An article published in the journal “Current Biology” describes a research on the reasons for the survival of primitive birds the great extinction that struck the dinosaurs. According to a team led by Derek Larson, a paleontologist at the Philip J. Currie Dinosaur Museum in Alberta, Canada, at the end of the Cretaceous the conditions became such that winged dinosaurs and carnivorous birds became extinct while the ancestors of modern birds that ate seeds survived.
For decades, paleontologists have been discussing about the dinosaur extinction timeline: now it’s determined that an asteroid struck the Earth about 65 million years ago but was it the cause of sudden extinction of animals that were thriving? Many scientists believe that dinosaurs had been in decline for some time and the catastrophe gave them the coup de grace. This new research focused on maniraptorans (Maniraptora), a large group that includes carnivorous dinosaurs but also birds.
The winged dinosaur-like birds that were part of the maniraptoran group are among the closest relatives of birds but they became extinct at the end of Cretaceous. Over the past few decades several species of dinosaurs with feathers and wings more or less suitable for flight were found. The Archaeopteryx is the most popular species but there were many others.
Derek Larson and his team wondered why maniraptoran dinosaurs and various birds became extinct while other birds survived. To understand this, they collected data on 3,104 fossil teeth from four different maniraptoran families. In some cases the data had already been provided by previous publications but most were the result of the description and cataloging work of the team that carried out this research.
The teeth examined had ages crossing about 18 million years of history until the end of the Cretaceous. According to the researchers, if their diversity declined over time it would be an indication of an ecosystem in decline with a loss of species. In a stable ecosystem, teeth diversity would remain similar over time suggesting the asteroid impact as the sole cause of their sudden extinction.
The analysis of the data showed that the diversity in the teeth in maniraptorans remained steady over the last 18 million years of the Cretaceous. The dinosaurs belonging to the maniraptoran group suddenly disappeared during the great extinction occurred at the end of this geological period.
According to the researchers, the diet was the factor that favored the survival of the species from which modern birds descended. Analyzing the data on the diet of modern birds, Derek Larson and his colleagues reconstructed some possible characteristics of their ancestors and concluded that they had a beak with no teeth and they ate seeds.
After the impact of the asteroid that struck the Earth about 65 million years ago, many plants were affected because a lot of dust remained in the air for a long time darkening the sky and seriously limiting photosynthesis. However, probably a lot of seeds remained in the soil, favoring the birds that used them as their food source.
Paleontologists have always wondered why certain species survived that great extinction. This research offers a plausible explanation for the survival of certain species of birds which subsequently started evolving more rapidly to form the groups that exist today.