Hung out with some new fishy friends this morning: Meet Tiktaalik and Neil Shubin! I’m holding my 375 million-year-old great-great-(etc.)-fish-grandfather.
Meet Lucy, a 3.2 million-year-old hominid. Discovered in 1974, she is one of our oldest ancestors to walk on 2 legs.
Learn more with host Neil Shubin in this clip from YOUR INNER FISH.
The new 3-part series premieres April 9th at 10/9c on PBS’ THINK WEDNESDAY.
If my excitement about Cosmos represents a “10” on the excitement scale, then Your Inner Fish checks in at a very solid “9”.
I highly recommend this one. If you’re gonna learn the story of vertebrate evolution, I couldn’t think of a better teacher than Neil Shubin.
If you enjoyed the last post about the changing shape of Tyrannosaurus rex and want to dig deeper (see what I did there?) into the awesome world of modern dinosaur science, there’s nobody better than Brian Switek.
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.
How do we know that dinosaurs RAWR-ed?
That is far from a silly question! I mean, how DO we really know? That’s the hardest part of studying a long-extinct group of animals like dinosaurs: None of us were around when they were around.
When we see dinos in the movies, they always come complete with fearsome roars. From the jerky rubber lizards of the 1940’s to the blood-curdling thunderclap of the T. rex in Jurassic Park, where there’s a saur, there’s a rawr. But those movie roars are created by sound engineers from a mixture of modern sounds. The T. rex shriek in Jurassic Park is actually a mix of the calls from a baby elephant, a tiger and an alligator.
The problem is that the anatomy that animals use to make sounds doesn’t fossilize. Soft tissues like vocal chords and resonating throat sacs don’t last the way bones do. So we have to play dino detective, using a combination of structures that do fossilize and studying reptilian relatives that exist today.
Crocodilian reptiless and birds, two modern evolutionary cousins of dinosaurs, use soft tissues to make noises. The deep groaning vibrations used by crocodiles and reptiles come from the larynx. Much like in our own vocal chords, air from the lungs vibrates folds of tissue to create rather intimidating vibrations that sound like this. Birds, on the other hand … or wing … use a structure called the syrinx, which is close to a larynx but probably evolved independently. That means that roars and rooster calls could have a different evolutionary origin. One, both or neither of those structures may have existed in various families of dinosaurs.
But that’s not the only way dinos made noise. You’ve probably seen this fossil before in a childhood dinosaur book, a hadrosaur:
That large crest on top of the duck-billed head is hollow, like our sinuses. Many paleontologists think that hadrosaurs could have used them as resonating sound chambers to communicate over long distances, like a built-in didgeridoo used to warn of danger. These otherwise average herbivorous dinos, called the “cows of the Cretaceous”, roamed in huge herds (numbering into the thousands), and these sound chambers may have helped them communicate when predators were near.
Of course, we also know that dinosaurs had ears of some kind. Evolution wouldn’t have kept them if they weren’t useful (it’s not quite that simple, actually, but go with me here), and studying those fossilized skull structures may give clues as to what they heard. While we can be sure that they didn’t sound like they do in the movies, the precise nature of Cretaceous cacophony and Triassic tumult may forever remain a mystery. But I’m confident there would have been plenty to hear in the Age of the Dinosaurs.
Brian Switek, science writer and distant cousin of Tyrannosaurus rex, loves his dinos. But when people perpetuate myths about the great lizards of yesteryear, Brian gets very angry. And like T. rex, you wouldn’t like him when he’s angry.
Or maybe I’m thinking of The Hulk. You get the point.
Check out his list of 10 dinosaur myths that need to go extinct and learn something today!
Dinosaurs vs. People
Just stumbled upon a fantastic gallery on WIkipedia of illustrated size comparisons between humans and dinosaurs. So many tiny dino-chickens!
Check them all out here. Lots of them look like the blue waving guy is about to get chomped Jurassic Park “lawyer in the bathroom” style, but that’s probably pretty accurate.
(via Kyle Hill)
Jurassic Park states this as if it’s accepted dino science, but there’s really not much to back up the idea that standing still would save you from becoming dino chow. From Mental Floss:
In 2006, Kent Stevens from the University of Oregon did an experiment inspired by that very scene to figure out what sort of binocular range (the field of view both eyes can see simultaneously) T. rex might have had. The wider that range, the better an animal’s depth perception and capacity to distinguish objects that are motionless or camouflaged.
Stevens built a scale model of the T. rex’s head and popped in some taxidermic eyes based on the eyes of three animals pretty closely related to T. rex—alligators, ostriches, and eagles—and adapted for situations that a dinosaur would have likely encountered. As he explains on his website, he used a technique called “inverse perimetry” to estimate “whether a given probe would be visible, based on whether there is a clear, unobstructed view of the pupil along a line of sight,” and mapped the model’s field of view.
I won’t spoil the ending for you, but … uh … maybe try running away instead of standing still, should you ever find yourself nose-to-chompers with the tyrant lizard. More on dinosaur vision factoids and research here.
And of course with velociraptors, you never see them coming …
That’s the half-life of DNA, according to new research from scientists in Denmark and Australia. That means that dinosaur DNA is pretty much out of the question, but that the Earth’s primary genetic material lasts longer than once thought.
By studying DNA left over in leg bones of extinct moa birds of different ages, they were able to determine how fast it naturally degrades. Water, essential for life, can be pretty reactive over the span of hundreds and thousands of years, slowly breaking the bonds that hold DNA molecules together.
If half the DNA is gone in 521 years, then even at optimal temperatures any sample would be almost totally degraded after 6.8 million years.
I guess there’s a few questions that remain, like if different environments could lead to different numbers, or what different soils could do to move that number up or down … but I’d sell your stock in any Jurassic Park-type ventures.