Apparently it was about 16 centimeters long, with a very extended tail, and that it moved easily near the dinosaurs. While its appearance might suggest it, it is not a lizard, but a mysterious reptilewhose existence was discovered by a group of researchers from the Smithsonian Institution. Scientists have renamed this reptile with the name of Tuatara and, at present, I am of the opinion that it represents another important step in the history of evolution on planet Earth.
In fact, even if the remains found by scientists seem to be those of a “simple” lizard, the presence of the Tuatara in the Jurassic of North Americaabout 150 million years old, would embody a huge evolutionary epic, dating back more than 200 million years ago.
The discovery of the mysterious reptile
How was this mysterious reptile found? Basically a team of scientists, including the curator of the section Dinosauria of the National Museum of Natural History Matthew Carrano and the associate researcher David DeMar Jr. they were carrying out excavations in the interior-western area of the USA (close to northern Wyoming). The excavations were aimed at finding new information on dinosaurs, with searches for skeletons and fossils.
Specifically, the team was working on what has been identified as a very ancient Allosaurus nest. And, in fact, a fossil has been found. Except that it was not what was expected: the skeleton, perfectly preserved, looked a bit like those of a particularly robust iguana. However, after the first analyzes, it became clear that it was closer to the characteristics of the order of rhinoccephalswhich diverged from the lizards at least 230 million years ago.
The tuatara and the evolutionary history
Closer, however, does not mean it belonged to the same species. As Carrano and DeMar explained in their research, published in the Journal of Systematic Palaeontology, the mysterious reptile had substantial ones differences with the rhinoccephals. The latter, in fact, were widespread all over the world. They played “ecological” roles, hunting aquatic fish, parasites and weeds.
Rhinoccephals apparently disappeared when reptiles such as lizards and snakes became common, and here is the key role of the tuatara: it is themissing link, which would justify the “empty” evolutionary space between rhinocephali and lizards. Like the first ones, the tuatara in fact, would have had no problems surviving alongside the most common dinosaurs, thanks also to the particular conformation of the jaw and the particular membranes that would have helped it to survive both heat and cold.
The hypotheses on the disappearance of the tuatara
But what caused the tuatara to disappear? And what has allowed, consequently, the widespread diffusion of lizards and snakes? According to Carrano and DeMar, this mysterious reptile may have disappeared due to the habitat change and, consequently, of food and reproductive resources. Most likely, moreover, the tuatara fed on insects and vegetables which then became the “menu” of lizards and snakes, making the competition increasingly fierce.
“It is fascinating to watch the passage of dominance of a space from one group to another – Carrano said – just as it is interesting to suppose that, somehow, a species has disappeared to make way for something new and more “effective” evolutionarily speaking. However, more research is needed to find out if anything else escapes us. And I am sure it is so ».