The facts
The PNAS paper, published online on 2 November, describes heme-derived molecules and ellipsoidal microstructures in vascular canals within limb bones of the 115-million-year-old theropod Aratasaurus museunacionali. [1][2]
The authors report that mass-spectrometry testing identified parent and altered heme B as the main tetrapyrrole signals in the bone extract, distinct from chlorophyll-related compounds in surrounding material. [1][4]
The study combines chemical analysis with Raman spectroscopy and electron microscopy to locate heme-related signals and relevant elements in the microstructures; the authors infer that these are mineralized red blood cells. [1][4]
Paleontologist Mary Schweitzer told ABC and the Guardian that she was not convinced the structures were red blood cells, citing their shape and the absence of the nuclear bulge expected in bird and reptile cells. Another outside researcher said the structures were consistent with mineralized red cells but urged caution. [2][3]
The findings concern chemical traces and mineralized structures, not intact blood or recoverable dinosaur DNA. The authors and outside researchers say further testing of other fossils is needed. [2][4]
Relevant context
Earlier reports of blood-like structures in dinosaur fossils have been controversial because minerals or later contamination can resemble biological material. This study adds chemical and spatially resolved analyses, while leaving the cell identification open to debate. [1][2][3]
Still unconfirmed
- Whether the cell-like structures are definitively dinosaur red blood cells remains disputed; the paper concerns one fossil specimen and independent replication in other fossils has not been reported.
- The study does not establish intact hemoglobin, genetic material, or detailed physiological characteristics of Aratasaurus.
Sources
References support the numbered facts above. Source checks: 5 Nov 2026, 04:12 UTC.
The primary PNAS DOI and abstract-level record establish what the authors reported; the full paper text was not accessible through the journal page. ABC and the Guardian independently describe the study and the scientific disagreement, while ScienceAlert adds the replication caveat. The article distinguishes heme-related traces from intact blood, preserves the disputed cell identification, and gives the 2 November online publication date rather than implying a new event today.
- Heme signatures in mineralized red blood cells within vascular canals of a 115-million-year-old dinosaur bone
Proceedings of the National Academy of Sciences · Primary source · 2 Nov 2026
The PNAS DOI and abstract record were checked. The journal page redirected to a cookie/sign-in landing screen; the PubMed-imported abstract record states that authors infer red blood cells from vascular-canal microstructures and report heme-derived tetrapyrroles. The full article body was not accessible in this browser pass.
- Mineralised red blood cells detected in 115-million-year-old dinosaur bone
Australian Broadcasting Corporation · Reporting · 3 Nov 2026
Opened ABC’s report. It explains the methods, interviews outside paleontologists Mauricio Barbi and Mary Schweitzer, distinguishes cell-like mineralized structures from intact cells or hemoglobin, and reports that DNA testing was negative.
- Fossilised red blood cells found in 115m-year-old dinosaur’s bone, say scientists
The Guardian · Reporting · 2 Nov 2026
Opened the Guardian science report. It independently describes the heme finding and quotes an outside researcher who disputes the identification of the structures as red blood cells.
- Dinosaur Blood Cells Detected in 115-Million-Year-Old Fossil
ScienceAlert · Reporting · 3 Nov 2026
Opened the report for a separate account of the analytical methods and the authors’ stated need to replicate results in additional specimens and geological settings.