My Mistake – Autapomorphy Leads to Reexamination

Updated March 30, 2016 with a new tracing and reconstruction.

The Pester specimen (Figs. 1-2, ELTE V 256) is the holotype species for Pterodactylus micronyx (Meyer 1856, Wellnhofer 1970, Osi et al. 2010). Osi et al (2010) reported, “The anatomical revision of the holotype of P. micronyx indicated the osteological immaturity of the specimen; however, there is insufficient data on this taxon to assess its taxonomic validity.”

Earlier I reported that this headless specimen was no Pterodactylus despite a first-glance similarity. I nested the Pester specimen within the Ctenochasmatidae, despite the long metatarsal 1 found in the specimen (which is an autapomorphy within the Ctenochasmatidae and a trait otherwise restricted to Scaphognathus through Anhanguera, including the Cynorhamphidae) and, by convergence the PAL 3830 limb specimen and a sister taxon, Noripterus.

Figure 1. Tracing of the Pester specimen. The smear at the rostral end of the descending cervical series appears to be an elongate skull with larger sclerotic rings. This is where one should excavate to discover a buried skull.

Figure 1. Tracing of the Pester specimen. The smear at the rostral end of the descending cervical series appears to be an elongate skull with larger sclerotic rings. This is where one should excavate to discover a buried skull.

A Headless Skeleton
The lack of a skull is a problem, but I noticed this time that the cervicals extended to a lower stratum layer. I wonder if the skull does too, hidden now beneath a thin blanket of rock? The presence of two feet help identify the Pester specimen as a cycnorhamphid. That long manual digit 3 is also a trait shared with Cycnorhamphus.

Figure 2. The holotype of Pterodactylus micronys, aka the Pester specimen, may preserve ephemeral hints of its apparently missing skull.

Figure 2. The holotype of Pterodactylus micronys, aka the Pester specimen, may preserve ephemeral hints of its apparently missing skull.

A New Reconstruction
Taking another look at the specimen cleared up certain problems and produced others. The cervicals were lengthened according to the lower level bones missed earlier. The scapula and coracoid were updated. In other cycnorhamphids pedal unguals 2-4 were aligned with digit 2 the longest. In the Pester specimen they are not. Now an elongated metatarsal 1 finds less convergence in the family tree. The short pedal digit 2 of the pedal specimen is an autapomorphy within the Cycnorhamphidae.

Autapomorphies
Sometimes autapomorphies are simply unique characters. Some, however, turn out to be clues that a nesting may be wrong and needs another examination and a fresh observation. Finding and fixing errors with more precise observations is the process of science.  No one should be wedded to their observations and concepts if new data sheds light on them.

Parsimony
Moving the Pester specimen to nest next to either Ctenochasma or Pterodactylus adds 19 steps. Certainly these taxa all resemble one another. A more thorough examination, especially of the feet, reveal their identities, even in the absence of a skull.

 

References
von Meyer CEH 1856.  Zur Fauna der Vorwelt. Saurier aus dem Kupferschiefer der Zechstein-Formation. Frankfurt-am-Main. vi + 28 pp., 9 pls.
Osi A, Prondvai E and Géczy B 2010. The history of Late Jurassic pterosaurs housed in Hungarian collections and the revision of the holotype of Pterodactylus micronyx Meyer 1856 (a ‘Pester Exemplar’). In: Moody RTJ., Buffetaut E, Naish D and Martill DM (eds) Dinosaurs and Other Extinct Saurians: A Historical Perspective. Geological Society, London, Special Publications, 343, 277–286. DOI: 10.1144/SP343.17 0305-8719/10/
Wellnhofer P 1970. Die Pterodactyloidea (Pterosauria) der Oberjura-Plattenkalke Süddeutschlands. Abhandlungen der Bayerischen Akademie der Wissenschaften, N.F., Munich 141: 1-133.

wiki/Pterodactylus

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One thought on “My Mistake – Autapomorphy Leads to Reexamination

  1. Pingback: DinoAstur - » Ardeadactylus, nuevo nombre para Pterodactylus longicollum

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