Newly discovered prehistoric bird re-writes bird evolution

[Prehistory Resurrection]

Meet Janavis finalidens. Image credit: Phillip Krzeminski.

- A tiny broken bone, misidentified for decades, has upended scientists' view of bird evolution. For nearly 200 years, zoologists have divided birds into two categories: those with mobile joints in their upper jaw that allow their upper beak to move, and a much smaller group, including ostriches and emus, with a fused upper palate that gives them a less agile upper beak. This fused palate is also found in dinosaurs, including the feathered ones that were ancestors to today's birds, so zoologists thought ostriches and their kin were the evolutionary older group of birds, with mobile upper beaks arriving later in the history of birds.

-Now, paleontologists have identified a key skull bone in an ancient bird that lived nearly 67 million years ago—just before the devastating asteroid impact that killed off the dinosaurs. The bone, a piece of the upper jaw, closely resembles its mobile counterpart in today's chickens or ducks, leading the researchers to conclude the ancient bird also had a jointed upper beak. They suspect the jointed beak was present in even older birds, because the rest of the specimen indicates it was a relative of Ichthyornis, another ancient bird and to which Janavis was related that lived about 20 million years earlier. Overall, the new analysis suggests a jointed beak was already present in the ancient birds, and a fused palate re-evolved later in ostriches and their kin.

"It's changing how we've been looking at the evolution of birds since the time of Linneaus," says Christopher Torres, a paleontologist at Ohio University, Athens, who was not part of the new work. "We thought we had this worked out centuries ago, and now we're finally finding fossils that are showing that we didn't. We got it mixed up."

-The fossil, discovered more than 2 decades ago in a Belgian quarry near the Dutch border, was partially described for the first time in 2002, but many of its pieces remained inside a block of sediment. Juan Benito and Daniel Field, paleontologists at the University of Cambridge who study bird evolution, borrowed the fossil in 2018 from the Natural History Museum of Maastricht so they could use computerized tomography to image these remaining bones.

-They hoped to find more of the animal's skull, but initial scans only turned up vertebrae and ribs. Disappointed, they put the project aside for more than a year. When Benito returned to the fossil, he was puzzled by a bone the earlier analysis had identified as part of a shoulder but that seemed too small. He realized the piece was a fragment of a bone that had been broken in two.

-After identifying the companion piece and putting the two together, Benito, Field, and colleagues concluded the full structure was a particularly delicate part of the upper palate, a bone called the pterygoid that is key to the jointed upper beak. The researchers, who describe the more complete fossil today in Nature, argue the bird is a previously unknown species and name it Janavis finalidens, for Janus, the Roman god of beginnings, endings, and transitions. It was a coastal flyer, plying the shallow seas that at the time covered what is now Belgium and the Netherlands, and weighed an estimated 1.5 kilograms—about the size of a gray heron.


Article from science.org.

[Halichoeres]

Obligatory:


Well, I'd prefer the Ichthyornis, since it's known from many complete specimens, but the novelty of Janavis probably gives it better odds.

[Faelrin]

@Halichoeres I'm surprised Ichthyornis hasn't gotten a single figure yet. Both Hesperornis and Pelagornis have at least one option though. Granted extinct birds (and close relatives) as a whole are pretty neglected outside of the dodo, Gastornis, and recently Dinornis.

[Halichoeres]

@Halichoeres I'm surprised Ichthyornis hasn't gotten a single figure yet. Both Hesperornis and Pelagornis have at least one option though. Granted extinct birds (and close relatives) as a whole are pretty neglected outside of the dodo, Gastornis, and recently Dinornis.

Very true. I guess to most people an Ichthyornis would just look like a modern tern or something.

[Gwangi]

Even extant birds are largely neglected by toy companies. With a few popular species like ostriches, flamingos, and eagles being the exception.

[Newt]

So, the neognath condition is plesiomorphic and the paleognath condition is derived (or at least, a reversal)? Interesting. It does make me wonder why paleognaths would re-develop a fused palate. What's the advantage? Reduced mobility is often associated with increased rigidity, which would make sense if early paleognaths were durophagous, but I'm not aware of any evidence that they were; in fact, most fossil paleognaths that I'm aware of seem to have pretty generalized bills and probably weren't doing anything contemporary neognaths weren't also doing. Besides, various neognaths (parrots, gastornithids, seed-eating passerines) have managed durophagy quite well without sacrificing bill mobility. 

Anyhow, I'm not holding my breath for a Janavis figure. If manufacturers can't even be bothered with spectacular giants like Dromornis, Anthropornis, Argentavis, Titanis, and so on, what chance has a toothy seabird got?

[Halichoeres]

Anyhow, I'm not holding my breath for a Janavis figure. If manufacturers can't even be bothered with spectacular giants like Dromornis, Anthropornis, Argentavis, Titanis, and so on, what chance has a toothy seabird got?

Oh yeah, definitely not holding my breath. I'm no incel, I know the difference between hoping and expecting!

[Newt]

@Halichoeres - I had to look up "incel" and now I'm sad.

[jc_4130]

Even extant birds are largely neglected by toy companies. With a few popular species like ostriches, flamingos, and eagles being the exception.

There's always taxidermy

[Gwangi]

Even extant birds are largely neglected by toy companies. With a few popular species like ostriches, flamingos, and eagles being the exception.

There's always taxidermy

You joke but I do have a small collection of taxidermied birds. Of course, they're game birds because most other birds are protected by law and you cannot own taxidermy of them, so it's still not a viable alternative to plastic toys. That said, I also have a small collection of carved wooden birds and decoys, a popular hobby in its own right.

[Halichoeres]

@Halichoeres - I had to look up "incel" and now I'm sad.

Oh no, I'm sorry! Unfortunately my sense of humor has just one setting: "it's funny because it's tragic."

[VD231991]

Obligatory:


Well, I'd prefer the Ichthyornis, since it's known from many complete specimens, but the novelty of Janavis probably gives it better odds.

The Late Cretaceous taxa Iaceornis and Austinornis were once referred to Ichthyornis, but Clarke (2004) found Austinornis and Iaceornisto be morphologically more related to Neornithes than to Ichthyornis. Since Janavis itself is 20 million years younger than Ichthyornis and was found in the same geologic unit as Asteriornis, it is thus the youngest unequivocal member of Ichthyornithes and indicates that the last ichthyornitheans were coeval with the earliest members of Neognathae during the Maastrichtian.

Clarke, J.A., 2004. Morphology, phylogenetic taxonomy, and systematics of Ichthyornis and Apatornis (Avialae: Ornithurae). Bulletin of the American Museum of Natural History 286: 1-179.