Male And Female Dinos Shared Nesting Duties, Says New Study
April Flowers for redOrbit.com – Your Universe Online
New research into the incubation behavior of modern birds is shedding new light on the type of parental care carried out by their extinct ancestors.
Geoff Birchard from the Department of Environmental Science and Policy at George Mason University, along with Charles Deeming and Marcello Ruta from the University of Lincoln’s School of Life Sciences, wanted to test the theory that data from modern birds could be used to predict the incubation behavior of the group of carnivorous dinosaurs from which birds evolved, Theropods. Their findings were published in a recent issue of Biology Letters.
A previous study published in Science in 2009 suggested that it was males of the small, carnivorous dinosaurs Troodon and Oviraptor that incubated the eggs. The authors, by looking at factors known to affect egg and clutch mass in modern bird species, found that shared incubation with mature young was the ancestral incubation behavior rather than male-only incubation.
“The previous study was carried out to infer the type of parental care in dinosaurs that are closely related to birds,” said Birchard. “That study proposed that paternal care was present in these dinosaurs and this form of care was the ancestral condition for birds. Our new analysis, based on three times as many species as in the previous study, indicates that parental care cannot be inferred from simple analyses of the relationship of body size to clutch mass. Such analyses have to take into account factors such as shared evolutionary history and maturity at hatching.”
Because other paleontologists were starting to use the Science data to predict the incubation behavior of other dinosaur species, Birchard and his colleagues decided to repeat the previous study with a larger data set and a deeper understanding of bird biology.
“Irrespective of whether you accept the idea of Theropod dinosaurs sitting on eggs like birds or not, the analysis raised some concerns that we wanted to address,” said Deeming. “Our analysis of the relationship between female body mass and clutch mass was interesting in its own right, but also showed that it was not possible to conclude anything about incubation in extinct distant relatives of the birds.”
The new findings have furthered our understanding the factors affecting the evolution of bird incubation behavior. The researchers hope that their findings will help other paleontologists in constructing their interpretation of future finds of dinosaur reproduction in the fossil record.