Ancient Shorebirds Pecked and Scratched just like their Modern Counterparts
A trace fossil discovered in South Korea indicates that Cretaceous shorebirds pecked and scratched at the ground just like their modern counterparts. University of Kansas researchers, studying the fossil have suggested that ancient birds shuffled along muddy flats and pecked at the ground, behaviour seen in today’s shorebirds. The marks and scratches found in the fossil are very similar to the marks left behind as shorebirds scratch and peck at the mud looking for invertebrates to eat.
Commenting on the paper which describes the research, due to be presented at the meeting of the Geological Society of America in Denver at the end of this month, palaeontologist Amanda Falk (University of Kansas) stated:
“These tell us what animals were doing. The behaviours are pretty much identical to modern plovers and sandpipers.”
Falk and her adviser Dr Stephen T. Hasiotis in their study suggest that the trace fossils represent two different species of birds, or perhaps a single species working at two different speeds as they patrol the mud looking for food.
These are not the first bird trace fossils to have been discovered, other fossils have been excavated in Utah and Alaska, but such ancient bird trackways are very rare. This is the first time the behaviour of birds has been recorded from the Early Cretaceous (110 million years ago – Aptian faunal stage). For graduate student Amanda, the fossilised trackways are helping her to understand more about the different types of bird that existed alongside the dinosaurs during this part of the Mesozoic. Her studies of trackways is helping her to identify different types of birds, such as ground dwelling ones and those that were capable of perching, indicating an arboreal habit.
Amanda’s Masters thesis concerned a behavioural analysis of Cretaceous bird tracks from two locations in North America. Her work is assisting scientists allowing them to distinguish different types of bird from the trackways and other trace fossils the birds have left behind.
Associate professor, Dr. Hasiotis will be presenting a paper on this study at the forthcoming meeting of the Geological Society of America with his student Amanda Falk.
The South Korean tracks say a lot about the feeding behaviour of ancient birds. Martin Lockley of the University of Colorado in Denver, commented:
“Herons do a shuffling behaviour to stir up the substrate and find food. These are just the sort of tracks seen in the rocks. Then again, there are no herons known from the Cretaceous.”
He went onto to propose that the tracks plus the behavioural marks suggest two interesting possibilities. Firstly, it could suggest that some clades of modern birds are very old, dating from the Cretaceous, making some birds seen today “living fossils”.
Secondly, that these trace fossils are examples of convergent evolution. Organisms not related to each other develop the same solutions to a problem such as the Australian marsupial the Echidna and a hedgehog having spines. Early Cretaceous birds were not closely related to modern birds but evolved the same kind of feet, beaks and feeding strategies because they occupied the same type of ecological niches.
Dr Lockley, a professor of geology added:
“All these wader and water birds have very similar feet and so there’s no reason to think they could not have evolved 110 million years ago as well.”
The Haman Formation, where the bird tracks were found, has been the focus of research into ancient birds and other Mesozoic creatures for some time, but until now most of the work on the trace fossils dealt with classifying the tracks. It is scientists like Amanda Falk and her supervisor Stephen who are now extending the research and looking into the behavioural aspects of the trackways.
The Haman Formation of South Korea is proving a happy hunting ground for trace fossils including dinosaur trackways. Recently, Everything Dinosaur reported on the discovery of dromaeosaur trackways (raptor footprints) in the Haman Formation.
To read more about this discovery: Dromaeosaur Trackway Discovered in South Korea.