• Researchers retracted a study they published in March about a tiny dinosaur species
  • The original paper described a hummingbird-sized dinosaur from the Mesozoic era
  • Other scientists were convinced that the specimen was of a lizard, not a dinosaur
  • Researchers say the description remains accurate but, doubt has been cast in classification

A paper describing a previously unknown species of a hummingbird-sized dinosaur has been retracted months after it was first published. According to the authors, while the classification may be in question, their description of the species remains accurate.

It was in March this year when a paper describing a hummingbird-sized dinosaur was published in the journal Nature. The paper described a very small skull encased in amber and it was believed to be that of the smallest known dinosaur from the Mesozoic era.

The study fascinated many in the scientific community but, there were also some who questioned whether the specimen was really of a dinosaur. A team of scientists even wrote a paper, titled "Is Oculudentavis a bird or even archsaur?", questioning it and suggesting that the species is more likely to be a lizard than a dinosaur.

Although they seem similar, dinosaurs and lizards are classified in different groups.

The preserved skull of the Oculudentavis khaungraae is just 7.1 millimetres long, likely making it the smallest dinosaur yet discovered
The preserved skull of the Oculudentavis khaungraae is just 7.1 millimeters long, likely making it the smallest dinosaur yet discovered China University of Geosciences / XING Lida

"Regardless the intriguing evolutional hypotheses about the bauplan of Mesozoic dinosaurs (including birds) posited therein, this enigmatic animal, however, demonstrates various lizard-like morphologies," the researchers wrote.

Another team also found similar specimens and, upon examination, concluded it to be a lizard.

According to, the paper and the new evidence led the editors at Nature to retract the original paper.

Although the original authors are divided, with some acknowledging a possible classification mistake while others seeing no reason for the retraction, they are all in agreement in terms of the validity of their work and description of the species.

"We, the authors, are retracting this Article to prevent inaccurate information from remaining in the literature," the researchers wrote in the retraction note. "Although the description of Oculudentavis khaungraae remains accurate, a new unpublished specimen casts doubts upon our hypothesis regarding the phylogenetic position of HPG-15-3."

This is not the first time that researchers have had to correct an initially published description of a species. In December 2019, a team of researchers, including the lead author of the original paper, described a mistake that was made in the initial description of a massive spider fossil from China.

That time, there was a more malicious reason behind the mistake. As it turns out, what they thought was the fossil specimen of an unknown ancient spider species turned out to be a hoax as it was actually a crayfish fossil that was merely painted on by locals to look like a spider.