In the warm, lush world of the Middle Jurassic, nearly 166 million years ago, an unassuming reptile scampered across the branches of prehistoric trees—its tiny claws gripping bark, its nimble body darting between leaves in search of food and safety. This creature, known as Marmoretta oxoniensis, has spent decades puzzling paleontologists, its lifestyle misinterpreted, its story obscured by stone. But thanks to cutting-edge technology and a fresh look at its fragile fossils, scientists are now rewriting the narrative of this ancient survivor. Marmoretta, it turns out, was no swimmer of lagoons, but a tree-climber—a pioneer of vertical life at a time when dinosaurs ruled the Earth.
Cracking the Jurassic Code
The Middle Jurassic epoch, spanning roughly from 174 to 161 million years ago, was a dynamic chapter in Earth’s history. The planet was warmer, sea levels were higher, and the continents—still drifting into their modern shapes—were blanketed in thick forests, teeming with ancient life. Dinosaurs dominated the land, pterosaurs ruled the skies, and marine reptiles glided through shallow seas. But alongside these titans lived a quieter, lesser-known world of small reptiles, insects, and early mammals—creatures whose stories are often overlooked due to the rarity and delicacy of their remains.
Fossils from this period are scarce, especially those of tiny terrestrial animals. Often, the bones are so fragile that removing them from rock destroys their structure, and traditional techniques fall short of preserving crucial anatomical details. Among these elusive species is Marmoretta oxoniensis, first discovered in the 1960s in limestone deposits of Oxfordshire, England, and later on the Isle of Skye in Scotland. For decades, paleontologists believed it was semi-aquatic, based on its proximity to fossilized marine life. The assumption made sense—after all, Marmoretta had been found in what were once coastal lagoon environments. But as it turns out, the story was more complex.
The Tech That Turned the Tables
The revelation that Marmoretta was not an aquatic reptile but a skilled climber owes much to modern scanning technologies—specifically, high-resolution CT imaging and synchrotron radiation. These tools allow scientists to peer inside fossils without destroying them, capturing microscopic details invisible to the naked eye.
Dr. David Ford, a paleontologist specializing in early reptiles, led the new investigation into Marmoretta’s anatomy. “It’s important not just to find out that a species exists, but how it lived,” he explains. “That’s the heart of paleobiology—reconstructing life from ancient bones.”
The skull of Marmoretta is barely two centimeters long, its finger bones just millimeters. Yet within those minuscule structures lay the secrets to a different lifestyle. Traditional fossil preparation—acid baths and manual extraction—would have destroyed these associations. Synchrotron scans, however, offered a pristine window into its world.
What the scans revealed was nothing short of astonishing.
A Climber in the Canopy
The limbs of Marmoretta were unlike those of known aquatic reptiles. Its fingers were elongated and curved—traits found in modern climbing lizards, such as geckos and anoles. Rather than flattened, paddle-like hands suited for swimming, Marmoretta’s grasping digits suggested an animal evolved for a life in the trees.
Its spine was also telling. Unlike the flexible, serpentine vertebrae of swimmers, Marmoretta possessed a stiffer backbone—a trait that would aid in balance and coordination as it navigated the vertical world of trunks and branches. To test these observations, Ford and his team developed a new analytical method: comparing the bone measurements of Marmoretta to those of modern reptiles using statistical modeling. The results were conclusive—Marmoretta had more in common with today’s arboreal reptiles than with aquatic species.
“While it certainly looked like Marmoretta was a climbing animal, we needed to back that up with hard data,” says Ford. “This method allowed us to do just that—and it opens the door to re-examining other early reptiles with fresh eyes.”
The Reptilian Family Tree
Marmoretta occupies a key branch in the reptilian evolutionary tree. It is classified as a stem lepidosaur, an early relative of a group that includes all modern lizards and snakes, as well as the tuatara—a rare, ancient reptile still living in New Zealand. The lepidosaurs are one of the two major reptile lineages that emerged after the Permian extinction, diverging from their archosaur cousins (the group that includes crocodiles, birds, and dinosaurs) around 260 million years ago.
Fossils from the early days of these groups are vanishingly rare. The bones are tiny, brittle, and often lost to time or misidentified. “In the main, all that’s left of these animals are quite small and fragile fossils that we haven’t had the technology to delve into until recently,” Ford says. As such, discoveries like Marmoretta offer rare and invaluable glimpses into the early evolution of reptiles—especially how they diversified to fill new ecological niches.
Life in a Jurassic Lagoon Forest
So, what did life look like for Marmoretta? Based on the geological context and its newly revealed anatomy, the researchers believe it lived in coastal forests surrounding subtropical lagoons. Imagine something akin to modern mangrove swamps, where trees rise from brackish water and are draped in vines and ferns. Here, Marmoretta could climb out of reach of predators, feeding on insects or perhaps plant matter, and basking in sunlight filtering through Jurassic leaves.
Living in trees would have offered distinct advantages. Ground-level ecosystems were crowded and dangerous. Larger carnivorous dinosaurs and early mammals prowled the underbrush, and aquatic reptiles lurked in nearby waters. By evolving the ability to exploit vertical space, Marmoretta and its kin could carve out a safer, less competitive lifestyle.
This strategy—taking to the trees—may have been a crucial evolutionary move. “Taking advantage of the vertical realm could have been the secret of these animals’ survival,” Ford says. “It’s a strategy that other small animals used later in history, including mammals during the Triassic. It definitely seems to have its benefits.”
A Blueprint for Survival
The implications of this discovery stretch beyond one small reptile. The story of Marmoretta sheds light on broader patterns in evolutionary biology—how animals adapt to their environments, how behavior influences morphology, and how niches drive diversity.
Vertical living, for instance, requires significant anatomical adaptations—strong limbs, prehensile hands, and acute spatial awareness. These traits emerged multiple times in different lineages, from primates to tree frogs. Marmoretta’s climb into the canopy might represent one of the earliest examples of this evolutionary trend.
Moreover, its success may have helped pave the way for the explosive diversification of lizards and snakes in later periods. The lepidosaurs would eventually spread across the globe, from desert-dwelling geckos to sea snakes and monitor lizards. Today, more than 10,000 species trace their lineage back to ancestors like Marmoretta.
The Future of Fossil Research
The rediscovery of Marmoretta‘s true lifestyle underscores the transformative power of modern technology in paleontology. With CT scans and synchrotron imaging, researchers can now explore delicate fossils without harming them, reconstructing skeletons in three dimensions, and drawing conclusions that would have been impossible a generation ago.
Ford’s team hopes their new method for analyzing small fossilized reptiles will be adopted by others. “There are hundreds of tiny fossils sitting in drawers around the world,” he says. “We now have the tools to bring them to life—to find out what they did, where they lived, and how they survived.”
It’s a thrilling time for paleobiology. As imaging becomes more accessible and databases grow, we may soon uncover entire ecosystems from the Jurassic and beyond—not just the giants, but the underdogs, the climbers, the clever survivors like Marmoretta oxoniensis.
A Window into an Ancient World
In the end, the story of Marmoretta is a story of perspective—of how science evolves, how assumptions are overturned, and how even the smallest creatures can reshape our understanding of the past. What was once thought to be a lagoon swimmer is now recognized as an agile climber, living high among the trees while dinosaurs thundered below.
It’s a reminder that the fossil record is not just a catalog of bones, but a narrative waiting to be read—a story written in stone, unlocked by curiosity, and brought to life through ingenuity. And thanks to researchers like David Ford and his team, the canopy-dwelling world of Marmoretta is no longer lost to time. It is, at last, part of our living history.
Reference: David P. Ford et al, Evidence for clinging arboreality in a Middle Jurassic stem lepidosaur, Proceedings of the Royal Society B: Biological Sciences (2025). DOI: 10.1098/rspb.2025.0080