Imagine having a toe as long as your shin. This is essentially what researchers have discovered in a bird's foot caught in amber for nearly 100 million years. The appendix presents a third extremely long toe, never seen in birds.
Amber traders suspected that the fossil foot, originally found in the Hukawng Valley in Myanmar in 2014, belonged to a lizard, known for its long toes. But the lizards have five fingers, suggesting that the sample belonged to a bird.
In the new study, researchers used detailed x-ray scans to create a 3D model of the foot. They then compared it to the feet of more than 80 modern and ancient birds. The third toe of the fossil, which measures nearly 10 millimeters, is 20% longer than the lower leg and more than 40% longer than the second toe, the team said today. Current biology. No other bird – living or extinct – has such an appendage.
We do not know what is the bird – that researchers have dubbed Elektorornis chenguangi (seen in the design of this artist) – used the toe for. (Elektorornis means "amber bird", and the second half of the name is a nod to the discoverer of the fossil, Chen Guang.) Long toes are a common feature of arboreal animals such as squirrels and monkeys because they improve the adhesion of branches. The researchers assume that the unusual adaptation may have been used to extract food from tree trunks. Whatever the reason, it's not a feature that has made its way. Elektorornis disappeared with the dinosaurs 66 million years ago, without leaving any modern descendants.