World’s ‘Smallest Dinosaur’ Revealed to Be a Mystery Reptile

Scientists have confirmed in a peer-reviewed paper published today in Biology Current that this small creature, which appeared in the Cretaceous period around 100 million years ago in Myanmar, is indeed a bird. The identity of this strange fossil, known as Oculudentavis khaungraae, has sparked controversy and debate, and its peculiar skull has attracted more attention than its tiny size. Described as an avian dinosaur, this bird-like creature was presented as the smallest dinosaur fossil ever found, resembling a toothed hummingbird in size. The fossil, which was encased in amber, has been featured in the pages of Nature.

The researchers quickly pointed out that Oculudentavis was not really a bird, but rather a small reptile fossil that seemed to represent a small, bird-like reptile. The fossil had a narrow, almost beak-like snout and a large eye opening in the skull, which made it resemble a bird. However, further evidence and a reanalysis of the dataset by another team supported the idea that the fossil was far from the avian perch on the tree of life. As a result, the original Nature paper on the study was retracted and a new Current Biology paper has since evolved, suggesting that Oculudentavis might not be what it initially appeared to be. Another specimen, which added to the evidence, also appeared in a pre-print publication in the same year.

How could a little reptile be mistaken for a bird in the first place? Several factors played into the confusion, says Bolet, the lead author and paleontologist at the University of Bristol. The overall appearance of the fossil gave it the first impression of a bird-like creature, with a vaulted skull roof, a tapering snout, and a long jaw. However, upon closer examination of the fossil, Bolet notes that it showed many lizard-like traits, such as the fused jaw and teeth seen in snakes and lizards. One particular connection between the bones of the skull and the shape of the skull, in particular, are not seen in birds and reptiles like lizards.

Experts from the University of Alberta, like Michael Caldwell, propose that Oculudentavis, an ancient and unusual lizard-like creature, represents a mysterious and unique species. Researchers suggest that there are enough differences between the skull bones of at least two Oculudentavis specimens to indicate distinct species. These creatures, named after the Naga people who live in the vicinity of Myanmar’s amber mines, are known as Oculudentavis naga. The second fossil, slightly distorted, was given the name “Bolet” by colleagues, and it differs in some ways from the first fossil. The team created CT scans of both the original specimen and the second specimen, which made it difficult to study the reptile from outside the amber.

“Squamates” encompasses snakes and “worm lizards” that are part of a specific category of reptiles specifically classified as a lizard. The contemporary tuatara, for instance, belongs to a distinct evolutionary lineage that diverged from lizards over 250 million years ago, although it resembles a lizard. Despite its colloquial usage, “lizard” does not refer to any random reptile with four legs.

“What is this object? I believe it continues to be an unanswered inquiry,” Caldwell states.

Oculudentavis, a weird lizard, has many peculiarities that make it difficult to determine its affinities with other lizard fossils. Bolet notes that it is not unusual for the discovery of more fossils of a specific group of lizards to help in working out the affinities. However, in the case of Oculudentavis, there have been no consistent answers provided, despite attempts to find an answer in hypothetical evolutionary trees. It seems to be related to the ancestors of seagoing mosasaurs that thrived during the Cretaceous period, while also potentially being one of the earliest lizards.

Paleontologists undoubtedly find many new fossils that will help them better understand the small reptiles of the Age of Dinosaurs. There are over 10,000 species of squamates, which are small animals that can become part of the fossil record. Even now, paleontologists are accounting for how these small animals can fill the gap in our knowledge. However, it is suggested that there is much more to be found, as Flores Herrera points out that there are many more discoveries to be made. The fossils of Oculudentavis, a species of squamate, are extremely scarce and rare, making them helpful in filling this gap. Oculudentavis comes from deposits of amber that are about 98 million years old. “Reptiles and lizards, such as Oculudentavis,” says Jorge Flores Herrera, a paleontologist from the University of Bristol, “are still little known to paleontologists.”

The search for additional fossils similar to Oculudentavis is hindered by the presence of the “blood amber” market, which frequently brings attention to these fossils. One of the affected groups are the Muslim Rohingya people of the country, who have been victims of genocide committed by the Myanmar military. This military seized control of the country earlier this year and has been responsible for acts of genocide for many years. The conflict has been exacerbated by the lucrative trade of amber specimens, and even ethically-sourced fossils often end up in the possession of private dealers who restrict researchers’ access and impede efforts to re-examine previous findings. The Myanmar military controls the mines where Cretaceous amber fossils are located.

Caldwell expresses, “however, due to their resemblance to proto-lizard creatures,” not because of their avian or reptilian qualities, I find these two entities genuinely intriguing. Particularly when compared to other amber-preserved lizards from the same era and location, the ambiguity surrounding Oculudentavis is understandable considering how peculiar the fossils appear, even upon a cursory examination.

Caldwell states that there are some very unique things and an ancient evolved ancestry, “I can see what remains of vertebrates from.” The area was encapsulated as an isolated island in the ancient sea, often acting as a refuge for ancient lineages to evolve. Myanmar, which is now what surrounds Oculudentavis’ climbing time, was a piece of land that split off from other landmasses. This might explain why Myanmar, an isolated location of prehistoric creatures, was the first place where such a confounding creature evolved.

Another enigma is the function that the Oculudentavis species fulfilled in their ecological system. Bolet asserts that the structure of the mandibles and minuscule dentition suggest that this reptile seized insects. Conceivably, this creature traversed prehistoric woodlands in search of invertebrate delicacies to consume. “Additionally, there are indications from the dermal folds beneath the cranium that these creatures employed them for a type of exhibition,” remarks Susan Evans, co-author of the study, akin to the behavior observed in anole lizards in contemporary times.

The story of Oculudentavis has raised further inquiries instead of reaching a definitive conclusion. What species does this reptile belong to, if indeed it is a reptile? And why is it so distinct? Moreover, does the fossil narrate an evolutionary tale, assuming it is not a lizard? These peculiar characteristics exhibited by the two specimens may indicate that they represent a divergent evolutionary lineage that extends far into ancient times, a concept that experts are just starting to comprehend.