In 1890, the fossil-hunter Othniel Charles Marsh described a new species of dinosaur from Colorado. He only had a foot and part of a hand to go on, but they were so bird-like that Marsh called the beast Ornithomimus – the bird mimic. As the rest of Ornithomimus’ skeleton was later discovered, Marsh’s description seemed more and more apt. It ran on two legs, and had a beaked, toothless mouth. Despite the long tail and grasping arms, it vaguely resembled an ostrich, and it lent its name to an entire family – the ornithomimids—which are colloquially known as “ostrich dinosaurs”.
Now, the bird mimic has become even more bird-like. By analysing two new specimens, and poring over an old famous one, Darla Zelenitsky from the University of Calgary has found evidence that Ornithomimus had feathers. And not just simple filaments, but wings – fans of long feathers splaying from the arms of adults. (More technically, it had “pennibrachia” – a word for wing-like arms that couldn’t be used to glide or fly.)
Yutyrannus, by Brian Choo
Meet the largest feathered animal in history – an early version of Tyrannosaurus rex, clad in long, fuzzy filaments. This newly discovered beast has been named Yutyrannus huali, a mix of Mandarin and Latin that means “beautiful feathered tyrant”. And its existence re-opens a debate about whether the iconic T.rex might have been covered in feathers.
“This is a tremendously important fossil. Paleontologists have been waiting for a gigantic feathered theropod to turn up for some time,” says Lindsay Zanno from the Field Museum. Larry Witmer from Ohio University, agrees. “The big thing is the one-two punch of being huge AND feathered,” he says.
For the longest time, artists could only speculate about what dinosaurs looked like. Sure, we could reconstruct their silhouettes from their bones, but the colour of their skin was a mystery. That’s not quite true anymore. Thanks to some well preserved fossils and some ingenuous detective work, scientists have started to assign the right palettes to these prehistoric reptiles.
The latest species to get this treatment is Microraptor. This Chinese dinosaur was about the size of a crow. Its body was covered in feathers. Long plumes on both its arms and legs gave it a distinctive four-winged, baggy-trousered look, and may have allowed it to glide or fly. And thanks to a new study by Quanguo Li form the Beijing Museum of Natural History, we know that Microraptor was probably black and certainly shiny.
It was a iridescent dinosaur, with the same metallic sheen that you see on today’s hummingbirds, peacocks, and swallows. If you travelled back in time and stumbled across Microraptor, you might think that you’d found a Cretaceous starling.
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.”
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.
The eleven specimens of Archaeopteryx are some of the most iconic and captivating fossils in existence. The fingers end in claws, the tail is long and bony, and the head – arched back in the throes of death – contains toothed jaws. But the splayed arms are lined with the faint but unmistakeable outlines of feathers. This was an animal halfway between a small flesh-eating dinosaur and a modern bird. In fact, Archaeopteryx is widely heralded as the first bird, occupying a pivotal position in the origins of this group.
But Xing Xu from Linyi University thinks that this first bird was nothing of the sort. The Chinese palaeontologist, who has found one fascinating dinosaur after another, has identified a new species called Xiaotingia that threatens to oust Archaeopteryx from its position.
By comparing Xiaotingia’s features with those of Archaeopteryx and other related birds and dinosaurs, Xu has drawn up a new family tree (see slideshow below). In it, Archaeopteryx sits with Xiaotingia among the deinonychosaurs, a celebrity-filled group of small, predatory dinosaurs that includes Deinonychus and Velociraptor. The lineage that led to modern birds perches on a different branch of the tree.
Dinosaur bodies are covered in all sorts of spikes, horns, plates that were used for defence, combat and identification. But sometimes, these body parts are so bizarre that their purpose is a mystery. The latest in these strange projections belongs to Concavenator, a new giant predator with two spikes sticking up from the vertebrae just in front of its hips. They would probably have given the dinosaur a strange hump on its back.
Meet Archaeopteryx, one of the most primitive of all birds. It beautifully illustrates the transition between small predatory dinosaurs and their bird descendants. It has toothed jaws and three clawed fingers on each hand, but it also had broad wings with well-developed flight feathers. Like those of modern birds, these feathers had two asymmetrical vanes coming off a central shaft or ‘rachis’.
But despite this striking resemblance, Archaeopteryx’s feathers differed from those of modern birds in a critical way. Robert Nudds from the University of Manchester and Gareth Dyke from University College Dublin have found that they were thinner and weaker than today’s feathers. If this early bird had tried the same flapping flight that its descendants do so effortlessly, its feathers would have buckled under the stress. It seems that this pioneer among birds wasn’t a very good flier.
Since its discovery, palaeontologists have argued about Archaeopteryx’s flying abilities. Sure, the animal had broad wings and sophisticated feathers. Its skull had an inner ear that resembled that of modern birds, suggesting that it had the coordination necessary for flight. It also lacked the bony breastbone that the larger flight muscles of modern birds attach to but those muscles could equally have attached elsewhere. Perhaps more compellingly, its shoulder joint would have prevented it from lifting its wings far enough to carry out a full upstroke.
Enter Nudds and Dyke. They studied the feathers of two of the earliest birds – Archaeopteryx, which lived around 145 million years ago in the Late Jurassic, and Confuciusornis, which lived 120 million years ago in the Early Cretaceous.
At the Chinese Academy of Sciences, Xing Xu is looking at two beautiful dinosaur fossils, both with clear feathers on their arms and tails. In the smaller specimen, the feathers are like thin ribbons at their base and quills at their tips (with vanes coming off a central shaft). The larger specimen is different – its arm and tail feathers are like quills across their entire length.
With such different feather structures, you might assume that these animals belonged to different species, but you’d be wrong. They’re actually different life stages of the same animal – Similicaudipteryx. Both are youngsters, but the one with the quill-like feathers is an older version of the one with the ribbons. Together, they demonstrate that the feather of some dinosaurs changed dramatically as they grew older, in a way that we don’t see in any modern bird.
By now, readers of this blog should be familiar with the idea of feathered dinosaurs (and, indeed, Xing Xu has discovered many of them). A spectacular series of fossils have revealed a wide range of plumes in a wide range of species, and we even know something about their colour. But we still know very little about how these feathers developed as the animals matured, because fossils of young feathered dinosaurs are few and far between. So for Xu to find two, and two of the same species no less, is a real treat.
Both hailed from Liaoning province of China (where else?), and based on their skulls, spines and hips, Xu has confidently classified them both as Similicaudipteryx, a small predator from the oviraptosaur group. Both animals are clearly youngsters. Although one is larger than the other, they’re both smaller than adult specimens of the same dinosaurs, and some of their bones haven’t fused completely yet.
The younger animal (a-c below) has downy feathers over much of its back and hips. Elsewhere, it has larger pennaceous feathers (with a shaft and vanes) – 10 on each arm, and 11 much larger ones on its tail. All of these are ribbon-like at the base and quill-like at the tips. The more senior juvenile (d-f below) also had downy feathers on its head, back and hips but its pennaceous feathers are very different to its younger peer. Each arm has 10 primary feathers and 12 secondary ones, and the tail had at least 12 pairs. All of them are quill-like from base to tip and the arm feathers are just as long as the tail ones.