The huge dinosaur just discovered has an evolutionary path similar to “Tyrannosaurus rex”

The fossil record shows life forms that have existed for countless centuries. Studying ancient species and ecosystems can improve our understanding of life in the past and the differences between ancient Earth and Earth today. Fossils can also help us understand how evolution works and what is most likely to develop in certain situations.

This is what it does Merax gigas, new theropod dinosaurit is central to our understanding of dinosaur evolution and biodiversity.

I was part of an international team of paleontologists, led by Juan Canale of the Ernesto Bachmann Museum of Paleontology in Argentina, who named and described Merax gigas. The specimen was collected between 2012 and 2014 near Villa El Chocón in Argentina, on the rocks Formasi Huincul that is about 95 million years ago.

Apex predator

Merax is a large theropod dinosaur belonging to the bipedal group that often ate meat, including birds. As members of the Carcharodontosauridae, they are relatives of dinosaurs like Carcharodontosaurus, Giganotosaurus And Acrocantosaurus.

The specimen found measured about 11 meters in length and weighed about 4,200 kg. It has a proportionately large skull that features quite frightening teeth, along with long legs and large claws, a powerful tail, and small arms and hands.

More likely, Merax they are the best predators. It appeared simultaneously with other large theropods, such as Skorpiovenatoreand together the large herbivorous sauropod dinosaur and the smallest Iguanadonian ornithopod dinosaur.

Distant relatives

Merax very important in the evolution of large dinosaurs. His body – a large head and small arms – was very similar to that seen in a tyrannosaurus, like Tyrannosaurus Rexand abelisaurid, as Carnotaur.

These three groups of theropod dinosaurs were all distant relatives. Each of them evolved independently with a large build and a combination of large heads and small arms.

We analyzed the evolution of these changes in all three groups by looking at changes in arm size relative to other body measurements, such as legs and body size. We found that each group underwent similar changes through evolution and that there was a lower limit to how small their arms could be compared to the rest of their bodies. This can be a developmental or mechanical constraint: the arm can only be very small compared to the body, despite other developmental pressures in this context.

There are several things that could potentially explain the size of their arms; the front legs themselves may have retained some of their functions despite their small size. Our data directly supports the idea that the reduced arm size in this group of dinosaurs is more likely to trace other traits rather than being the selective subject of evolution itself. In other words, as the relative size of the skull increased during evolution, the arms decreased proportionally in size as an evolutionary compromise.

Growth chart

Merax it also provides other important information on the evolution of dinosaurs regarding their growth and age. As a paleontologist, one of my areas of expertise is using the microstructure of bones to understand the growth of extinct animals such as dinosaurs. I also study variation in bone growth between individuals within and between species.

This involves cutting the bone in half (usually one of the long bones of the hind limb, such as the femur or tibia), attaching the piece to a microscope glass, and grinding the piece so that it is thin enough to allow light to pass through and the microstructure of the bone to be seen under the microscope.

From here, changes in bone tissue can be observed, and this tells us about their physiology and relative maturity. We can also see signs of annual growth similar to tree rings. By counting these growth indicators, measuring their location through the bone and analyzing them using statistical growth models, we can estimate not only how much the animal grew year after year, but also how old it was when it died.

Learn Merax Using this approach helped us determine that this dinosaur was probably around 50 years old when it died and that its skeleton had stopped growing around four years before it died. This would make it the oldest non-avian theropod dinosaur and one of the oldest known dinosaurs.

We also found that Merax, compared to other giant theropods such as tyrannosaurusreaching large sizes through very distinct growth changes. Merax it continues to grow for a longer period of time than its smaller relatives. tyrannosaurus it had a higher relative growth rate than smaller tyrannosaur species, but reached adult size in the same amount of time.

Independent evolution

Consequentially, Merax And tyrannosaurus is a complex example of evolutionary convergence: both have reached enormous sizes compared to their relatives and independently developed a combination of large skulls and small arms. However, they achieve this through very different modifications to their growth patterns throughout their lives.

Continuing to study Merax and other dinosaurs, our understanding of extraordinary biodiversity and changes throughout Earth’s history will continue to improve. By doing so, we will also gain a better understanding of the mechanism of evolution itself.

Zalfa Imani Trijatna of the University of Indonesia translated this article from English.