Primitive land birds, or enantiornithines, were among the earliest known birds. Mainly tree dwellers that were poor fliers, these birds warmed their bodies by basking in the sun, like lizards and other reptiles.
The newly found bird, meanwhile, belonged to ornithurines, a group that maintained body temperature internally by dilating or contracting blood vessels, sweating, or shivering.
This trait, known as endothermy, is associated with a more active lifestyle. The prehistoric wading bird may have developed the trait as a result of shoreline living, says Zhonghe Zhou, a palaeontologist at the Chinese Academy of Sciences in Beijing.
Zhou says the freshwater lakes where the birds made their home would have provided the animals with high quality foods, such as fish and other aquatic prey.
Better food means better metabolism, providing the energy to support endothermic life.
Competitive Edge
H. longicresta also had "sophisticated flight skill nearly identical to modern birds," the researchers wrote in the journal paper.
They note that body features associated with advanced flight first appear in birds such as the newly found species.
"There is no doubt this bird could fly for a long distance," Zhou said, raising the intriguing possibility that it was capable of migration.
Zhou suggests this could have given the bird a competitive edge over other primitive flyers.
"Most recent study has shown that there existed great seasonal temperature change at the time," he said. "There was also evidence of seasonal diet change in early Cretaceous birds."
Migration might have allowed the wading bird to seek out more suitable habitat and spread its range to new regions, Zhou added.
The birds' strong wings, coupled with a quick reaction time, also would have been advantageous for life along the lakeshore.
"Lakeshore birds had to have the ability to quickly take to the air and escape from predators, [such as] dinosaurs or pterosaurs," Zhou said.
"The wading adaptation as seen in H. longicresta could have helped the early ornithurine birds to quickly improve flying skill."
University of North Carolina's Feduccia agrees that the fossil suggests "strong flight and migratory ability" due to the bird's endothermic design.
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