Today’s show: “Dinosaurs Among Us” is on view at the American Museum of Natural History in New York through Monday, January 2, 2017. The exhibition “highlights the unbroken line between the charismatic dinosaurs that dominated the planet for about 170 million years and modern birds,” according to a press release.
Mark Dion writes:
This exhibit coveys the amazingly positive news that dinosaurs are alive and well today, embodied by our glorious, earthly cohabitants: the birds.
X-ray studies, including those done by Museum researchers, reveal that baby birds flap their tiny wings to help them climb steep slopes. The force generated by flapping pushes them forward as well as upward, improving traction as they climb. Non-bird dinosaurs might have done the same thing with their mini-wings before flight evolved.
ASHLEY HEERS/BROWN UNIVERSITY XROMM FACILITY
This remarkable fossil of an adult Velociraptor mongoliensis is missing only the end of its tail. This species is a member of the group called theropods, which also includes T. rex and living birds.
These Khaan mckennai dinosaurs are similar to birds in many ways. While these animals are nearly identical, scientists suspect the specimen on the left is a male, based on the presence of large structures beneath its tail that have a triangular, spearheaded shape. Those structures are smaller in the animal on the right, and lack the triangular, or “chevron,” shape, suggesting that the larger structures could have supported the muscles used in a tail-feather display, much like those still put on by birds, including the sage grouse and peacock.
This extraordinary fossil of a Byronosaurus nest, discovered in Mongolia, preserves a recently hatched animal atop the eggs of what would have been its nest mates. The eggs are not paired, suggesting the egg-layer had only one egg tube—the modern bird condition. The tiny animal is a troodontid, which is a group of small, feathered, non-bird dinosaurs with large brains.
Had it hatched, this remarkable fossil embryo of an Oviraptorosaur would have grown into a type of theropod dinosaur. Its head is tucked toward its knees, a position found in embryos today. This dinosaur embryo, a cast of which is in the exhibition, is the first ever found in which the bones were still in place. It often goes by the nickname Baby Louie.
This cast is of a remarkable fossil of an oviraptorid dinosaur, Citipati osmolskae, positioned over the center of its nest with forearms spread to protect its eggs. Today, many birds assume this same position when brooding their eggs. This fossil was discovered by Museum scientists in Mongolia’s Gobi Desert.
The first Citipati osmolskae specimens were discovered by scientists from the American Museum of Natural History and the Mongolian Academy of Sciences in 1993 at Ukhaa Tolgod, Mongolia. In traditional Himalayan Buddhism, Citipati are the dancing skeletons that guard funeral pyres. The name osmolskae honors Halszka Osmólska, a Polish paleontologist who specialized in dinosaurs and was an explorer of the Gobi Desert.
When Archaeopteryx was described in 1861, it caused a sensation. With wings and feathers, it was considered the first bird, although now scientists don’t think it could fly that well. But unlike modern birds, it also had teeth and a bony tail. Discovered not long after Charles Darwin proposed the theory of evolution by means of natural selection, Archaeopteryx provided an example of evolution in action—a fossil that showed the transition between non-avian dinosaurs and birds.
This bizarre, birdlike dinosaur, called Microraptor gui, has feathers on both its front and back limbs. And those rear leg feathers weren’t just decorative; they show adaptations for flight. But could this creature really fly? Probably not far under its own power. But it might have glided down from trees, perhaps even flapping its front limbs.
This giant, flightless bird—Gastornis gigantea—would have been an intimidating opponent. It’s even bigger than a Velociraptor, its not-so-distant relative. But while it might have looked frightening, scientists now think this extinct bird was actually a vegetarian related to ducks and geese.
Khaan mckennai belonged to the group known as oviraptorids: fairly small, birdlike dinosaurs, most with toothless beaks, wishbones, and skulls filled with air pockets. Some have even been found sitting on eggs, in the brooding posture characteristic of modern birds.
Oviraptorosaurs are cousins to T. rex, but closer cousins to modern birds. They are fairly small, birdlike dinosaurs, most with toothless beaks, wishbones, and skulls filled with air pockets. Some have even been found sitting on eggs, in the brooding posture characteristic of modern birds.
Yutyrannus huali, which means “beautiful feathered tyrant,” weighed 1.5 tons and was a fearsome predator like its relative T. rex. It also sported a shaggy coat of filaments called “proto-feathers.” It was discovered in northeastern China in 2012.
Confuciusornis sanctus is considered a bird, not just a birdlike dinosaur. Instead of dinosaur teeth, it has a beak. And instead of a long, bony tail, it has a short, feathered tail. Yet it probably couldn’t fly as well as modern birds, because its breastbone could not support strong wing muscles. Skeletal features like these continued to evolve after birds first appeared.
Lithornis is a close relative of ostriches and emus, but it could fly. It was once thought that large, flightless birds like ostriches were a separate evolutionary group from flying birds. But in fact, all birds alive today—even ostriches, emus, and other hefty ground-dwellers—evolved from smaller, flying birds.
This dinosaur, Juravenator starki, is closely related to other dinosaurs that are completely covered in feathers, but Juravenator has a mix of feathers and scales. Different dinosaur species almost certainly had variable patterns of feathering, just like living birds: think of a flamingo’s legs or a vulture’s head, which have no feathers.
The feathered dinosaur Sinornithosaurus millennii had feathers similar to those of modern birds—even though the animal could not fly. This species was discovered by Chinese and American Museum of Natural History scientists.
This small, horned dinosaur is Psittacosaurus, meaning “parrot lizard.” Scientists initially named this relative of Triceratops for its parrotlike beak; later they found evidence that it had feathery fibers along its tail. These simple fibers are an early stage of feather evolution and have been found on many dinosaurs.
The name of the animal represented by this model, Mei long, means “soundly sleeping dragon,” and the little animal was either covered by an ash fall as it slept or poisoned by toxic gases from a nearby volcano. Fossils preserved in a life pose are rare, and this one looks very similar to that of a sleeping bird.
Dating back 210 million years, Effigia okeeffeae isn’t a dinosaur—it is an archosaur more closely related to crocodiles. Still, scientists think this species, like all archosaurs, had much of the genetic toolkit for producing feathers. That’s because scales and feathers originate from the same type of thickened cells in a developing embryo.
This feathered dinosaur, Anchiornis huxleyi, which lived in what’s now China about 161 million years ago, embodies the gradual transition from non-avian dinosaurs to birds. Its skeleton wasn’t built for powerful flapping, but its feathered limbs could have provided enough lift to run or jump up to high perches, and flap or glide back down again.