115-Million-year-old Fossil May Preserve Dinosaur Blood Cells

WHO:

IJR - Researchers reported evidence in a leg bone attributed to a Brazilian *Aratasaurus*; some experts cautioned that the structures have not been definitively identified as blood cells.

Phys.org - An international research team led by Curtin University reported fossilized red blood cells and collagen amino acids.

Yahoo - Paleontologists identified biomolecules in fossils of a juvenile *Aratasaurus museunacionali*.

Yahoo - Study co-author Kliti Grice is a chemist at Curtin University in Australia.

WHAT:

IJR - Researchers reported mineralized structures resembling red blood cells and chemical traces of heme in a 115-million-year-old dinosaur leg bone.

Phys.org - The team described its findings as the first unequivocal evidence of fossilized red blood cells and collagen amino acids.

Yahoo - The study reported intact biomolecules and mineralized red blood cells inside dinosaur fossils, and chemically identified heme, an oxygen-carrying blood compound.

Yahoo - Grice called the finding “a landmark discovery” and said it “challenge[s] longstanding assumptions that certain biomolecules such as hemoglobin cannot survive deep time.”

Yahoo - Fossil evidence suggests the dinosaur was over 10 feet long and weighed about 75 pounds; because it was young, it likely grew larger.

WHERE:

Yahoo - The fossilized limb bones were from an Early Cretaceous theropod that lived in what is now northeastern Brazil.

WHEN:

WHAT:

Yahoo - The dinosaur fossils are 115 million years old.

WHY:

Yahoo - The researchers theorized that preservation required rapid burial in an environment rich in microbes but low in oxygen.

HOW:

Yahoo - Researchers examined thin slices of fossil and found mineralized red blood cell components and hausmannite, a manganese oxide that helped preserve heme’s cellular structures and other biomolecules, including collagen amino acids.

IJR - Researchers said the evidence could expand studies of dinosaur biology and fossil preservation.

Yahoo - The researchers said further study could inform understanding of blood evolution, dinosaur metabolism, and ancient animals’ activity levels; the findings also suggest delicate biomolecules may persist in harsh environments over millions of years.

(UPDATED November 3, 2026 02:04 UTC)

Researchers found heme and collagen traces in a 115-million-year-old Brazilian dinosaur fossil. Mineralized structures resemble red blood cells, though experts caution their identity remains unconfirmed. The findings could expand research into dinosaur biology and how fragile molecules survive fossilization.