Researchers have found mineralized red blood cells and chemical traces of blood molecules in bones from a dinosaur that lived 115 million years ago.

Changed into a hard material by minerals over time.

Researchers have found mineralized red blood cells and chemical traces of blood molecules in bones from a dinosaur that lived 115 million years ago.

Very small amounts of chemicals that remain as signs of something once present.

My reading is that the discovery changes what scientists may look for in fossils: not just visible structures, but chemical traces too.

Small chemical signs that can show what was once present.

The team detected heme, a component of hemoglobin, the protein that lets red blood cells carry oxygen.

A substance in hemoglobin that helps blood carry oxygen.

The team detected heme, a component of hemoglobin, the protein that lets red blood cells carry oxygen.

One part of a larger substance.

That distinction matters because the result gives researchers a way to study biological traces that can survive inside fossils.

The important difference between chemical signs of blood and preserved liquid blood.

That distinction matters because the result gives researchers a way to study biological traces that can survive inside fossils.

Small signs left by living things.

They also suspect the dinosaur was quickly covered by sediment in conditions with little oxygen and abundant microbial activity.

Loose material, such as sand or mud, that settles and can cover remains.

They also suspect the dinosaur was quickly covered by sediment in conditions with little oxygen and abundant microbial activity.

Present in large amounts.

But it shows that, under some conditions, molecules linked to blood can remain detectable for an extraordinary length of time.

Still able to be found or noticed.