In 2021 Wei Xuefang and colleagues named and illustrated a new genus and species of anurognathid pterosaur, Sinomacrops bondei. It’s based on a single specimen found in rocks of the Middle to Late Jurassic Daohugou Beds of the Tiaojishan Formation in Hebei Province, China. The genus name translates to both “China large face” and “China large eyes.” This references the wide face and large eyes of anurognathids, and relies on a dual meaning of the Greek word “ops.” The species name honors paleontologist Niels Bonde.
The only known skeleton of Sinomacrops is preserved on its back with wings folded on a slab of stone. It is articulated, and mostly complete, missing only parts of the left wing finger. Many bones, especially in the skull, are crushed and difficult to interpret because they were so thin and delicate.
The specimen is quite small, with a wingspan of about 33 cm (13 inches), and a body length of roughly 15 cm (6 inches). Like all anurognathids, Sinomacrops had a short, rounded skull with huge eyes. Even though the skull is crushed, the jaws and teeth show some unique features that set it apart from other anurognathids. The first three teeth of the maxilla, a bone in the upper jaw, are very tightly packed. Additionally, the bones of the lower jaw show that the skull and jaws were slightly pointed when seen from above, rather than U-shaped like many other anurognathids. The femur is especially short, roughly half the length of the tibia. Finally, unlike most other anurognathids which have very short tails, the tail of Sinomacrops was at least as long as the legs.
Wei and colleagues found Sinomacrops to be most closely related to Batrachognathus volans, known from roughly contemporaneous rocks in Kazakhstan. They are linked by features of the humerus and short femora. The batrachognathines were the sister group to the anurognathines, which account for most of the other anurognathids.
Sinomacrops lived approximately 160 million years ago in a temperate to subtropical forested environment, with plentiful lakes, rivers, and swamps. Anurognathids were aerial insect hunters, living a life quite like living bats and birds like swifts and nightjars. They’re known to have lived from the Middle Jurassic to the end of the Early Cretaceous and are almost all found in extraordinary fossil sites known as Konservat-Lagerstätten. These sites preserve fine details of fossils including soft tissues in many cases. Preservation of this type allowed the delicate bones of anurognathids become fossils. It’s possible that anurognathids lived until the end of the Mesozoic, but so far there are no known pterosaur-bearing Konservat-Lagerstätten from Upper Cretaceous rocks.