Argentine, American, and Canadian paleontologists simply introduced a brand new species of large carnivorous dinosaur – Meraxes gigas – first unearthed in 2012 in Neuquén, a province in Argentina’s Patagonia area. The primary full scientific research of this species has now been revealed in Present Biology, a journal that publishes authentic analysis throughout all areas of biology.
The species is a carcharondontosaurid theropod dinosaur, the most important predators from the Cretaceous age (90-100 million years in the past). Like all theropods, they had been short-armed and light-boned bipeds. Members of this specific household of dinosaurs had been the longest of the theropods, measuring about 40 toes (12-13 meters) from snout to tail. Considered one of its most distinctive options had been its sharply serrated and curved enamel that resembled four-inch pruning saws (Carcharodontosaurus means shark-toothed lizard in Greek). Weighing greater than 4 tons, “the good dinosaur eater,” because the press launch from the Nationwide College of Río Negro dubbed it, was as soon as one of many largest carnivorous lizards in South America.
Paleontologist Juan Ignacio Canale, a researcher with Argentina’s Nationwide Council for Scientific and Technical Analysis (CONICET) and the Nationwide College of Río Negro, is the lead creator of the Present Biology article. In a video interview from wintry Patagonia, Canale mentioned it reminded him of 1 specific dragon. “I got here up with the title as a result of I really like A Track of Ice and Hearth,” the collection of epic fantasy novels that impressed the hit Recreation of Thrones TV collection. “I really like the names George R. R. Martin selected for his dragons, and this one [Meraxes] match completely as a result of each are very giant reptiles with large skulls. We additionally wanted a brand new title to differentiate Meraxes from two different large carcharodontosaurs present in Neuquén: Giganotosaurus carolinii – the ‘villain’ from the final Jurassic World film – and Mapusaurus. That is the third of its sort, just like the three dragons from A Track of Ice and Hearth,” mentioned Canale.
Ten years of analysis funded by the municipality of El Chocón (the fossil-rich city in Neuquén), Nationwide Geographic, and the Discipline Museum in Chicago (USA) preceded this dramatic announcement. Unearthing the dinosaur went rapidly compared. On the primary day of fieldwork, they noticed an uncovered spinal vertebra. “We began digging and increasingly more bones appeared. We had been shocked,” mentioned Canale. “We discovered a cranium with no mandible, however with an intact maxilla and a few enamel.” They had been truly incipient enamel as a result of in contrast to people, dinosaurs and crocodiles produce a number of generations of enamel all through their lives. The Neuquén Meraxes was 45 years outdated when it perished, making it one of many oldest carnivorous dinosaurs to be found.
Virtually the entire arm and leg bones had been discovered intact, “which could be very uncommon as a result of on the whole, not a lot remained of the legs and arms of the most important carcharodontosaurs found from the Center to Late Cretaceous interval,” mentioned Canale. This enabled the analysis crew to determine a brand new and distinctive function of this species – a strong claw on the interior toe that’s a lot bigger and sharper than the opposite two.
The hips are additionally distinctive. Spines on the dinosaur’s again mission upward above the waist and are paying homage to the hump on the Concavenator, found in 2015 in Cuenca (Spain). Making one other nod to the literary inspiration for the dinosaur’s title, the press launch describes this a part of the dinosaur as “Queen Rhaenys Targaryen’s saddle,” after the dragon mounted by the fictional queen.
The cranium is one other wonderful specimen. In addition to being huge, it’s the most full instance discovered up to now and reveals intricate bones with protuberances, ridges, and grooves. It offered the researchers with beneficial info not solely about Meraxes, however about all of the species of the household, together with the well-known Gigantosaurus.
“It offered loads of details about their anatomy,” mentioned Canale. “We noticed that the arms had been very quick, one thing that we beforehand suspected, however can now say for sure since we have now precise measurements.” The evaluation concluded that, like different recognized teams of carnivores such because the Tyrannosaurus and the Abelisaurus, the arms grew to become shorter over time till they had been solely 40% of the femur’s dimension. Then they stopped shrinking and nobody is aware of why. “The query is why did they attain that restrict? Why didn’t the arms preserve shrinking? The proportion of the arms to the femur is analogous in all of those species,” mentioned Canale. Like many scientific endeavors, some solutions simply increase extra questions.
The analysis crew examined numerous hypotheses. “We noticed that the pectoral girdle, which is the place the arm, scapula, and different bones are inserted, shouldn’t be small the place the arm suits in. It’s a really giant and well-developed bone that encapsulates loads of the musculature that extends to the extremities. Since that musculature has to slot in someplace, maybe that is the rationale why the arms didn’t shrink any additional. All of the musculature that originated within the scapula needed to be inserted someplace.” The usefulness of such quick limbs remains to be a matter of controversy. Some speculate that they served for assist throughout copulation, for tearing aside prey, or just to keep away from hitting the bottom. However arm dimension doesn’t appear so vital when you may have an enormous cranium. The cranium of Meraxes gigas was a bit over 4 toes (1.27 meters) lengthy. Different Carcharodontosaurus additionally had giant heads, such because the Tyrannosaurus rex (4.6 toes or 1.40 meters) and the Giganotosaurus carolinii (5.3 toes or 1.63 meters). “Issues that different carnivorous hunters did with their arms, these dinosaurs may do with their heads – seize and manipulate prey, pin it to the bottom, and kill it,” mentioned Canale. Subsequently, the arms wouldn’t have been very helpful for consuming, particularly after they tried to devour different giants just like the Argentinosaurus, one of many largest herbivores within the historical past of the planet. “Absolutely, it’s no coincidence that carnivores and the bigger herbivores coexisted. There’s in all probability a meals chain relationship. It’s like an arms race: the prey grows bigger as a protection mechanism, and their predators additionally develop to have the ability to hunt them,” mentioned the paleontologist.
By different coexisting species, scientists can theorize concerning the evolutionary finish of the carcharodontosaurus household of dinosaurs. Specimens of two different species – Mapusaurus and Taurovenator – from the identical geological interval (93-96 million years in the past) have been found. “This leads us to posit that earlier than changing into extinct, they reached a peak degree of diversification. It was a gaggle that diversified an important deal simply earlier than its extinction. That’s after they died out and had been now not the highest terrestrial predators of their time in South America.” Later, they might be succeeded by the abelisaurids and the megaraptors, however that’s one other story.
The crew of scientists contains Sebastián Apesteguía, Pablo Gallina, Alejandro Haluza and Federico Gianechini from Argentina; Jonathan Mitchell, Nathan Smith, Akiko Shinya, and Peter Macovicky from the USA; and Thomas Cullen from Canada. The crew plans to proceed its analysis utilizing extra refined methods resembling CT scans and detailed reconstructions, because it searches for extra solutions concerning the bones, muscular tissues, and basic anatomy of the “Ice and Hearth” dragon.