Laser-excited fluorescent Microraptor feet. Microraptors were close relatives of early Cretaceous birds and lived in present-day northeastern China. Microraptors had a special way of life, similar to the current eagle. Image from the author
Michael Pittman, a professor at Hong Kong’s Chinese University, and Wang Xiaoli, a professor at Linyi University’s School of Life Sciences, and collaborators report new data on the shape of toe pads and scales in early flying theropods, a class of three-toed dinosaurs including Tyrannosaurus rex, velociraptors and birds. The findings may help further understand the behavior and lifestyle of extinct cousins of living birds, including their grasping and hunting abilities. The results were published in Nature Communications on 21 December.
The foot shape and size of living birds are known to correspond to their ability to jump, perch, wade, swim, climb and grip. The shape of claws, bones, and joints in fossilized early flying theropods can be used to infer the function of these features. Although we have learned about the function of the soft tissues of the feet of living birds, such as toe pads and scales, these soft tissues are generally difficult to preserve in the fossil record, making it difficult to judge their role in extinct species.
The researchers analyzed foot soft tissue details from 12 fossil samples associated with cousins of 8 species of living birds, including early small birds the size of crows, such as Nymphaean and Confucius; There are also bird close relatives, the Microraptor. The authors then combined this data with measurements of fossilized claws and bones.
They found that foot evolved to adapt to similar fossil species—such as the well-developed, bulging rounded toe pads found in microraptors—to use their feet to hunt in a manner similar to modern birds of prey such as eagles. Fossilized species with flat-toed pads, such as Nymphaenosaurus, use their feet for a lifestyle closer to the ground, while others use their feet to fiddle with food like living parrots.
However, not all fossil species analysed in the study found perfect comparisons in living birds, suggesting that extinct species such as willbirds may have behaviors and lifestyles that we do not find in living birds today.
The results show that in the process of flight theropods evolving flight behavior, there is an unimaginable diversity of evolutionary adaptations related to their behavior and lifestyle, and non-avian flying theropod dinosaurs similar to living birds of prey also have complex evolutionary adaptations. (Source: China Science News Feng Lifei)
Related paper information:https://doi.org/10.1038/s41467-022-35039-1