Evolution at the base of Dorygnathus

The large pterosaur tree offers new insights into pterosaur evolution. Today we’ll look at the base of Dorygnathus (Middle Jurassic, Fig. 1), once thought an evolutionary oddity, but today is the key taxon at the base of all Cretaceous pterosaurs.

Figure 1. Evolution at the base of Dorygnathus. Top: the BSP 1994 specimen assigned (erroneously) to Eudimorphodon. Top middle: Sordes. Bottom middle: Dorygnathus. Bottom: Jianchangnathus, a basal dorygnathid at the base of Wukongopteridae and Scaphognathia.

Figure 1. Evolution at the base of Dorygnathus to scale. Top: the BSP 1994 specimen assigned (erroneously) to Eudimorphodon. Top middle: Sordes. Bottom middle: Dorygnathus. Bottom: Jianchangnathus, a basal dorygnathid at the base of Wukongopteridae and Scaphognathia.

Sometimes a picture is worth a 1000 words. Here Sordes is derived from a sister to the BSP specimen, itself derived from the holotype Eudimorphodon, Dorygnathus is derived from a sister to Sordes. Jianchangnathus is derived from a sister to the basalmost Dorygnathus.

Other than the jianchangnathids, dorygnathus ultimately gave rise to ctenochasmatids and azhdarchids.

Jianchangnathids ultimately gave rise to wukongopteripterids and a more successful lineage, the scaphognathids, which ultimately gave rise to most other Cretaceous pterosaurs.

So, the generalized “plain brown sparrow” look of Sordes belies its genetic potential to create giant pterosaurs, crested pterosaurs and even flightless pterosaurs. And the large variation demonstrated by these four “sister” taxa indicates that there are many more taxa waiting to be discovered that will be transitional forms nesting between them.

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