Archaeopteryx was a small, bird-like dinosaur. It lived during the Late Jurassic Period in what is now Europe.

The discovery of the first Archaeopteryx fossil in Germany in 1861 caused a lot of confusion. No birds were known from so far back. Some people even thought it might be an angel.

Since then, multiple fossils of Archaeopteryx have been discovered. Many show clear evidence of long feathers. But we don't know whether Archaeopteryx was fully able to fly or if it could only glide.

Archaeopteryx also has a common name - Urvogel, a German name meaning 'primeval bird'.

Is Archaeopteryx a bird or a dinosaur?

Strictly speaking, all birds are dinosaurs. But not all dinosaurs are birds. Scientists sometimes use the term 'non-avian dinosaurs' when talking about prehistoric dinosaurs that aren't birds.

The line between bird and non-avian dinosaur can be vague, and many experts have discussed which way to class Archaeopteryx. For many years, scientists spoke about it as an ancient bird. These days, many people believe it should be called a dinosaur.

Ultimately, categories like bird and non-avian dinosaur are invented by humans. The natural world doesn't always fit neatly into them. Animals such as Archaeopteryx that could sit across two or more categories are sometimes called transitional fossils.

While Archaeopteryx is sometimes called the first bird or the earliest bird, scientists now think that there could be even older bird ancestors. Dinosaurs such as Anchiornis and Aurornis might sit even further back on the bird branch of the dinosaur family tree. If so, they're even earlier relatives of true birds. It's very difficult to say for sure.

How similar was Archaeopteryx to modern birds?

Archaeopteryx had some features in common with the birds of today. It had broad feathered wings and a small body, roughly the size of a magpie.

After comparing its eyes to those of modern birds and reptiles, experts concluded that Archaeopteryx was probably diurnal. This means that it would have been active during the day and slept at night, like many of today's birds.

We don't know whether Archaeopteryx mostly lived on the ground or in trees. Some scientists think it might have been equally comfortable with either, like a crow.

Unlike modern birds, however, Archaeopteryx had sharp teeth and a long, bony tail.

Where have Archaeopteryx fossils been found?

Many specimens of Archaeopteryx have been recovered over the years. All are from the limestone quarries near Solnhofen in Germany.

In the Jurassic Period, this area was a lagoon surrounded by sub-tropical islands. Other small creatures such as insects and lizards - which Archaeopteryx may have preyed on - have been unearthed there too. So have some pterosaurs - flying reptiles - and the small dinosaur Compsognathus.

The first Archaeopteryx fossil ever found was a single feather.

Later, full skeletons were discovered showing feather impressions. We bought the first of these in 1862. It is now known as 'the London specimen' and is on display in our Cadogan gallery.

There has since been debate over whether the first feather discovered really belongs to Archaeopteryx.

Why is Archaeopteryx important?

Two years before the discovery of Archaeopteryx, Charles Darwin had just written On the Origin of Species. The book was the first to lay out the theory of evolution.

Many people back then - scientists included - strongly disagreed with Darwin's concept and claimed that it wasn't possible for animals to evolve over time. But the discovery of the Archaeopteryx fossils, clearly showing a feathered and bird-like dinosaur, seemed to prove that dinosaurs had evolved into birds.

Even 100 years later, there were still those who didn't accept it. Some people published articles claiming that the feathers must be fake. The controversy didn't last long, however, as our scientists were able to show that the fossils were real.

The discovery of Archaeopteryx was a landmark moment for dinosaur scientists, and it is still considered to be one of the most important finds in history.

What colour was Archaeopteryx?

It's usually almost impossible for scientists to know what colour a dinosaur would have been in life.

But thanks to modern scanning technology, experts have been able to find out the colour of one Archaeopteryx wing feather - which seems to have been jet-black.

We don't know whether Archaeopteryx was black all over or only on its wings.