What do a leaping lizard, a Velociraptor and a tiny robot at Bob Full’s laboratory have in common? They all use their tails to correct the angle of their bodies when they jump.
Thomas Libby filmed rainbow agamas – a beautiful species with the no-frills scientific name of Agama agama – as they leapt from a horizontal platform onto a vertical wall. Before they jumped, they first had to vault onto a small platform. If the platform was covered in sandpaper, which provided a good grip, the agama could angle its body perfectly. In slow motion, it looks like an arrow, launching from platform to wall in a smooth arc (below, left)
If the platform was covered in a slippery piece of card, the agama lost its footing and it leapt at the wrong angle. It ought to have face-planted into the wall, but Libby found that it used its long, slender tail to correct itself (below, right). If its nose was pointing down, the agama could tilt it back up by swinging its tail upwards.
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A cat-like animal explodes from the long grass and leaps onto an antelope. Its huge bulk drags the target to the ground and its muscled forelegs pin it down. With two long sabre-shaped canine teeth, it stabs its victim in the throat, just the once, severing its blood vessels and windpipe. Death comes quickly.
The hunter could be Smilodon, a sabre-toothed cat that lived throughout North and South America, around one or two million years ago.
Or, it could be a nimravid, another group of hunters that looked like cats, but belonged to a separate, closely-related family. Some of them had sabre-teeth too, and they wielded these weapons between 42 and 7 million years ago, well before Smilodon or its relatives did.
Or, it could be Barbourofelis, a member of yet another group of sabre-toothed not-quite-cats, which lived between 16 and 9 million years ago. Its long sabres slipped into long grooves in its lower jaw, which looked like it was about to melt away.
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The sickle-shaped “killing claws” of dinosaurs like Deinonychus and Velociraptor have captured the imagination for decades. They were held aloft from the second toe, and were far bigger than the neighbouring claws. In Jurassic Park, Alan Grant tells an annoying child that the dinosaurs used their claws to disembowel their prey with slashing motions. That seems unlikely – they didn’t have a suitable cutting edge. Others have suggested that they were used for climbing onto larger prey.
But neither idea made sense to Denver Fowler from Montana State University, who has put forward a very different idea about how these animals used their infamous claws. He compared the feet of extinct dinosaurs like Deinonychus to those of living dinosaurs like eagles, hawks and other birds of prey. Both groups are known as “raptors” and Fowler thinks that they share more than their nicknames.
In his vision, which he calls the “ripper” model, Deinonychus killed small and medium-sized prey in a similar style to a hawk or eagle dispatching on a rabbit. Deinonychus leapt onto its target and pinned it down with its full body weight. The large sickle-shaped claws dug into its victim, gripping tightly to prevent it from escaping. Then, Deinonychus leant down and tore into it with its jaws. The killer claws were neither knives nor climbing hooks; they were more like anchors.
It’s a simple idea, but a potentially important one, for it casts Deinonychus’s entire body into a new light. Fowler thinks that it flapped its large feathered arms to keep its balance while killing a struggling victim. And its feet, which were adapted for grasping prey, would have given its descendants the right shape for perching on branches. Fowler says, “It really helps to make sense of the weird anatomy of these little carnivorous dinosaurs.”
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Before killer whales and polar bears, before sharks and tyrannosaurs, the world’s top predator was probably a bizarre animal called Anomalocaris. It lived in the Cambrian period, over half a billion years ago, when life was confined to the seas and animals took on bizarre shapes that haven’t been seen since.
Many scientists believe that Anomalocaris ruled this primordial world as a top predator. At up to a metre in length, it was the largest hunter of its time. It chased after prey with undulating flaps on its sides and a large fan-shaped tail. It grabbed at them with large spiked arms. It bit into them with a square, tooth-lined mouth. And it tracked them with large stalked eyes. (See the Prezi below for a tour of Anomalocaris’ anatomy, or load a single image with all the info.)
Now, John Paterson from the University of New England, Armidale, has uncovered new fossilised eyes that he thinks belonged to Anomalocaris. If he is right, this hunter had extraordinarily acute vision for its day, rivalling that of almost all modern insects.
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In the Field Museum of Natural History, there is a piece of bone about the size of a child’s torso. It’s an osteoderm – a scale-like bone embedded in the skin of an animal. In this case, the owner was Rapetosaurus, one of the giant armoured dinosaurs known as titanosaurs. The osteoderm probably sat on the animal’s back, and the standard interpretation is that they provided a sturdy defence.
But Kristina Curry Rogers from Malacaster College thinks that these “skin bones” did something else. She was the scientist who discovered Rapetosaurus, and she has been analysing two new osteoderms from northwest Madagascar, where the titan used to live. The larger of these is the biggest one ever found – 57 centimetres in length, 27 across and 19 deep.
It’s also hollow. When Rogers put the bone in a CT scanner, she found a big cavity inside it, big enough to hold five litres. She now thinks that the osteoderm was a store for minerals that the dinosaur could draw upon when times got tough.
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We now know that birds evolved from small, feathered dinosaurs. It’s easy to think that since birds are still around today, they must have come after their dinosaur* cousins, but that’s not true. In the Cretaceous period, dinosaurs were still around while their descendants flitted through the skies. And some dinosaurs made meals of their flighty relatives. Jingmai O’Connor from the Chinese Academy of Sciences has uncovered the remains of a small dinosaur called Microraptor that has the bones of small bird in its gut.
O’Connor analysed the fossil with Xing Xu, a Chinese scientist who has made a career from discovering beautiful feathered dinosaurs. Microraptor is one of his most important finds. This tiny animal, about the size of a pigeon, had four wings, with long feathers on both of its legs as well as its arms. It was, at the very least, a very competent glider, if not a true flier.
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Some of you know Brian Switek, ace blogger who covers all things fossil. What you may not have realised is that Brian Switek hates your childhood dreams and is out to crush them by making all badass prehistoric predators seem a bit rubbish. This is the latest volley in his ongoing campaign.
Last night, I decided enough was enough and drastic action was needed to preserve the predators that stalked our young imaginations, in the face of Switek’s tawdry “facts”. After all, you could prove just about anything that’s true using facts.
Thus was born the #GRAWR hashtag on Twitter, a collection of trivia about prehistoric animals based solely on how awesome they would be, and leaving aside silly notions like evidence. I collected some of my favourites (you should see a stream of tweets below; if not, check on a different browser): (more…)
In July 2002, an Italian man named Mr Francioni found something strange. Francioni owns a marble-cutting company in the Tuscan town of Pietrasanta, and he had just acquired a block of Egyptian marbleized limestone. After slicing the block into six slabs, he discovered the fossilised bones of an animal within. Fossils weaken the strength of cut stone and many people discard them outright. But Francioni was excited: he thought he had found a dinosaur, and contacted the nearby University of Pisa.
He got through to Giovanni Bianucci. “As soon as I saw the slabs, I realized that the finding was even more important than a dinosaur, at least for me. I study marine mammals,” he says. Bianucci realised that the bones belonged to an archaeocete, one of the predecessors of modern whales and dolphins. The story might have ended there: Francioni already had an offer from a foreign private collector, who wanted to slabs for his living room. Thankfully, Pisa’s local government intervened. They bought the fossils for the University’s Natural History Museum, where they are now on permanent display.
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Each of our eyes sees a slightly different view of the world, and our brain combines these signals into a single three-dimensional image. But this only works in one direction, because our eyes face straight ahead and their respective fields of vision only overlap in a narrow zone. But there was once a creature that had binocular vision in a massive arc around its body, not just in front but to the sides as well. It’s called Henningsmoenicaris scutula and it lived around half a billion years ago.
H.scutula lived in the Cambrian period, the part of Earth’s history when most of today’s major animal groups exploded into existence. It was a crustacean, one of the earliest members of the group that includes crabs, prawns and lobsters. It was just a millimetre long and almost totally encased within a bowl-shaped shield. From beneath the shield, weird spike-tipped legs propelled it along, while two stalked eyes, each just half a millimetre across, peered out at the Cambrian oceans.
These eyes are compound ones, made up of several units or ‘ommatidia’. They’ve also withstood the test of time. Their organic tissues have since been converted into the mineral apatite, and the resulting fossils perfectly retain the shape and angle of each ommatidium. The eyes are so well-preserved that Brigitte Schoenemann from the University of Bonn could use them to reconstruct how H.scotula saw the world to a “quite impressive degree”.
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We’re in western America in the late Jurassic period, and a herd of Camarasaurus dinosaurs is on the move. It’s the dry season and the giants are running out of water. Fortunately, they know exactly where to find a drink: a range of volcanic highlands to the west. To quench their titanic thirst, they must head for the hills. Now, 150 million years later, Henry Fricke from Colorado College had discovered a way of reconstructing their migration.
Vast migrations are a common feature among modern animals, and it’s reasonable to think that some dinosaurs undertook similar treks. But how do you work out the routes of long-extinct animals, when you only know about the spot where they died? The answer, as with many aspects of dinosaur life, is to look at their skeletons. As well as revealing the shape and size of these beasts, dinosaur fossils can also hold a record of their travel plans.
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