The amber block provides a rare opportunity for researchers to study the skeleton, scales, and even eyelids of an ancient lizard species.
Dr. Juan Daza from Sam Houston State University and his colleagues discovered a lizard trapped in an amber block (fossilized tree resin) in Myanmar dating back 110 million years, as reported by IFL Science on March 17. The new research was published in the journal Scientific Reports.
Retinosaurus hkamtiensis lizard trapped in amber. (Photo: Adolf Peretti and the Peretti Museum Foundation)
“We have a rare opportunity to study the skeleton that is still intact and observe the external shape of the lizard (scales), similar to how experts study modern amphibians and reptiles,” Daza stated.
The lizard was immature and likely did not know how to avoid the incoming tree resin that ultimately led to its demise. The research team found the lizard in Hkamti, located 100 km from the famous amber mines in Hukawng, which have yielded numerous vertebrate fossils from the Cretaceous period and have preserved soft tissues thanks to the amber.
The lizard belongs to a completely new species, distantly related to modern skinks. The research team named it Retinosaurus hkamtiensis and classified it into the superfamily of skinks Scincoidea. In addition to skinks, Scincoidea also includes armadillo lizards and night lizards. In terms of appearance, these are the modern species most similar to Retinosaurus.
This similarity is intriguing because today, night lizards are only found in North and Central America, far from Southeast Asia. Historically, Hkamti was not part of the Asian continent. It was once part of the supercontinent Gondwana, linked to Australia, which separated for a long time before reuniting with Asia.
The ancestors of Retinosaurus may have survived on those isolated islands for about 50 million years. This explains their presence in Myanmar, while another group migrated to North America, the research team noted.
Although the amber did not preserve the lizard’s tail and hind legs, it still retained many features that other fossils do not, such as scales and the left eyelid. The eyelid is the most distinctive difference compared to night lizards. The eyelids of night lizards form a transparent scale similar to those found in snakes.
Despite this difference, experts believe that Retinosaurus had a lifestyle similar to that of night lizards, meaning it spent most of its time living in rock crevices and tree hollows. In addition to the lizard, the amber also contained several beetles, a common presence in rainforests.
