TM 10341 (no. 1 in the Wellnhofer 1970 catalog) is a key taxon tying Dorygnathus to Beipiaopterus and the long metacarpal pre-azhdarchids like no. 44 and no. 42 in the large pterosaur tree. Note that TM 10341 does NOT have such a long metacarpal, so it’s lagging int this trait and is distinct from other short-tail pterosaurs. This lineage also gives rise to flightless pterosaurs, Huanhepterus, a ctenochasmatid- mimic and other tall, skinny pterosaurs like Quetzalcoatlus. They all had their origin in the cute, big-headed TM 10341 (Late Jurassic, Solnhofen).
TM 10341 had a reduced tail, a short antebrachium (radius + ulna) and a big head, but it was a tiny pterosaur. It looks like an adorable infant Dorygnathus, but we know from embryos that they actually have the proportions of adults, so TM 10341 is something new. Since pterosaurs grew isometrically from hatchlings on up, so the changes that made TM 10341 “cute” all occurred in the egg or the gene.
This is one of the surviving remnants of Dorygnathus in the Late Jurassic. Others include the similarly reduced Scaphognathus and all of its ancestors from a different line of dorygnathids along with Ctenochasma and kin from a third lineage of dorygnathids.
Size reduction is what drives pterosaur evolution, bringing with it the largest changes in structure and proportion. Most of these changes are retained as subsequent taxa become larger and larger. Size reduction takes place when sexually mature half size adults lay half-size eggs over several to several thousand generations. TM 10341 was about 7.5 cm tall. Hatchlings of TM 10341 would have been only 1 cm tall.
Wellnhofer P 1970. Die Pterodactyloidea (Pterosauria) der Oberjura-Plattenkalke Süddeutschlands. Abhandlungen der Bayerischen Akademie der Wissenschaften, N.F., Munich 141: 1-133.