New Perspectives on Pterosaur Palaeobiology volume

The 2015 pterosaur meeting in Portsmouth, England
brings us several new papers. The meeting and abstracts were previewed here and reported on here by a participant.

From the intro: “The field of pterosaur research in palaeontology continues its rapid growth and diversification that began in recent decades. This volume is a collection of papers on these extinct flying reptiles that includes work on their taxonomy, behaviour, ecology and relationships.”

Oddly, the number of abstracts far exceeded the very few papers this time.

Palmer 2017 wrote:
“The preservation of the wing membrane of pterosaurs is very poor and the available fossil evidence does not allow its properties to be reconstructed. In contrast, the fossil record for the wing bones is relatively good and the advent of CT scanning has made it possible to build high-fidelity structural models of the wing spar. The bending strength of the wing spar of a 6 m wingspan ornithocheirid pterosaur is used to infer the likely membrane tension. The tensions required to suppress aeroelastic flutter and to minimize ballooning of the membrane under flight loads are also estimated. All three estimates are of similar magnitude and imply that the membrane must have contained high-modulus material, supporting the view that the reinforcing aktinofibrils were keratinous.”

Contra Palmer’s unfounded assertion, there are several specimens of pterosaurs that provide an excellent view of the wing membrane. For the most part wing shape designs continue to be stuck in the Dark Ages among several pterosaur workers with some actually flipping the wing tips. Those problems need to improve before further work on pterosaur wings.

Dalla Vecchia 2017 wrote:
“An incomplete bone from the latest Cretaceous dinosaur site of Villaggio del Pescatore (Trieste Province, Italy) is definitely a wing metacarpal of a pterodactyloid pterosaur. It represents the only Italian Cretaceous pterosaur remains known, as well as the only pterosaur from the Adriatic Carbonate Platform. With an estimated minimum length of 136 mm, it belongs to a relatively small individual relative to the standard of latest Cretaceous pterodactyloids. It is not as elongated and gracile as azhdarchid wing metacarpals and shows a mix of features found in Pteranodon and some more basal pterodactyloids. It is one of the very few remains of putative non-azhdarchid pterosaurs from the upper Campanian–Maastrichtian worldwide and supports the view that the Azhdarchidae were not the only pterosaur clade existing during latest Cretaceous times.”

Always good to see the gamut of pterosaurs increase.

Witton 2017 wrote:
“Understanding the ecological roles of pterosaurs is a challenging pursuit, but one aided by a growing body of fossil evidence for their dietary preferences and roles as food sources for other species. Pterosaur foraging behaviour is represented by preserved gut content, stomach regurgitates, coprolites and feeding traces. Pterosaurs being eaten by other species are recorded by tooth marks and teeth embedded in their fossil bones, consumer gut content and regurgitate, and their preservation entangled with predatory animals. This palaeoecological record has improved in recent years, but remains highly selective. The Jurassic rhamphorhynchid Rhamphorhynchus, Cretaceous ornithocheiroid Pteranodon and azhdarchid pterosaurs currently have the most substantial palaeoecological records. The food species and consumers of these taxa conform to lifestyle predictions for these groups. Rhamphorhynchus and Pteranodon ate and were eaten by aquatic species, matching expectations of these animals as sea-going, perhaps partly aquatic species. Possible azhdarchid pterosaur foraging traces alongside pterosaur tracks, and evidence that these animals were eaten by dinosaurs and Crocodyliformes, are consistent with hypotheses that azhdarchids foraged and lived in terrestrial settings. Fossil evidence of pterosaur palaeoecology remains rare: researchers are strongly encouraged to put specimens showing details of dietary preferences, foraging strategies or interactions with other animals on record.”

When Pteranodon is no longer considered an ornithocheiroid by ptero workers, I will celebrate.

Bennett and Penkalski 2017 wrote:
“Four specimens of the pterosaur Pteranodon exhibit patterns of irregular alternating light and dark bands on the lateral surfaces of the upper jaw anterior to the nasoantorbital fenestra. Examinations reveal that the maxilla and premaxilla of Pteranodon consisted of two thin sheets of bone interconnected by regularly spaced septa with the spaces contained within presumably pneumatized, resulting in a structure analogous to modern honeycomb sandwich panels. The alternating light and dark bands resulted from waves of bone deposition moving anteriorly along the external surface of the lateral sheet of bone and laying down thin laminae of new bone while bone was simultaneously resorbed from the internal surface of the lateral sheet to maintain its thickness. The specimens that exhibit the bands were immature males and no banding was found in mature specimens or immature females. Therefore, the presence of the bands in immature males is interpreted as correlated with the enlargement and reshaping of the rostrum as males approached and attained sexual maturity.”

Wonder if those immature males were really just more primitive species with smaller size and smaller crest? Earlier Bennett erred by considering the morphological differences in various Pteranodon specimens ontogenetic, rather than phylogenetic. He failed to realize that Pteranodon specimens don’t get to giant size with giant crests without going through transitional mid-size specimens derived from certain small, crestless Germanodactylus specimens. The lamination of pterosaur skull bones is something first described here with the anterior extension of the jugal nearly to the tip of the rostrum. However, what these two workers are describing appears to be another thing entirely.

Martill and Moser 2017 wrote:
“Six specimens accessioned to the Bavarian State Collection for Palaeontology and Geology in Munich, Germany, in 1966 are identified as coming from a gigantic pterodactyloid pterosaur. The previously undescribed material was obtained in 1955 by Jean Otto Haas and compares favourably in size with the type specimen of the Late Cretaceous (Maastrichtian) azhdarchid pterosaur Arambourgiania philadelphiae (Arambourg 1959) from the same locality/region. The material represents fragments of two cervical vertebrae, a neural arch, a left femur, a ?radius, and a metacarpal IV and bones of problematic identity, and does not duplicate the type material of Arambourgiania. The timing of its collection and its locality of Ruseifa, Jordan suggest it might pertain to the same individual as the holotype.” 

Interesting. More parts for the same specimen? That’s like more pieces to the same puzzle. On the other hand, when the term ‘pterodactyloid’ pterosaur falls by the wayside, I will also celebrate. Azhdarchids are not closely related tp Pterodactylus.

Rigal et al. 2017 wrote:
“A specimen of a pterodactyloid pterosaur from the Upper Tunbridge Wells Sand Formation (Early Cretaceous, Valanginian) of Bexhill, East Sussex, southern England is described. It comprises a small fragment of jaw with teeth, a partial vertebral column and associated incomplete wing bones. The juxtaposition of the bones suggests that the specimen was originally more complete and articulated. Its precise phylogenetic relationships are uncertain but it represents an indeterminate lonchodectid with affinities to Lonchodectes sagittirostris (Owen 1874) which is reviewed here, and may belong in Lonchodraco Rodrigues & Kellner 2013. This specimen is only the third record of pterosaurs from this formation.”

England is famous for excellent preservation of pterosaur bits and pieces, mostly jaws, as is the case here. The specimen is named Serradraco and has been known for over 150 years.

Henderson 2017 wrote:
“Simple, three-dimensional, digital models of the crania and mandibles of 22 pterosaurs – 13 pterodactyloids and nine non-pterodactyloids (‘rhamphorhynchoids’) – were generated to investigate gross-level mechanical aspects of the skulls as they would related to feeding behaviour such as bite force and speed of jaw motions. The key parameter was the determination of second moments of area of the mid-muzzle region and the computation of the bending moment relative to the occiput. The shorter, stockier skulls of basal ‘rhamphorhynchoids’ were the strongest for their size in terms of potential resistance to dorso-ventral bending, and this finding correlates with their robust dentitions. More derived ‘rhamphorhynchoids’ showed the start of a trend towards weaker skulls, but faster jaw adduction was interpreted to be an adaptation for the snatching of small prey. Pterodactyloids continued the trend to lengthen the skull and to reduce its cross-sectional area, resulting in less stiff skulls, but more rapid opening and closing of the jaws. Changes in the rear of the skulls and the development of coronoid eminences on the mandibles of all the pterodactyloids are correlated with the reduction in bite force and a concomitant increase in jaw closing speed.”

This makes sense, though I worry that ‘simple digital models’ by Henderson have not fared well in the past.

Hone, Jiang and Xu 2017 wrote: 
“After being inaccessible for a number of years, the holotype and other specimens of the dsungaripterid pterodactyloid pterosaur Noripterus complicidens are again available for study. Numerous taxa assigned to the Dsungaripteridae have been described since the erection of Noripterus, but with limited comparisons to this genus. Based on the information from Young’s original material here we revise the taxonomic identity of N. complicidens and that of other Asian dsungaripterids. We conclude that N. complicidens is likely to be distinct from the material recovered from Mongolia and this latter material should be placed in a separate genus.”

Okay. Wonderful. Thought I think some of us knew that already based on photo data.

And speaking of southern England…
did the U. of Leicester clade ever find the grad student they advertised for to prove the pterosaur quad leap hypothesis?

References
2017. New Perspectives on Pterosaur Palaeobiology. Hone  DWE, Witton MP and Martill DM editors. Geological Society, London SP455.
Bennett SC and Penkalski P 2017. Waves of bone deposition on the rostrum of the pterosaur Pteranodon.
Dalla Vecchia FM 2017. A wing metacarpal from Italy and its implications for latest Cretaceous pterosaur diversity.
Henderson DM 2017. Using three-dimensional, digital models of pterosaur skulls for the investigation of their relative bite forces and feeding styles.
Hone DWE, Jiang S, and Xu X 2017. A taxonomic revision of Noripterus complicidens and Asian members of the Dsungaripteridae.
Martill DM and Moser M 2017. Topotype specimens probably attributable to the giant azhdarchid pterosaur Arambourgiania philadelphiae (Arambourg 1959).
Palmer C 2017. Inferring the properties of the pterosaur wing membrane.
Rigal S, Martill DM, and Sweetman SC 2017. A new pterosaur specimen from the Upper Tunbridge Wells Sand Formation (Cretaceous, Valanginian) of southern England and a review of Lonchodectes sagittirostris (Owen 1874).
Witton MP 2017. Pterosaurs in Mesozoic food webs: a review of fossil evidence.

 

Pterodactyls Alive! 1984 BBC video with David Attenborough on YouTube

Pterodactyls Alive! on YouTube click here

It’s more than 30 years old.
It’s not HD. It still supports the notion of a inverted hanging pterosaur. It precedes the discovery of eggs. Even so, it features a gliding Pteranodon model, lots of great sea bird scenes (including diving pelicans, soaring, dipping frigate birds and skimming skimmers) along with several great bat scenes (including grounded bats taking off).

And Mr. Attenborough was just starting to get gray hair back then.  :  )

The video also stars a bipedal animated Dimorphodon following the then recent release of Padian’s early work on that pterosaur.

 

Fun cardboard Pteranodon costume and model

Figure 1. Pteranodon costume with wings that fold in the plane of the wing.

Figure 1. Pteranodon costume with wings that fold in the plane of the wing with a distal membrane that extends to the anterior femur! Or is this a giant woodpecker team mascot?

Lisa Glover is a very creative person, doing great things with cardboard. Although this could be a woodpecker, Glover promotes it as a Pteranodon. More pix on her website where she writes, “what started as a homework assignment, quickly became a time machine to the cretaceous period. glover originally created a walking, wearable velociraptor and has now progressed to something a bit more challenging.”

Figure 2. Smaller more complete cardboard model of Pteranodon.

Figure 2. Smaller more complete cardboard model of Pteranodon. I like the widespread hind limbs and narrow chord wing membrane no deeper than the knee. 

On a similar note
If you’re in the mood for a cardboard cut out model, a few years earlier I offered this version of Pteranodon which you can download as a pdf then print on cover stock, cut out, fold, glue and hang from a string.

Build Your Own Pteranodon Paper Model

Click to download pdf. Build Your Own Pteranodon model on 8.5×11 inch paper.

The Tanking-Davis Pteranodon (private collection)

Americo Michael Minotti
recently let me know of a new Pteranodon skull in his collection that he considered the largest Pteranodon skull yet discovered (Figs. 1-3). Discovered by fossil collector David Tanking, within the Niobrara formation at Gove Co. Kansas and was added to the private collection of  Stanley Davis. Mr. Davis introduced the skull to Dr. Bennett, Associate professor at Fort Hays State University, who did an onsite detailed analysis of it. According to the reports of Davis and Tanking, Dr. Bennett stated that the skull had significant scientific value and was the largest and most complete sample of the species he had ever seen.

Sometime after the senescence of this animal, both cranial and mandibular sections of the skull may have sunk together in a nose-down position causing the rostrum to be splintered on impact with the sea floor and the tip of the mandible lost. The post-crania, a primary food source, was likely scattered by scavengers, etc.

Figure 1. Tanking-Davis Pteranodon in situ and with parts traced out and restored. The rostrum indicates a probable shorter rostrum, but the mandible does not taper as quickly as would be expected for the relatively short rostrum in a conventional linear digression model. It is conceivable that the distal maxillary and mandibular beaks may have therefore taken a less conventional configuration in this specimen. Click to enlarge. Photos courtesy of A. M. Minotti.

Figure 1. Tanking-Davis Pteranodon in situ and with parts traced out and restored. The rostrum indicates a probable shorter rostrum, but the mandible does not taper as quickly as would be expected for the relatively short rostrum in a conventional linear digression model. It is conceivable that the distal maxillary and mandibular beaks may have therefore taken a less conventional configuration in this specimen. Crest and ventral mandible are restored. The two gray maxillary triangles were retrieved from deeper matrix. Click to enlarge. Photos courtesy of A. M. Minotti.

The rostrum indicates a possible shorter rostrum, but the mandible does not taper as quickly as would be required for that short rostrum. In Pteranodon the rostrum extends beyond the mandible. In Nyctosaurus just the opposite.

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. 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. The Tanking-Davis specimen may not have been the largest Pteranodon of all, but it currently represents the longest skull of preserved elements. Click to enlarge

The reconstructed specimen (Fig. 3) appears to be largely complete, lacking only the crest and the rostral tooth (an empty space remains at the root) and the mandible tip.

Figure 1. Tanking-Davis Pteranodon reconstructed and with bones identified.

Figure 3. Tanking-Davis Pteranodon reconstructed and with bones identified. Click to enlarge.

The size of the skull, the type of taper in the rostrum, the small size of the orbit, and the placement of the anterior most portion of the crest just superior to the orbit all suggest that this specimen is most closely related to the UALVP 24238 specimen, but distinct. Note that in the UALVP 24238 specimen (Fig. 3, specimen z) the orbit is slightly higher relative to the dorsal crest margin and the Tanking-David specimen locates the orbit below this margin. The orbit is also slightly larger in the Tanking-Davis specimen. The  USNM 12167 specimen (specimen w) is also similar.

Figure 3. The UALVP specimen of Pteranodon. Note the lack of taper in the rostrum along with the small size of the orbit.

Figure 4. The UALVP specimen of Pteranodon. Note the lack of taper in the rostrum along with the small size of the orbit. UALVP 24238 (Dawndraco kanzai according to Kellner 2010)

 

With regard to females vs. males,
I still don’t see any male/female pairings here, and certainly none associated with pelves. The deep pelvis formerly attributed to a female Pteranodon actually belongs to a rare giant Nyctosaurus, as discussed here earlier.

Missing anterior tooth?
We looked at that subject earlier here.

References
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.

wiki/Pteranodon

 

 

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)

Cocking back the cranium of the Denver Pteranodon

Earlier we added the DMNH Pteranodon skull to the large pterosaur tree and the Pteranodon skull page. What I had for data was the tracing by Chris Bennett from his 1991 PhD thesis. Always looking for more precision, I contacted the stewards of the skull.

Rene Payne and Rick Wicker of the Denver Museum of Natural History (aka Denver Museum of Nature & Science) were kind enough to send me jpegs of  both lateral views of their big crested Pteranodon skull  (DMNH 1732). Their contract stipulated that I not publish the photos themselves. One photograph had to be slightly distorted to remove parallax to exactly match the outlines of the second photo. That made tracing less of a headache. The tracing (Fig. 1, above) comes off data from both sides.

With the tracing in hand, I compared the cranium and jawline to sister taxa and found the occiput angle of the DMNH specimen to be a little too erect. So the revision (Fig. 1, below) cocks the skull back a little bit, rotating on the quadrate axis. Now it more closely matches sister taxa. The dentary was also straightened out at the break.

Figure 1. The Denver Pteranodon, DMNH 1732. Above, traced from the mounted specimen. Below, cranium and jaw slightly rotated to match more complete sister taxa skulls.

Figure 1. The Denver Pteranodon, DMNH 1732. Above, traced from the mounted specimen. Below, cranium and jaw slightly rotated to match more complete sister taxa skulls. Yellow = premaxilla. Dark blue = nasal. Light blue = frontal. Orange = parietal. Pink = restored. And yes, that’s a single tooth in the anterior mandible.

The specimen is incomplete, yet saves some interesting parts. The mandible preserves and exposes the robust anterior tooth. The crest is long, but not the longest of all known crests. It is superbly preserved with long grain on the frontal that looks like parallel lines extending in the direction of growth. The anterior single mandible tooth is preserved.

Figure 2. The DMNH specimen is in color, nesting between the short crest KS specimen and the long crest AMNH specimen.

Figure 2. Click to enlarge. The DMNH specimen is in color, nesting between the short crest KS specimen and the long crest AMNH specimen. Note the cocking back of the cranium of the DMNH specimen more closely matches closest known sisters.

In size and proportion the DMNH specimen nests neatly between the KUVP 2212 and the YPM 2594 specimens of Pteranodon. It’s not quite as unique as once supposed, but does provide clues to the length of the mandible, which is incomplete in YPM 2594.

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 2000. New information on the skeletons of Nyctosaurus. Journal of Vertebrate Paleontology 20 (Supplement to Number 3):29A.
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.
Eaton GF 1910. Osteology of Pteranodon.  Memoirs of the Connectictut Academy of Arts and Sciences 2:1-38.
Marsh OC 1876. Notice of a new sub-order of Pterosauria. American Journal of Science, Series 3, 11:507-509.

wiki/Pteranodon

Pteranodon skull evolution movie

Earlier we looked at Pteranodon skulls all to the same scale and in phylogenetic order.  Today there’s a GIF movie that presents the same data (Fig. 1).

Figure 1. Click to animate. Pteranodon skull movie. All the skulls are to the same scale and in phylogenetic order.

Figure 1. Click to animate. Pteranodon skull movie. All the skulls are to the same scale and in phylogenetic order. Each skull appears for 2 seconds and the animation recycles when the page is reloaded. And yes, the long-crested clade does terminate with three smaller taxa.

The first tiny specimen is actually an outgroup Germanodactylus. Long crests and great size evolve from small crests and small size. Learn more about Pteranodon variety here.

Long-crested taxa had digitigrade feet. Tall-crested taxa had flat feet. Other postcranial differences are discussed here.