Exactas y Naturales Divulgación
IN ISCHIGUALASTO, NORTHWESTERN ARGENTINA
Paleontologists discover a 231 million years old species nearly identical to the ‘squirrel’, Scrat, of the Ice Age
Because of its tremendous resemblance, paleontologists thought of naming this new species in allusion to Scrat, the renowned squirrel-like character with saber teeth in the movie, Ice Age. Although they finally named it Pseudotherium argentinus, meaning, false Theria from Argentina. The entire skull is less than six centimeters in length and was found in Ischigualasto with two of the oldest dinosaurs known to date.
Emanuel Pujol (Agencia CTyS-UNLaM) - Dr. Ricardo Martínez, a researcher at the Institute and Museum of Natural Sciences of the University of San Juan (IMCN), told the Agency CTyS-UNLaM: “The new species has a very long, flat, and shallow snout, and its very long fangs located almost at the tip of the snout, so the resemblance [to Scrat] is tremendous”.
The skull was surprisingly well preserved, so that, at first glance, the similarity was obvious. "At some point, I thought of calling it Scrat", said Martinez, who conducted a very thorough study of the skull of this mammaliamorph (mammal-relative) along with Rachel Wallace and Timothy Rowe, both at the Jackson School of Geosciences, University of Texas at Austin. The study was recently published in the scientific journal Plos One.
Arguably, paleontologist Martínez, who has more than a dozen species discovered in his record, has made a kind of paleontological ‘hat trick’. Just as Lionel Messi and Cristiano Ronaldo usually make triplets (three goals) and take the ball home, Martinez made his ‘hat trick’ to find this little animal along with two new species of primitive dinosaurs. It is true, he did not take a ball home, but he took to the Museum the jacket, which is the plastered block of stone containing the fossils, so they can be safely studied in a laboratory.
This little animal had to wait more than 230 million years to be discovered. It was frozen in time, although not on ice like Scrat, but on the multicolored rocks of the famous Ischigualasto site located in the San Juan province of northwestern Argentina.
On this site, also known as the Moon Valley, this Triassic ‘Scrat’ waited to be rescued next to the dinosaur, Panphagia protos, one of the oldest known sauropodomorphs (related to long-neck dinosaurs) known today, and to the femur of the first and only lagerpetid dinosaur relative discovered in this deposit. These three very different species shared their long stay until Martínez's ‘hat trick’ in 2006, at which point their respective studies began (see illustrations by artist Jorge A. González in the photo and video gallery).
Unlike the ‘squirrel’ of the film, this mammaliamorph, Pseudotherium argentinus, lived in an environment warmer than today, with abundant flora mostly made up of ferns and conifers, since there were no flowering plants during its time.
According to Martínez, this animal would have been about 25 centimeters in length, from nose to tail, and had a different diet than the character of the animated film created by Blue Sky Studios: "He did not feed on acorns, but surely ate insects or smaller animals", he asserted.
Since he did not need his saber teeth to open acorns, the IMCN paleontologist affirmed that his long fangs could have served him “on one hand, to nail and trap insects or prey, but another option is that this animal has been a male and we are in the presence of sexual dimorphism, that is, that the males of this species had developed these great fangs as a way to attract females. But, at this point, you can't know much, because we only have one specimen," Martínez said. He added: "If there were many individuals to analyze, one could see if there is variability and could think that males and females had different lengths of fangs”.
A hat trick with two great goals
Of these three individuals that Martínez found together, two were found to be new species. Meanwhile, the preservation of the skull was so good that a very detailed study of its internal structure could be performed with a state-of-the-art computed tomography (CT) scanner at the University of Texas.
Dr. Martínez commented that "until now, a mammal relative has not been found so advanced in Ischigualasto, in which the growth of the brain cavity, a precursor to the great encephals of mammals, is observed”.
"With these images, we could observe the developed inner ear, the loss of the post-orbital bar, as well as the presence of the turbinals that are like partitions that allowed this animal to heat the air entering its respiratory system, which would indicate that he had hot blood”, said the expert.
The Triassic Scrat and the Cretaceous Scrat
In 2011, researchers Guillermo Rougier, Sebastián Apesteguía and Leandro Gaetano unveiled an animal they named as Cronopio dentiacus, in tribute to Cortázar and alluding to the small size of this species that measured between 10 and 15 centimeters.
At that time, the researchers highlighted the similarities that this animal also had with Scrat and, in dialogue with the Agency CTyS-UNLaM, Dr. Apesteguía highlighted the imagination of the creators of the film who anticipated the existence of an animal with fangs of saber before such a species was known.
The surprising thing is that nature created ‘two Scrats’ at very different times. While the Ischigualasto mammal-relative, Pseudotherium argentinus, is 231 million years old, Cronopio was found in La Buitrera, a site located in Río Negro that has an age of 95 million of years.
Dr. Ricardo Martínez, mentioning the finding and investigation of Cronopio dentiacus and his Pseudotherium argentinus, joked to the Agency CTyS-UNLaM "it is as if we were rebuilding Scrat's phylogenetic ties".