A team of Chinese paleontologists has made a significant discovery by identifying remnants of a vegetable diet in the stomach contents of a 120-million-year-old fossilized bird found in northeastern China.

The findings, published recently in the journal Nature Communications, provide direct dietary evidence that the earliest bird on our planet called Jeholornis consumed leaves of plants that produce flowers and bear their seeds in fruits.

Birds are believed to play a pivotal role in the origin of angiosperm, the largest and most diverse plant group representing approximately 80 percent of all known living green plants in the modern terrestrial ecosystem of the earth.

Living birds and those seed-bearing plants exhibit strong interactions across pollination and seed dispersal, but dietary records remain scarce in their early evolution.

The researchers from the Institute of Vertebrate Paleontology and Paleoanthropology (IVPP) under the Chinese Academy of Sciences for the first time extracted fossilized particles, mainly silicon dioxide, from digestive tracts in a nearly complete bird skeleton.

The subadult specimen of the ancient bird was excavated near Chaoyang City in western Liaoning Province of northeastern China, according to the study.

The blocky particles are most likely derived from magnolia leaves, according to the researchers.

"The findings also revealed how birds started to fly up onto the tree branches to explore a new ecological niche," said Wu Yan, the first author of the paper and a researcher from the IVPP.

The lower jaw of Jeholornis further supported the shape shared with other plant-eating birds, including an extant herbivorous bird, the hoatzin, according to the study.

"Our discovery reinforces knowledge of the early ecological linkages among birds and angiosperms from fruit or seed consumption and possible dispersal to the utilization of the most abundant and common plant parts like leaves for dietary purposes," Wu said. (Xinhua)