Lizard tail preserved in amber sheds light on a 100-million-year-old defense mechanism

Lizard tail preserved in amber sheds light on a 100-million-year-old defense mechanism Gaby Clark Scientific Editor Robert Egan Senior Editor A lizard making a dramatic escape, leaving its tail wriggling behind as it darts to safety, is an image familiar to many. Tail-shedding is one of the most widespread defenses against predators among living lizards, yet tracing the origins of this extraordinary ability has proved to be surprisingly difficult—how can we tell when this escape tactic first arose in lizards? A new Tel Aviv University study has found answers to this enigma inside a piece of amber just 18 millimeters (0.7 inches) long—the size of a fingertip—discovered in northern Myanmar. Trapped within it is a lizard's tail that detached from its body approximately 99 million years ago. According to the researchers, it represents the best-preserved direct fossil evidence of a voluntarily dropped lizard tail through a defensive mechanism known as autotomy. The study was led by Dolev Fabrikant, a Ph.D. candidate at Tel Aviv University's New Environmental School, and his supervisor, Dr. Leonidas-Romanos Davranoglou of the university's School of Zoology and Steinhardt Museum of Natural History, in collaboration with researchers from the National and Kapodistrian University of Athens and Israel's Volcani Institute. The findings are published in Palaeontologia Electronica. The researchers explain that previously studied reptile fossils have offered evidence of tail-shedding through natural fracture planes in tail vertebrae and regenerated tails. Such features suggest an animal could shed its tail, but in the case of fracture planes, they do not always establish that it did so voluntarily. Micro-CT reveals a clean break In the new fossil, the end of the detached tail contains the best-preserved telltale features that allowed the team to investigate precisely how the separation occurred. For years, the significance of the amber went unnoticed. What initially looked like a tiny twig or a fragment of an insect caught Fabrikant's eye as he examined the specimen more closely. "I realized that what seemed to be a twig was covered in tiny scales," he recalls. "It was a lizard's tail." When Fabrikant told his supervisor, the response was immediate. "I nearly jumped out of my chair," says 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." Because the amber is cloudy and microscopic, an ordinary microscope could reveal little of the fossil's fine detail. The team turned to micro-CT scanning at the 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 point where the tail detached, the scans revealed a distinctive ring of tissue resembling the structure seen in tails shed by living lizards. The separation was also relatively clean and symmetrical, without the damage patterns expected from an accidental injury. Identity and fate remain unknown Despite the fossil's remarkable preservation, the tail alone cannot establish which group of lizards the animal belonged to. "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 Ph.D. candidate at the National and Kapodistrian University of Athens. Nor can the researchers say what prompted it to shed its tail. The lizard may have become stuck in sticky resin and detached its tail to break free. Alternatively, it may have shed the tail during a predator attack, with the discarded tail subsequently landing in resin. The fossil cannot reveal whether the lizard survived or later regrew its tail. What the fossil does show is that the mechanism was already operating in lizards around 99 million years ago. Preserved in a piece of ancient resin small enough to rest on a fingertip, there is evidence of a survival strategy still unfolding in gardens and on sunlit walls today. Publication details Ahmed Nasser et al., Direct fossil evidence of caudal autotomy in a Cretaceous lizard, Palaeontologia Electronica (2026). DOI: 10.26879/1706 Journal information: Palaeontologia electronica Provided by Tel-Aviv University