Researchers have discovered the earliest known fossil evidence of predatory birds, shedding light on the diverse ecosystem that existed alongside the mighty Triceratops and Tyrannosaurus rex in the Hell Creek Formation of the Dakotas, Montana, and Wyoming. These new species, Avisaurus darwini and Magnusavis ekalakaenis, provide a glimpse into the avian hunters that roamed the same lands as the iconic dinosaurs 68 million years ago.
Revealing The Lethal Talons of Ancient Birds
Almost overnight, the discovery of two new predators from the Hell Creek Formation has captured attention across the scientific community. Only one specimen — and that a single foot bone, but the power-punching foot bone called a tarsometatarsus which would have allowed birds like Avisaurus to snatch prey from the ground before flying it off to dismantle.
Alex Clark, Ph. D the lead author of the study said: According to Peter Makovicky, a Ph. D. student at the Field Museum and the University of Chicago, these fossil ankle bones closely resemble those found today in birds of prey like hawks or owls. Their suits of armor would have given them an appearance not unlike wood chipper-equipped snow plows, with the researchers going on to say that: “from other evidence in their feet bones, we also think these birds could grasp and work a prey similar to what modern day hawk or owl does.” Using a series of biomechanical analyses, the researchers tested this hypothesis by comparing fossilised foot bones with those from different modern birds, which confirmed that these ancient birds were highly skilled hunters.
Adding 40% to Known Avian Diversity of the Hell Creek Formation
What makes the finding of these two birds species especially notable is that they effectively double the number of known bird species from the Hell Creek Formation. This area is one of the best places to discover dinosaur bones in Prodigal Sun fossil Probably the most familiar inhabitants from this region are Triceratops and “everyone’s favorite” Tyrannosaurus rex.
“These discoveries have more than doubled the number of bird species we thought were present in the Hell Creek Formation, providing a much clearer picture of how birds recovered from this extinction event-a recovery that eventually gave us the wonderful assemblage of common birds we know today,” says Jingmai O’Connor, Associate Curator at the Field Museum for fossil reptiles at its Negaunee Integrative Research Center and coauthor on the study.
The avisaurids, including the newly identified species Avisaurus darwini and Magnusavis ekalakaenis, represented a smaller subgroup within the larger enantiornithines. And this lineage of birds may have perished like most of their fellow dinosaurs when an asteroid hit the Earth 66 million years ago.
A single bone holds ecological secrets
The special thing about this discovery is that the researchers knew quite a bit about the lives and hunting styles of these extinct birds, just from one bone: their tarsometatarsus. “Any little groove or hole or bump that happens on a bone can be indicative of where a muscle or tendon attached and how big it was,” says Clark.
The one thing the researchers really caught on to when they studied these fossil bones and the anatomy was this really deep groove called a tubercle – where large muscles would attach – located further down the bone than what’s usually found in most birds. How to Valotarsuut, which allows them to firmly grab and hold prey thus seen in most modern birds of prey.
O’Connor says Clark’s work is impressive as he “has managed to get so much amazing ecological information out of just one bone.” “Each one of these fossils, simple fragments though they may seem, offers us a fascinating glimpse into the ecology of this lost world and the birds that were the undisputed masters of its Cretaceous skies,” said Zanno.
