Ichthyornis dispar: A Toothy Seabird That Connects Dinosaurs To Modern-Day Birds

November 17, 2021 // 8 minutes read

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Ichthyornis dispar

Are birds dinosaurs? 

If you’ve been researching birds for so long, then you already probably know that birds descended from dinosaurs. Yes, this is despite looking different from each other. 

Various studies have been done throughout the years to prove this connection and just a few years ago, scientists have finally found it. The Ichthyornis dispar is said to be one of their biggest links that will connect dinosaurs to our modern-day birds. It’s believed that the fossil found on this birds’ skull shows a transition from a dinosaur to a bird. 

In this article, we’ll explore more on the connection between birds and dinosaurs. We’ll tackle topics under bird evolution, dive deeper into what the Ichthyornis dispar is, and how the discovery of the fossil of the Ichthyornis dispar is a breakthrough in science. 

So, if you’re as curious as I am, read on… 

Are Birds Dinosaurs?

Let’s start this article with the question, “Are birds dinosaurs?”.

Despite the vast difference between the look of the ancient dinosaurs and our modern-day birds, the fact remains that birds are descendants of dinosaurs. They are actually referred to as avian dinosaurs, which are dinosaurs that have the ability to fly. 

If you still don’t believe it, well, there is actually a lot of proof to this: 

1. The Archaeopteryx

Archaeopteryx was discovered around the year 1860 and 1861 in Germany. One specimen researchers had found still incredibly intact and contained feathers, which made them believe that this was the first bird. 

However, upon further research and study, it was discovered that the fossil found is more closely related to dinosaurs than our birds. Because of this, it was considered as the missing link between dinosaurs and birds. 


The Archaeopteryx lived around 150 million years ago. It is believed to weigh about 1.8 – 2.2 pounds, around the size of a magpie, but the largest would be around the size of a raven. It is described to have broad wings (ends rounded) and a very long tail that reaches up to 20 inches. 

Based on several data, it’s also believed that these birds have feathers on the tail, wings, and lower body. And it’s thought that they’re colored black. 

Ichthyornis dispar
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El fosilmaníaco, CC BY-SA 4.0, via Wikimedia Commons

2. The Theropod Dinosaurs

Another fact that linked birds to dinosaurs are the group of dinosaurs called theropod dinosaurs. These are dinosaurs that walk on two legs, and one best example that belongs to this group is the famous T. Rex. 

If you compare an ostrich skeleton to that of the dinosaur, you’ll see some close similarities. The same goes with chickens, which is quite amazing because chickens are really small, yet they came from big dinosaurs. 

3. Scales and Feathers

Did you know that birds have scales like many dinosaurs, and some dinosaurs have feathers like birds? This is one of the most significant evidence that scientists have found that links birds to dinosaurs. 

Studies have found that the tissues in birds said to produce feathers are similar to the tissues that can produce scales. On top of that, there was a dinosaur discovered in China that still has preserved feathers or proto-feathers.

4. Egg Similarity

It has always been observed that reptile and bird eggs look very similar, but the same could be said with dinosaur eggs. Both eggs are made up of two basic elements – calcium and carbon, which help make the eggshells harder. 

5. Maniraptoran Dinosaurs

Lastly, birds are believed to have descended from one specific group of theropods, the Maniraptoran dinosaurs or also called seizing hands. One famous dinosaur belonging to this group is the raptors. 

If you look at birds closely, you’ll observe that some have very sharp talons, which are very similar to the raptors. For eagles, these talons help them catch their prey, and for other birds, the talons are perfect for self-defense. 

The Bird Evolution

We got all the proof that birds descended from dinosaurs, but how did the big dinosaurs shrink to our small birds? 

Well, research is still ongoing as to how this happened, and it will probably take years before scientists would be able to connect everything. But, it has been found that through the years, theropod dinosaurs have seen to be getting smaller and smaller, which probably led to the transformation. 

Take a close look at this image below: 

It was found that the first theropod dinosaurs contained a hand with smaller fourth and fifth digits. As years passed, the next dinosaurs lost the fifth digit while the second and third digits were about the same length. The loss of the fourth digit then followed this, and the second digit became a lot longer than the other two. 

When the dinosaurs had three digits only, a pubic boot was also seen. The next generation of dinosaurs only then had three digits, but now there’s an appearance of feathers in the area where their hands should be. Wings are starting to form, and tails are becoming more feathered. 

So, throughout millions of years, dinosaurs are making the transition. With their hands forming wings, digits were decreasing, and feathers were growing. 

And now have our modern-day birds who have fused wing digits and short feathered tails, the last transition. However, I would also like to emphasize one pretty clear transformation: the modern-day birds’ toothless beak. 

As we know, dinosaurs are carnivores. And I’m sure you’ve seen movies showing how dinosaurs have big teeth. So, you might be wondering, if birds really did come from dinosaurs, why don’t they have teeth? 

How did the dinosaurs lose all their teeth through the years? 

Well, that’s where the Ichthyornis dispar comes in. It’s believed to be the only fossil that proves how dinosaurs became birds. 

What Is the Ichthyornis dispar

So, what is the Ichthyornis dispar?

The Ichthyornis dispar is a seabird that lived during the Late Cretaceous period in North America. It is said that these birds are the equivalent of our modern-day seabirds, which include the gulls and the terns. 

Based on some research, the Ichthyornis is estimated to be the size of a pigeon. They were said to have really long and strong wings, a large breast, strong legs, long front toes, and a long, well-developed tail. 

In other words, the Ichthyornis are almost similar to our modern-day birds, with one big exception; they have teeth like that of dinosaurs. These teeth are what the birds use to hold their prey and clean their feathers, pretty much like what our modern-day birds do with their beaks. 

So, how does the Ichthyornis dispar connect our modern-day birds to dinosaurs? 

Well, let me explain below… 

How the Ichthyornis dispar Connects Modern-Day Birds to Dinosaurs

The Ichthyornis dispar fossil was first discovered in 1870. However, it wasn’t until three years ago that scientists saw that it’s the key to finally understanding how dinosaurs turned into birds. 

When the fossil was initially found, researchers were confused. At first, they thought that they saw a body of an ancient bird and a jaw of a marine reptile. It took years of research for them to finally understand that the jaw was actually that of a dinosaur, and a few more years for them to finally conclude that these fossils all belong to one animal. 

From that alone, you can already see that this animal was in the middle of a transition. But the biggest clue was in its jaw. 

Remember how I mentioned that the jaw has the teeth of a dinosaur? Well, just at the tip of the upper jaw, researchers noticed that the shape and structure were actually similar to a beak. But it was indeed later concluded that this was the first beak. 

At this point, this creature was actually in the middle of a transition. 

So, when did the dinosaurs lose their teeth? Well, we don’t know yet. But I’m guessing we’re almost reaching that point. Research is ongoing, and we’ll get to discover more soon about bird evolution. 


What bird species resemble the Ichthyornis dispar?

The Ichthyornis dispar resembles our modern-day gulls and terns. 

They are about the same size as the domestic pigeon, have very long and strong wings, large breasts, strong legs, long toes, and a well-developed tail. It’s also thought that they have webbed feet. 

What fossil linked dinosaurs to birds?

The first fossil that linked dinosaurs to birds was the Archaeopteryx. It was the first and the only link for decades before researchers made more discoveries. These avian dinosaurs are said to have the feathered wings of a bird, and sharp teeth, and the long, bony tail of a dinosaur. 

Final Thoughts On the Ichthyornis dispar and How It Connects Dinosaurs to Modern-Day Birds

Isn’t the theory of evolution interesting? 

Who would have thought that our small and beautiful birds today came from big scary dinosaurs? And with all the evidence found, it’s actually hard to deny this fact. But the best part is that everything doesn’t end with the discovery of the Ichthyornis dispar’s beak. 

There is more to learn, and soon, we might actually uncover how dinosaurs transitioned to birds.

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