Aurorazhdarcho: a new phylogenetic wastebasket for pterosaurs

While researching
the tiny new/old Aurorazhdarcho (Fig. 2) described during Flugsaurier 2018, I gazed upon the Wikipedia page for Auroazhdarcho and was less than delighted to see how many unrelated specimens the webpage authors attributed to that genus (Fig. 1).

Figure 1. Aurorazhdarcho specimens in the LRT according to Wikipedia.

Figure 1. Aurorazhdarcho specimens in the LRT according to Wikipedia.

These generic determinations
were not done as a result of phylogenetic analysis, as in the large pterosaur tree (LPT). Rather, ‘someone’ eyeballed these specimens and made it so. That’s not good science. And it was not validated by phylogenetic analysis.

  1. ‘Pester Exemplar’ – originally Pterodactylus micronyx (Meyer 1856) ELTE V 256 (Osi, Prondvai and Géczy 2010) is a basal member of the Cycnorhamphidae.
  2. CM 11426 – originally Pterodactylus micronyx (Meyer 1856) is a tiny basal member of the Azhdarcho clade.
  3. TM 13104 – is a tiny scaphognathid basal to the Cycnorhamphus/Ornithocheirus clade.
  4. Pterodactylus? pulchellus BM NHM 42735 — is a tiny scaphognathid basal to the Cycnorhamphus/Ornithocheirus clade.
  5. Auroazhdarcho primordius – (Frey et al. 2011) NMB Sh 110 is the holotype specimen, related to Eopteranodon, Eoazhdarcho a clade that begins with Germanodactylus and ends with Pteranodon.
  6. Aurorazhdarcho micronyx – (Habib and Pittman 2018) MB.R.3531 nests with Eopteranodon, Eoazhdarcho and Auroazhdarcho, but is much smaller.

Remember
juvenile pterosaurs are identical to adults. So small pterosaurs with a distinct morphology are not juveniles of larger adults. Small pterosaurs with a distinct morphology need to be tested in phylogenetic analysis to determine where they nest. They typically nest at the base of major and minor clades. Shrinking in size creates new types of pterosaurs.

Frey et al. 2011 rejected the use of cladistic analysis,
but chose to compare Aurorazhdarcho to Ctenochasma, but then considered Aurorazhdarcho an azhdarchoid, itself an invalid diphyletic clade. According to Wikipedia, “Bennett (2013) considered this species to be a ctenochasmatid.” In the LPT, none of the specimens are ctenochasmatids. Prior workers did not recognize the process of phylogenetic miniaturization (Peters 2007), but decided on their own that small pterosaurs were juveniles (Bennett 2013, Frey et al. 2011).

Figure 1. Aurorazhdarcho primordial and the smaller Aurorazhdarcho micronyx to scale.

Figure 2. Aurorazhdarcho primordial and the smaller Aurorazhdarcho micronyx to scale.

If things were different,
and others had produced a phylogenetic analysis of virtually all known pterosaurs and several specimens of each genus and I had, by eyeball, determined that small pterosaurs were juveniles of distinctly different larger adults, then everyone would be justified in refuting that conclusion. As it is, workers are suppressing the results of inclusive phylogenetic analysis and supporting the eyeballing of specimens. Yes, the rules are different if you have a PhD.

References
Bennett SC 2013. New information on body size and cranial display structures of Pterodactylus antiquus, with a revision of the genus. Paläontologische Zeitschrift. 87(2): 269–289.
Frey E, Meyer CA and Tischlinger H 2011. The oldest azhdarchoid pterosaur from the Late Jurassic Solnhofen Limestone (Early Tithonian) of Southern Germany. Swiss Journal of Geosciences 104 (Supplement 1): 35–55. doi:10.1007/s00015-011-0073-1.
Habib M and Pittman M 2018. An “old” specimen of Aurorazhdarcho micronyx with exceptional preservation and implications for the mechanical function of webbed
feet in pterosaurs. Flugsaurier 2018: The 6th International Symposium on Pterosaurs. Los Angeles, USA. Abstracts: 41–43.
Lü J-C and Ji Q 2005. New azhdarchid pterosaur from the Early Cretaceous of western Liaoning. Acta Geologica Sinica 79 (3): 301–307.
Lü J-C and Ji Q 2006. Preliminary results of a phylogenetic analysis of the pterosaurs from western Liaoning and surrounding area. Journal of the Paleontological Society of Korea 22 (1): 239–261.
Peters D 2007. The origin and radiation of the Pterosauria. Flugsaurier. The Wellnhofer Pterosaur Meeting, Munich 27

wiki/Aurorazhdarcho

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