By Jonny Lupsha, Wondrium Staff Writer
The closest living relatives to dinosaurs aren’t lizards, but birds. In even simpler terms, it’s often said that birds are dinosaurs. A new Wondrium series shines a light on their link.
Scientists make use of cladistics, a method of biologically associating animals based on latest common ancestors and common characteristics. When they make cladistic analyses of birds, they find that the avian world lies deep within dinosauria. Of course, this understanding came about in a backward fashion, since dinosaurs were discovered and studied far more recently than birds.
For example, much like birds, some dinosaurs had feathers and wings, which biologists had considered exclusively traits of birds, until that point.
How was the link between birds and dinosaurs established? In her video series Rediscovering the Age of Dinosaurs, Dr. Kristi Curry Rogers, Professor of Biology and Geology at Macalester College, takes viewers back to the dinosaur that changed the world: Archaeopteryx.
Why Did the Discovery of Archaeopteryx Matter?
“One of the predictions that Charles Darwin made about evolution by natural selection was that, if his theory was correct, we should find ‘transitional forms’ in the fossil record—creatures that could not easily fit into existing taxonomic categories because they exhibited characteristics of more than one group,” Dr. Rogers said. “Just two years after Darwin’s publication of Origin of Species, just such a specimen was uncovered at the Jurassic-aged Solnhofen limestone Lagerstätte.”
Archaeologists first found a single fossilized feather preserved as a carbonized impression. It led to the unearthing of an entire skeleton that had a reptile’s toothed skull and long bony tail, but a bird’s wings and feathers. It was dubbed Archaeopteryx, meaning “ancient wing.”
However, this new skeleton—and the several other Archaeopteryx finds that followed it over the next century—lacked the bird’s furcula, more commonly known as the wishbone. Theropod dinosaurs also lacked a furcula. This caused many to believe that dinosaurs were all overgrown, slow-moving, cold-blooded reptiles—until the 1960s, when a Yale paleontologist named John Ostrom turned the dinosaur world on its ear.
How Did the Dinosaur Renaissance Happen?
“One afternoon in late August 1964, John was prospecting for fossils in the Cloverly Formation, an outcrop of Early Cretaceous sedimentary rocks in southern Montana,” Dr. Rogers said. “Eyes to the ground, suddenly Ostrom and his assistant, Grant E. Meyer, noticed a black, shiny bone sticking out from the rocky slope a few feet below them. They slid down to the bone-bearing horizon and realized that they were seeing a large, sharp-clawed dinosaur hand!”
Ostrom and Meyer had unearthed a three-toed theropod dinosaur with a large, sickle-shaped toe, which came to be known as Deinonychus. In 1969, Ostrom published his findings, abandoning the “cold-blooded dino” stereotype and suggesting instead that dinosaurs were fleet-footed, agile, highly mobile animals.
“One of the undergraduate student members of the 1964 expedition, a young paleontologist named Robert Bakker, contributed a drawing to accompany Ostrom’s paper,” Dr. Rogers said. “The illustration depicted Deinonychus in full sprint, with its ‘terrible claw’ uplifted and its sharp-clawed hands curled, ready for grasping prey.
“The discovery, the paper, and the imagery would launch a revolution in dinosaur biology that we paleontologists call the Dinosaur Renaissance.”
Rediscovering the Age of Dinosaurs is now available to stream on Wondrium.