Tabla de contenidos para Dinosaurs en Dinosaurs

...to a new age of dinosaurs – the age of discovery. In the last 20 years, about three quarters of all known dinosaur species have been found, and a new species is discovered almost every week. Indeed, dinosaurs are being unearthed at such an incredible rate that I’m half hoping one day I’ll walk out the front door and trip up on what looks like a 2m-long Brachiosaurus bone, only to find that I’ve stumbled on a whole new species. (Bennettosaurus does have a nice ring to it.) The wealth of new specimens are keeping palaeontologists busy – plenty of fodder for all sorts of new theories about what dinosaurs looked like and how they lived. This special issue of BBC Focus Magazine reports on the latest findings, busting a…

The latest evidence shows that the dinosaurs owe their rise to world domination to two extinction events at the end of the Triassic period. But what if these extinction events never occurred? For starters, it’s likely that the croc-line archosaurs would have persisted as top predators. Ironically, this means that the appearance of amphibious, freshwater crocodiles and alligators would have been prevented. The persistence of their ancestors would have le! no ecological niches to fill in swamps and rivers. Dinosaurs and other bird-line archosaurs would have continued to live in the background and would have remained small. The dominance of the croc-line archosaurs would have le! few ecological niches for the dinosaurs to exploit, so many of the species we know to have existed would not have developed. Interestingly, this…

How fast – or slow – was T. rex? How did Spinosaurus catch its prey? Did the gigantic sauropods crane their necks upwards to feed from trees, or bend down to reach food on the ground? Palaeontology – the study of ancient life – has more than its fair share of questions, and this is especially true when it comes to dinosaurs. There exists no one specific technique that allows scientists to answer questions on the biology and behaviour of extinct animals. Instead, numerous different methods are employed. These include the examination of internal structure via microscopes, x-rays and CT-scanners, the identification of scars left by muscles and wear marks caused by contact with food, the study of stomach contents, droppings, footprints and nests, and the creation of real-world models, calculations…

No-one knows for sure. The old-school image of dinosaurs as cold-blooded plodding reptiles went out of favour in the 1970s with new discoveries of agile, bird-like Deinonychus. Indeed, evidence from fossil bones suggests a rate of growth compatible with endothermic metabolism – that is, producing heat from within to maintain body temperature. Also many dinosaurs lived in cold environments where getting enough heat from the surroundings might have been too difficult for gold blooded animals to survive. Finally, some of the largest dinosaurs, such as Brachiosaurus, had such long necks that they would have needed endothermic metabolism to fuel their blood circulation. But some scientists think they had ‘mesothermic’ metabolisms, somewhere between cold-blooded reptiles and warm-blooded birds.…

No-one knows for sure. Atmospheric conditions were certainly different to today. Recent studies suggest oxygen levels in the Mesozoic were low and carbon dioxide levels high, so they might have struggled to survive from that perspective. But, many dinosaurs would have been fine in current subtropical and temperate climates – and could even have flourished (see page 94). The one thing they couldn’t deal with is recently evolved microbes.…

Core 40. To the untrained eye, this threemetre section of rock winched up from a borehole beneath the Gulf of Mexico might not look like much. But for Prof Sean Gulick, a geologist at the University of Texas, it’s a sample that holds secrets about one of the most catastrophic events in the history of planet Earth. For Gulick, the core will tell him the story of the day the Earth shook. Sixty-six million years ago, a 14km-wide meteorite slammed into our planet. Wildfires raged, earthquakes rumbled, and a dusty curtain fell upon the Earth. It was the beginning of the end for around 75 per cent of the planet’s species, including all non-avian dinosaurs. Travelling at 20km per second when it entered Earth’s atmosphere, the meteorite left a crater…

HOURS Huge earthquakes, megatsunamis up to 300m high, winds of over 1,000km/h and rampant wildfires result in instant annihilation for many species. WEEKS Dust from the impact and soot from wildfires block out sunlight for many years. Plants that survived the impact soon struggle. Food webs start to unravel. YEARS Prior to the impact, non-avian dinosaurs are already in decline, but the impact seals their fate. If any species survive the impact, it’s not for long. Over 90 per cent of all mammal species also go extinct. The largest mammals are hardest hit; the survivors are all smaller than a cat. On land, forests and flowering plants struggle with the low light levels, resulting in a preponderance of species like ferns, algae and moss. 300,000 YEARS Because mammals from several…

An estimated 15 billion tonnes of soot spread through the atmosphere creating one long night that lasted several years, making photosynthesis all but impossible and heralding an endless winter that saw average temperatures fall by as much as 28oC. This was the fate awaiting those few wretched creatures that survived the initial impact of a 14km-wide asteroid 66 million years ago – and the earthquakes, tsunamis, wildfires and volcanic eruptions that swiftly followed in its wake. Around three quarters of all species went extinct and no animal bigger than a Labrador dog survived – but things could have been very different say researchers at the University of Texas. They reported findings that had the asteroid struck Earth just a few minutes earlier it would have hit deep ocean, rather than…

Microraptor Dark and glossy iridescent plumage, with large flight feathers on its hind and forelimbs, making for a beautiful pet. Likes to preen, nap and observe everything with its hawk-like watchful eyes. SIZE: One of the very smallest dinosaurs at less than 1kg in weight and about 80cm in length PROS: Four wings of awesomeness; intelligent and responds well to commands CONS: Can attempt to disembowel the cat Sinosauropteryx The first known feathered dinosaur, found in 1996. This relative of Compsognathus has lovely, fluffy ginger plumage and enjoys scratches and strokes. Likes to chase toys in lieu of fast-moving prey. SIZE: A metre in length including the long tail but very dainty, weighing just 0.5kg PROS: Loves to snuggle; fetching ginger-andwhite tail stripes CONS: Can be neurotic and restless; requires…

EORAPTOR (DINOSAUR) SIZE: 1m long DIET: Leaves, buds and small animals ATTACK AND DEFENCE: Mostly relied on speed to escape danger Eoraptor was a typical early dinosaur. Like the dinosauromorphs that were its close relatives, it was a small, slender, long-legged omnivore that would have been in danger of being eaten by big, predatory croc-line archosaurs. Short forelimbs show that Eoraptor was bipedal. It had five slender digits on each ‘hand’ with curved claws on the end of three of them. These claws could have been used in fighting as well as manipulating plants during foraging. Its jaws contained both leaf-shaped teeth as well as re-curved fangs. SILESAURUS (DINOSAUR0MORPH) SIZE: 2.3m long DIET: Leaves, buds, small animals ATTACK AND DEFENCE: Weak bite – mostly relied on running from danger Silesaurus…

Its outer layer of skin was reinforced with bones called osteoderms, forming an impenetrable sheet of armour, a feature shared with modern-day crocodiles. But most predators wouldn’t even manage to reach its robust body because of the deadly swinging club at the end of its tail. With this arsenal of weaponry, you might expect Ankylosaurus to be a formidable predator, however, it was actually a herbivore, using its artillery for defence. Ankylosaurus had numerous leaf-shaped teeth at the back of its jaws, but the front of the mouth was toothless and equipped with a horny beak to pluck plants from the undergrowth. It may have digested the plant maer via fermentation, the same process used to produce alcohol. DID YOU KNOW 70% OF ALL ANKYLOSAURS THAT HAVE BEEN DISCOVERED WERE…

All vertebrates shed their skin, along with virtually all animals that actually have a skin. The difference is that most of them don’t shed it all in one piece. But neither do all reptiles. Moulting a complete skin in one go seems to be restricted to snakes, legless lizards (like the slowworm) and some soft-shelled turtles. Presumably, this is because they have flexible, streamlined body shapes that make it easy to wriggle out of their old skins. Most lizards shed their skins in small patches. Crocs and other large reptiles have much thicker scales for protection and shedding the entire skin would leave them too vulnerable while the new one hardened. Instead they shed individual scales – a model copied by mammals and birds. It seems overwhelmingly likely that dinosaurs,…

Palaeontologists know that Brachiosaurus had an incredibly long neck, formed of 13 long air-filled neck bones. The neck was flexible and mostly held erect. Due to its colossal size and herbivorous diet, it had to eat a whopping 400kg every day. Once thought to have made its home in water because of the high position of its bony nostril openings, it is now understood that it had nostrils close to the front of its snout and, hence, lived on land. It probably roamed in herds in dry, park-like environments. DID YOU KNOW BRACHIOSAURUS HAD WIDE JAWS AND COULD TAKE HUGE MOUTHFULS OF FOOD WITH EVERY BITE, WHICH WERE MOSTLY SWALLOWED WHOLE FOUND IN USA, Portugal, Algeria, Tanzania FACT FILE MEANING OF NAME: Arm lizard PRONOUNCED: Brak-ee-oh-sore-us SIZE: 30m long, 7m…

Stegosaurus is famed for its two rows of tall, thin plates lining its back that were embedded in the skin above its spine, rather than directly attached to the skeleton itself. Why they evolved is still a bit of a mystery. Most probably they were used for display, but also possibly for controlling body temperature. Stegosaurus used the four sharp spines on its tail tip (collectively called a ‘thagomizer’) to protect itself from attacking predators like Allosaurus and Ceratosaurus. DID YOU KNOW WITH A BODY THE SIZE OF A BUS BUT A BRAIN THE SIZE OF A LIME, STEGOSAURUS HAD ONE OF THE SMALLEST BRAIN-TO-BODY WEIGHT RATIOS OF ALL THE DINOSAURS FOUND IN USA FACT FILE MEANING OF NAME: Roof lizard PRONOUNCED: Steg-oh-sore-us SIZE: 9m long, 2.75m tall, 1,800kg DIET:…

The Mesozoic Era – the vast span of time that extended from 250 to 66 million years ago – is famously described as the ‘Age of Dinosaurs’. It was once thought that these mighty reptiles were able to rule the planet due to sheer brute force alone, but a discovery made over 50 years ago of the earliest large dinosaur known, called Herrerasaurus, would turn this idea on its head. Subsequent fossil finds in recent years have added weight to the argument that the dinosaurs didn’t out-muscle rivals to become the dominant force. Indeed, it now seems that their success was nothing more than a fluke. Discovering how the dinosaur age got started has never been an easy task. Species from the Triassic period at the dawn of the Mesozoic…

With a bite three times stronger than a lion’s, and around 60 saw-edged teeth each measuring up to 20cm long, T. rex could chomp through bone. It hunted some of the largest and most heavily armoured dinosaurs around. But it also scavenged for food – the part of the brain responsible for smell was fairly large, meaning it could sniff out carcasses. Groups of skeletons from close relatives of T. rex have been found, suggesting T. rex might have also hunted in packs. Fossil evidence of bite marks from other tyrannosaurs show they definitely fought one another, competing for food or mates. And there is even some evidence that T. rex indulged in a spot of cannibalism. DID YOU KNOW T. REX COULD RUN AT UP TO 20KM/H (12MPH) –…

Boasting a mix of avian and reptilian characteristics, Archaeopteryx was a cross between a dinosaur and a bird – the crucial evolutionary missing link. Its dinosaur-like features included pointed peg-like teeth and a long bony tail, while it also sported bird-like fight feathers and wide wings. This small carnivore was roughly the size of a raven and feasted on anything from insects to small mammals. Although there is some debate as to whether Archaeopteryx could take to the skies, the general consensus is that it could fly just not very effectively, perhaps employing a range of gliding and flapping motions. DID YOU KNOW ARCHAEOPTERYX IS THE MISSING LINK BETWEEN DINOSAURS AND MODERN-DAY BIRDS, WHICH PROVIDES EVIDENCE THAT BIRDS ARE DESCENDANTS OF DINOSAURS FOUND IN Germany FACT FILE MEANING OF NAME:…

AT THEIR PEAK, HOW MANY DINOSAURS ROAMED EARTH? There could have been around 1,800 different genera of dinosaurs. We can’t directly measure the size of populations because we don’t know what percentage of individuals are preserved in the fossil record. Twenty million bison roamed America in the 18th Century and dinosaurs, being egg layers, could have reproduced faster. Assuming that the availability of plants was the limiting factor, large dinosaurs probably reached comparable population sizes in the Jurassic, 150 million years ago. What dinosaur was found most recently? About 50 new dinosaur species are discovered every year, so that’s roughly one a week. At time of printing, the most recent discovery was Matheronodon provincialis. Discovered in October in the south of France, the herbivore chewed foliage using 6cm-long teeth adapted…

The oldest DNA fragments recovered are only 800,000 years old, so dinosaur cloning is probably impossible. True cloning also requires an intact, living cell and it has only ever been successful using a host animal of the same species. That rules out mammoth cloning too. What we might be able to do is splice some mammoth genes into the DNA of the Asian elephant, their closest relative. Most of the mammoth genome has already been sequenced from fragments recovered from mammoths frozen in permafrost. In 2015, a team at Harvard managed to insert 14 mammoth genes into an elephant cell in a petri dish. But Asian elephants and mammoths are thought to differ by at least 400 genes, and figuring out exactly which ones are different will take a while.…

The two enormous horns protruding from above its eyes and smaller horn from its nose gave Triceratops its name – ‘threehorned face’. But the beast also had a number of pointed bones jutting out from the enormous bony frill that crowned its head. All these weapons were used to battle for mates, like stags when they rut, but also to defend against predators such as ferocious T. rex. The bony frill was probably also used to impress potential mates. Triceratops had a powerful yet toothless beak. At the back of its jaws were great batteries of interlocking, diamond-shaped teeth for rasping and shearing. DID YOU KNOW TRICERATOPS HAD A STAGGERING 800 SHARP TEETH ASSEMBLED IN GROUPS NAMED BATTERIES, WHICH WERE CONTINUOUSLY REPLACED FOUND IN USA FACT FILE MEANING OF NAME:…

0m Seabed. 503m Coring begins. As the focus of the expedition is on the impact crater, the scientists race through the first 500m of limestone before beginning to pull up cores of rock, 3m at a time. 550m Algal blooms. Around 55 million years ago, some 10 million years a!er the asteroid impact, the Earth was around 5°C warmer than at present. Scientists are hoping to recover black shales, the geological remnants of carbon-rich algal blooms predicted to have thrived in the warmer conditions. 550-620m Approaching ground zero. As the drill reaches the top of the impact layer, the ecology is expected to thin out to just a few, rather simple species. By studying the chemical make-up of the very first foraminifera to colonise the site a!er the impact, it…

The small, swift and nimble dinosaur was a lethal predator. It had a long snout and slender jaws, housing 28 dagger-like teeth. An enormous, curved talon on each foot was used to pin down struggling prey – anything from insects to other dinosaurs. When not in use the talon was raised up off the ground. Velociraptor’s body was fully covered in a bird-like plummage. DID YOU KNOW VELOCIRAPTOR WAS 12 TIMES SHORTER THAN T. REX BUT COULD RUN FASTER AT A MAXIMUM SPEED OF 40KM/H (25MPH) FOUND IN Mongolia FACT FILE MEANING OF NAME: Quick plunderer PRONOUNCED: Vel-oss-ee-rap-tor SIZE: 1.8m long, 0.5m tall, 7-15kg DIET: Amphibians, insects, reptiles, mammals, pterosaurs and other dinosaurs (like Protoceratops) WHEN IT LIVED: Late Cretaceous (84-80 million years ago) DISCOVERED BY: Henry F. Osborn in…

HOW TO BRING BACK EXTINCT CREATURES Dinosaurs have captured imaginations for decades, but recreating them is a formidable challenge. Jurassic Park author Michael Crichton suggested getting dino DNA from blood-sucking insects that had been preserved in amber. The good news is that amber (fossilised tree sap) does sometimes contain well-preserved insects. The bad news is we can’t get useful DNA this way. The problem is the half-life of DNA molecules. DNA is a complex, fragile substance. Over time it breaks down, becoming less and less readable. A team from the University of Copenhagen and Murdoch University in Perth found that in 521 years, half of a sample of DNA would be broken into useless fragments, after another 521 years another half and so on. This means that no part of…