The Evolution of Tyrannosaurus rex
The terrible lizards of your childhood have changed quite a bit, despite having been dead for millions of years. Perhaps nowhere is that more evident than in ol’ Sharptooth: T. rex
Many folks without strong paleontology backgrounds (which, let’s face it, includes most people … including me) don’t appreciate how little we really know for sure about these prehistoric forms. We go to a museum, we see a fossil reconstruction of an immense dinosaur, and we assume that’s how it came out of the ground. That’s not the case.
While the Field Museum’s famous T. rex ”Sue” was 80% complete upon excavation, the first specimen ever constructed was done so with just a suitcase’s worth of bones. See the shaded regions in the upper left drawing? That’s the 108-year-old first reconstruction of T. rex done by W.D. Matthew. And it’s very wrong.
Even into the 1940’s, when Rudolph Zallinger painted The Age of Reptiles mural (top right) for Yale’s Peabody Museum, T. rex was still a clumsy, chubby, upright tail-dragger that looked more like a drunk Godzilla than king of the dinosaurs. By the 1970’s it was clear to scientists that T. rex could not have have held its body that way, and instead moved holding its head and tail nearly parallel to the ground.
But the tail-dragger myth persisted, and in 1988’s The Land Before Time (which, let’s face it, is where most of us first formed our images of dinosaurs) Sharptooth was frustratingly upright (see middle left). Combine that with the ridiculously impossible, ninja-like aerial assault on Littlefoot’s mom, and we have a real dino science stinker on our hands. Stan Winston’s Jurassic Park finally got the head-down pose right (middle right). Yet children and college students still overwhelmingly draw T. rex as upright.
Modern paleoartists (like Raul Martin, lower left) get it consistently right, but the public doesn’t. It shows you just how important it is to deliver good science to kids, because even today I can feel the upright pose of my T. rex dinobot calling me back to wrongville.
And as we continue to learn more about Tyrannosaur relatives and the feathery frills they sported, we are beginning to see many artists add them to the great hunter (lower right, by pheaston). Plumage rarely shows up in fossils, and scientists and artists have to be careful not to make errors of incompleteness like we saw 108 years ago. But considering how good Velociraptor looks with that fancy outfit on, I think we’ll see more and more feathery fury on T. rex in the future.
At least none of YOU will ever draw it incorrectly again, right? :)
For more cool dino illustration, check out Fuck Yeah Dino Art.
Rylands Medieval Collection, Latin MS 53, f. 58v. Christianus Prolianus and Joachinus de Gigantibus (?), Astronomia (1478)
“Comparative view of the magnitudes of the Sun (a large disc of burnished gold), the Moon (silver), Mars (gold), Venus (gold), Mercury (gold) and Earth (pale). Framed in a green wreath of leaves and blue background.”
Idea: What if the federal government gave someone like Neil DeGrasse Tyson a “Science Laureate” role, like we do for poets? Sound like a good idea? Fortunately, members of Congress are already working on it.
The post could be rotated among different fields so that each could get more public exposure.
How genetic plunder transformed a microbe into a pink, salt-loving scavenger
Most cells would shrivel to death in a salt lake. But not the Halobacteria. These microbes thrive in brine, painting waters a gentle pink or crimson red wherever they bloom. The Halobacteria live in every salt lake on this planet, from the Dead Sea of Israel to the vast salt flats at the feet of the Sierra Nevada. But these hardy microbes haven’t always called salty depths their home. Their genomes reveal a tale of a dramatic transformation through genetic plunder.
Organisms that can survive in waters of extreme salinity are called ‘halophiles’ – or salt lovers. There exist salt-tolerant algae, fungi and even shrimp. But of all the salt lovers in the world, the pink Halobacteria are the most passionate. They don’t just cope with brine. They embrace it.
Most halophiles do their best to keep their cells clear of salt. But the Halobacteria just don’t care. The insides of their cells are as salty as the lakes they live in. This strategy, the Halobacteria have come to utterly dependent on salt, up to the point were fresh water is as deadly for them as salt water is for others. Placed in a freshwater lake, their cells would swell and pop like bloated water balloons.
Confusing enough, Halobacteria are not bacteria, but archaea, which have a completely different biochemistry. As a general rule, archaea are more hardy and robust than their bacterial counterparts, living in a wider range of extreme environments.
Microbiologists have long noted something odd about the Halobacteria. In all their evolutionary analyses, they found that Halobacteria are part of a branch of archaea called the ‘methanogens’. What bothers microbiologists is that as microbes, methanogens and Halobacteria couldn’t be more different. In every scheme ever devised to differentiate among micro-organisms, methanogens and Halobacteria end up on opposing sides of the divide. If microbes were spices, methanogens would be the pepper to the halobacterial salt.
Methanogens are the self-reliant survivalists, able to liberate energy from the most basic of molecules. A pinch of hydrogen (H2), a dash of carbon dioxide (CO2) and a spoonful of minerals is all a methanogen needs to carve out a living. This sober lifestyle has earned them the moniker of ‘rock eaters’ (lithotrophs).
Halobacteria, on the other hand, fancy their molecules ready-to-eat. They are scavengers, scrounging the salty waters for carbon compounds that they burn using oxygen (methanogens loathe oxygen). As an alternative energy supply, halobacteria are also able to harvest energy from sunlight.
Two types of microbes with radically different life strategies, yet one evolved from the other. So how did the Halobacteria cross the line?
Shijulal Nelson-Sathi thinks he has found the answer. In their latest paper, he and his colleagues show that the ancestor of all Halobacteria acquired as much as a thousand genes from another microbe, a bacterium. And through this act of plunder, the microbiologists write, the Halobacteria left their methanogenic ways behind, becoming salt-loving scavengers in the process.
Exploring Space
The BBC has created a monster infographic illustrating “every attempt to leave Earth’s orbit and reach a destination in extraterrestrial space – be it with probes, orbiters, rovers, or of course manned missions.”
The graphic shows successful and failed missions, country of launch origin and type of mission (eg., fly-by, rover, actual landing).
Related: How Big is Space?
Image: Screenshot, detail from Spacial Awareness: Ultimate guide to exploring space, via the BBC. Select to embiggen.
The skull of a Bengal tiger rests along side the skull of a domestic cat.
Notice the proportionally smaller braincase and eyes in the tiger, and the much larger flanges for muscle attachment, in comparison to the overall size of the skull.
As animals scale up in size, more muscle is needed to bear the additional weight and counteract the effects of gravity. To anchor the increased mass of the muscle, bones become more robust. Thicker, heavier, with larger flanges, and deeper hollows to provide the additional muscle with leverage.
It’s a cyclic system. More muscle is needed to support heavier bone which in turn supports more muscle…etc.
You’d think it could go on forever, but as animals become larger and more powerful, they also become heavier. For land predators, the cycle reaches a cutoff size when the increasing weight begins to negatively affect agility, maneuverability, and the ability to successfully catch prey.
Lateral Line
The lateral line is a system of sense organs found in many fish, and is visible as horizontal line running across its body. The line senses mechanical changes in the surrounding water, such as changing water pressures. In some species, electrical impulses can also be detected.
The lateral line plays an important role in schooling behaviour, predation and orientation. For example, a predatory fish may use it to sense water vortices created by fleeing prey. Conversely, the changing water pressures from approaching predator can warn a prey fish.
In an experiment, individuals of a group of Pollachius virens (pictured) were removed and subjected to different procedures, and their ability to rejoin the school observed. Those that were blinded were able to rejoin to reintegrate into the school, whereas those which had their lateral lines severed were unable to do so.
Thomas Haslwanter and Tino Strauss on Wikimedia Commons
Researchers have identified a burst of high-energy radiation known as ‘dark lightning” immediately preceding a flash of ordinary lightning. The new finding provides observational evidence that the two phenomena are connected, although the exact nature of the relationship between ordinary bright lightning and the dark variety is still unclear, the scientists said
“Our results indicate that both these phenomena, dark and bright lightning, are intrinsic processes in the discharge of lightning,” said Nikolai Østgaard, who is a space scientist at the University of Bergen in Norway and led the research team.
He and his collaborators describe their findings in an article recently accepted in Geophysical Research Letters—a journal of the American Geophysical Union.OK, can science get any cooler? Like really can it? Read more here
