A recently analyzed near-complete fossil skull found in Antarctica has revealed Vegavis iaai to be the oldest known modern bird, according to a study published in Nature. The fossil, which dates back approximately 68 million years, provides insights into the evolution of modern birds, particularly waterfowl.
The fossil skull was discovered in 2011 during an expedition by the Antarctic Peninsula Paleontology Project and was found encased in rock that dated back 68.4 to 69.2 million years. Researchers from Ohio University analyzed the skull using X-ray micro-computed tomography (µCT) to study its anatomy, according to CNN.
"This fossil underscores that Antarctica has much to tell us about the earliest stages of modern bird evolution," said Professor Patrick O'Connor of Ohio University, a co-author of the study.
Vegavis iaai lived in Antarctica approximately 68.7 million years ago, placing it at the end of the Mesozoic Era, commonly called the age of dinosaurs. At that time, Tyrannosaurus rex dominated North America, providing insights into avian evolution just before the catastrophic event that reshaped life on Earth, according to Live Science.
The new skull of Vegavis iaai exhibits features consistent with modern birds, including a long, pointed beak characterized by the absence of teeth and a reduced maxilla, with a unique bone in the upper beak. It also features a brain shape typical of modern birds, considered unique among all known Mesozoic birds, as stated in Nature.
"Vegavis iaai had a beak suited to fish hunting along with musculature adapted for pursuit diving, like loons and grebes," said Chris Torres, an evolutionary biologist at the University of the Pacific in California and lead author of the study.
The discovery of the skull has helped resolve longstanding debates about the evolutionary position of Vegavis iaai within the bird family tree. Previously, only fragments of Vegavis iaai skulls had been found, preventing scientists from agreeing on what kind of bird it was or whether it was a bird-like, non-avian dinosaur. The new fossil provides the necessary cranial evidence to place Vegavis iaai among modern birds, specifically within waterfowl.
"The new fossil is going to help resolve a lot of those arguments. Chief among them: Where is Vegavis perched in the bird tree of life?" said Torres.
Vegavis iaai appears to have been ecologically specialized to pursue fish and other prey underwater in a shallow marine ecosystem, using its feet to dart underwater and employing strong jaws for snatching fish. This indicates a diving lifestyle similar to that of modern loons and grebes, as reported by The Sun.
Unlike most of today's waterfowl, the Vegavis iaai skull preserves traces of powerful jaw muscles useful for overcoming water resistance while diving to snap up fish, indicating specialization for diving.
Vegavis iaai is considered the oldest evidence of a successful evolutionary development that has spread worldwide, supporting the theory that birds found refuge in ancient Antarctica.
The discovery of Vegavis iaai could finally put a longstanding debate about the origin of modern birds to rest, as it provides new insights into bird evolution, representing the earliest evidence of a now widespread and successful evolutionary radiation across the planet.
Birds were the only dinosaurs to survive the end-Cretaceous mass extinction event, which led to the extinction of about 75 percent of species on Earth, including all nonavian dinosaurs. The survival of Vegavis iaai and its placement among modern birds offer valuable insights into how some avian lineages endured this catastrophic event.
Researchers suspect that Antarctica functioned as a safe haven at the time of the mass extinction 66 million years ago. "Antarctica is in many ways the final frontier for humanity's understanding of life during the Age of Dinosaurs," said Dr. Matthew Lamanna of Carnegie Museum of Natural History.
Vegavis iaai was first reported 20 years ago by Dr. Julia Clarke of The University of Texas at Austin and several colleagues, who proposed it as an early member of modern birds evolutionarily nested within waterfowl.
Fossil evidence suggests that Antarctica had a temperate climate with lush vegetation during the Late Cretaceous Period, possibly serving as an incubator for the earliest members of the group that now includes ducks and geese, providing a refuge for some species.
The article was written with the assistance of a news analysis system.