F Rosa Rubicondior: Creationism in Crisis - Earliest Toothless Bird From 120 Million Years Ago

Wednesday 6 March 2024

Creationism in Crisis - Earliest Toothless Bird From 120 Million Years Ago

Imparavis attenboroughi, a 'strange bird' named after Sir David Attenborough, British broadcaster and naturalist
Fossil named “Attenborough’s strange bird” was the first of its kind without teeth - Field Museum

It seems every week is a bad week for creationists, yet the wackadoodle cult staggers on, albeit with dwindling numbers, managing as always to ignore anything that shows their childish superstition to be wrong.

On top of the recently-reported predatory marine lizard, from 66 million years ago, we now have the earliest bird without the teeth of its enantiornithine ancestors. The enantiornithines were a diverse class of avian dinosaurs that went extinct 66 million years ago following the meteor impact that killed most of the dinosaurs. Only the ornithuromorphs survived, for reasons not completely understood, and they gave rise to all modern birds.

What information do you have on the evolution of the enantiornithines and ornithuromorphs dinosaurs? Enantiornithines and ornithuromorphs are two important groups of birds that evolved during the Mesozoic Era, specifically during the Cretaceous period. Here's an overview of their evolution:
  1. Enantiornithines:
    • Enantiornithines were a diverse group of birds that lived during the Cretaceous period. They are often referred to as "opposite birds" because their shoulder joints were structured differently from modern birds, giving them a somewhat opposite appearance.
    • These birds were globally distributed and occupied various ecological niches, ranging from aquatic to terrestrial habitats.
    • Enantiornithines had teeth and clawed wings, features not present in modern birds. They also lacked a specialized breastbone (sternum) like that of modern birds.
    • Fossil evidence suggests that enantiornithines were quite successful and abundant during the Cretaceous, but they went extinct along with non-avian dinosaurs at the end of the Cretaceous period, about 66 million years ago.
  2. Ornithuromorphs:
    • Ornithuromorphs are another group of birds that lived during the Cretaceous period. They are considered more closely related to modern birds than enantiornithines.
    • Unlike enantiornithines, ornithuromorphs had a keeled sternum, similar to modern birds, which likely provided a more efficient attachment for flight muscles.
    • Ornithuromorphs also had a toothless beak, indicating a more specialized diet compared to enantiornithines.
    • Fossil evidence suggests that ornithuromorphs evolved diverse body forms and lifestyles, including some species that were capable of powered flight over long distances.
    • Ornithuromorphs survived the mass extinction event at the end of the Cretaceous period and are believed to be the ancestors of modern birds.
The evolution of both enantiornithines and ornithuromorphs represents important stages in the development of avian diversity and flight adaptation. While enantiornithines represent an early radiation of avian forms that ultimately went extinct, ornithuromorphs are thought to have given rise to the lineage that led to modern birds. Further discoveries and research continue to refine our understanding of the evolutionary relationships between these ancient birds and their modern descendants.
The team of palaeontologists, which included researchers from the Field Museum, University of Chicago, IL, USA and the Institute of Geology and Paleontology, Linyi University, Linyi, China, who discovered this early bird have published their results in Cretaceous Research and explain it in a Field Museum news release:
No birds alive today have teeth. But that wasn’t always the case—many early fossil birds had beaks full of sharp, tiny teeth. In a paper in the journal Cretaceous Research, scientists have described a new species of fossil bird that was the first of its kind to evolve toothless-ness; its name, in honor of naturalist Sir David Attenborough, means “Attenborough’s strange bird.”

It is a great honour to have one’s name attached to a fossil, particularly one as spectacular and important as this. It seems the history of birds is more complex than we knew

Sir David Attenborough.

All birds are dinosaurs, but not all dinosaurs fall into the specialized type of dinosaurs known as birds, sort of like how all squares are rectangles, but not all rectangles are squares. The newly described Imparavis attenboroughi is a bird, and therefore, also a dinosaur.

Imparavis attenboroughi was a member of a group of birds called enantiornithines, or “opposite birds,” named for a feature in their shoulder joints that is “opposite” from what’s seen in modern birds. Enantiornithines were once the most diverse group of birds, but they went extinct 66 million years ago following the meteor impact that killed most of the dinosaurs. Scientists are still working to figure out why the enantiornithines went extinct and the ornithuromorphs, the group that gave rise to modern birds, survived.

Enantiornithines are very weird. Most of them had teeth and still had clawed digits. If you were to go back in time 120 million years in northeastern China and walk around, you might have seen something that looked like a robin or a cardinal, but then it would open its mouth, and it would be filled with teeth, and it would raise its wing, and you would realize that it had little fingers.

[But] Attenborough’s strange bird [bucked this trend]. Scientists previously thought that the first record of toothlessness in this group was about 72 million years ago, in the late Cretaceous. This little guy, Imparavis, pushes that back by about 48 to 50 million years. So toothlessness, or edentulism, evolved much earlier in this group than we thought.

Alexander D. Clark, corresponding author.
Committee on Evolutionary Biology
University of Chicago, Chicago, IL, USA.

The specimen was found by an amateur fossil collector near the village of Toudaoyingzi in northeastern China and donated to the Shandong Tianyu Museum of Nature. Clark’s advisor and co-author on the paper, Field Museum associate curator of fossil reptiles Jingmai O’Connor, first noticed something unusual about this fossil several years ago, when she was visiting the Shandong Tianyu Museum’s collections.

I think what drew me to the specimen wasn’t its lack of teeth—it was its forelimbs. It had a giant bicipital crest—a bony process jutting out at the top of the upper arm bone, where muscles attach. I’d seen crests like that in Late Cretaceous birds, but not in the Early Cretaceous like this one. That’s when I first suspected it might be a new species.

Jingmai K. O'Connor, co-author
Negaunee Integrative Resource Center
Field Museum of Natural History
Chicago, IL, USA.
O’Connor, Clark, and their coauthors in China, Xiaoli Wang, Xiangyu Zhang, Xing Wang, Xiaoting Zheng, and Zhonghe Zhou, undertook further study of the specimen and determined that it did indeed represent an animal new to science.

The unusual wing bones could have allowed for muscle attachments that let this bird flap its wings with extra power.

We’re potentially looking at really strong wing beats. Some features of the bones resemble those of modern birds like puffins or murres, which can flap crazy fast, or quails and pheasants, which are stout little birds but produce enough power to launch nearly vertically at a moment’s notice when threatened.

Alexander D. Clark.

Meanwhile, the bird’s toothless beak doesn’t necessarily tell scientists what it was eating, since modern toothless birds have a wide variety of diets. Like its fellow enantiornithines, and unlike modern birds, it does not appear to have a digestive organ called a gizzard, or gastric mill, that helped it crush up its food.

While Clark notes that “an animal is more than the sum of its parts, and we can’t fully know what an animal’s life was like just by looking at single components of its body,” he and his coauthors have been able to hypothesize about some of Imparavis’s behavior and ecology, based on the details of its wings, feet, and beak together. “I like to think of these guys kind of acting like modern robins. They can perch in trees just fine, but for the most part, you see them foraging on the ground, hopping around and walking,” says Clark.

It seems like most enantiornithines were pretty arboreal, but the differences in the forelimb structure of Imparavis suggests that even though it's still probably lived in the trees, it maybe ventured down to the ground to feed, and that might mean it had a unique diet compared to other enantiornithines, which also might explain why it lost its teeth.

Jingmai K. O'Connor

In the paper, the researchers also revisited a previously described fossil bird, Chiappeavis (which O’Connor named eight years ago after her PhD advisor), and suggest that it too was an early toothless enantiornithine. This finding, along with Imparavis, indicates that toothlessness may not have been quite as unique in Early Cretaceous enantiornithines as previously thought.

Clark said that nature documentaries by Sir David Attenborough, in which the renowned British naturalist narrates the behavior of different animals, were pivotal to his own interest in science. "I most likely wouldn't be in the natural sciences if it weren’t for David Attenborough’s documentaries,” says Clark, explaining why he chose to name the new fossil after Attenborough.

Clark and O’Connor noted the importance of Attenborough’s messaging that not only celebrates life on earth, but also warns against the mass extinction the planet is undergoing due to human-caused climate change and habitat destruction.

Learning about enantiornithines like Imparavis attenboroughi helps us understand why they went extinct and why modern birds survived, which is really important for understanding the sixth mass extinction that we’re in now. The biggest crisis humanity is facing is the sixth mass extinction, and paleontology provides the only evidence we have for how organisms respond to environmental changes and how animals respond to the stress of other organisms going extinct.

Jingmai K. O'Connor

Among Mesozoic birds, enantiornithines exhibit great morphological variation, which likely reflects their species diversity, range, and overall success throughout the Cretaceous. The majority of enantiornithines come from the Lower Cretaceous Jehol deposits (130–120 Ma) in northeastern China. In contrast to living birds, most enantiornithines were fully toothed. However, the rostral lengths, appendicular proportions, and pedal morphologies of extant birds can still inform on possible diet, flight mode, and ecology. Both partial (e.g., Longipterygidae) and complete tooth loss (e.g., Yuornis, Gobipteryx) are observed among enantiornithines, with edentulous rostra previously restricted to Upper Cretaceous taxa. Here, we describe the first edentulous enantiornithine from the Lower Cretaceous, Imparavis attenboroughi gen. et sp. nov., indicating a toothless beak evolved in this group 48 Ma earlier than previously recognized. Additionally, we reinterpret Chiappeavis as edentulous which together with the discovery of Imparavis indicates the complete loss of teeth in enantiornithines was not uncommon although still less frequent than observed in ornithuromorphs. The absence of gastroliths in all known enantiornithines suggests that the loss of teeth evolved under different pressures in these two ornithothoracine clades. Differences in rostral occlusion between Imparavis and Chiappeavis suggest they utilized different foraging strategies and possibly diet. Appendicular morphology in Imparavis suggest the capacity for relatively high wing beat frequency and powerful take-off capabilities. Together with the morphology of the hindlimb, we suggest Imparavis was primarily a terrestrial forager that could utilize sudden bursts of flight to escape into arboreal settings as a prey evasion strategy.

So much more interesting an informative about the origins of life on Earth today, than putting your hands over your eyes and ears, diving into the creationist cult rabbit hole and eschewing learning in order to retain a childish belief in magic, in case an invisible mind-reading sky thug gets angry if you know too much.

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