Evolving “Backward” – Discovery Overturns More Than a Century of Knowledge About the Origin of Modern Birds

Artist’s Reconstruction of Janavis finalidens

Artist’s reconstruction of the last known toothed bird, Janavis finalidens, in its original environment surrounded by the co-occurring ‘wonderchicken’, Asteriornis. 66.7 million years ago parts of Belgium were covered by a shallow sea, and conditions were similar to modern tropical beaches in places like the Bahamas. Janavis was a very large marine bird, with long wings and teeth in its jaws. It would have hunted fish and squid-like creatures in the tropical sea. Credit: Phillip Krzeminski

Fossilized remains of a skeleton found within a small rock have challenged a long-held belief about the evolution of modern birds.

A team of researchers from the University of Cambridge and the Natuurhistorisch Museum Maastricht discovered that a crucial skull feature of modern birds, the mobile beak, had developed prior to the mass extinction event that wiped out the dinosaurs 66 million years ago.

This finding also suggests that the skulls of ostriches, emus and their relatives evolved ‘backward’, reverting to a more primitive condition after modern birds arose.

Using CT scanning techniques, the Cambridge team identified bones from the palate, or the roof of the mouth, of a new species of large ancient bird, which they named Janavis finalidens. It lived at the very end of the Age of Dinosaurs and was one of the last-toothed birds to ever live. The arrangement of its palate bones shows that this ‘dino-bird’ had a mobile, dexterous beak, almost indistinguishable from that of most modern birds.

Video showing the rotating pterygoid (a palate bone) of Janavis finalidens, which is very similar to that of living duck- and chicken-like birds. The bone was found as two matching fragments, which have been digitally fitted together. The bone is hollow and was likely full of air in life, as shown by the large opening on its side. Credit: Dr. Juan Benito and Dr. Daniel Field, University of Cambridge

For more than a century, it had been assumed that the mechanism enabling a mobile beak evolved after the extinction of the dinosaurs. However, the new discovery, reported in the journal Nature, suggests that our understanding of how the modern bird skull came to be needs to be re-evaluated.

Each of the roughly 11,000 species of birds on Earth today is classified into one of two over-arching groups, based on the arrangement of their palate bones. Ostriches, emus, and their relatives are classified into the palaeognath, or ‘ancient jaw’ group, meaning that, like humans, their palate bones are fused together into a solid mass.

Pterygoid Comparision

Palate of Janavis finalidens in comparison with that of a pheasant and an ostrich. The palate anatomy of Janavis likely approximates that of the most recent common ancestor of all living birds and is more similar to that of chicken- and duck-like birds, such as pheasants, than to birds like ostriches and emus, which were previously thought to exhibit the ancestral bird condition. Credit: Juan Benito and Daniel Field, University of Cambridge

All other groups of birds are classified into the neognath, or ‘modern jaw’ group, meaning that their palate bones are connected by a mobile joint. This makes their beaks much more dexterous, and helpful for nest-building, grooming, food-gathering, and defense.

The two groups were originally classified by Thomas Huxley, the British biologist known as ‘Darwin’s Bulldog’ for his vocal support of Charles Darwin’s theory of evolution. In 1867, he divided all living birds into either the ‘ancient’ or ‘modern’ jaw groups. Huxley’s assumption was that the ‘ancient’ jaw configuration was the original condition for modern birds, with the ‘modern’ jaw arising later.

“This assumption has been taken as a given ever since,” said Dr. Daniel Field from Cambridge’s Department of Earth Sciences, the paper’s senior author. “The main reason this assumption has lasted is that we haven’t had any well-preserved fossil bird palates from the period when modern birds originated.”

Janavis Bird

Artist’s reconstruction of the world’s last known toothed bird, Janavis finalidens. This reconstruction is based on the original fossil bones of Janavis and comparisons with its close relative Ichthyornis, as well as inspiration from modern marine birds such as gulls and petrels. Janavis was a large marine bird with long wings and teeth in its jaws and would have hunted for fish and squid in warm Late Cretaceous seas. Credit: Phillip Krzeminski

The fossil, Janavis, was found in a limestone quarry near the Belgian-Dutch border in the 1990s and was first studied in 2002. It dates from 66.7 million years ago, during the last days of the dinosaurs. Since the fossil is encased in rock, scientists at the time could only base their descriptions on what they could see from the outside. They described the bits of bone sticking out from the rock as fragments of skull and shoulder bones and put the unremarkable-looking fossil back in storage.

Nearly 20 years later, the fossil was loaned to Field’s group in Cambridge, and Dr. Juan Benito, then a Ph.D. student, started giving it another look.

“Since this fossil was first described, we’ve started using CT scanning on fossils, which enables us to see through the rock and view the entire fossil,” said Benito, now a postdoctoral researcher at Cambridge, and the paper’s lead author. “We had high hopes for this fossil – it was originally said to have skull material, which isn’t often preserved, but we couldn’t see anything that looked like it came from a skull in our CT scans, so we gave up and put the fossil aside.”

During the early days of the Covid-19 lockdown, Benito took the fossil out again. “The earlier descriptions of the fossil just didn’t make sense – there was a bone I was really puzzled by. I couldn’t see how what was first described as a shoulder bone could actually be a shoulder bone,” he said.

“It was my first in-person interaction in months: Juan and I had a socially distanced outdoor meeting, and he passed the mystery fossil bone to me,” said Field, who is also the Curator of Ornithology at Cambridge’s Museum of Zoology. “I could see it wasn’t a shoulder bone, but there was something familiar about it.”

“Then we realized we’d seen a similar bone before, in a turkey skull,” said Benito. “And because of the research we do at Cambridge, we happen to have things like turkey skulls in our lab, so we brought one out and the two bones were almost identical.”

The realization that the bone was a skull bone, and not a shoulder bone, led the researchers to conclude that the unfused ‘modern jaw’ condition, which turkeys share, evolved before the ‘ancient jaw’ condition of ostriches and their relatives. For an unknown reason, the fused palates of ostriches and kin must have evolved at some point after modern birds were already established.

Two of the key characteristics we use to differentiate modern birds from their dinosaur ancestors are a toothless beak and a mobile upper jaw. While Janavis finalidens still had teeth, making it a pre-modern bird, its jaw structure is that of the modern, mobile kind.

“Using geometric analyses, we were able to show that the shape of the fossil palate bone was extremely similar to those of living chickens and ducks,” said Pei-Chen Kuo, a co-author of the study. Added co-author Klara Widrig: “Surprisingly, the bird palate bones that are the least similar to that of Janavis are from ostriches and their kin.” Both Kuo and Widrig are Ph.D. students in Field’s lab at Cambridge.

“Evolution doesn’t happen in a straight line,” said Field. “This fossil shows that the mobile beak – a condition we had always thought post-dated the origin of modern birds, actually evolved before modern birds existed. We’ve been completely backward in our assumptions of how the modern bird skull evolved for well over a century.”

The researchers say that while this discovery does not mean that the entire bird family tree needs to be redrawn, it does rewrite our understanding of a key evolutionary feature of modern birds.

And what happened to Janavis? It, like the large dinosaurs and other toothed birds, did not survive the mass extinction event at the end of the Cretaceous period. The researchers say that this may be because of its large size: Janavis weighed around 1.5 kilograms and was the size of a modern vulture. It’s likely that smaller animals – like the ‘wonderchicken’, identified by Field, Benito, and colleagues in 2020, which comes from the same area and lived alongside Janavis – had an advantage at this point in Earth’s history since they had to eat less to survive. This would have been beneficial after the asteroid struck the Earth and disrupted global food chains.

Reference: “Cretaceous ornithurine supports a neognathous crown bird ancestor” by Juan Benito, Pei-Chen Kuo, Klara E. Widrig, John W. M. Jagt and Daniel J. Field, 30 November 2022, Nature.
DOI: 10.1038/s41586-022-05445-y

The study was funded by the by the American Ornithological Society, the Jurassic Foundation, the Paleontological Society, and UK Research and Innovation (UKRI).

10 Comments on "Evolving “Backward” – Discovery Overturns More Than a Century of Knowledge About the Origin of Modern Birds"

  1. “It’s likely that smaller animals … had an advantage at this point in Earth’s history since they had to eat less to survive.”

    That is an interesting speculation because small animals often have a very high metabolic rate to generate heat to compensate for the relatively high surface area to volume. They burn calories rapidly, consuming several times their own weight in some species, thus eating as much as a larger animal.

  2. There many dinosaur alive today they are won of the most successful animal today spinosauridae is last living dinosaur modern crocodilian is superior to dinosaur. gator is advance animal allways was that why they are million of them in Florida there are no links between gator and birds the gator is the last living tyrannosaur .modern crocodilian have superior technology over dinosaur the first mesoeucrocodylia spinosauridae is superior to dinosaur.spinosauridae lead to the gator won of top animal to be king of the beast .they are many different between gator and a bird first the gator and dinosaurs are thecodont animal a crocodilian type of animal thecodont mean crocodilian teeth most dinosaur died in a death roll the death roll is won of the greatest dinosaur technology spinosauridae is first to develope it .dinosaur is a primitive animal when match up against a gator .modern crocodilian is the king of the dinosaur the champ.is Janavis beak like modern bird because I know of fossil bird beak link to modern birds .

    • You don’t have any clue about any of this. You are completely wrong. lol

      • I am not make this up that boring I read things on the internet and science is fun.spinosauridae is a mesoeucrocodylia it lack neural arch like the gator it’s part of the death roll system there jaws are design to kill bigger animal so they can swallow them that is mesoeucrocodylia feature spinosauridae have unique teeth found in early mesoeucrocodylia .modern crocodilian have the same complex herd behavior they cliam only found in dinosaur reptiles in fact YouTube had 2 video before this dumb story came out I give you the link … the spectacled caiman up loaded by globalzoo .by look at gator easy see that it’s a dinosaur it’s eye like a house cat it glow at night like many mammal predator a clear evidence it Is warm blooded most reptile shut down a night it’s a well design night predator .if look at Nile crocodile skull the nose clearly see it’s advance predator .dinosaur and most reptile has 2 nose hole if look at Nile crocodile it has one nose hole like all mammal predator it’s a feature to get more oxygen to work the muscle .reptile do not work a lot like mammal because they are cold blooded.for basking not all crocodile bask today land crocodilian do not bask and nile crocodilian open it’s mouth and night too this show it has nothing to do with coldbloodness .crocodilian walk have no links to amphibian this show it’s a bipedal animal by look at there legs the arm is smaller than the legs a classic bipedal feature and by looking at lizard there 4th finger is largest even more largest in the toe even in the bipedal lizard basilisk these came from tree ancestor that why they lack of osteoderm skin all modern crocodilian 4 toe is reduce and modern crocodilian has a giant thumb claw like theropod a grasping predator feature .lizard were never grasping predator .and modern crocodilian has a human ankle a very rare feature in the animal kingdom.and human is well known bipedal animal. When they first found dinosaur they say it’s like a mammal very advance reptile the 66 million animal today dinosaur they thought that how dinosaur should look like very fast very dangerous that the gator a very advance animal modern crocodilian has fully secondary bony palate that should answer the question .spinosauridae is a fully form mesoeucrocodylia the top dinosaur group the crown of dinosaur group . I know more but I am lazy but that enough any way.

  3. Janavis is flight skull bird so it’s a modern bird it’s early modern bird it lack antitrochanter so bipedal not like dinosaur and the later bird antitrochanter have no link to dinosaur antitrochanter .Janavis is a ichthyornis the ichthyornithes the palate is simular all birds palate are simular from velociraptor to chicken because they have real vomer not like reptile vomer which is not fuse they have pterygoid wing which is bird feature not dinosaur feature .gator very akinetic reptile the vomer is fuse because link with mammal full palate and they were never anything primitive about the gator.Janavis is advance ichthyornithes they have more hollow bone beyond the skull like the more modern bird so Janavis did not turn into ichthyornis and have a primitive jaw it lead to antitrochanter bird about the beak it’s ichthyornithes so I sopose they have beak link to today albatross the beak of confuciusornis is convergent confuciusornis is primitive than archaeopteryx .confuciusornis is 1 2 3 mandible fenestra bird the dromaeosaur bird number 2 mandible bird in later bird none have this feature include archaeopteryx .Janavis is ornithurine bird some modern bird only have 3 mandible fenestra not I,2,

  4. And yet they are still so confident in stating it evolved over 60 million years ago. The utter absurdity and narcissism of modern science blows my mind.

  5. A few traits do not determine clades. Janavis exhibits convergence with modern birds. Convergence is common. Details here: https://pterosaurheresies.wordpress.com/2022/12/03/a-mobile-pterygoid-creates-superfluous-worldwide-headlines/

  6. Evolution proven wrong again.
    Creation always proven correct in the end.

  7. Janavis lead to toothless bird the toothless primitive jaw and advance jaw bird with pterygoid not fuse to braincase with many joints and the modern beak and antitrochanter . So antitrochanter bird deevolution on the bird palatal complex some today bird lack nasal joint a primitive feature not like today most birds .they cliam the gator is primitive the most advance dinosaur ever how can you cover that up the feature is still there a animal that made t.rex extinct allso made rest of mesoeucrocodylia extinct they were a lot of them and they were diverse.mesoeucrocodylia is the king of deevolution .noteble the theropod neck now it’s aquatic neck like the duckbill dinosaur the question is the gator type mesoeucrocodylia with a s neck is it deevolution .

  8. segredos de cleópatra | April 19, 2023 at 6:34 pm | Reply

    Great article, I liked it very much congratulations!! 73985186

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