Evolution is not always a process of gradual change. Shifts in entire body shapes, leading to the foundation of whole new groups of animals or plants, sometimes take place. These involve the near-simultaneous alteration of many body parts and it is rare for the fossil record to catch such palaeolycanthropes in mid-shape-shift, as it were. Lu Junchang of the Chinese Academy of Geological Sciences in Beijing and his colleagues, however, think that they may have done so in the case of a newly discovered flying reptile called Darwinopterus modularis.

As they report in the Proceedings of the Royal Society, the 160m-year-old Darwinopterus, which has been dug up in Liaoning Province, catches the flying reptiles in transition between the primitive, long-tailed forms exemplified by Rhamphorhynchus and the advanced, almost tailless creatures typified by Pteranodon. This confirms what has been observed in two other transitional fossils, Archaeopteryx (the oldest known bird) and Rodhocetus (a proto-whale). Both of these fossils suggest such transitions are not smooth, simultaneous transformations of all bodily features from old to new. Instead, some features shift to the advanced form at the beginning of the process, while others stay resolutely primitive until near the end.

In the case of Darwinopterus it is the head and neck that have changed, while the rest of the body remains in the ancestral state. These changes were probably in response to the arrival of new prey as other reptiles, the proto-birds, took to the air. Once the first changes had happened, the rest of the body had to alter to accommodate them, and a new shape emerged.

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