Stories tagged Biological Populations Change Over Time
What on earth am I supposed to do with this thing?: A pterosaur considers his situation.
Courtesy John ConwayPaleontology, y’all, paleontology. We’ve got these bones, these fossilized bones. And they’re nice bones, don’t get me wrong, but sometimes they leave a little to be desired when it comes to reconstructing the nitty gritty and sticky details of what living dinosaurs (and pterosaurs, ichthyosaurs, mosasaurs, therapsids, etc) were actually like. A skeleton can give us a good idea of a creature’s general shape; it can show where the muscles went (more or less), what sort of food it ate, how it probably moved—that kind of thing. But how did they behave? What color were they? Exactly how strong were they? There are a whole slew of questions that get to be a little tricky.
So, how do paleontologists go about answering these questions? They get creative, they study all the tiniest details of the fossils, and, sometimes, they look to living animals for analogy—that is to say, if an animal alive today that lives in a similar environment to that of an extinct animal, and has a similar body type to the extinct animal, you might be able to base knowledge of the extinct animal on what you know of the living animal.
It’s a valuable avenue of study, but dinosaurs and their ilk were pretty different, after all, so how far do you think can we take analogies to living creatures?
And now on to the news item.
A Japanese researcher has opened up his sass-box and gotten all up in the faces of paleontologists around the world. Pterosaur specialist paleontologists are particularly fired up, and they’re a dangerous bunch. “Peer review” among pterosaur specialists, as I understand it, involves switchblades, and the majority of the community sports eye-patches.
This scientist, Katsufumi Sato of the University of Tokyo, is saying that pterosaurs (all of the huge extinct flying reptiles) probably maybe couldn’t actually, you know… fly.
Oh no you di’en’t!
Says Sato: Yes, yes I did. Specifically, what the scientist did was place accelerometers on the wings of a couple dozen sea birds on the Crozet Islands. The accelerometers measured, more or less, the flapping force and speed of the birds’ wings.
Among the birds studied were wandering albatrosses, which have the largest wingspans of any living birds. Large seabirds like this have often been used as analogies for pterosaurs for their somewhat similar body shapes. Many pterosaurs probably lived in a similar habitat to modern seabirds as well.
Albatrosses fly by riding shifting wind currents, and by flapping their wings when the wind isn’t suitable, or is absent entirely. Sato found that the seabirds he studied have two flapping speeds, a faster speed for taking off, and a slower speed for staying aloft in the absence of wind. He also noticed that, as this flapping speed is limited by the birds’ strength, it decreases in heavier birds with longer wings.
According to the calculations Sato based off of this data, birds (or pterosaurs) weighing more than about 90 pounds would be unable to fly without using wind currents—they simply wouldn’t be able to flap their wings fast enough to stay in the air. There were certainly pterosaurs that size and much smaller, but a lot of flying reptiles were probably a great deal larger than that (a very conservative estimate for the quetzalcoatlus, for example, would have it weighing around 220 pounds).
The article I read on this research doesn’t get into Sato’s hypothesis much more than that, but I’d assume that this means that larger pterosaurs would then also be unable to take off from anywhere other than, say, a cliff face. I wonder if the implication is also that they wouldn’t be doing any flying at all; that medium to large pterosaurs wouldn’t even be gliding on wind currents because, at some point, they’d need to gain some altitude on their own steam.
But, whatever the specifics, them’s fightin’ words, and pterosaur specialists the world over are no doubt sharpening their boot-spikes, and wrapping their fists in chains.
Is it a valid analogy? Maaaaybeeee… But I’m betting against it. There have been some interesting theories lately about how the largest of the pterosaurs may not have flown as much as we used to think, but they don’t imply that they couldn’t fly at all. In fact, the study I’m thinking of would further distance pterosaurs from large seabirds in terms of behavior and their ecological niches (making any analogies a little less apt).
Other scientists argue that in addition to anatomical and physiological differences that should be considered, the atmosphere of the Mesozoic was, on the whole, somewhat denser, and had higher concentrations of oxygen—factors that would have allowed flight for larger, heavier animals. Actually, I recommend checking out the discussion following the article. There are a bunch of explanations of how pterosaurs could have flown, despite what this study suggests. But, if you do go, bring your knives—they’re an angry bunch.
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What, I can only lock this from the outside?: Scientists have observed behavior in ants in Brazil where a small group of ants sacrifice themselves each night for the good of the colony by covering the colony entrance from the outside, leaving them outside at night exposed to all sorts of natural forc
Courtesy Fir0002How do you secure your home at night? With a deadbolt lock? Switching on some high-tech electronic security system? A pit bulls (without lipstick)?
Whatever you do, it's probably not as problematic as what a few ants do each night in Brazil. Researchers have observed that one to eight ants from a colony each night sacrifice themselves for the well being of the colony. They stay above ground pushing sand over the entrance to the colony to protect their peers from predators during the night. Because they're left outside, they most often die in the night, either from freezing in chilly temperatures, getting blown away in high winds or being a midnight snack for a predator.
A typical ant colony in Brazil can number over 100,000, so the few ants lost each night for security is not a huge mathematical loss. How exactly the night workers are selected isn't known for sure, but researchers think they're probably older ants who are approaching the end of their natural life span.
Six-toed cats can remain at Hemingway museum
in Life Science, Diversity of Organisms, and Biological Populations Change Over Time
Hemingway cat: One of Snowball's many descendants takes it easy behind the Hemingway Home and Museum in Key West, Florida.
Courtesy Mark RyanThe fifty or so cats living around the former estate of author Ernest Hemingway in Key West, Florida, have been granted a reprieve from the US Department of Agriculture and are being allowed to remain on the grounds where the famed novelist once lived. The island property is now the Hemingway Home and Museum, and one of Key West’s more popular attractions. The federal agency originally wanted the cats removed or caged because the museum lacked the proper license to exhibit animals.
All the cats roaming the grounds are descended from a cat named Snowball given to the author by a ship’s captain in the 1930s. Snowball was a polydactyl cat, meaning its paws contained more than the usual number of toes. Typically a cat has 18 toes – five on the front and four on back. Polydactyls commonly have six or seven toes on the front, and sometimes an extra one on the rear, but the record is held by a California cat that had an incredible eight toes on each foot! Polydactyly is a congenital abnormality genetically passed down to offspring. In some cases the extra toes are like opposable thumbs giving the cats an almost human-like dexterity. Snowball’s descendents all carry the genetic trait but not all are polydactyl.
Ernie the cat
Courtesy Mark RyanOur family cat was a polydactyl, and we named him Ernie in honor of Hemingway and his six-toed cats. Ernie’s extra-large feet allowed him to gain lots of weight during his life with us. At his heftiest he weighed 24 pounds. He was huge, a real lard butt. His full name - Ernesto ”El Gato Gordo” Hemingway - was well deserved.
Science Buzz Creature Spotlight: The Crocowhale
in Life Science, Diversity of Organisms, and Biological Populations Change Over Time
The Ambulocetus: Not looking very fearsome at the moment, but it's thinking horrible, horrible thoughts.
Courtesy ArthurWeasleyIt’s Friday, y’all, and you know what that means!
No, not falling asleep at a booth in Applebee’s (should have gone to TGIF, right?)!
No, not a methadone suppository (not from me, anyway)!
And, no, not matching butterfly tattoos (that’s a Saturday thing)!
What’s left? Why a Science Buzz creature feature, of course! Sure, Friday has never been Creature Spotlight day before, sure, and, yes, it’s unlikely that I’ll remember to do it next Friday… But, hey, we’re Buzzketeers, right? We live in the now.
And so, with a small current science introduction, the creature of the week:
The crocowhale* (also known as ambulocetus, or “walking whale”).
If you’re keeping up on your cetacean evolution paleontology, you might have noticed this story recently. The ancestors of whales, paleontologists are quite certain, were land animals. Finding the evolutionary steps of their return to the water has been a challenge, however.
The distant ancestors of whales were carnivorous ungulates (ungulates are hoofed animals), that probably looked a little like dogs (with hooves). At some point these creatures began adapting to live and hunt in and around the water, eventually evolving into fully aquatic species.
Living vertebrates that swim employ a variety of propulsion methods. Several swimming styles seem to develop in sequence as a group of animals becomes more fully adapted to living in the water: swimming with four legs, paddling with just the back legs, undulation of the hips, undulation of the tale, and finally oscillation of the tail. The sequence of whale ancestor fossils seemed to follow this pattern (with modern whales having lost their hind legs to propel themselves with just their tails), except that for a long time it appeared that the step of swimming by hip undulation.
Recent fossil discoveries, however, show a whale ancestor that appeared to have a long fluke-less tail (it didn’t have big tail fins, like a modern whale), along with long hind legs and large, webbed feet. The skeleton seems to indicate that this creature would have propelled itself by undulating its hips, using its webbed hind feet as hydrofoils. And so, la de da, we have an important step in whale evolution in the bag. But, for the creature spotlight, we’re going back a couple branches in the cetacean family tree.
Before the group had evolved to the point of the hip wiggler above (called georgiacetus, by the way), there was the ambulocetus. Ambulocetus was a creature that probably still spent some of its time on land. It was about 10 feet long, and moved around on short, powerful legs. With its eyes and nostrils located on top of its long head, it probably looked something like a furry crocodile. Indeed, paleontologists think that ambulocetus probably acted very much like a crocodile, and filled a similar ecological niche.
Ambulocetus could have waited for large prey almost entirely submerged in shallow water, with only its eyes and nostrils breaking the surface. When something worthwhile came down to the water’s edge, it could have launched its body out of the water with its particularly powerful hind legs, ambushing its prey. The ambulocetus would have then dragged its struggling meal back into the water, and waited for it to drown. Yes! Crocowhale!
Here’s a cool illustration of ambulocetus in action.
* “Crocowhale” is a brand new term, and while I’m all for you using it in everyday life, don’t put it in any biology papers or anything. Yet.
Eat up!: Technically, these aren't the right kind of parasitic worms. But it couldn't hurt to have a few, right?
Courtesy TeseumFinally, folks, we have yet another reason to get infected with parasitic worms!
Don’t get me wrong—there are already reasons that you should look into getting worms, plenty of reasons. The company, for one; you’re never alone when you’ve got worms, after all. And the excuse that you’re eating for two (or two hundred) is always useful at big dinners. And the day that “Hey, I have worms! Let’s kiss!” stops being an effective icebreaker at parties is the day I’m not interested in living any more.
And yet there will always be naysayers. Killjoys and health nuts, for whom no pro-worm argument seems to be adequate. Hey, worm-haters, guess who had worms. Your great grandparents, probably, and were they bad people?
In any case, the obstinate will soon have an even harder time ignoring the cold, hard face of reason.
It has been observed that in tropical regions where infection by a particular type of parasitic worm is common, auto-immune diseases—like rheumatoid arthritis, multiple sclerosis, and type-1 diabetes—are particularly uncommon. Scientsts, clever devils that they are, have figured out why this is.
Certains type of parasitic nematodes (nematodes are round worms) are capable of causing filariasis in their hosts. Among other things, filariasis causes elephantiasis. Elephantiasis for those of you blocking out memories, elephantiasis (often misheard as “elephantitis”) is characterized by severe “thickening of the skin and underlying tissues,” occurring most often in the legs and genitals. And it’s pretty gross.
It isn’t in the worm’s interest, as it were, to have this massive inflammatory response in its host, so it secretes a large molecule called “ES-62.” ES-62, according to researchers, seems to act like a “thermostat” for inflammation. With no known adverse health effects, ES-62 reduces the inflammatory immune response that causes elephantiasis, as well as rheumatoid arthritis, while leaving intact the immune system’s other mechanisms for fighting infections.
Similar research has been done on parasitic schistosomes (blood flukes). Populations with high infection rates of certain schistosomes have a greatly reduced incidence of allergies and asthma, and the thought is that the blood flukes are also able to regulate their host’s immune response so that it ignores some irritants (like the flukes) but still doesn’t allow the body to become too sick.
Wild, huh?
So get yourself some worms, y’all. Foxy boys and girls can tell when you’re sneezing and limping (not attractive), but they can’t see the worms and blood flukes teeming through your system. So you decide.
Are you tracking me?: GPS technology saved the life of an elephant in Africa last week and is being used extensively to track the migration patterns of many types of animals.
Courtesy Lee R. BergerGPS – global positioning systems – can do some amazing things. Even saving the life of an elephant.
Here’s an account of how a GPS unit spared an African elephant in Kenya from being slaughtered by irate farmers. Mountain Bull, which wears a GPS unit on around his neck, was noticed missing one day last week from his herd near Mount Kenya. Using the GPS tracking technology, his biologist observes tracked him down with a rogue pack of elephants ravaging the goodies of farm field nearby.
Efforts to rebuilt Africa’s elephant population have had the unintended consequence of putting more pressure on Kenyan agriculture. Elephant herds looking for easy food are more commonly heading to the farm field buffet.
The Kenyan Wildlife Services officials followed the GPS signal to find Mountain Bull in the sights of being exterminated by local farmers. Equipped with GPS tracking information showing that Mountain Bull had never been out looking for a farm-field free lunch before, they were able to talk the farmers into granting him mercy on this indiscretion.
While this is a pretty dramatic story of GPS coming to the aid of wildlife, biologists are using the technology in many other ways.
Integrating the GPS readings with Google Maps technology, researchers are able to map migration patterns and find out which locations are high traffic areas for different animals. Armed with that information, biologists can better target their efforts for habitat preservation and improving species numbers.
That’s all good news if you’re an African elephant; maybe not so good news if you’re a Kenyan farmer.
Scientists blaspheme dinosaurs…using science!
in Life Science, Diversity of Organisms, Heredity, and Biological Populations Change Over Time
A crurotarsan: Pretty cool, but don't put any bets on it.
Courtesy ArthurWeasleyJust as those of us who have hands know the backs of them well, just as all of us know that the Hulk is stronger than the Thing, just as we know that it’s a good idea to keep our lips off that thing… We all know that dinosaurs are pretty awesome. They are, perhaps, the most awesome.
Dinosaurs did, after all, strut their fine stuff across the surface of the planet for more than 150 million years. How else would one explain that, if not for the fact that dinosaurs were clearly more awesome than any and all of the competition? It can’t be done.
Except…
Scientists at the American Museum of Natural History are now saying that at the outset of their reign, the during Triassic, dinosaurs succeeded where other groups did not simply because they were lucky. Dinosaurs didn’t make it because they were stronger or able to adapt more quickly, but because they did well at the craps table. As it were.
See, the reptiles that survived the Permian extinction would eventually give rise to dinosaurs and a group called “crurotarsans.” The only living descendants of the crurotarsans are crocodiles and their ilk, but during the Triassic the group included a wide range of large predators, armored herbivores, and agile little crocodilians. At the end of the Triassic, however, the crurotarsans became almost entirely extinct, while the dinosaurs flourished.
When one group dies out and another succeeds under the same conditions, scientists usually expect to find that the “winning” group has a greater range of physical traits, or appears to be able to adapt much faster. The study done by the AMNH indicates the opposite in this case: as a group, the crurotarsans had twice the range of body plans as the dinosaurs, and seemed to be adapting just as fast. Subjected to the changing environmental conditions at the end of the Triassic, the greater variety of body designs should have given the crurotarsans a leg up in surviving to the Jurassic.
Not only should they not have died out, but the scientists behind the study say that if they could have bet—during the Triassic—who would dominate the planet for the next 130 million years, they would have picked the crurotarsans, not dinos. It just so happened that the crurotarsans were hit particularly hard at the end of the Triassic. Of all the extinction-inducing changes that could have occurred, the planet went through one that the crurotarsans couldn’t deal with: global warming. Dumb luck.
It seems like the study was missing something, however. What was it about global warming (or about the crurotarsans) that made them die out, even with their great diversity? Even if luck was the reason, what was the mechanism?
I’m inclined to think that the dinosaurs’ coolness had something to do with it. Sort of an opposite James Dean effect.
How about that, though? But for the roll of the biological dice, children across the world could have lunch boxes and notebooks covered in crurotarsans.
Illinois landscape, 300 million years ago: Late 19th Century illustration portraying a Carboniferous rainforest
Courtesy Mark RyanLast year, news came out about the discovery of a large fossil forest dating from 300 million years ago in a coal mine located in eastern Illinois. Now, five more prehistoric forests have been identified in the same region.
Central Illinois above the coal mine: The terrain and vegetation today is a far cry from how it looked 300 million years ago.
Courtesy Illinois State Geological SurveyThe remains of the ancient tropical rainforests cover a tremendous area – 36 square miles – and have been under study by scientists from the Smithsonian, the UK, and the Illinois State Geological Survey. A presentation given at the British Association Science Festival held in Liverpool this week detailed some of the highlights of this incredible find.
"Theses are the largest fossil forests found anywhere in the world at any point in geological time,” said Dr Howard Falcon-Lang a paleobotanist at the University of Bristol.
The prehistoric landscapes existed within only a few million years of each other – a short span geologically speaking – and are found stacked one upon the other. Segments of the forest fossilized in their original vertical position. At places, scientists can trace the original ground cover in well-preserved fossils.
Donning cap lamps, battery packs, and rock hammers Falcon-Lang and his colleagues rode an armored vehicle 250 feet beneath the Herrin coal seam in the Riola and Vermillion Grove coal mine. Once underground, the scientists took an incredible hike through a long-gone prehistoric fossil forest, illuminated only by lights on their caps.
Ancient tree trunk protruding from coal mine ceiling
Courtesy Illinois State Geological Survey“We walked for miles and miles along pitch-black passages with the fossil forest just above our heads,” Falcon-Lang said. "It's kind of an odd view looking at a forest bottom-up. You can actually see upright tree stumps that are pointed vertically up above your head with the roots coming down; and adjacent to those tree stumps you see all the litter.”
Fallen fossil tree in coal mine: Howard Falcon-Lang (University of Bristol) and John Nelson (Illinois State Geological Survey) mark off the width of a large fossil tree trunk lying just above the contact of the coal bed.
Courtesy Illinois State Geological SurveyIn some cases toppled trees – complete with crowns – and over 100 feet long were measured lying stretched out in the shale across the ceiling. For paleobotanists it presents a remarkable opportunity to actually stroll through a 300 million year-old ecological system as if taking a walk in the local woods today.
The reason for this unusual preservation is thought to be due to the prehistoric rain forest growing in an estuary near the Royal Center fault in Indiana, which caused the terrain to subside below sea level making it vulnerable to incidents of flooding and abrupt drowning. Geologists suspect earthquakes along the fault are the reason for the subsidence.
The soil that once supported these rainforests was later transformed into coal. Once this coal seam was mined from underground, the base of the fossilized forest was revealed encased in a shale matrix.
These tropical rain forests originally flourished during the Pennsylvania period (known as the Upper Carboniferous in Britain), back when the US Midwest was located near the equator. Forests of giant club moss trees and tree-sized horsetails came and went over a geologically short span of time. At the same time, major shifts in climate were taking place, alternating from cooler temperatures with large planetary ice caps to periods of extreme warming.
The episodes of climatic change coincide with changes in the forest ecology. Close study of the fossil vegetation show that several times the climatic stress pushed the rain forests into extinction, making way for skimpier fern growths to replace them.
Over the next five years Dr. Falcon-Lang’s team will search for reasons why this rainforest extinction took place. Understanding how the first rainforests responded to global warming could help shed light on how climatic change may affect present day rainforests.
Additional photos of the amazing fossil forest can be found here. But if you want to see some of the real thing, visit the coal-mining exhibit at the Museum of Science and Industry in Chicago where an actual slab of the gray roof shale is on display.
LINKS
Illinois State Geological Survey story
University of Bristol story
BBC website story
Coal-mining info
More about the Carboniferous period
Think this looks weird?: Creatures you create in Spore will put this trilobite to shame.
Courtesy kevinzimA new computer simulation game based on the theory of evolution is being released today by Electronic Arts, the same company that created the vastly popular SimCity and The Sims. I lost interest in playing video games years ago, but my kids were big fans of the Sims series.
The new game, called Spore, begins with a meteorite delivering the building blocks of life into a primordial planetary ocean. As your life-form eats and grows it acquires DNA points and traits that help it survive. Single-cell organism gradually transform into more complex multi-cellular ones that eventually develop brains, defense mechanisms, and alliances to survive long enough to further evolve - eventually - into advanced civilizations and societies.
When a new generation appears, you’re given access to the game’s Editor, and the ability to add mutations to your creature’s offspring. According to Will Wright the game’s creator the Editor is “roughly a mixture of Mr. Potato Head, an Erector Set, and clay”. Parts can be given more than just one function, so, for example, a tail can be used both as a grasper and stinging weapon if that’s what you want.
Along the way your creature can be designated a predator or prey, whichever strategy proves more useful for it to flourish. It can co-operate with other species, or you can make it competitive and just have it run roughshod over everyone else, and see how that works out for you.
Neil Shubin, a paleontologist at the University of Chicago who studies how evolutionary modifications produce different body plans, was shown the game recently and delighted by it.
“Playing the game you can’t help but feel amazed how, from a few simple rules and instructions, you can get a complex functioning world with bodies, behaviors and whole ecosystems,” he said.
Luckily, (if you haven't already done so on the earlier Spore link) you can also see a great demonstration of the game yourself just by clicking below. The rather extensive demo is given by Will Wright himself.
In the end, I think the idea is to become civilized enough to develop into a society of space colonizers (I suppose so the process can start again).
Some scientists like Shubin love the game, while others aren’t so impressed, complaining it simplifies a very complicated process. But so what? Small mutations over millions of years would take…well, millions of years to play out properly in a more realistic simulation. Do they really want my kids playing computers games more than they already are? I don’t think so.
At least by presenting some of evolution’s grand ideas, Spore just might inspire some gangly, pimple-faced kid to let go of the controller long enough to investigate further the intricacies of the science and natural selection. How could that be bad? But, I have to tell you, after watching the above video demonstration, I’m very eager to try out the game myself.
SOURCES
Mammoths on display: Early engraving from the St. Petersburg museum
Courtesy Mark RyanPaleontologists have uncovered the skull of a rare mammoth species in southern France that could help fill in a gap of knowledge about mammoth evolution.
The skull belongs to a steppe mammoth (Mammuthus trogontherii), a large creature that roamed the Ice Age landscape during the Middle Pleistocene some 400,000 years ago. While alive, the steppe mammoth stood about 12 feet tall at the shoulder and spent its life grazing on grasses. Few skulls of this intermediate beast have been found so this latest discovery could help link the evolutionary path between the earlier southern mammoth (Mammuthus meridionalis) and the later woolly mammoth (Mammuthus primigenius).
"This specimen is of extreme importance because we don't know that much about the Middle Pleistocene," said Dick Mol, an amateur paleontologist from the Natural History Museum in Rotterdam, who discovered the skull with French paleontologist Frederic Lacombat. Photos of the dig can be viewed here.
Mammoth skull: American Museum of Natural History
Courtesy Mark RyanThe earlier southern mammoth lived life browsing on trees and shrubs in a savannah-type environment, much like that found today in Senegal, Africa. But the steppe mammoth, and its descendent the woolly mammoth, lived in a colder, harsher environment. Their molars show an adaptation to the tougher steppe grasses that took over the savannah as the climate got colder and the latest ice age began.
SOURCE and LINKS
BBC site story
Origin and evolution of mammaths
More mammoth facts
Mammoth museum in Russia video
Mammoth site in South Dakota
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