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Looking at ancient bird fossils is an opportunity to see what birding might have been like millions of years ago. Back then, many birds had enormous teeth, long snouts and long, bony tails.
"The birds that lived during the age of the dinosaurs were very different from the birds that live today," said Los Angeles County Natural History Museum curator and dino-bird expert Luis Chiappe. "And it would have been a completely different experience to go out birding in the Mesozoic Era."
During the Mesozoic, from 250 to 65 million years ago, the planet also looked and felt very different. Earth was much warmer, and the ice caps didn't exist. The continents were only beginning to split into their modern configurations. Sea levels were higher, and large dinosaurs ruled the land. Primitive birds emerged at this time and became prey for non-avian dinosaurs, which were usually much bigger.
We've compiled a quick guide to birding in China's primitive forest-filled aviary, which thrived about 125 to 120 million years ago. We've tried to give a sense of how big these ancient birds were by comparing them to modern birds. The comparisons are based on the size of the femur, or thigh muscle.