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Dinosaur family tree gives fresh insight into rapid rise of birds

Swarthmore College

The most comprehensive family tree of meat-eating dinosaurs ever created is enabling scientists to discover key details of how birds evolved from them.

The study, published in the journal Current Biology, shows that the familiar anatomical features of birds — such as feathers, wings and wishbones — all first evolved piecemeal in their dinosaur ancestors over tens of millions of years.

However, once a fully functioning bird body shape was complete, an evolutionary explosion began, causing a rapid increase in the rate at which birds evolved. This led eventually to the thousands of avian species that we know today.

A team of researchers, led by the University of Edinburgh (UK) and including Swarthmore College Associate Professor of Statistics Steve C. Wang, examined the evolutionary links between ancient birds and their closest dinosaur relatives. They did this by analyzing the anatomical make-up of more than 850 body features in 150 extinct species and used statistical techniques to analyze their findings and assemble a detailed family tree.

Based on their findings from fossil records, researchers say the emergence of birds some 150 million years ago was a gradual process, as some dinosaurs became more bird-like over time. This makes it very difficult to draw a dividing line on the family tree between dinosaurs and birds.

Findings from the study support a controversial theory proposed in the 1940s that the emergence of new body shapes in groups of species could result in a surge in their evolution.

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