by LAUREN RUESINK '18
A mammoth asteroid plummets through Earth’s atmosphere, a searing ball of iron, gold, platinum, and other precious metals. Goliath plumes of smoke and dust suffocate the sun; forest fires consume the world’s devastated landscape. 65 million years ago, in that wink of time, half of Earth’s species went extinct, among them the dinosaurs. Or so the story went, until scientists discovered that thousands of known dinosaur species must have had feathers.One of the most groundbreaking among these species is the Yutyrannus huali, whose discovery challenges the popular image of its close relative, the Tyrannosaurus rex, as a great, green, scaly lizard.
In light of these discoveries, paleontologists have put together an exhibit at The American Museum of Natural History in New York bringing to life the dinosaurs among us. Instead of perishing in the Jurassic Period’s mass extinction, a new theory suggests that dinosaurs, most specifically theropods, developed larger brains and shrunk in body size to become what is known today as the bird. Following this basis, birds are in no way separate from dinosaurs, but are rather their posterity.
This rendering of an Anchiornis huxleyi is an example of just one of many species that support this theory. While it wouldn’t have been capable of long-distance flight, it could have used its wings for gliding.
It closely resembles the hoatzin, a modern-day bird found in the Amazon.
The hoatzin’s young may be the world’s greatest flashback to the Cretaceous. Chicks are born with claws used to grip branches, which at the very least make them a missing link between dinosaurs and avians. This feature, including muscle attachments and its skeletal structure, call to mind the species that opened the conversation about the relation between birds and dinosaurs: the Archaeopteryx.
In many ways, the Archaeopteryx is a classic example of evolution. Chances are if you’ve taken biology, you’ve heard about it, even if you don’t remember how its name is spelt. The size of a raven, it possessed flight-feathers, but also had sharp teeth, clawed fingers, and a long bony tail, similar to its theropod ancestors. These characteristics make it a missing link between birds and dinosaurs, and for a while, scientists thought that the Archaeopteryx provided the only solid connection between these two groups, but recent discoveries, especially in the Liaoning Province of China, have revealed a vast host of other species that blur the line between bird and dinosaur, like the Microraptor and Sinornithosaurus.
In fact, some scientists believe that all dinosaurs had some form of feathers, even if some species’ feathers were less visible than others’. For instance, all mammals possess hair, but it is much easier to point out a monkey’s fur than the thin hairs on a dolphin. Even with birds, feathers can be multifunctional, useful for thermoregulation, attracting a mate, and waterproofing as well as flight.
The titanosaur, the elephant amongst dinosaurs, is now suspected to have had feathers as well, although these feathers would have been too small to be preserved in the fossil record. The Psittacosaurus, otherwise known as the parrot lizard and a close relative of the triceratops, is a certain example of a sparsely feathered dinosaur, having a thin row of feathers at the front of its tail.
The striking similarities between birds and dinosaurs do not stop at feathers, however, but stretch into their parental behavior. Most birds are noted as being exceptionally good parents. The majority of them are monogamous and raising chicks is a cooperative effort that each parent invests much time and energy into. Depicted below is a brooding bald eagle in Decorah, Iowa.
While one parent remains at the nest to protect the offspring from predators and the harsh environment, the other hunts. The parents will continue to care for the chicks until they have grown their flight feathers and are able to depart from the nest on their own. It is this behavior that inspired the age-old adage “empty nest.”
A newly-discovered fossil suggests that at least some dinosaurs behaved in a similar way when raising their young. With its forelimbs outstretched over a nest, the Citipati, situated in the center of the fossil, suggests that she was brooding her young, just as eagles and most other birds do today.
These discoveries are already pushing the limits of what we once thought we knew about evolution, but as paleontologists further digest them and unearth even more supporting evidence, the bounds of avian evolution may be completely shattered. Scientists have reached a general consensus that dinosaurs and birds share more similarities than dinosaurs or birds share with anything else. While this may be a setback for pop culture, which seems to devour green scaly scary dinosaurs, it may just be the recognition dinosaurs have awaited for centuries. They aren’t extinct. They’re perched in the trees in your backyard, singing in the morning, and soaring overhead.
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