Guesswork parades as science: the ‘Dawndraco’ debate continues

Kellner 2017 rebutted Martin-Silverstone et al. 2017
who rebutted Kellner 2010 in their taxonomic assessment of a Pteranodon specimen UALVP 24238. Is it congeneric with FHSM VP 339 (GeoternbergiiaP. sternbergi)? Or is the UALVP specimen a distinct genus? Or something else…?

Figure 1. Pteranoodn (Dawndraco) UALVP 24238 in situ, with Martin-Silverstone tracing applied, with mandible moved and missing parts colorized. The putative rostral tip looks more like displaced manus elements.

Figure 1. Pteranoodn (Dawndraco) UALVP 24238 in situ, with Martin-Silverstone tracing applied, with mandible moved and missing parts colorized. The putative rostral tip looks more like displaced manus elements.

Both parties wondered about
gender differences based on pelvis shape. (Both had no clue that the one ‘female’ pelvis they pin their hopes on actually belongs to a giant Nyctosaurus).

Both parties wondered about
maturity at the age of death and used bone fusion as an ontogenetic marker. (Both have no clue that fusion patterns are phylogenetic in pterosaurs because pterosaurs are lepidosaurs and fusion patterns don’t match those of archosaurs, according to Maisano 2002a, b and confirmed by phylogenetic analysis).

Martin-Silverstone et al. dismiss
several observed variations due to postmortem distortion, evidently a favorite excuse of many paleontologists when they have run out of answers that fit their paradigm. (No distortion is found in UALVP 24238).

Name calling, too…
Kellner felt he had to defend being labeled as a ‘splitter’.

Kellner adds one more thought:
“As I have stressed before (Kellner 2010), morphology is crucial for establishing or synonymizing species.” (Very unfortunately both authors do not understand what pterosaurs are: they are fenestrasaur tritosaur lepidosaurs, because they had not performed a phylogenetic analysis in arriving at their conclusions. Only when that happens, THEN establishing and synonymizing species can happen as a result. You just have to read the tree to see who is, or is not, related to who.

Lately everyone in pterosaurs seems to be avoiding
this thing called, “phylogenetic analysis” which, in the large pterosaur tree (LPT, 232 taxa) successfully split and lumped every tested pterosaur specimen, including over a dozen Pteranodon specimens (Fig. 2). It turns out UALVP 24283 (fig. 2, specimen ‘Z’) is not a sister to FHSM VP 339 (Fig. 2, specimen ‘Y’), but both have a common ancestor close to specimen ‘W’ USNM 12167 (Fig. 2, undescribed). Do not accept pterosaur topologies that test only genera and avoid the tiny Solnhofen pterosaurs. You won’t get the big picture and you won’t speak with authority. You’ll floundering in guesswork.

Figure 2. The Tanking-Davis specimen compared to other forms. Specimen w and specimen z appear to be the closest to the Tanking-David specimen. Specimen 'w' = Pteranodon sternbergi? USNM 12167 (undescribed). Specimen 'z' = Pteranodon longiceps? Dawndraco? UALVP 24238. Click to enlarge.

Figure 2.  Click to enlarge. Every reasonably complete Pteranodon skull to scale and in phylogenetic order.

In phylogenetic analysis a big crest
is a derived trait, and yet some small crests and small skulls are derived from big crest ancestors. Only analysis reveals this.

There are no gender differences here.
No two skulls (Fig. 2) are identical except for their crests. And every Pteranodon pelvis is different. The variety here is due to phylogeny, not gender or ontogeny.

Ontogeny is only demonstrated
by the smallest Pteranodon specimens (next to specimen ‘Q’).

Why so much variety in Pteranodon?
Well, there is so much variety in every putative genus in pterosaurs. Add to that, Pteranodon lived for several million years along the long Niobrara Sea that crossed North America from Canada to the Gulf of Mexico… and who knows wherever else. That provides many latitudes for this genus to inhabit and niches to evolve to.

Pterosaur workers,
stop being so lazy! Use specimens for taxa, not a single representative from each genus. That will solve so many taxon exclusion problems, as I can tell you from experience. When you do, let me know what you get. You can safely ignore all previously published topologies that exclude so many taxa. That they are all different teaches us that those all teach us nothing.

If you want my opinion:
Keep all Pteranodon specimens (shown above in Fig. 2) within the genus Pteranodon. Divide them into species. Each one should get it’s own species. Currently ‘Dawndraco‘ nests between several other specimens referred to Pteranodon. That’s how you know ‘Dawndraco‘ really is Pteranodon.

And while you’re at it:
Keep all Rhamphorhynchus specimens (Fig. 3) within the genus Rhamphorhynchus. Divide them into species. Do the same with all Pterodactylus, Dorygnathus, Scaphognathus, etc. genera. Employ more specimens/taxa. Exclude them at your scientific peril.

Figure 3. Bennett 1975 determined that all these Rhamphorhynchus specimens were conspecific and that all differences could be attributed to ontogeny, otherwise known as growth to maturity and old age. Thus only the two largest specimens were adults. O'Sullivan and Martill took the brave step of erecting a new species. The n52 specimen is at the lower right. Click to enlarge.

Figure 3. Bennett 1975 determined that all these Rhamphorhynchus specimens were conspecific and that all differences could be attributed to ontogeny, otherwise known as growth to maturity and old age. Thus only the two largest specimens were adults. O’Sullivan and Martill took the brave step of erecting a new species. The n52 specimen is at the lower right. Click to enlarge.

References
Bennett SC 1991. Morphology of the Late Cretaceous Pterosaur Pteranodon and Systematics of the Pterodactyloidea. [Volumes I & II]. Ph.D. thesis, University of Kansas, University Microfilms International/ProQuest.
Bennett SC 1992. Sexual dimorphism of Pteranodon and other pterosaurs, with comments on cranial crests. Journal of Vertebrate Paleontology 12: 422–434.
Bennett SC 1994. Taxonomy and systematics of the Late Cretaceous pterosaur Pteranodon (Pterosauria, Pterodactyloidea). Occassional Papers of the Natural History Museum University of Kansas 169: 1–70.
Bennett SC 2001. The osteology and functional morphology of the Late Cretaceous pterosaur Pteranodon. Part I. General description of osteology. Palaeontographica, Abteilung A, 260: 1–112. Part II. Functional morphology. Palaeontographica, Abteilung A, 260: 113–153.
Kellner AWA 2010. Comments on the Pteranodontidae (Pterosauria, Pterodactyloidea)
with the description of two new species. Anais da Academia Brasileira de Ciências 82(4): 1063-1084.
Kellner A 2017.  Rebuttal of Martin-Silverstone et al. 2017, ‘Reassessment of Dawndraco kanzai Kellner 2010 and reassignment of the type specimen to Pteranodon sternbergi Harksen, 1966’Vertebrate Anatomy Morphology Palaeontology 3:81–89.
Maisano JA 2002a. The potential utility of postnatal skeletal developmental patterns in squamate phylogenetics. Journal of Vertebrate Paleontology 22:82A.
Maisano JA 2002b. Terminal fusions of skeletal elements as indicators of maturity in squamates. Journal of Vertebrae Paleontology 22: 268–275.
Martin-Silverstone E, Glaser JRN, Acorn JH, Mohr S and Currie PJ 2017. Reassesment of Dawndraco kanzai Kellner, 2010 and reassignment of the type specimen to Pteranodon sternbergi Harksen, 1966.  Vertebrate Anatomy Morphology Palaeontology 3:47-59.
Marsh OC 1876a. Notice of a new sub-order of Pterosauria. American Journal of Science, Series 3, 11:507-509.
Miller HW 1971. A skull of Pteranodon (Longicepia) longiceps Marsh associated with wing and body parts. Kansas Academy of Science, Transactions 74(10):20-33.

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