A clean break in 99-million-year-old amber offers rare direct evidence that ancient lizards shed their tails using a defensive mechanism still common today.
A lizard can escape a predator by leaving its tail behind, sometimes with the detached piece still wriggling as the animal makes its getaway. It’s a remarkable defense, but scientists have struggled to determine how far back it goes. Ancient reptile fossils can show where a tail was capable of breaking, yet that doesn’t necessarily mean the animal could shed it to escape danger.
An unusually revealing clue has now emerged from a tiny piece of amber discovered in northern Myanmar. Measuring just 18 millimeters (about 0.7 inches) long, the amber holds a lizard’s tail that detached approximately 99 million years ago. What makes it so valuable is the remarkably preserved point where the tail separated from the body. Researchers say it provides the best-preserved direct fossil evidence of autotomy, the defensive mechanism that allows lizards to shed their tails.
An ancient tail mistaken for a twig
For years, no one recognized what was trapped inside the amber. Dolev Fabrikant, a PhD candidate at Tel Aviv University’s New Environmental School, was examining what appeared to be a tiny twig or fragment of an insect when he noticed something unusual about its surface. “I realized that what seemed to be a twig was covered in tiny scales,” he recalls. “It was a lizard’s tail.”
Fabrikant shared his discovery with his supervisor, Dr. Leonidas-Romanos Davranoglou of Tel Aviv University’s School of Zoology and Steinhardt Museum of Natural History, whose reaction was immediate.
“I nearly jumped out of my chair,” says Dr. Davranoglou. “I instantly realized that this tiny fossil could open an extraordinary window into the past, helping us understand the history of one of the most widespread survival strategies among reptiles. Until now, we could only speculate on whether ancient lizards could shed their tails. We now have direct evidence that one could.”
Scans reveal a clean, deliberate break
Getting a closer look at the fossil was another challenge. The amber was cloudy, and the structures inside were too small for an ordinary microscope to reveal the details researchers needed. Rather than cutting open the specimen, the team turned to micro-CT scanning at Israel’s Volcani Institute.
“Micro-CT takes X-ray images from many angles and combines them into a three-dimensional reconstruction. It allowed us to examine structures hidden by the amber without needing to cut this one-of-a-kind piece open,” explains Dr. Ahmed Nasser, Head of the institute’s Inter-Institutional Analytical Unit.
At the severed end of the tail, the scans revealed a distinctive ring of tissue closely resembling the structure found in tails shed by living lizards. The separation itself was relatively clean and symmetrical, without the damage patterns that would be expected if the tail had broken off in an accident.
That distinction matters because other reptile fossils have offered less conclusive evidence. Some preserve natural fracture planes in the tail vertebrae, while others contain regenerated tails, indicating that the animals had lost part of their tails previously. Although these features suggest that ancient reptiles possessed the ability to shed their tails, the presence of fracture planes alone cannot establish that they actually used this defense. In the Myanmar specimen, the preserved tissue and clean separation provide much stronger evidence that the tail was released through autotomy.
The lizard’s identity and fate remain unknown
The researchers still cannot determine exactly what kind of lizard left the tail behind. Without the rest of its skeleton, including the skull, there are too few anatomical clues to identify its closest relatives.
“Although we can securely identify this specimen as a lizard, we lack the skull and other skeletal features that would allow a more secure identification. Possible affinities include the groups containing today’s wall lizards or, alternatively, slow worms and monitor lizards,” says Apostolos Christopoulos, a PhD candidate at the National and Kapodistrian University of Athens.
How the tail ended up in amber is another mystery. The lizard might have become stuck in sticky resin and shed its tail to free itself. It is also possible that a predator attacked the animal, prompting it to release its tail, which later landed in resin.
Reference: “Direct fossil evidence of caudal autotomy in a Cretaceous lizard” by Dolev Fabrikant, Apostolos Christopoulos, Ahmed Nasser and Leonidas-Romanos Davranoglou, October 2026, Palaeontologia Electronica.
DOI: 10.26879/1706
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