BEIJING, Feb. 26 (Xinhua) -- A team of paleontologists has discovered the first-known evidence of a bone tumor in a vertebrate preserved in amber, in the form of a 99-million-year-old lizard specimen that offers a rare glimpse into the ancient origins of disease.
This international collaboration, led by Xing Lida from the China University of Geosciences (Beijing) and including researchers from the United States and Canada, had its findings published on Wednesday in the journal Palaeoentomology.
The discovery fills a gap in the study of paleopathology and provides direct evidence for understanding diseases in ancient animals, according to the researchers.
The specimen, sourced from a mine site in Kachin State in Myanmar, dates back to the mid-Cretaceous period, when this region was a tropical forest ecosystem.
Researchers were drawn to the partial lizard skeleton, classified under the Anguimorpha suborder, by an abnormality in its toe. High-resolution observation revealed irregular erosion on the distal end of the first phalanx of the fourth digit and its adjacent joint surface, a marking highly reminiscent of modern bone tumors.
The team employed micro-CT (micro-computed tomography), a technology that can penetrate the amber to create three-dimensional reconstructions of the fossilized bone. The scans revealed a distinct geographic lesion characterized by expanded bone tissue and multiple small, cyst-like cavities, which is a pattern consistent with a non-sclerotic, destructive process.
Through a differential diagnosis process, the team compared the lesion with more than 30 pathological conditions, including fractures, infections and other tumor types.
The analysis resulted in the conclusion that the lizard had suffered from a giant cell tumor (GCT), a type of bone neoplasm commonly found near the joints of modern animals, including mammals. While tumors have been previously identified in dinosaur skeletons, this marks the first time such a condition has been documented in a vertebrate preserved in amber.
It offers a new perspective for evolutionary medicine by allowing scientists to trace the history of diseases. The fact that the pathological features of this ancient tumor closely resemble those seen today, suggests the disease's progression may be deeply conservative, already existing for nearly 100 million years.
"Every piece of amber is a time capsule of Earth's history, and traces of disease are a unique footnote in the story of evolution," said Xing. "This glimpse into the health of a lizard from 100 million years ago opens a new window for understanding the evolution of life." ■
