Science2 distinct publishers3 min readPublished
The lesion stops short of the marrow cavity, and that is what sends the Spanish team's diagnosis outward into soft tissue rather than inward to a fracture or a tumour, though the bacteria themselves are inferred from modern ulcers.
The Scientist · Science desk
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Confinement to the outer shell is the load-bearing observation here, because it points the search away from the bone. The scans describe a low thickening and moderate expansion of the cortical bone, the dense outer casing of a long bone [6], and the authors read a lesion that never reaches the marrow space as one that began in the tissue lying over the bone [7]. The mechanism they invoke is specific: when an infected skin ulcer works down to the tissue covering the bone, it can set off inflammation and new bone formation at the surface [11].
The exclusions came from the same images. No pattern of fracture or bone bruising appeared, and neither did the reparative phase that follows those injuries [8]. Nothing indicated a malignant tumour, which took neoplasia off the list [9]. On scale, the reported 17.4 cm overgrowth spanning about 17 percent of the shaft implies a tibia of roughly 102 cm [20], and the patch is about 11.7 cm across at its widest [21] on that metre of bone.
The word carrying the most weight is in the paper's title, which reports a first occurrence of polymicrobial ulcer in dinosaurs [1]. That word is the one the specimen cannot supply. In living patients, tropical ulcer infection is typically polymicrobial, involving a variety of microorganisms [17], and a tropical ulcer is defined clinically as a painful, rapidly enlarging sore that usually appears on a lower limb in hot, humid conditions [15]. Europe in the Early Cretaceous was warm and humid, subtropical to warm-temperate, which the authors note suited such ulcers [16]. That is a chain of analogy and setting rather than a recovered pathogen, which is why the body of the paper is more guarded than its title: the claim as written is that this is, to the authors' knowledge, the first report of this type of pathological response to a bacterial infection in a dinosaur [13].
The denominator is one. The swelling turned up on a single shinbone from one of two carcasses recovered at the quarry [23], so the study says nothing about how often Iguanodon carried open sores, or how long this one lasted. It is also worth knowing what the surrounding literature looks like: fractures and trauma dominate the recorded pathologies of non-avian dinosaurs, according to a 2020 study in Scientific Reports [18], and firsts in this field arrive with tools and attention as much as with new disease. The first dinosaur osteosarcoma was only named in 2020, in the fibula of a Centrosaurus that lived about 76 million years ago [19].
What the work does buy is a template. A surface reaction with a healthy marrow cavity beneath it is now a described signature that points to skin, and that is a route into disease of tissue that does not fossilise. On consequence for the animal, the authors stay narrow: the progression of ulceration towards the periosteum "may have caused persistent pain, which was aggravated by normal walking and muscle pressure" [14].
Ranked by verification strength, evidence, and original report placement.
The study is Javier Salas-Herrera et al, "First occurrence of polymicrobial ulcer in dinosaurs", published in Royal Society Open Science (2026), DOI 10.1098/rsos.261293.
Researchers in Spain were working on two fossil carcasses of Iguanodon bernissartensis from the Early Cretaceous, discovered at the Mas de la Parreta quarry in Morella, eastern Spain.
The team came across the strange swelling on the shinbone of one of the two sets of remains.
The swelling is a 17.4-centimetre (6.9-inch) bone overgrowth along the middle of the shinbone, covering about 17% of its length.
The swelling measured around 6.9 inches in length and 4.6 inches in width.
The researchers scanned the bone with a hospital scanner to create 3D digital models revealing its inner structure.
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Evidence-backed comparisons of source perspectives and observed adoption signals. Read the methodology
Which Builder, Operator, and Investor concerns the observed source mix emphasized—not a truth score.
Evidence, demonstrated adoption, hype gap, incentives, and confidence are assessed independently, each on its own current evidence. How these are measured.
One paper, read twice
The imaging and the eliminations are specific enough to argue with — a lesion that spares the marrow cavity, no reparative healing, no malignancy — and that is real evidentiary work. But every number and every negative in both accounts comes from the same Spanish team's paper, and the infection is diagnosed from the shape of a bone reaction rather than from anything microbial left in it.
Nothing yet to count
A finding like this is taken up by citation, by other collections re-checking their own pathological bones, or by a rebuttal — and none of that could have happened yet. Neither account points to anyone outside the original team who has looked at this tibia.
The paper's title hedges less than the coverage
Both write-ups behave: "may be," "likely," "to our knowledge" survive intact in each. The unhedged claim is the paper's own title, which asserts a polymicrobial ulcer flatly when the microbes are an inference from how such sores behave in hot climates today. The small overstatement here was made upstream of the journalism.
Firsts are the currency
The value of this diagnosis is almost entirely its priority, and the priority is asserted by the people who made it — self-hedged, unchecked by anyone else in either account. On the publishing side the pressures are visible rather than hidden: Phys.org attaches a donation appeal and a fact-check credit to the piece, Discover lists its sources and repackages the same study with context. Ordinary novelty pull, no more.
Sure about the bone, less sure about the bug
Two independent write-ups agree on the anatomy without contradicting each other on a single figure, which makes the description trustworthy. What holds the number down is that agreement between two retellings of one paper is not verification, and the bacterial half of the diagnosis has no direct evidence in play.