How did dinosaurs become a dominant species on the planet?
It is known that the end of that long domain occurred after the impact of an asteroid 66 million years ago.
But the mystery of how these giants surpassed other species and came to rule the planet has occupied scientists for years.
The answer, according to a new study in the journal Nature, can be found in Fossilized dinosaur feces and vomit from more than 200 million years ago.
Fecal fossils are called coprolites. Vomit fossils are called regurgitates. Together they are called bromalites.
These fossils allow us to reconstruct the food webs of past ecosystems and what they contain, including insects, is extraordinary.
“The bugs were amazing! Some were only 1mm long, but preserved with all their tiny legs, antennae and intricate details: in a 230 million year old coprolite! “paleontologist Martin Qvarnström from Uppsala University in Sweden, lead author of the study, told BBC Mundo.
“We also discovered coprolites full of chewed bone fragments and crushed teeth. It turns out that the first Smok archosaur chewed bones like modern hyenas to extract marrow and nutrients, but in doing so it crushed and swallowed its own teeth,” adds Qvarnström.
“These are just a few surprises, but taken together, they reveal the structure of entire ecosystems of that time!”
The rise of the giants
Dinosaurs emerged approximately 230 million years ago.
But they were initially overshadowed by other animals, including large relatives of crocodiles and herbivores the size of elephants.
However, about 200 million years ago, dinosaurs came to dominate and their main competitors disappeared.
“We approached the emergence of dinosaurs in a completely new way,” explains Qvarnström.
“We analyze the dietary evidence to deduce the ecological role of dinosaurs throughout their first 30 million years of evolution“.
The study focused on a region of Poland with a large number of fossils from that crucial period.
“We studied more than 100 kilograms of fossilized feces,” says Grzegorz Niedźwiedzki, a paleontologist and geologist at Uppsala University and the Polish Geological Institute and another of the authors of the study.
Qvarnström and his colleagues examined more than 500 bromalites and analyzed their content.
The scientists used different types of microscopes and a technique known as synchrotron microtomographywhich uses a particle accelerator to see in detail inside the fossils.
Analysis of the digestive materials allowed the researchers to decipher “who was eating who and see this trend over such a long period of time,” Qvarnström says.
How can researchers know who produced those feces?
Fossil bones and footprints show which animals were present at a given time.
and the researchers deduced who produced a given coprolite based on factors such as the size and shape of the fossil, and in the digestive system of living relatives of these extinct animals.
Adapt or go extinct
The team found that the number and variety of fossil content increased over time.
This indicates that Larger dinosaurs with more diverse eating habits began to gain prominence in the late Triassic period (between 237 million and 201 million years ago).
By comparing the fossils with plant data from the time, scientists discovered that the rise of the dinosaurs was determined by chance and adaptations.
For example, the climate changed and there was an increase in humidity, which modified the available vegetation.
Dinosaurs were able to adapt better than other land animals to this changing climate and to changes in diet than other land animals.
Other environmental changes related to increased volcanic activity precipitated a broader range of plants that exploited increasingly larger, herbivorous dinosaurs.
The proliferation of large herbivorous dinosaurs led in turn to the evolution of larger carnivorous dinosaurs.
“What we learned was that the emergence of dinosaurs took quite a long time and was really complex,” says Qvarnström.
The dominion of the dinosaursIt didn’t happen overnight.; “The dinosaurs had to compete fiercely with other groups of animals, and a little luck played a part.”
The adaptability of the first dinosaurs was vital, according to the scientist.
“Animals with more specialized diets struggled with changing climates.”
Instead, “animals with more varied diets seem to have coped better with environmental changeswhich was crucial to the early success of the dinosaurs, while the first dinosaurs fared better with their varied diets and flexibility.”
The study helps understand how life responds to different pressures, including those derived from climate change.
“Understanding past faunal changes can influence our knowledge of current ecosystems, which face significant challenges due to climate change,” Qvarnström explains to BBC Mundo.
In the future, scientists hope to study bromalites from other regions.
“We plan to test this model with key early dinosaur fossils in other regions. South America, where the first true dinosaurs were found, is an area we are especially excited to explore next”.
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