Smallest Pteranodon: Bennett 2017

Figure 1. The new small Pteranodon wing, FHSM 17956, compared to Ptweety and the adult NMC41-358 specimen.

Figure 1. The new small Pteranodon wing, FHSM 17956, compared to Ptweety and the adult NMC41-358 specimen. At half the size of the adult, the FHSM specimen would have been 4x the size of a hatchling.

A new small partial wing specimen of Pteranodon
discovered by Glen Rockers, was described by Bennett 2017 (Figs. 1-4). It is virtually identical to similar bones in Ptweety (Fig. 1), a specimen now lost to science and half the size of the Triebold specimen NMC41-358, which is similarly gracile. Click here to see more robust Pteranodon adults compared to the new small FHSM specimen.

Figure 2. FHSM 17956 compared to Ptweety. They are virtually identical, though Ptweety looks like a juvenile of a more robust variety of Pteranodon, thus a younger specimen because adults would be larger.

Figure 2. FHSM 17956 compared to Ptweety. They are virtually identical, though Ptweety looks like a juvenile of a more robust variety of Pteranodon, thus a younger specimen because adults would be larger.

Young (small) Pteranodon specimens
were essentially unknown prior to the Bennett paper. So this is important news.

Figure 2. Small Pteranodon, FHSM 17956, carpus insitu and reconstructed. Here several bones were reidentified.

Figure 3. Small Pteranodon, FHSM 17956, carpus insitu and reconstructed. Here several bones were reidentified. See reconstruction in figure 3. It demonstrates that all the newly identified parts fit together.

Unfortunately
a reconstruction based on Digital Graphic Segregation (DGS, Fig. 4) shows that Bennett, widely known as THE expert on Pteranodon going back to his PhD thesis, misidentified several carpal bones here. In his defense, that was easy to do. The distal carpal is beneath the other carpal bones and it has splinters that extend beyond it. Rather than using DGS, Bennett chose to outline bones the old fashioned way. This leads to problems that can be solved when you color each bone and bone splinter THEN test your colors with a reconstruction. Bennett provided no reconstruction that tested his outline tracings. Bennett also overlooked manual digit 5. The fragment (FR) probably comes from the crushed and splintered distal carpal. Bennett reported, “All carpal elements are severely deformed by compression such that they preserve little of their original morphology…” That’s because he misidentified elements that are otherwise identical to those of adult specimens.

Figure 3. Small Pteranodon (FHSM 17956) carpus reconstructed after several bones were reidentified.

Figure 4. Small Pteranodon (FHSM 17956) carpus reconstructed after several bones were reidentified.

 

Bennett also upholds several invalid paradigms

  1. Other small, short crested Pteranodon specimens represent young ones. Actually they represent taxa closer to the outgroup, Germanodacytylus
  2. Short-crested specimens are females. No male/female pairs have ever been documented. Rather short-crested taxa are closer to the crestless outgroup. 
  3. Large pelvis specimens  are females. No, they are large nyctosaurs. 
  4. Small size Rhamphorhynchus were juveniles of larger ones. No, phylogenetic analysis indicates a period of phylogenetic miniaturization followed the genesis of Rhamphorhynchus from larger Campylognathoides ancestors. Bone histology would include juvenile bone tissue in adults of these small, precocial and fast-breeding taxa. It is important that someday Bennett runs a phylogenetic analysis, something he told me decades ago was critical to understanding taxonomy. 
  5. There is no such thing as manual digit 5 in pterosaurs. He overlooked it here. 

Bennett now realizes:
“A new juvenile specimen of Pteranodon collected from the Smoky Hill Chalk Member is so small that it challenges the interpretation of rapid growth to large size before flying and feeding (Bennett, 2014a).” As everyone knows now, hatchling pterosaurs were able to fly shortly after hatching. To his credit, Bennett continues, “The interpretation of rapid growth while under parental care is rejected.”

Bennett examined the specimen under stereo microscope
and made mistakes here re-identified on a computer monitor applying colors to each bone to visually segregate one from another and facilitate accurate reconstruction. This is something that cannot take place using old-fashioned stereo microscopes.

Bennett occasionally
misidentifies small pterosaur bones. This was documented here dealing with the flat-headed anurognathid SMNS 81928, in which he considered the mandible a giant sclerotic ring in the front half the skull, different from all other pterosaurs. Bennett 2008 promoted an invalid hypothesis on the origin of the pterosaur wing based on imagination rather than taxa, documented here. Bennett’s (2007) interpretation of pteroid articulation against the preaxial carpal. was invalidated by Peters 2009 who nested it on the anterior radiale (Fig. 4).

Note
The extensor tendon process is articulated with the rest of m4.1, as in all Pteranodon specimens. Bennett once considered unfused  extensor tendon processes a sign of immaturity. This is not correct. As reported earlier, since pterosaurs are lepidosaurs they display lepidosaur fusion traits, typically not ontogenetic, but phylogenetic. As an example, in Nyctosaurus the extensor tendon process remains unfused, distinct from Pteranodon. Bennett insists that the extensor tendon process in the juvenile specimen is unfused but notes that the fragile cortical bone was lost during preparation. And just think about it.. the carpals, typically wrapped tightly in ligaments were scattered while the extensor tendon process didn’t move during taphonomy. By contrast, in Nyctosaurus the extensor tendon process popped off before the toes disarticulate.

Bennett avoid mentioning or citing
work by Peters 2009, which disputed Bennett 2007, who articulated the pteroid with the preaxial carpal. In order to do so, Bennett 2017 did not cite Bennett 2007, but did manage to cite nearly every other one of his papers. Kids.. sometimes you have to look for what’s not mentioned.

Pteranodon variety
is best seen and appreciated by direct comparison of the skulls and the post-crania. FHSM 17956 is a juvenile of a gracile form, similar to the Triebold specimen NMC41-358 (Fig. 1), a short-crested gracile variety. By contrast, Ptweety appears to be more similar to the more robust long-crested taxa. 

Bennett describes ontogenetic niches
for hatchling, juvenile and adult Pteranodon. This is necessary for 8x smaller hatchlings incapable of handling adult-sized prey.

In Bennett’s Acknowledgements he reports, 
“Constructive reviews from M. Witton and L. Codorniú led to improvements in the manuscript, and an anonymous reviewer disagreed with everything.” That anonymous reviewer was not me. That would be blackwashing. I always try to find something of value in any manuscript I review, even if I disagree with some of what is presented.

Bennett first described this taxon
in a 2014 SVP abstract. See how long traditional studies take to get published? I was just about to call Chris to see if he was okay. I’m glad to see he is still out there publishing important specimens.

References
Bennett SC 2007. Articulation and Function of the Pteroid Bone of Pterosaurs. Journal of Vertebrate Paleontology 27(4):881–891.
Bennett SC 2008. Morphological evolution of the forelimb of pterosaurs: myology and function. Pp. 127–141 in E Buffetaut and DWE Hone eds., Flugsaurier: pterosaur papers in honour of Peter Wellnhofer. Zitteliana, B28.
Bennett SC 2017. New smallest specimen of the pterosaur Pteranodon and ontogenetic niches in pterosaurs. Journal of Paleontology. pp.1-18. 0022-3360/15/0088-0906
doi: 10.1017/jpa.2017.84
Peters D 2009. A reinterpretation of pteroid articulation in pterosaurs. Journal of Vertebrate Paleontology 29:1327-1330.

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