There is life beyond the famous Tyrannosaurus . This gigantic carnivorous dinosaur is the favorite of many people and the undisputed protagonist of the Jurassic Park saga. But the truth is that when this popular dinosaur appeared, the age of the dinosaurs was practically coming to an end. And it is that Tyrannosaurus rex inhabited North America during the Maastrichtian floor or epoch, between 70 and 66 million years ago. And before this, the dinosaurs had already been dominating the terrestrial fauna of the planet for 150 million years. And of course, it gave time for large carnivorous dinosaurs to appear more than once.
Dinosaurs are traditionally divided into two main groups, Saurischians and Ornithischians. And within the Saurischians there are two large groups, the Sauropodomorphs (large long-necked dinosaurs and their close relatives, such popular forms as Diplodocus , Brachiosaurus , Camarasaurus or Brontosaurus belong to this group) and the Theropods (mainly carnivores, with sharp teeth and claws, which include forms as famous as Tyrannosaurus , Velociraptor or Deinonychus , as well as the lineage of birds). These theropod dinosaurs, like the other groups of dinosaurs, appeared in the middle of the Triassic period . At first they were small and medium-sized animals, since they shared the world with other animals, such as the ” rauisuchios “, relatives of crocodiles that were great predators of their time. But at the end of the Triassic, a great mass extinction took place that wiped out all competition. And there the dinosaurs began to dominate the world. In this period, the famous Jurassic , the dinosaurs diversified and became giants. Dinosaur faunas appeared and emerged over the next 140 million years. And among the theropods really formidable forms appeared.
Spinosaurus
It was described in 1915 by the German paleontologist Ernst Stromer from a partial skeleton found in Egypt which was unfortunately destroyed in the World War II bombing of Munich. Spinosaurus (whose name means “spiny lizard”), has a very distinctive appearance due to its very tall vertebral spines forming a sail along its back . However, the few fossils with which it was described in 1915, and the little knowledge about its close relatives that we had at the time, led to its reconstruction being a very generalist theropod with a sail.
Over the decades and thanks to new discoveries, its appearance could be better refined. For example, with the finding of its relative Baryonyx , discovered much later, in 1983. Baryonyx was a strange theropod, with an elongated snout, conical teeth, and huge claws on its hands. Its anatomy allowed it to be related to Spinosaurus , whose reconstruction was corrected, now including an elongated snout similar to that of a crocodile, and large claws on its hands.
In 2014, just 100 years after Stromer’s original description, paleontologist Nizar Ibrahim and his collaborators, including Paul Sereno , published the finding of new specimens of Spinosaurus found in Morocco . These revealed that while reconstructions of this dinosaur were not far off, it was even stranger. Short legs, elongated back, long arms that possibly reached the ground. Its sail seemed to have a more square and irregular morphology and, most surprisingly, it is possibly the first non-avian dinosaur that could be adapted to an amphibious life. Thanks to the new findings, moreover, it has been possible to estimate that its length exceeded the 13 meters of Tyrannosaurus rex . It lived in the Lower Cretaceous in what is now Africa.
Carcharodontosaurus
Stromer also described in 1931 another impressive theropod found on African expeditions, Carcharodontosaurus (whose name means “shark-toothed lizard”), a theropod related to the Jurassic Allosaurus . But he lived in the middle of the Cretaceous . Although a complete skeleton has not been found, the remains found to date (a gigantic, very complete skull, hind legs, loose vertebrae) allow us to estimate that it would be a large theropod dinosaur, capable of rivaling Tyrannosaurus rex in dimensions. . Sadly, the fossils that were part of Stromer’s original publication were also lost in the same bombardment as the Spinosaurus ones , but thankfully, more finds have been made since then.
Giganotosaurus
It is a close relative of Carcharodontosaurus , only it lived in South America in the mid- Cretaceous . Its first fossils were discovered in 1993 by the amateur Rubén Carolini in the province of Neuquén , in Argentina. It was studied and published in 1995 by paleontologists Leonardo Salgado and Rodolfo Coria . Its skeleton is more complete than that of Carcharodontosaurus , and allows us to estimate that it would have a size comparable to that of Tyrannosaurus , or greater. Hence its name, which means “giant southern lizard”.
Torvosaurus
Although all of the giant theropod dinosaurs we’ve mentioned so far are from the Cretaceous period, the first age of the giants was the Jurassic . And for theropod dinosaurs it was no less. Megalosaurus (the first dinosaur discovered by science) was a theropod dinosaur from the Middle Jurassic of Europe that would have easily reached 9 meters in length. But a relative of itss, Torvosaurus , could easily have surpassed that size, making it a candidate to have been “the rival” of Tyrannosaurus rex during the Late Jurassic . Torvosaurus was described by Peter Galton and James Jensen in 1979 from a partial skeleton found in Colorado , United States. Similar remains, belonging to Torvosaurus or a very close relative, have also been described in Uruguay. And even in the Iberian Peninsula: fossils of Torvosaurus have been described in Portugal, and among the late Jurassic faunas whose remains are found in sites in the Iberian mountain range (as in sites in Teruel or Valencia) the presence of a gigantic Megalosaurus that could reach or exceed 10 meters in length.
Beyond how fearsome these dinosaurs may seem to us, and beyond the passions they arouse for their teeth and claws, the presence of apex predators in Mesozoic ecosystems had its effect. Engaged in an arms race, predators and prey swelled to the largest life on Earth has ever seen. The physiological adaptations that allowed this increase in size and its limits are a topic of research in current dinosaur paleobiology. And, therefore, and as is often said, that is another matter.
References :
Stromer, E. 1931. Vertebrate remains of the Baharije stage (lower Canoman). A skeletal remains of Carcharodontosaurus nov. Gen. Papers of the Bavarian Academy of Sciences , Mathematical and Natural Sciences Department, 9 (New Series): 1-23.
Brusatte, S.L.; Sereno, P.C. 2007. A new species of Carcharodontosaurus (dinosauria: theropoda) from the Cenomanian of Niger and a revision of the genus. Journal of Vertebrate Paleontology, 27(4): 902-916.
Ibrahim, N. et al. 2014. Semiaquatic adaptations in a giant predatory dinosaur. Science. doi:10.1126/science.1258750
Coria, R. A.; Salgado, L. 1995. A new giant carnivorous dinosaur from the Cretaceous of Patagonia. Nature, 377 (6546): 224–226.
Galton, P.M.; Jensen, J.A. 1979. A new large theropod dinosaur from the Upper Jurassic of Colorado. Brigham Young University Geology Studies, 26(1):1-12.
Cobos, A. et al. 2014. Megatheropods as apex predators in the typically Jurassic ecosystems of the Villar del Arzobispo Formation (Iberian Range, Spain). Palaeogeography, Palaeoclimatology, Palaeoecology, 399: 31-41.
