What is Archaeopteryx? What is its significance in evolution?

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A non-living model of the extinct Archaeopteryx
A non-living model of the extinct Archaeopteryx

What is Archaeopteryx?

Archaeopteryx was the first flying reptile (dinosaur). It is considered as a connecting link between reptiles and birds.

It is a transitional fossil between non-avian feathered dinosaurs and modern birds.

Researchers often say that it is an extinct bird and is a transitional stage showing characters of both reptiles and birds.

It was the first reptilian fossil found with clear evidence of feathers, a trait long considered the key distinction between birds and “non-birds.”

Archaeopteryx is now a fossil and once lived in the Late Jurassic period around 150 million years ago, in present-day southern Germany and Portugal.

In fact, Archaeopteryx is the first bird on earth considered to be about 150 million years old.

These organisms were seen during the time when Europe was an archipelago of islands in a shallow warm tropical sea, much closer to the equator than it is now.

Two perfectly preserved specimens of Archaeopteryx were found in Bavaria in the fine-grained lithographic limestone of the Upper Jurassic period. It was discovered by Andreas Wagner in 1861.

Another fossil was found in 1877 and the third was also found in 1956 from the same place.

Archaeopteryx is an example of Mosaic evolution (or modular evolution) which states that the evolutionary change only took place in some body parts or systems without simultaneous changes in other parts.

Fossil of Archaeopteryx as seen in the lithographic limestone
Fossil of Archaeopteryx as seen in the lithographic limestone

What Archaeopteryx looked like?

Archaeopteryx looked more like a bird, but as a reptile too. Its body anatomy cannot be considered as that of a real bird and a real reptile, but that of a partial bird and a partial reptile.

This oldest known fossil bird, of the late Jurassic period, had feathers, wings, and hollow bones like a bird, had beaks but with teeth, a bony tail, and legs like a small coelurosaur dinosaur reptile.

Archaeopteryx roughly represented the size of a raven or crow due to the presence of its broad wings that were rounded at the ends.

It also had a long tail compared to its body length. Its feathers were very similar in structure to modern-day bird feathers.

Its body length was roughly 20 inches, with an estimated mass of 0.8 to 1 kilogram (1.8 to 2.2 lb).

Like many dinosaurs (reptiles), Archaeopteryx had a bony tail, teeth, and clawed fingers, and a hyperextendable claw on each foot. Its body axis was elongated like that of a lizard.

Like many birds, Archaeopteryx had body feathers, wings, wishbone, and reduced tail vertebrae.

They are classified under the Therapod family of Animal Kingdom because these belonged to dinosaur clade that is characterized by hollow bones and three-toed limbs.

It’s also why scientists call Archaeopteryx a “missing link” between birds and more primitive reptiles.


Significance of Archaeopteryx in evolution

The significance of Archaeopteryx in evolution is a lot especially in bringing light into the evolutionary link between reptiles and birds.

Archaeopteryx plays an important role in evolution because it is a connecting link between Aves (birds) and Reptiles.

Like birds, Archaeopteryx had wings, feathers, beaks, hollow bones. And, like reptiles, it had a bony tail, teeth, and clawed fingers, and hyperextendable claws suggesting that birds have evolved from reptiles.

Archaeopteryx was an organism that had feathers and a heavy jaw, along with scales and claws, showing the traits of both reptiles and birds. In fact, it is more like a bird and so considered as the common ancestors of all birds.

Many characteristics of birds show a close resemblance to the archosaurian reptiles. Archaeopteryx had achieved some powers of flight or gliding, but they were less specialized for that purpose as compared to those of the modern birds.

Their whole body axis was still elongated and lizard-like. Its fossils and other like fossils suggest that the birds arose from a race of bipedal arboreal reptiles, living in the forests and acquired with capabilities for running, jumping, and gliding among the branches.

There has been much controversy about the origin of flight in Archaeopteryx or others. Some declared that the earliest birds were all terrestrial and used the wings to assist in running, leading eventually to a take-off, perhaps at first for short distances.

A recent theory proposed by Osborn in 1979 states that the enlarged feathers on the back of the hands of Archaeopteryx may have served as nets to assist in catching insects.

In fact, Archaeopteryx showed both reptilian and avian characters. It was certainly not a bird like the present-day modern birds and also it was not a true reptile.

Except for the feathers, it mostly resembled to archosaurian reptiles. It also wasn’t presumably the immediate ancestor of modern birds. Its immediate descendants are also not known.

It wasn’t completely separate from the birds due to the presence of partially pneumatized hollow bones, forelimbs ended in 3-clawed digits, with separate metacarpals and phalanges and elongated tail as well.

Hence, Archaeopteryx was placed in a separate sub-class Archaeornithes since it had certain different characteristics not found in fossil birds and modern birds placed in Neornithes.

But, it had many reptilian and avian characters that made it stand in between the reptiles and the birds as a connecting link to better understand evolution.


Is Archaeopteryx a bird or reptile?

Archaeopteryx is neither a bird nor a reptile, but it is a connecting link between the reptiles and birds. It’s because it shows the characters of both reptiles and birds.

It can be said as a partial reptile or a partial bird because it has half of the characteristics of birds and half of the characteristics of reptiles.

With its outer appearance, it seems more like a bird than a reptile, that’s why people often call it a bird. But, evolutionary it is more similar to small theropod dinosaurs (reptiles) than it is to modern birds.

Scientifically if you see, it can neither be termed as a bird nor a reptile without any strong evidence. So, it’s just a connecting link between the reptiles and birds.

This fossil is truly a mixture of bird-like and reptile-like traits and was first reported only two years after Charles Darwin published his book, “The Origin of Species.”

Another point to note is that not all Archaeopteryx species are the same and can vary considerably, especially in the limb bones and dentition.

The problem of classifying Archaeopteryx is still there as it is unable to fit under either birds or reptiles. Some consider it the first birds, some say it was a reptile.

In either way, it is sure that Archaeopteryx is like a mosaic, with a mixture of traits not found in any living species.

Scientists also say that Archaeopteryx is neither a bird nor a reptile but belongs in a category of its own in the classification system. But this answer has not been generally regarded as satisfactory due to the lack of proper evidence.

Any scientific answer depends on proper evidence. So due to the lack of proper evidence, it can be concluded that Archaeopteryx is neither a reptile nor a bird, but something of its own category that acts as a connecting link between the birds and reptiles.


How did Archaeopteryx fly?

Scientists have recently proposed that Archaeopteryx flew like a pheasant or quail. Yes, they have concluded that Archaeopteryx was capable of flying.

Archaeopteryx was able to fly fast for short distances but, they preferred to run more often. If needed, however, they were able to burst to the sky in a “flush” with a quick powerful jump.

Scientists have researched the bone structure of Archaeopteryx by passing powerful X-ray beams through its fossilized bones. They have also scanned the Archaeopteryx fossils in a particle accelerator known as a Synchrotron.

After their extensive studies, they have found that its wing bones matched modern birds that flap their wings to fly short distances.

They have also concluded that Archaeopteryx had hollow pneumatized bones, as present in modern birds that helped them to be lightweight and thus helping them in flight.

They concluded that Archaeopteryx were very optimized for incidental active flight and their flight style was something like those of pheasants and quails.

They also concluded that Archaeopteryx had the ability to make a very quick jump, typically followed by a very short horizontal flight, and they were also able to run super-fast whenever required.


Some facts about Archaeopteryx

1. The most prominent fact is that Archaeopteryx is neither a bird nor a reptile. It’s something of its own kind and is an evolutionary link between the birds and reptiles.

2. Archaeopteryx was the first feathered dinosaurs known to animal science that was able to fly. That’s also why scientists often call it the first flying bird.

3. At present, Archaeopteryx is not only the one but there are dozens of other feathered dinosaurs that have been unearthed, that also show various connecting links between the birds and reptiles.

4. The structure of Archaeopteryx looked more like a Raven or Crow. And, it flew more like a pheasant or quail.

5. Archaeopteryx had a curved killing-claw on the second toe of each foot. These digits were hyperextendable, meaning that they could be held high off the ground to keep the tips sharp and ready for action.

6. Archaeopteryx was discovered in 1861, just two years after Charles Darwin published the book “Origin of Species” in 1859. In his book, Darwin had predicted that a new transitional fossil would soon be found and such a fossil was Archaeopteryx that was indeed discovered after two years as it was predicted in that book.

7. According to a 2009 study, it was seen that Archaeopteryx hatchlings had a much slower growth rate like the kiwi birds which can take more than five years to reach maturity.

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