New smallest Pteranodon: Bennett 2014 JVP abstract

Figure 1. Pteranodon ingens. Full size and little Ptweety the baby Pteranodon, not curated.

Figure 1. Pteranodon ingens. Full size and little Ptweety the baby Pteranodon, not curated. Alongside in black is a hypothetical hatchling half the size of Ptweety. With a 1.5m wingspan, Ptweety is still the smallest, compared to Bennett’s 1.76 m wingspan. The Bennett Pteranodon is not shown.

I was hoping a curated specimen would follow Ptweety, the baby Pteranodon (Fig. 1). It was just a matter of time. Here it is in the 2014 JVP abstracts.

From the Bennett abstract:
“An earlier study of all available specimens of the pterosaur Pteranodon from the
Smoky Hill Chalk Member of the Niobrara Formation found a bimodal size distribution. The small size class with estimated wingspans in life of ~3.1-4.8 m was twice as abundant as the large, with wingspans of ~4.8-6.7 m, and immature specimens formed ~15% of each class suggesting that they cannot be age classes. The bimodal distribution was interpreted as evidence of sexual dimorphism and the absence of specimens smaller than ~3 m wingspan was interpreted as evidence of bird-like parental care during rapid growth to adult size before flying and feeding independently. A new immature specimen of Pteranodon with an estimated wingspan of only 1.76 m demonstrates that juveniles were capable of flying and feeding independently, contradicting the interpretation of parental care during rapid growth. Instead Pteranodon apparently was precocial, flying and feeding independently during several years of growth to adult size as previously observed in Rhamphorhynchus, Pterodactylus, and Pterodaustro. Therefore, the absence of Pteranodon juveniles and a similar absence of Nyctosaurus juveniles from the Smoky Hill Chalk indicates those taxa had multi-niche ontogenies, occupying distinct niches in different locations and environments at different stages of their life history. Thus, the Smoky Hill Chalk represents a pelagic feeding environment of Pteranodon and Nyctosaurus adults whereas hatchlings and juveniles presumably fed on smaller prey in lacustrine, riverine, estuarine, or coastal environments. The pterosaur records of most other Lagerstätten are consistent with multi-niche ontogeny being the norm in pterosaurs. For example, the record of Azhdarcho in the Bissekty Formation consists of hatchlings and adults and represents a breeding ground, that of the Solnhofen Limestone consists primarily of hatchlings and juveniles and represents a nursery environment of juveniles in sheltered lagoons near breeding grounds whereas those of the Romualdo and Cambridge Greensand Formations consist of adults and represent coastal feeding environments of adults. One exception seems to be the record of Pterodaustro in the Lagarcito Formation, which consists of eggs, hatchlings, juveniles, and adults in a single location and environment; however, that may reflect a special environment required to effectively utilize the filter-feeding specializations of the taxon.”

Bennett has been the target of many Pterosaur Heresies blogposts.
And for good reason: (no gender classes, this represent several species evolving from small, small-crest forms to several clades of large, large-crest forms, etc. etc. etc.).

Here Bennett is right on the money
when he agrees to different niches for juvenile and adult pterosaurs, which we discussed earlier here, due to the rarity of juvenile pterosaurs in the fossil record, a topic in which Bennett takes the opposite stance.

Not mentioned in the Bennett abstract
is the fusion of the extensor tendon process to manual 4.1, which occurs in all Pteranodon specimens (even Ptweety) and no Nyctosaurus specimens except the crested ones. The same goes for scapula and coracoid fusion (fused in Pteranodon, not in Nyctosaurus). I wonder what the data is on his new juvenile Pteranodon?

Figure 2. Ptweety the juvenile Pteranodon. Note the presence of a fused extensor tendon process, a long rostrum and small orbit in this isometrically identical juvenile pterosaur.

Figure 2. Ptweety the juvenile Pteranodon. Note the presence of a fused extensor tendon process, a long rostrum and small orbit in this isometrically identical juvenile pterosaur.

The presence of hatchling Azhdarcho specimens in a breeding ground comes as something of a surprise. Good news! The literature (Averianov 2010) only refers to a juvenile/immature specimen represented by a notarium (4cm long, compared to a 6.5 notarium for an unrelated adult mid-size Pteranodon adult.)

Bennett does not mention the growth series in Tapejara and Zhejiangopterus. The abstract was probably written before the Caiuajara nesting site. Pterodaustro embryos and hatchlings are well known (Chiappe et al. 2004, Chinsamy et al. 2008, Codorniú and Chiappe 2004). The various growth series described by Bennett (1995, 1996) actually represent individual species if not genera. This he would discover by phylogenetic analysis.

Ptweety will never be published because it was extracted and prepared without documentation and the last I heard it was a standing mount at an online retail store. Good to hear that another juvie Pteranodon is out there and hopefully will soon be published.

On a side note: 
The blog post on the evolution of frogs is getting an unusually large number of hits. Not sure why. Let me know if there is anything else you want to learn more about.

References
Averianov AO 2010. The osteology of Azhdarcho lancicollis Nessov 1984 (Pterosauria, Azhdarchidae) from the Late Cretaceous of Uzbekistan. Proceedings of the Zoological Institute RAS. 314(3):264–317.
Averianov AO 2013. 
Reconstruction of the neck of Azhdarcho lancicollis and lifestyle of azhdarchids (Pterosauria, Azhdarchidae). Paleontological Journal 47 (2): 203-209. DOI: 10.1134/S0031030113020020
Bennett SC 1995. A statistical study of Rhamphorhynchus from the Solnhofen limestone of Germany: year classes of a single large species. Journal of Paleontology 69, 569–580.
Bennett SC 1996. Year-classes of pterosaurs from the Solnhofen limestones of Germany: taxonomic and systematic implications. Journal of Vertebrate Paleontology 16:432–444.
Bennett, SC 2014. New smallest specimen of the pterosaur Pteranodon and multi-niche ontogeny in pterosaurs. Journal of Vertebrate Paleontology abstracts, Berlin Conference 2014.
Chinsamy A, Codorniú L and Chiappe LM 2008. Developmental growth patterns of the filter-feeder pterosaur, Pterodaustro guinazui. Biology Letters, 4: 282-285.
Chiappe LM, Codorniú L, Grellet-Tinner G and Rivarola D. 2004. Argentinian unhatched pterosaur fossil. Nature, 432: 571.
Codorniú L and Chiappe LM 2004. Early juvenile pterosaurs (Pterodactyloidea: Pterodaustro guinazui) from the Lower Cretaceous of central Argentina. Canadian Journal of Earth Science 41, 9–18. (doi:10.1139/e03-080)

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