Two thousand ordinary people are helping restore a 240-million-year-old predator.

Fossil preparation is usually invisible to the public.

A museum visitor sees the finished skeleton. Between discovery and display can sit thousands of hours of slow, delicate work removing stone without destroying the bone inside it.

At the Copernicus Science Centre in Warsaw, that hidden stage has become the exhibit.

More than 2,000 volunteers have joined scientists to prepare the skeleton of a Mastodonsaurus, a giant amphibian that lived around 240 million years ago.

What was Mastodonsaurus?

Despite the name, it was not a dinosaur and had nothing to do with mastodons.

Mastodonsaurus was a huge amphibian from the Triassic period. It had a broad, flat skull, long jaws and an aquatic ambush-predator lifestyle that can make reconstructions look vaguely crocodile-like.

The Polish specimen is unusually large, at nearly six metres long.

Why restoration takes so long

A fossil is not excavated from the ground as a clean museum-ready bone.

Bone can be locked inside rock, fractured, compressed or difficult to distinguish from the surrounding material.

The Warsaw team uses pneumatic chisels and ultraviolet light to separate fossil from rock millimetre by millimetre.

Why let volunteers touch it?

The obvious risk is damage, which is why the volunteers are trained, equipped and supervised rather than simply handed tools.

The advantage is that a huge amount of careful labor can be distributed while turning the preparation process into a form of public participation.

Managers, cleaners, tattoo artists and people with no paleontology background have taken part.

The glass wall matters

Visitors can watch the work in progress.

That changes what a science museum is showing. Instead of presenting knowledge as a finished product, the laboratory exposes the process: uncertainty, repetition, patience and technique.

The specimen may change what scientists know

The team says the skeleton differs in body structure from smaller Mastodonsaurus specimens found elsewhere in Europe and could provide new information about the animal.

When restoration is complete, researchers expect it to become the largest Mastodonsaurus skeleton on museum display.

The TAP perspective is that public science works best when participation does not pretend expertise is unnecessary. The volunteers contribute because the experts designed a system that makes careful participation possible.