Clocking in at about 0.0053 ounces—boasting all the weight of a hefty kernel of popped corn—it likely spent its days underfoot of gargantuan dinosaurs, wriggling through the leaf litter of muggy mid-Cretaceous forests. Measuring less than two inches from snout to tail, it never lived particularly large—but its death would be immortalized for 100 million years to come.
Yesterday, in the journal Breviora, researchers reported the discovery of a never-before-seen lizard species entombed in Burmese amber. This rare fossil represents one of the smallest and most complete Cretaceous lizards ever found. Despite its diminutive stature, the finding speaks volumes about the diversity contained within prehistoric jungles.
“The Early Cretaceous seems to be a time when lizards really diversified,” says Susan Evans, a paleontologist who studies the evolution of amphibians and reptiles at University College London and did not participate in the new research. The finding, she explains, “adds a piece to the puzzle: It is the first example we have of a long-bodied, but fully-limbed, terrestrial lizard.”
Dubbed Barlochersaurus winhtini, the new lizard has been tentatively sorted into a group of lizards called Anguimorpha, which originates at least as far back as the Late Jurassic (some 150 million years ago), but includes contemporaries like Komodo dragons and Gila monsters. If truly an ancestor in this lineage, B. winhtini would be the smallest known anguimorph, alive or dead.
A hundred million years ago, long before the invention of camcorders, fossilization begat the only remaining commemorations of the immense diversity that once decorated the mid-Cretaceous Earth. But small, fragile bones don’t tend to survive the test of time in rock-based records, leaving gaps in researchers’ knowledge of the most pint-sized reptiles from this period.
Amber, on the other hand, preserves life’s littlest forms far better than rock. And as it hardens around whatever it engulfs, this plant-based resin remains translucent: Through the years, tree-hugging insects, plants, microbes and more have been frozen in amber’s warm, hazy glow. Bigger-bodied creatures can’t usually be contained by the ooze (though amber has certainly trapped parts of big animals, often resulting in inadvertently amputated limbs).
B. winhtini lies between these two extremes of encapsulation. “You tend to get small, soft-bodied, terrestrial organisms in amber,” explains Victoria McCoy, a paleobiologist at the University of Bonn who studies fossil preservation in amber, but was not involved in the new find. But bony lizards, she adds, don’t often fossilize—meaning understanding these old lineages is the paleontological equivalent of fishing a needle out of a haystack of giants.
When lead author Juan Daza, a lizard morphologist at Sam Houston State University, first came across the resin-suspended corpse after a private collector loaned it to Harvard University’s Museum of Comparative Zoology, he knew it was an unmissable opportunity. The fossil was first discovered in the rich tropics of Myanmar, the source of amber deposits unearthed in the past several years that have already yielded an astounding array of ancient frogs, insects, and even a feathered dinosaur tail in the past several years.
“It was so intriguing,” Daza says of the new lizard fossil. “The amber is translucent, but there’s a lot of distortion, like looking into a glass bottle.”
Daza and his team used CT scanning, a non-destructive method for probing the interior of the lizard’s amber mausoleum, to discern the lizard’s visible features. Its slinky shape and skeletal structure indicate that it was probably an anguimorph—but not everything about B. winhtini falls neatly in line with its modern relatives, making it difficult to determine exactly where it belongs in the ancient tree of lizard life. For now, the lizard is the sole ambassador of its genus and species.
“The new specimen brings us important information [about] the diversity of lizards in the late Cretaceous in Myanmar,” explains Lida Xing, a paleontologist at the China University of Geosciences in Beijing who did not participate in the new research. “This means that the evolution of lizards is more complicated than we might think.”
And although the researchers could see straight through the amber shell, the fossil turned out to be murkier than its capsule. Over time, sediment from the exterior had penetrated the little lizard’s body, mixing with its muscles and organs. This process, called permineralization, reduced the contrast between bone and soft tissue, blurring the boundaries of its skeleton.
But the exquisite preservation of the lizard’s exterior still yielded some key insights. Curiously, its legs were extremely tiny—even for its size. B. winhtini somewhat resembles a snake with gangly, misplaced hands awkwardly lashed to its sides. But Daza thinks this odd physique may have actually served the lizard in navigating the dense forest floor of Myanmar.
“If you’re going to be small, you need a well-built body—otherwise you’ll be too fragile to survive these environments,” Daza explains. “If you live in the leaf litter, it’s a great locomotion strategy to stop using your legs”—which, if anything, might slow you down. In fact, B. winhtini’s slippery slide might have helped it better evade predators.
B. winhtini stopped short of shedding its legs entirely, though: “They’re not running away all the time,” Daza explains. “They can use their limbs to stabilize their bodies… if they’re resting, foraging, [or] eating insects.”
Despite its puny limbs, the amber anguimorph boasted quite the tail. Though a couple chunks of it have been lost to time, Daza believes this appendage made up half the lizard’s total length of 1.5 inches, acting as a rudder as B. winhtini undulated through fallen foliage.
More intensive imaging methods might have yielded more information about the lizard’s mysterious heritage, but such techniques can often be destructive to the quality of amber. Because it’s currently a one-of-a-kind find, B. winhtini is too precious to pick at—so its full story remains shrouded in mystery.
The combination of resin-secreting trees and the rich, nurturing environment of the tropics have made Myanmar a goldmine—or ambermine—for the study of ancient life. To entirely entomb even the teeniest of tropical lizards, Cretaceous trees were probably belching up a lot of soft, sticky amber, explains McCoy. With so much free-flowing resin, this little lizard may yet find a friend.
“I think there’s definitely a chance we’ll find more specimens,” McCoy says.
Though don’t expect clones of this mini-lizard to be walking the earth anytime soon: Contrary to what Jurassic Park might have you believe, DNA is far too fragile to survive 100 million years—even in the most perfectly preserved of amber prisons.
Endnote: The original fossil will reside in Switzerland in a private collection. However, Daza and his team 3D-printed replicas, blown up to 10 times the specimen’s original size. The replicas will be publicly accessible at Florida’s Museum of Natural History and Harvard’s Museum of Comparative Zoology.