Washington: A new research has shown that the Archaeopteryx, which has long been considered the iconic first bird, was less bird like, and more like dinosaurs.
The research, by Gregory Erickson of the Department of Biological Science at Florida State University, involved microscopic imaging of bone structure, which showed that the famously feathered fossil of the archaeopteryx grew much slower than living birds and more like non-avian dinosaurs.
The first Archaeopteryx skeleton was found in Munich, Germany, in the 1860’s and dating to 150 million years ago.
“For a long time, Archaeopteryx was considered the archetypical bird primarily because it had feathers, although it retained typical dinosaur features like a long tail and teeth,” said Mark Norell, Chair of the Division of Paleontology at the Museum and a co-author of the research paper.
“But the discovery of classical bird features like feathers and wishbones have recently been found in many non-avian dinosaurs blurring the line of what constitutes a bird,” he added.
Norell, Erickson, and colleagues looked at growth rate in Archaeopteryx and in birds and dinosaurs up and down the family tree by removing tiny, 250-micron chips from the long bones (specifically thigh bones and one of the shinbones).
The Munich Archaeopteryx was sampled with the help of co-author Oliver Rauhut of the Bavarian State Collection for Palaeontology and Geology in Munich.
According to Rauhut, “The Munich specimen is one of the more recently discovered specimens. Nevertheless, ‘cutting up’ this fossil to take samples of the bones was almost considered blasphemous until recently. But because the samples were very small and were removed with great skill by our preparator, the knowledge gained was more than worth the sacrifice.”
Surprisingly, the bones of the juvenile Archaeopteryx were not the highly vascularized, fast-growing type, as in other avian dinosaurs. Instead, Erickson found lizard-like, dense, nearly avascular bone.
To explain the strange bone type, the researchers also examined different-size species of dinosaurs that were close relatives of Archaeopteryx, including Deinonychosaurs.
They then looked to colleagues in China for specimens of two of the earliest birds: Jeholornis prima, a long-tailed creature, and the short-tailed Sapeornis chaochengensi, which had three fingers and teeth.
Next, the research team plugged bone formation rates into the sizes of the Archaeopteryx femora (thigh bones) to predict its rate of growth.
“We learned that the adult would have been raven-sized and taken about 970 days to mature,” Erickson said.
“Some same-size birds today can do likewise in eight or nine weeks. In contrast, maximal growth rates for Archaeopteryx resemble dinosaur rates, which are three times slower than living birds and four times faster than living reptiles,” he added.
ANI
