In the northeast of Chinaa group of researchers found an almost complete skeleton of a rare dinosaur: the iguanodont. And the research, led by researchers linked to the CNRS of France and published in Nature Ecology & Evolution, revealed previously unknown details of the species.
According to the studythe fossil preserves large areas of exquisitely fossilized skin and, between its scales, a system of hollow skin spines unprecedented in dinosaurs.
The new animal was named Please, pleasein homage to the Chinese paleontologist Dong Zhiming, and its age is estimated at about 125 million years.
“Haolong dongi”, a 125 million year old dinosaur
The study is based on a very rare type of evidence in the fossil record: soft tissues preserved at a microscopic level of detail.
According to the description, the integument of Haolong dongi combined large overlapping scales along the tail with tuberculated scales around the neck and thorax. But what was truly unexpected was to find, sandwiched between those scales, skin spines preserved “at the cellular level”. To confirm this, the team used high-resolution X-ray scans and histological sections.
The analyzes revealed that these spines were structures cylindrical and hollowformed by a stratum corneum that covered an epidermis with keratinocytes preserved up to the level of the nuclei, an extraordinary degree of conservation.
The authors emphasize that they do not resemble protofeathers of non-avian dinosaurs or scaly spines of modern reptiles, which suggests a different evolutionary origin.
What were they for? The main hypothesis points to defense: being a juvenile individual – more vulnerable due to its size – the quills would have functioned as a deterrent comparable to that of modern porcupines. In parallel, scientists do not rule out secondary roles in thermoregulation or sensory perception of the environment.
As the specimen is juvenile, it is not yet known if the adults also maintained these spines or if they disappeared with growth. This shows that perhaps other similar innovations went unnoticed, simply because the skin is almost never preserved.
What were iguanodonts like?
Los iguanodontes They were a group of dinosaurs herbivores belonging to ornithopods, that is, “bird-hip” dinosaurs. They lived mainly during early cretaceous (approximately 140–110 million years ago, depending on lineage and region) and were very successful: there were species in Europe, Asia, North America and Africa.
The name comes from the most famous of them, Iguanodon («iguana tooth»), because its first discoverers noticed that some teeth resembled those of a modern iguana. In fact, Iguanodon is one of the first dinosaurs scientifically identified in the 19th century and was key to understanding that extinct giant reptiles existed.
What were they like? In general, iguanodonts had a robust body, beak for cutting vegetation and batteries of teeth for crushing plants. Many could move on two legs (bipeds) when running or exploring, but also walk on all fours when grazing. One of its best known features is the thorn-shaped thumb (in several iguanodontids), which could have been used for defense or to manipulate food.
