Small dinosaurs can be said to have existed at the beginning and end of the dinosaur era. It first happened when they were just appearing, in the beginning moments of the species. And as we progressed from the Triassic to the Cretaceous they became larger.
Then the panorama began to change. From the huge sauropods they evolved towards the tiny Archeopteryx. This is how they advanced to become the birds we know today.
50 million years to get small dinosaurs
Research estimates that theropods were required to change to become the first small flying birds. What was done was to measure theropod fossils that include carnivorous dinosaurs like Velociraptor.
In this way they traced the transformation of giants with a maximum body volume of 238 kilograms until reaching the Archeopteryx which weighed only 800 g. The analysis revealed that the ancestors of birds shrank in an uninterrupted and very consistent manner. It’s something that offered them some benefits.
12 major evolutionary steps were identified that led theropods to divide to form new types of dinosaurs.
At each of the breakpoints, the theropods shrank into birds. They also changed four times faster than other theropods that did not become birds.
This showed that the birds’ iconic small size is the result of a sustained pattern of selection for smaller body size that took millions of years.
© Nobu Tamura
– Creative Commons
The advantages of being a small dinosaur
Each wave of contraction added survival traits that we now see in birds. As they reached a smaller body volume than before, this allowed them to explore new niches and body plans, something their ancestors would not have been able to do.
Some of these new terrains were chasing insects, climbing trees (something that allowed them to better protect themselves), and eventually developing powered flight.
A radical change occurred in the theropods called Tetanuraewhich include famous predators called Allosaurus. These evolved a thigh bone at an oblique angle.
As a result, this moved their center of gravity forward, pushing their bodies into a leaning posture like that of modern birds and ensuring their wings were close to the center of gravity. It was what paved the way to flight.
On the other hand, while the skulls on their bodies decreased in size, the skulls of the theropods remained relatively large. This means that they could carry larger brains relative to the size of their body volume.
Smaller dinosaurs were more likely than larger ones to develop insulating feathers, something that allowed them to hunt at night.
Its small body also appears to have helped birds survive the mass extinction that wiped out the rest of the dinosaurs 65 million years ago. This extinction eliminated all animals above a certain size. Birds were among those dinosaurs that were small and were able to cope with the changes that arose.
© Fred Wierum
– Creative Commons
The evolution of small dinosaurs
Scientists today are clear that there is a relationship between a humble pigeon and the once powerful Tyrannosaurus rex. The theropods shrank until they reached the size of a small dinosaur, with all the characteristics of a bird.
These species share a remarkable biological past, according to paleontologist Paul Barret, which has given new insight into the way scientists view the evolution of species.
The birds that populate the skies today are small dinosaurs that remind us how life can present notable changes.
Decades of new discoveries and important studies have convinced researchers that there is a direct link between modern birds and theropods.
Dinosaurs were once thought to be scale lizards. However, now they are seen differently. It is understood that its evolution involves much more.
The rebirth of the dinosaurs
With regard to paleontology, some specialists think that we are facing the dinosaur rebirth. It began in 1960 with the discovery of a specimen of Deinonychus a small predatory dinosaur that lived 115 million years ago.
Not only did it demonstrate unique similarities to birds. He also seemed to be an intelligent pack hunter and quick in his movements. The fact that he had feathers helped transform the way paleontologists think about dinosaurs.
New work on ancient specimens and discoveries of dinosaurs and early bird species in the field supported the idea that dinosaurs were ancestors of birds.
In fact, characteristics and behaviors that characterize birds were found in dinosaurs.
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Small dinosaurs with feathers
The most surprising thing about small dinosaurs is that many had feathers. They had more evolved characteristics than the feathers of other specimens.
That is why modern reconstructions now look more like birds, even if they would have been absurd to 19th century researchers. Every day they move further away from the scaly illustrations that used to be traditional in the field.
Theropods
Deinonychus was a theropod, a bipedal carnivore that belonged to the same group as the Tyrannosaurus rex.. Scientists now know that dinosaurs developed bird-like characteristics long before the appearance of Archeopteryx. This accounts for an evolution in the knowledge of fossil remains.