum of Natural History have several mounted specimens found at Como Bluff as does the Smithsonian in our nation's capitol. Well-known genera like Allosaurus, Diplodocus, Apatosaurus, Stegosaurus and Camptosaurus are just a few of the dinosaurs pulled from the mudstones and sandstones at Como Bluff. In the early 20th century it was thought that Como had exhausted its supply of dinosaur remains and exploration there for the most part tapered off for several decades. But in recent years, paleontologist Robert Bakker has been re-examining the quarries and uncovering additional secrets still buried in the Jurassic bluffs at Como.
Courtesy Mark RyanWilliam Reed worked for Marsh for several more years and the two men remained friends until the Yale professor's death in 1899. Reed continued in the field of paleontology, working independently, and for a time with the American Museum of Natural History in New York, and the Carnegie Museum in Pittsburgh. He finished out his career as a popular geology professor and museum curator at the University of Wyoming, just sixty miles from Como Bluff, the great dinosaur graveyard that changed not only the course his life but also that of American paleontology.
Como Bluff was added to the National Register of Historic Places in 1973. It's also been designated as one of Wyoming's National Natural Landmarks by the National Park Service.
We've all seen them, those great B-films where a giant, vicious monster from under the sea, or invaders from outer space arrive to cause mayhem across our cities and generally mess up our way of life. In the end, it seems no matter who or what it was that was attacking us, be it Mothra, Godzilla, or some race of belligerent extra-terrestrials, we could always count on the military to save our collective behind.
Unfortunately, with mosquitoes, that might now be the case anymore.
Scientists are reporting that Deet, one of the most widely used active ingredients in insect repellents, loses its effectiveness against mosquitoes shortly after those ubiquitous, blood-seeking winged vermin are first exposed to it.
Deet - the common name for N,N-diethyl-meta-toluamide - was developed by the US Army after the Second World War to help combat insects during jungle warfare. It was used extensively in the Korean and Vietnam wars, but mosquitoes seem to be able to adapt quickly to it.
"Mosquitoes are very good at evolving very very quickly", said Dr. James Logan of the London School of Hygiene and Tropical Medicine and co-author of the study. "There is something about being exposed to the chemical that first time that changes their olfactory system - changes their sense of smell - and their ability to smell Deet, which makes it less effective."
So what I want to know is where does that leave us here in Minnesota where the mosquito constantly competes with the Common Loon for the title of State Bird? Maybe it's time to start digging the bunker in the backyard.
Courtesy Dave Govoni (Va bene!)Is birdsong music? Does the tweeting and chirping of our feathered friends elicit the same emotional response in them as one of Chopin’s nocturnes does in us? Do they serve the same purpose? These are questions that have long been argued in scientific circles and elsewhere.
A new study published recently in Frontiers of Evolutionary Neuroscience shows some interesting results in how birds perceive birdsong.
Researcher Sarah Earp and neuroscientist Donna Maney, both of Emory University looked at brain imaging data gathered from studies of human neural responses to music and compared them with similar data from birdsong studies.
Some of the white-throated sparrows were given a boost of hormones (testosterone and estradiol) that made them all a-twitter and ready for love. When a male sparrow stepped up to the microphone and started serenading, the females showed a definite response.
“We found that the same neural reward system is activated in female birds in the breeding state that are listening to male birdsong, and in people listening to music that they like,” said Sarah Earp.
But what was music to the ears of the female sparrows was perceived by their male counterparts as discordant (and probably very annoying) noise from a rival suitor. An awkward third-wheel sort of deal, I suppose.
“Birdsong is a signal,” said Maney. “And the definition of a signal is that it elicits a response in the receiver. Previous studies hadn’t approached the question from that angle, and it’s an important one.”
The females in the sample group showed increased activity in the same region of their bird brains that humans display in their corresponding region when hearing a piece of music they enjoy. The response of the control group females - those not in a breeding state and without any hormonal boost - showed little response to song. Male sparrows treated with testosterone showed an amygdala response not unlike how the human brain responds to scary movie music.*
The brain’s mesolimbic reward pathway has counterparts in both humans and birds. In humans it lies beneath the cerebrum and is involved in emotions, memory, and olfaction. A neurotransmitter called dopamine is produced within the brain’s limbic system and spreads along the limbic pathways to help regulate the brain’s reward and pleasure centers. The chemical messenger also governs movement and emotions.
The study shows that not only does birdsong and music produce similar responses in corresponding brain regions linked to reward but also in areas thought to regulate emotions. And the response also seems to connected to social context in both birds and humans.
“Both birdsong and music elicit responses not only in brain regions associated directly with reward, but also in interconnected regions that are thought to regulate emotion,” Earp said. “That suggests that they both may activate evolutionarily ancient mechanisms that are necessary for reproduction and survival.”
*Rather than scary, I find composer Bernard Herrmann’s musical score used in Alfred Hitchcock’s PSYCHO very compelling – not sure what that response means. But it’s interesting to note that Herrmann’s music in the movie was also a big influence on record producer George Martin’s string arrangement for the Beatles’ melancholy ballad ELEANOR RIGBY.
Courtesy John Muir LawsToday is the kick-off of an eight-week effort that encourages us all to get to know our feathered friends a little bit better.
Feeder Watch: Sketch runs until January 20. You're welcome to flutter down into the project any time you'd like and "feed" as much or as little on it as you desire.
It's a simple concept with just one requirement – having access to an active bird feeder. Each day you watch the birds at the feeder, you're encouraged to sketch what you're seeing. The project also ties into Project Feeder Watch, which asks people to count and report the various types of birds they see at their feeders each day.
Why spend your time sketching birds? Sketching allows us to look at the world more closely and learn to observe details quickly and accurately. The project hopes to be a marriage between avid birders who might not have the most highly-developed sketching skills with artists who might not know much about birds.
Participants can share their thoughts at an online discussion site to learn from others. The entire Feeder Watch: Sketch run has been divided into four two-week blocks that will have specific themes for participants to dig into. Sketchers are also encouraged to take photos of their efforts to share online with others and participate in contests.
Not quite sure how to get started? Here are some beginner sketching tips from the John Muir Laws website.
Okay, so get out there and load up the bird feeder, sharpen those pencils and start sketching!!! It's bound to be a happier experience than playing Angry Birds one more time! And check back at Science Buzz as we update progress on the project.
Courtesy Mark RyanI don’t have a clue who or what entity officially proclaimed October as International Dinosaur Month (and there doesn’t seem to be any official site online), but whoever it was, it’s a great idea! This means not only do we get to celebrate Earth Science Week (October 14-20), and National Fossil Day (October 17*) this month but we also get to celebrate everyone’s favorite prehistoric beasts! A quick Internet search brought up a couple teacher sites here, here and here each offering some interesting ideas on how to celebrate the great Mesozoic monsters this month. There's also this International Dinosaur Month site on Pinterest , and another Pinterest site (mine) featuring dinosaur postcards. Or you could go view some dinosaurs at a local or nearby museum. Below, I’ve included a few museum links to dinosaur-related exhibits, and a site that lists dinosaur exhibitions around the world. If you or your classes are celebrating dinosaurs this month or have other suggestions on how to do so, please let us know.
*The Science Museum of Minnesota will celebrate National Fossil Day on Saturday, October 20 this year.
Courtesy Photo and sculpting by Tyler Keillor via ZookeysA fossil found in South Africa over 50 years ago has finally come to light as a new species of heterodontosaurid dinosaur and named Pegomastax africanus, or "thick jaw from Africa". No larger than a house cat, Pegamstax lived about 200 million years ago near the very beginning of the Jurassic period. The bizarre, two-legged herbivore had a beak like a parrot but also large, sharp vampire-like fangs that were backed up by a couple of equally nasty bottom teeth. Although unusual for a plant-eater, the sharp teeth would have been useful in nipping off leaves, twigs, and other tasty plant morsels, or for defending itself against predators or mating rivals. It may have also sported some nasty porcupine-like quills for further protection against predation.
Paleontologist Paul Sereno of the University of Chicago first laid eyes on the fossil while a graduate student at a Harvard University laboratory back in 1983. Other projects, however, diverted his attention from the rare specimen until recently when he finally found time to analyze it and publish his conclusions in the journal Zookeys.
News of the mini-dino “vampire" couldn’t have come at a better time, and all you little rug-rats out there who haven’t decided yet what to be for Halloween should find comfort in the announcement. A prickly Pegomastax costume would make for one scary night creature, and probably guarantee you bagfuls of delicious, (and perhaps, ironically) fang-rotting candy.
The mission of NFD is to “promote public awareness of fossils as well as to foster a greater appreciation of their scientific and educational value.”
This year the official day falls on October 17, but celebrations take place at various locations around the country over several days. Here at the Science Museum of Minnesota, the day will be celebrated on Saturday, October 20, 1pm-4pm throughout the museum. You can see what events are happening in your own area here.
Besides going out and hunting for fossils, one of my favorite NFD activities is the National Fossil Day Art & Photography Contest. As in previous years, the competition is open to anyone across several age groups. This year’s theme is “Careers in Paleontology”. A panel of NFD partners and paleontologists will select the winning entries. I’ve already sent in my submission but you have until October 5th (postmark deadline) to enter your own masterpiece.
National Fossil Day is usually observed in conjunction with Earth Science Week and this year is no different. EWS occurs October 14-20, and this year’s theme is Discovering Careers in the Earth Sciences.
Courtesy NASA / JPL-Caltech / Dr. Philip Bart, LSURecent investigations into microfossils show that Antarctica hasn’t been quite the icebox scientists have imagined it to be over the past 34 million years. Pollen and leaf wax samples from Miocene-aged sediments indicate the continent has experienced some periods of warming since the beginning of the most recent glacial period. The core samples studied came from ocean sediments collected near Antarctica, and particulates found in the samples indicate more rain fell on the ice-covered continent during the Middle Miocene epoch (15.5 – 20 million years ago) than previously thought, enough rain to spur the growth of forests of small, stunted trees.
Paleoclimatologist and organic geochemist Sarah Feakins of the University of Southern California and her colleagues analyzed core samples taken from between 144 and 1,100 meters beneath the ocean floor – levels dating back to the Middle Miocene. Spikes of concentrated amounts of pollens and leaf wax appeared in two periods – one about 16.4 million years ago, and another about 15.7 million years ago. The warm periods were relatively short, each lasting less than 30,000 years.
In a previous study, palynologist Sophie Warny of Louisiana State University had first described the pollen and leaf wax spikes found in the core samples, and she and Feakins eventually teamed up for the recent study. The team determined the particle spikes didn’t arise from the leaf wax and pollen blowing in from elsewhere but rather came from two species of trees that once lined the shores of Antarctica. The two species, podocarp conifer and southern beech wouldn’t have grown very tall – maybe knee-high – and neither spreads their pollen over wide areas. Had the pollens blown in from elsewhere - say South America or New Zealand - there were would have been more species in the mix.
Using a mass spectrometer, Feakins and NASA researchers analyzed the ratio of hydrogen to deuterium atoms in the wax molecules which indicated the temperature at the Antarctica location during the two warm periods was about 7 degrees Celsius during the summer. Today, summer temperatures in the same region are about –4 °C. The average global temperature at the time was about 3 °C higher than it is today. As the overall global temperature changes a relatively greater change in polar temperature isn't unexpected due to a process called polar amplification.
The data from Feakins and Warny’s study, which appeared in Nature Geoscience, adds to growing concerns over the sensitivity of Earth’s climatic and hydrological systems. At the moment, no trees line the shores of Antarctica, but current levels of carbon dioxide (393 parts per million) are not far off those thought to have existed during the Middle Miocene’s warm periods (400-600 parts per million) when forests did exist on the margins of the icy continent. This could indicate that even small changes in carbon dioxide levels can are capable of creating big changes in climate.