The avian world we know today is dominated by birds with beaks. But delve into the distant past, and you’ll encounter a fascinating lineage – early birds with a mouthful of sharp, tiny teeth. A recent discovery, however, has rewritten the narrative of bird evolution. Described in the journal Cretaceous Research, scientists have identified a new species, the first of its kind to shed its teeth – aptly named “Attenborough’s strange bird” in honor of Sir David Attenborough.
“Having a fossil named after me is a tremendous honor, especially one as extraordinary and significant as this,” says Sir David Attenborough, whose documentaries have captivated audiences for decades. “This discovery reveals that the history of birds is far more intricate than we previously understood.”
Let’s untangle the complexities. All birds are, in fact, dinosaurs, but not all dinosaurs qualify as birds – similar to how all squares are rectangles, but not all rectangles are squares. The newly described Imparavis attenboroughi belongs to the bird category, and therefore, is also a dinosaur.
Imparavis attenboroughi falls under the group of enantiornithines, or “opposite birds,” named for a unique shoulder joint feature. Once the most diverse bird group, they vanished 66 million years ago alongside most dinosaurs due to a catastrophic meteor impact. Paleontologists are still piecing together the puzzle – why did enantiornithines meet their demise, while ornithuromorphs, the ancestors of modern birds, thrived?
“Enantiornithines were quite bizarre creatures,” explains Alex Clark, the study’s lead author and a Ph.D. student at the University of Chicago and the Field Museum. “Most had teeth and even sported clawed digits. Imagine traveling 120 million years back to northeastern China. You might encounter a bird resembling a robin, but upon opening its mouth, you’d be greeted by a mouthful of teeth! Raise its wing, and surprise – tiny fingers!”
But “Attenborough’s strange bird” defied these norms.
“Previously, the earliest evidence of toothlessness in this group dated back to the Late Cretaceous period, around 72 million years ago. Imparavis pushes that date back a staggering 48-50 million years, indicating that toothlessness, or edentulism, emerged much earlier than we anticipated,” explains Clark.
The specimen, unearthed by an amateur fossil collector near a village in China, eventually landed in the Shandong Tianyu Museum of Nature. It was there that Jingmai O’Connor, Clark’s advisor and co-author on the paper, first spotted something unusual about the fossil several years ago.
“The lack of teeth wasn’t the initial giveaway,” recalls O’Connor, an associate curator of fossil reptiles at the Field Museum. “It was the forelimbs. The upper arm bone had a prominent bicipital crest, a bony projection where muscles attach. I’d seen similar crests in Late Cretaceous birds, but not in Early Cretaceous ones like this. That’s when I suspected we might be dealing with a new species.”
A closer examination by O’Connor, Clark, and their collaborators in China confirmed their hunch – this was indeed a novel discovery.
These unique wing bones hint at powerful muscles, potentially enabling the bird for vigorous wing flapping.
“We might be looking at exceptionally strong wing beats,” suggests Clark. “Some features resemble those of modern birds like puffins or murres, known for their rapid wing flapping, or quails and pheasants, which are compact birds capable of near-vertical takeoffs when threatened.”
The toothless beak, however, remains an enigma when it comes to diet, as modern toothless birds exhibit diverse dietary habits. Unlike their modern counterparts, Imparavis appears to have lacked a gizzard, a digestive organ used for grinding food.
“While a single fossil can’t tell the whole story,” says Clark, “by analyzing the wings, feet, and beak together, we can make some educated guesses about Imparavis’s behavior and ecological niche.”
“They might have behaved similarly to robins – comfortable perching on trees but primarily foraging on the ground, hopping and walking around,” Clark speculates.
“Most enantiornithines were likely tree-dwellers,” O’Connor adds. “However, the distinct forelimb structure of Imparavis suggests that while it probably still inhabited trees, it might have ventured to the ground for food. This unique diet could explain the loss of teeth compared to other enantiornithines.”
The study also revisits a previously described fossil bird, Chiappeavis (named by O’Connor after her Ph.D. advisor), suggesting it too might have been an early toothless enantiornithine. This finding, along with Imparavis, indicates that toothlessness in Early Cretaceous enantiornithines might have been more widespread than previously thought.
Clark expresses his deep gratitude towards Sir David Attenborough’s nature documentaries, crediting them for sparking his passion for science. “Documentaries narrated by Sir David Attenborough significantly influenced my decision to pursue a career in natural sciences,” he acknowledges. This sentiment extends beyond personal impact – Clark and O’Connor recognize the broader message Attenborough conveys: the importance of appreciating the wonders of life on Earth while urging action against the current mass extinction crisis driven by human activity.
“Understanding creatures like Imparavis attenboroughi sheds light on the factors that might have led to the demise of enantiornithines and the survival of modern birds,” explains O’Connor. “This knowledge is crucial in comprehending the sixth mass extinction event we currently face. Paleontology offers the only window into how organisms respond to environmental changes and the ripple effects of extinction events.”
The discovery of Imparavis attenboroughi isn’t merely about filling a gap in the fossil record; it’s a testament to the power of curiosity and collaboration. It compels us to reimagine the diversity of early bird life and underscores the importance of safeguarding the incredible biodiversity we have today.
Source: Field Museum