Chinese paleontologists Lü Junchang and Ji Qiang identified the genus Eoazhdarcho in 2005. It is an azhdarchoid pterodactyloid pterosaur. As far as we know, Eoazhdarcho liaoxiensis is the type species. The specimen was discovered in Chaoyang, Liaoning, China's Lower Cretaceous Jiufotang Formation, which is Aptian in age.
Etymology
The name of the genus Azhdarcho is combined with the Greek word eos, which means "dawn," to produce the genus Eoazhdarcho. This suggests that the former was an early related form of the latter. The ancient territory of Liaoxi is referenced in the specific name, liaoxiensis.
Classification
Eoazhdarcho was first likened to Azhdarcho and placed in a basal position within the Azhdarchidae family by the describers. But in 2006, they released a cladistic study in which they concluded that a number of taxa, including Eoazhdarcho, belonged to a distinct clade that could be distinguished from the Azhdarchidae proper. Eoazhdarcho was a member of the clade Lü, Unwin, and associates called the Chaoyangopteridae in 2008; this family is the sister group to the Azhdarchidae within the much broader Azhdarchoidea. The most basic member of the family Chaoyangopteridae, sister taxon of the subfamily Chaoyangopterinae, was identified as Eoazhdarcho in 2014 through a phylogenetic study carried out by Brian Andres and associates. On the left is the cladogram of their analysis. Paleontologist Nicholas Longrich and associates subsequently recovered Eoazhdarcho in 2018 through a phylogenetic study, placing it as a basal member of the clade Neopterodactyloidea and in a distinct location within the Neoazhdarchia. On the right, you can see the cladogram of their analysis:
Topology 1: Andres et al. (2014).
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Topology 2: Longrich et al. (2018).
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