AMNH 4908: at the genesis of Nyctosaurus and Pteranodon

Bennett 2017 described AMNH 4908:
“The smallest relatively complete previously known specimen of Pteranodon, AMNH 4908, consists of a partial trunk skeleton and tail, scapulocoracoid, humerus through WP2, both femora and tibiae, and a disarticulated foot (Bennett, 2001; Table 1), had an estimated wingspan in life of 3.33 m.”

AMNH 4908 is small because
it is primitive (Figs. 1–3), closer to its smaller germanodactylid ancestors (Fig. 4), not because it is ontogenetically young. That point was overlooked by Bennett 2017 who decided not to include a comprehensive phylogenetic analysis then or earlier (Bennett 1991, 1992). He thought smaller specimens, like AMNH 4908, were female.

Figure 1. The Niobrara specimen AMNH4908 in situ.

Figure 1. The Niobrara specimen AMNH4908 in situ. See figure 3 for reconstruction.

It is worth noting
AMNH 4908 has a type of pelvis with unfused ischia, a morphology common to Nyctosaurus. Earlier Bennett 1991, 1992 decided a large Nyctosaurus pelvis belonged to a female Pteranodon, which started that gender myth. Unfortunately, Bennett never used phylogenetic analysis to lump and split Pteranodon, the subject of his 1991 PhD thesis. Instead he relied on a statistical analysis, which led him astray. The large pterosaur tree (LPT, 246 taxa) is the only published pterosaur cladogram to include more than one or two Pteranodon and Nyctosaurus taxa. When you really want to know something in systermatics, use a comprehensive cladogram, not a graph.

Figure 2. Subset of the LPT focusing on pterandontids and their ancestors going back to Late Jurassic germanodactylids. AMNH 4908 nests between the Nyctosaurus clade and the Pteranodon clade.

Figure 2. Subset of the LPT focusing on pterandontids and their ancestors going back to Late Jurassic germanodactylids. AMNH 4908 nests between the Nyctosaurus clade and the Pteranodon clade.

Also worth noting
is the deltopectoral crest of the humerus in AMNH 4908, which has a round tongue shape like that of its predecessors among Eopteranodon and Germanodactylus (Fig. 4), rather than the hatchet shape found in Nyctosaurus or the warp found in Pteranodon.

Figure 3. AMNH 4908 pterosaur reconstructed. Transitional between Nyctosaurus and Pteranodon. Note the big feet, tiny sternal complex and round tip deltopectoral crest. Note the massive radius + ulna.

Figure 3. AMNH 4908 pterosaur reconstructed. Transitional between Nyctosaurus and Pteranodon. Note the big feet, tiny sternal complex and round tip deltopectoral crest. Note the massive radius + ulna.

Of course, any taxon basal to Nyctosaurus and Pteranodon
is also going to be close to the SMNK PAL 6592 specimen (Fig. 4) attributed to Germanodactylus.

Matching YPM 1179 to the post-crania of SMU 76476 (Myers 2010) and overprinted with SMNK PAL 6592. The resemblance is indeed remarkable.

Figure 4. Matching YPM 1179 to the post-crania of SMU 76476 (Myers 2010) and overprinted with SMNK PAL 6592. The resemblance is indeed remarkable.

Ever since 2003, traditional pterosaur workers (with PhDs)
have been linking toothless pteranodontids to toothy ornithocheirids. That they continue to do so, (due to taxon exclusion) is embarrassing to the profession.

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 5. Pteranodon and Nyctosaurus skulls. Click to enlarge.

Figure 6. AMNH 4908 specimen compared to a large Pteranodon specimen UNSM 50036.

Figure 6. AMNH 4908 specimen compared to a large Pteranodon specimen UNSM 50036.

In similar fashion and shame,
traditional paleontologists continue to insist that pterosaurs arose from Euparkeria, Scleromochlus or Erythrosuchus according to several authors, or from Macrocnemus bassaniiPostosuchus kirkpatricki and Herrerasaurus ischigualastensis according to Dalla Vecchia 2019. More closely related taxa (LangobardisaurusCosesaurus, Sharovipteryx and Longisquama) were validated as better pterosaur ancestors in four phylogenetic analyses 20 years ago.


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 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
Dalla Vecchia FM 2019. Seazzadactylus venieri gen. et sp. nov., a new pterosaur (Diapsida: Pterosauria) from the Upper Triassic (Norian) of northeastern Italy. PeerJ 7:e7363 DOI 10.7717/peerj.7363

Thanks to Alex Schiller for posting this specimen on Facebook.

https://pterosaurheresies.wordpress.com/2012/04/09/female-pterosaurs/

http://www.reptileevolution.com/pteranodon-postcrania.htm

Vestigial fingers on the UNSM 93000 Nyctosaurus

The UNSM 93000 specimen attributed to Nyctosaurus
has only three wing phalanges and the tiny vestigial free fingers have never been looked at using DGS methods before. Well, here they are (Fig. 1).

Figure 1. Closeup of the UNSM 93000 specimen of Nyctosaurus focusing on three vestige free fingers.

Figure 1. Closeup of the UNSM 93000 specimen of Nyctosaurus focusing on three vestige free fingers. This is what happens when you no longer need these fingers. You can tell Nyctosaurus from Pteranodon in that the former never fuses the sesamoid (extensor tendon process) to phalanx 4.1. Other wrongly consider this a trait of immaturity.

Nyctosaurus sp. UNSM 93000 (Brown 1978, 1986) was derived from a sister to Nyctosaurus gracilis and phylogenetically preceded the crested Nyctosaurus specimens. Except for the rostral tip, the skull and cervicals are missing. Distinct from Nyctosaurus gracilis, the dorsals of the Nebraska specimen relatively shorter. The scapula and coracoid were more robust. The deltopectoral crest of the humerus most closely resembled that of Muzquizopteryx. Fingers I-III were tiny vestiges. Manual 4.1 extended to mid ulna when folded. Manual 4.4 was probably fused to m4.3 or it was missing and m4.3 became curved.

Figure 1. The UNSM specimen of Nyctosaurus, the only one for which we are sure it had only three wing phalanges.

Figure 2. The UNSM specimen of Nyctosaurus, the only one for which we are sure it had only three wing phalanges.

The pubis and ischium did not touch, as in more primitive nyctosaurs. It would have been impossible for the forelimb to develop thrust during terrestrial locomotion. It was likely elevated or used like a ski-pole.


The family tree of the Ornithocephalia and Germanodactylia is here. The expanded family tree of the Pterosauria is here.


References
Brown GW 1978. Preliminary report on an articulated specimen of Pteranodon Nyctosaurusgracilis. Proceedings of the Nebraska Academy of Science 88: 39.
Brown GW 1986. Reassessment of Nyctosaurus: new wings for an old pterosaur. Proceedings of the Nebraska Academy of Science 96: 47.

 

New flightless and giant nyctosaurs: Alcione and Barbaridactylus

Scale bar problems
and a lack of reconstructions in the original paper are issues here.

Longrich, Martill and Andres 2018
bring us news of “a diverse pterosaur assemblage from the late Maastrichtian of Morocco that includes not only Azhdarchidae but the youngest known Pteranodontidae and Nyctosauridae. [This] dramatically increases the diversity of Maastrichtian pterosaurs. At least 3 families —Pteranodontidae, Nyctosauridae, and Azhdarchidae — persisted into the late Maastrichtian. These patterns suggest an abrupt mass extinction of pterosaurs at the K-Pg boundary.”

The authors summary starts off with an invalid statement:
“Pterosaurs were winged cousins of the dinosaurs.”  That was invalidated by Peters 2000, 2007 and ignored every since. We looked at that problem earlier here, here and here in a 3-part series testing all candidates. It’s time to realize that no one will ever find pterosaur kin among the dinos. They’ve already been clearly identified among the lepidosaurs.

The authors failed to include the Maastrictian tupuxuarid
found in southern Texas (Fig. 1; TMM 42489-2) and did not consider the Maastrichtian footprints discovered in 1954 and reexamined in 2018 that include two ctenochasmatids we will look at tomorrow.

TMM 42489-2, the tall crested Latest Cretaceous large rostrum and mandible. It's a close match to that of Tupuxuara, otherwise known only from Early Cretaceous South American strata.

Figure 1. TMM 42489-2, the tall crested Latest Cretaceous large rostrum and mandible. It’s a close match to that of Tupuxuara, otherwise known only from Early Cretaceous South American strata.

Alcione elainus gen. et sp. nov.
The new 1.5x larger nyctosaurid, Alcione elainus, known from disassociated bones including a shorter radius + ulna, a shorter metacarpal 4, a larger femur, and a tiny sternal complex (identified as a ‘sternum’ in the text) only 40 percent the size of a standard nyctosaur sternal complex (if the scale bars are correct). When placed on a reconstruction of a more complete Nyctosaurus (UNSM 93000; Fig. 2), scaled to the humerus, the result produces a likely flightless nyctosaur. Strangely, the authors called this a “small nyctosaur” even though it is half again larger than UNSM 93000. The authors mislabeled the shorter, straighter scapula as a coracoid, and vice versa.

Figure 2. GIF movie of Nyctosaurus and Alcione showing a likely flightless nyctosaur based on the parts preserved.

Figure 2. GIF movie of Nyctosaurus and Alcione showing a likely flightless nyctosaur based on the parts preserved. Three frames change every 5 seconds. The sternum is tiny (assuming the scale bars are correct), the metacarpus and antebrachium are short and the femur is long.

They did not mention the possibility of flightlessness.
They did report, “The abbreviated distal wing elements in Alcione indicate a specialized flight style. The short, robust proportions suggest reduced wingspan and increased wing loading, implying distinct flight mechanics and an ecological shift. Short wings would increase lift-induced drag at low speeds, but reduced wing areas would decrease parasite drag at high speeds, suggesting that Alcione may have been adapted for relatively fast flapping flight compared to other nyctosaurids. Alternatively, reductions in wingspan might represent an adaptation to underwater feeding, i.e., plunge diving of the sort practiced by gannets, tropicbirds, and kingfishers, where smaller wings would reduce drag underwater.”

Not sure why they mentioned
‘distal wing elements’ here. They did not list or discuss distal wing elements elsewhere. Perhaps they meant proximal.

The reconstructed mandible of Alcione
is narrower than the rostrum in UNSM 93000.

Based on the vestigial fingers of UNSM 93000
and the short metacarpus of the new specimen, Alcione might have been the first pterosaur to walk on metacarpal 4, albeit at the very end of the reign of pterosaurs.

Other flightless pterosaurs include:
the basal azhdarchid form the Solnhofen, Jme-Sos 2428 and the Late Jurassic anurognathid PIN 2585/4 from the Sordes slab. They demonstrate that the distal wing elements reduce first. Thus the reconstruction, based on nyctosaur patterns restores a wing that was not volant.

Longrich, Martill and Andres did find a giant nyctosaur
which they named Barbaridactylus grandis based on a large humerus (Fig. 3). The humerus of the more complete UNSM 93000 specimen is 9.5 cm. By comparison the humerus in Barbaridactylus is 22.5 cm. I’m going to trust the text comment that the ulna + radius are 1.3x longer than the humerus. The scale bars indicate about half that length. Similar problem possible in the scapula/coracoid, according to the nyctosaur bauplan.

Figure 3. Barbaridactylus, a giant nyctosaurid. If the wing was like UNSM 93000, then it could fly. If the wing was like Alcione, then it could not. The scale bars did not match the text description on the ulna + radius, so both sizes are shown.

Figure 3. Barbaridactylus, a giant nyctosaurid. If the wing was like UNSM 93000, then it could fly. If the wing was like Alcione, then it could not. The scale bars did not match the text description on the ulna + radius, so both sizes are shown. Sometimes you have to be prepared for the occasional mistake in a published paper.

Other giant nyctosaurs
Earlier and here we noted giant nyctosaurs were flying over the Niobrara Sea (midwest North America) based on a large wing finger with unfused extensor tendon process (YPM 2501) and a large nyctosaur pelvis (KUVP 993; misinterpreted by Bennett (1991, 1992) as belonging to a female Pteranodon). 

No reconstructions were provided
by Longrich, Martill and Andres 2018. Reconstructions and a nyctosaur blueprint might have helped these paleontologists with firsthand access to the specimens discover the issues they missed.

It’s good to know
more pterosaurs made it to the latest Cretaceous.

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.
Longrich NR, Martill DM, Andres B 2018.
Late Maastrichtian pterosaurs from North Africa and mass extinction of Pterosauria at the Cretaceous-Paleogene boundary. PLoS Biol 16(3): e2001663. https://doi.org/10.1371/journal.pbio.2001663
Peters D 2000b. A Redescription of Four Prolacertiform Genera and Implications for Pterosaur Phylogenesis. Rivista Italiana di Paleontologia e Stratigrafia 106 (3): 293–336.
Peters D 2007. 
The origin and radiation of the Pterosauria. In D. Hone ed. Flugsaurier. The Wellnhofer pterosaur meeting, 2007, Munich, Germany. p. 27.

Press coverage
Smithsonian
Newswise
PhysOrg

There’s a giant pterosaur in my front yard!!

Figure 1. The simple house with the blacktop front yard. The mural is hard to see from this angle.

Figure 1. The simple house in Collinsvilled, IL, USA with the blacktop front yard. The mural is hard to see from this angle.

Figure 2. Better angle on the major portion of the Nyctosaurus mural. Missing parts are added in blue.

Figure 2. Better angle on the major portion of the Nyctosaurus mural. Missing parts are added in blue.

A month ago
I moved into a Collinsville, IL, USA house with a 6-car parking lot instead of front yard. Not sure what overtook me, but with a little spare time, a lot of driveway sealer and a can of paint, I added a 30×50 foot Nyctosaurus, the Nebraska specimen (UNSM 93000, Fig. 3) described by Gregory Brown. Missing parts imagined in blue. I’ll need a drone to take a better picture of it. This might be the start of a more elaborate image. Ah, the simple life, with a bit of flair. First pterosaur I’ve painted with a brush in a few decades, I think…

Figure 1. The UNSM specimen of Nyctosaurus, the only one for which we are sure it had only three wing phalanges.

Figure 3. The UNSM specimen of Nyctosaurus, the only one for which we are sure it had only three wing phalanges.

Figure 5. Cast of the UNSM 93000 specimen of Nyctosaurus. Missing parts are modeled here.

Figure 5. Cast of the UNSM 93000 specimen of Nyctosaurus. Missing parts are modeled here.

Putting some meat (and membranes) on Nyctosaurus

Figure 1. The UNSM specimen of Nyctosaurus, the only one for which we are sure it had only three wing phalanges.

Figure 1. The UNSM specimen of Nyctosaurus, the only one for which we are sure it had only three wing phalanges.

The UNSM 93000 specimen of Nyctosaurus (Figs. 1-3), in the University of Nebraska State Museum, would have been complete and articulated, except for a small channel of erosion that cut through the skull and limbs before discovery. Nevertheless the post-crania is intact (Fig. 2) and a little cutting and pasting more or less reproduces the in vivo look of the specimen in dorsal view (my what big arms you have!).

So here it is.
Every 5 seconds the scene will change with 3 scenes total (including the blend). The hind limbs are in the flight position, acting like horizontal elevators on an airplane and like little wings able to provide lift for the hind limbs. The fuselage fillet is shown. Otherwise the wing finger and its trailing membrane (brahiopatagium) is stretched only between the wing tip and elbow with no hind limb connection. That makes a short chord wing, just like a sailplane.

Figure 1. Nyctosaurus GIF movie showing in situ and in vivo versions of the post-crania. Membranes (uropatagia and fuselage fillet) and muscles added.

Figure 2. Nyctosaurus GIF movie showing in situ and in vivo versions of the post-crania. Membranes (uropatagia and fuselage fillet) and muscles added. Note the axis of the femoral head is aligned with the axis of the acetabulum. Nyctosaurus has hind legs like those of Sharovipteryx. Note: only the deltopectoral crest of the right humerus is preserved and it was flipped during taphonomy.

This specimen of Nyctosaurus is the only one that had but three wing phalanges. Evidently none were lost distally as m4.4 is often curved in pterosaurs as it is here (Fig 3). Rather m4.2 and m4.3 appear to have fused into one long bone. No Nyctosaurus shows a shortening of either of these two bones, so one did not disappear. A tiny ungual completes the wingtip, by the way.

Standing model of Nyctosaurus by David Peters

Figure 3. Standing model of Nyctosauru based on UNSM 93000. This one did not have a crest.

In figure 2
note the length and shape of the posterior dorsal ribs. They don’t curve much. Nyctosaurus might have had more of a pancake-like (rather than sausage-like) posterior body to match its wide chest, as seen elsewhere in Sharovipteryx, Eudimorphodon and Jeholopterus. In UNSM 93000 the sternum remains buried.

On a side note:
For those interested in some VERY bizarre Nyctosaurus reconstructions by artists like Jaime Headden, Mark Witton, Matt Martyniuk and others, click the following links:

  1. Nyctosaurus-sebulbai
  2. nyctosaurus.png
  3. nyctosaurus_skeleton_crested.jpg
  4. pterosaur_quad_launching_by_gaffamondo-d7ve3di.jpg
  5. alternative_diagram_for_quadrupedal_launch_by_gaffamondo-d7xagyk.jpg
  6. Witton_crested_nyctosaurs_March_2009.jpg

Note:
the tall thin crests are NOT the bizarre aspect of these illustrations and sculptures. The crests, in some specimens only, are real (Fig. 4).

On the quad launch issue (see illustrations from the list above),
remember that no pterosaur ever impresses metacarpal 4 (the big one) into the substrate. The tiny fingers are all that are ever impressed. Furthermore, as noted earlier, the quad launch hypothesis has many problems solved by simply taking off like a bird does.

Not immediately apparent,
some of the above images by other artists also appear to abbreviate the big metacarpal 4 for artistic purposes.

Figure 5. The derived Nyctosaurus, KJ2 in a floating configuration using its long forelimbs as pontoons.

Figure 4. The derived Nyctosaurus, KJ2 in a floating configuration using its long forelimbs as pontoons. With hollow wing bones, this pterosaur might have floated a little higher on the surface, but it’s hard to judge with the weight of that big crest and skull pressing down. It is also easier to draw the forelimbs in this fashion, rather than out laterally, yet still folded, which would have been quite stable with those metacarpal pontoons, probably floating diagonally to laterally on the surface.

References
Brown GW 1978. Preliminary report on an articulated specimen of Pteranodon (Nyctosaurusgracilis. Proceedings of the Nebraska Academy of Science 88: 39.
Brown GW 1986. Reassessment of Nyctosaurus: new wings for an old pterosaur. Proceedings of the Nebraska Academy of Science 96: 47.

wiki/Nyctosaurus

New Nyctosaurus LACM 51130 (Perez 2012)

A recent paper, poster and online presentation by Teresa Perez (2012) introduced us to a new Nyctosaurus (LACM 51130) known from an articulated but incomplete post-crania sans cervicals (Fig. 1). Perez doesn’t indicate whether this is a ventral or dorsal presentation, but the exposure of the posterior tuberosity of the humerus, the layering of the radius slightly below the ulna, the layering of the coracoid on top of the scapula and the exposure of the prepubes on top of the left ilium indicate a ventral exposure.

Nyctosaurus (Perez 2012) LACM 51130.

Figure 1. Nyctosaurus (Perez 2012) LACM 51130. Note the original false scale bar (20cm) has been repaired here (0-2-10cm) in concert with published bone length data.

LACM 51130 was described by Perez as immature due to an unfused ETP (extensor tendon process), but that is a phylogenetic trait (contra Bennett 1991, 2001), not an ontogenetic one, as we noted earlier. (All basal Nyctos have unfused ETPs. Only derived crested forms fuse the ETPs.)

As noted by Perez, the specimen is about the same size as the other Nyctosaurus (Fig. 2) specimens, but morphologically not identical to any one of them. Thus it is probably an adult like the others are.

Figure 2. Reconstructions of several Nyctosaurus including UNSM 93000 and LACM 51130. To the right are three Nyctosaurus humeri showing morphological and size change toward the crested form, KJ2.

Figure 2. Click to enlarge. Reconstructions of several Nyctosaurus including UNSM 93000 and LACM 51130. To the upper right are three Nyctosaurus humeri showing morphological and size change toward the crested form, KJ2.

Interestingly
In the LACM specimen the humerus and antebrachium are shorter and more robust than in the UNSM 93000 specimen — yet the humerus of the LACM specimen is longer and not as robust as in the KJ2 specimen (Fig 2). Thus the LACM specimen appears to be a transitional taxon between these two previously known sister taxa. Perhaps it had a short skull crest in life, but all skull material is missing.

Or is it…????
There’s an interesting unidentified curved flat bone that disappears beneath the left manual 4.1(flipped to the right in ventral view). This gives every indication that it is a small portion of a crest of unknown length, likely smaller than in other crested Nyctosaurus based on its apparent cross section.

Perez considered the two preserved pectoral elements to both be coracoids, but they are different shapes and one is nearly identical to the scapula of UNSM 93000. Lack of fusion in the scapulocoracoid is also another crestless Nyctosaurus trait. Note that crested Nyctosaurus are no larger than crestless specimens and yet the humerus is smaller (Fig. 2). Odd that…

So not all Nyctosaurus had a crest. Not all had just three wing phalanges. Not all lost their free fingers. So far, every Nyctosaurus featured at reptileevolution.com is a distinct species (Fig. 2). The LACM specimen appears to be a basal crested specimen. These comparisons probably could not have been determined without making a reconstruction or two, a practice that focuses the eye and clarifies subtle differences and is, unfortunately, deemed to difficult for professional palaeontologists and their students to attempt.

That’s why I’m here.
And here’s yet another case in which I have not even seen the fossil yet am able to make small corrections and contributions. Photos, tracings and a catalog of reconstructions have value.

References
Perez T 2012. Diagnosis of an Immature Nyctosaurus (Pterosauria) Specimen. The Dinosaur Institute, Natural History Museum of Los Angeles County. Online here.

Evidence for a Giant Nyctosaurus or Two

Nyctosaurus is not just a genus. It is a clade with a wider variety of shapes and sizes than previously thought.

Bennett (1991, 1992, 1994, 2000, 2001) pretty much established the traditional concepts of Nyctosaurus by declaring that non-fusion of certain skeletal elements meant immaturity. He did this using “logic” and patterns found in archosaurs, not phylogenetic analysis. As it turns out, phylogenetically, no Nyctosaurus has fused skeletal elements or a crest — not until you get to the highly derived crested specimens.

What’s interesting is now, with this information, we can reclassify a large pterosaur knuckle, YPM 2501 (Fig. 1), as a giant basal Nyctosaurus, based on the nonfusion of its extensor tendon process, rather than as a Pteranodon, based on size alone. This giant element goes along with the giant Nyctosaurus pelvis, KUVP 993 (Fig. 1), previously misidentified as a “female” Pteranodon pelvis based on size alone by Bennett (1991, 1992, 1994, 2001). It is morphologically closer to Nyctosaurus.

Nyctosaurus clade

Figure 1. The clade of Nyctosaurus and kin. Click to enlarge.

Nyctosaurus nanus (known from a humerus and pectoral girdle) is the only Nyctosaurus that is genuinely and markedly smaller than the others pictured here. Earlier we looked at other aspects of sexual maturity and growth in Nyctosaurus, which is worth checking out.

This subject came up because I noticed an online pdf of the partial Nyctosaurus, LACM 51130, described as “immature,” despite being roughly the same size as other Nyctosaurus specimens. The author made reference to Bennett’s work regarding the non-fusion of certain elements, and this has to be nipped in the bud since it has been demonstrated to be invalid, unless you think that all known specimens of Nyctosaurus and that someday we’ll find adults. But that goes against the odds.

As always, I encourage readers to see specimens, make observations and come to your own conclusions. Test. Test. And test again.

Evidence and support in the form of nexus, pdf and jpeg files will be sent to all who request additional data.

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.
Bennett SC 2003. New crested specimens of the Late Cretaceous pterosaur Nyctosaurus.Paläontologische Zeitschrift 77: 61-75.
Chinsamy A, Codorniú L and Chiappe LM 2008. Developmental growth patterns of the filter-feeder pterosaur, Pterodaustro guinazui. Biology Letters, 4: 282-285.
Kaplan M 2007. Iguana Age and Expected Size. iguana/agesize online
Maisano JA 2002. Terminal fusions of skeletal elements as indicators of maturity in squamates. Journal of Vertebrae Paleontology 22: 268–275.
Pianka E 1971.
Notes on the Biology of Varanus tristis. West. Aust, Natur, 11(8):80-183.

wiki/Nyctosaurus

How Nyctosaurus UNSM93000 lost a wing phalanx, or two.

There is no doubt that the UNSM 93000 specimen of Nyctosaurus (Figs. 1, 2, Brown 1978, 1986) had three wing phalanges (not counting the hypothetical vestigial ungual perhaps still buried in the matrix, insufficiently excavated to reveal the possibility). All other pterosaurs have four wing phalanges, plus the ungual.

Cast of the UNSM93000 specimen of Nyctosaurus

Figure 3. Cast of the UNSM93000 specimen of Nyctosaurus (hanging in my office and taken by cellphone). Wing phalanges marked. The identity of the wing phalanges appears to be m4.1, m4.2 and m4.4 (curved). There is no vestige or indication of m4.3. Arrows point to joints and the extensor tendon process.

Due to this specimen, traditional thinking holds that all Nyctosaurus specimens had but three wing phalanges, having lost the fourth phalanx. We’ll test that paradigm today.

The UNSM specimen of Nyctosaurus

Figure 2. The UNSM specimen of Nyctosaurus, the only one for which we are sure it had only three wing phalanges.

Contra traditional thinking
I found four wing phalanges on the more basal nyctosaurs like the Field Museum specimen FMNH 25026 (Fig. 3) and the Fort Hays specimen, FHSM VP21 (Fig. 4). The more derived crested specimen, KJ2 has a split and shattered wing phalanx 2/3, so I can’t determine its status from available data. Its reconstructed length and phylogenetic nesting strongly suggests that m4.3 is simply missing. It never developed.

The Field Museum Nyctosaurus, FMNHVP21,

Figure 3. The Field Museum Nyctosaurus, FMNHVP21, with color overlays identifying the wing phalanges of one wing. Four are present. Only the proximal knuckle and distal third of m4.3 is preserved.

The Fort Hays specimen of Nyctosaurus, FHSM VP2148

Figure 4. The Fort Hays specimen of Nyctosaurus, FHSM VP2148 identifying all four wing phalanges and the extensor tendon process (ETP). The rostral crest is made of putty. Another unidentified curved m4.4 is beneath the distal end of the upper m4.1.

So what happened to the missing phalanx?
In the UNSM93000 specimen (Figs. 1, 2) m4.2 is roughly 85% of m4.1, which is similar in proportion to m4.2 in the other nyctosaurs. Manual 4.3 appears to be unreduced in the Field Museum specimen.  Manual 4.3 is relatively shorter in the Fort Hays specimen, but still substantial. In all Nyctosaurus manual 4.4 is curved and shorter than the other phalanges, and that pattern in followed in UNSM 93000, Thus it does not appear that manual 4.4 withered and disappeared in UNSM 93000.

No, something else happened to m4.3.
Manual 4.3 does not appear to have fused to m4.2. That would have made an elongated wing phalanx and finger. There are no marks on the middle phalanx to that effect. Rather, all the other bones are much the same as in other nyctosaurs. It seems that m4.3 simply did not appear, did not develop. Very strange.

If the ungual of UNSM 93000 turns out to be missing (after further excavation) I would not be surprised. I’m sure it could have happened on the most derived Cretaceous pterosaurs. Especially one that was losing m4.3! A vestige can only last so long, but this specimen needs just a little bit more excavation to find out.

As always, I encourage readers to see specimens, make observations and come to your own conclusions. Test. Test. And test again.

Evidence and support in the form of nexus, pdf and jpeg files will be sent to all who request additional data.

References
Brown GW 1978. Preliminary report on an articulated specimen of Pteranodon Nyctosaurusgracilis. Proceedings of the Nebraska Academy of Science 88: 39.
Brown GW 1986. Reassessment of Nyctosaurus: new wings for an old pterosaur. Proceedings of the Nebraska Academy of Science 96: 47.

wiki/Nyctosaurus

Pterosaurs with an overbite and an underbite

Pteranodon skulls

Figure 1. Click to enlarge. A family tree of Pteranodon. So many specimens do not preserve a rostrum and mandible, but many do. derived forms had an overbite. Just the opposite of Nyctosaurus, which had an underbite. Despite these differences, both had extremely sharp jaw tips, formed by sharp teeth.

Most pterosaurs had jaws of equal length.
Some pterosaurs even have interlocking teeth. However in Pteranodon there was an overbite, but only in derived specimens (Fig. 1. and from what we can tell with so few specimens preserving the beak). In Nyctosaurus, there was an underbite (Fig. 1), like a modern black skimmer. In both cases these pterosaur jaws had extremely sharp tips formed from a single tooth oriented anteriorly.

What did they do with such sharp beaks?
Whether the uppers were the sword, or the lowers, its clear that the Pteranodon/Nyctosaurus clade speared its food, like a heron does, likely on the wing at the surface of the Niobrara Sea. There’s a nice heron two-fer here. It’s probably no surprise that both of these pterosaurs descended from a heron-like progenitor like Eopteranodon. That’s where the long metacarpals came from!

Did they dive or remain airborne?  
We can look at gannets and pelicans for examples of divers. The albatross remains airborne or floats while feeding. Pteranodon and Nyctosaurus were likely similar.

And speaking of crests…
Which, we weren’t, but they’re fun to talk about anyway… and may be pertinent to this discussion. Crest shape has always been a key phylogenetic trait, enabling paleontologists and interested Pteranodons to distinguish one “race” from another. What’s also interesting is the cranial size (sans crest) of specimen  Y or Z5 compared to the relative pinhead, specimen Z, which compensates with a deep rostrum, with who knows how long of an overbite.

As always, I encourage readers to see specimens, make observations and come to your own conclusions. Test. Test. And test again. 

Evidence and support in the form of nexus, pdf and jpeg files will be sent to all who request additional data.

My, What Big Gastralia You Have, Nyctosaurus!

Little Red Riding Hood had it right.
Whenever something is out of the ordinary, like big teeth on ‘Grandma-ma’, we take notice.

Most pterosaurs have gracile gastralia, those boomerang-shaped bones that cover the belly of pterosaurs and many other reptiles. The most obvious exception is Nyctosaurus, in which the gastralia are quite robust and for good reason.

The various forces working on the gastralia of Nyctosaurus.

Figure 1. The various forces working on the gastralia of Nyctosaurus. Weight and long lever arm of the upper/anterior portion in red. The fulcrum at the lumbar/sacral interface above the lower/posterior portion in yellow. Ventral support of the fulcrum from the gastralia in blue.

While all pterosaurs had to support the long lever arm of their upper/anterior selves at the fulcrum of the lumbar/sacral series interface, perhaps no pterosaur had quite the imbalance of forces seen in Nyctosaurus, with its long metacarpals and rostrum. In any case, Nyctosaurus developed a strong ventral basket of robust gastralia to prevent rotation of the lower lumbar area, which would have acted to shorten the distance between the sternum and prepubes in Nyctosaurus. I learned about this mechanical problem while building a full scale Nyctosaurus model based on UNSM 93000 (skull largely unknown, Fig. 2).

Standing model of Nyctosaurus

Figure 2. Standing model of Nyctosaurus. This model slumped over its belly without substantial reinforcement in the gastralia.

Quadrupedal Pterosaurs Avoided This Problem
Whether you support yourself with long metacarpals, long antebrachia or long ski poles, the stress on the lower back goes away and you don’t need to develop such robust anti-rotational supports in your belly. And of course, the whole problem goes away when you are airborne and supporting yourself by lift from both wings and thighs.

As always, I encourage readers to see specimens, make observations and come to your own conclusions. Test. Test. And test again.

Evidence and support in the form of nexus, pdf and jpeg files will be sent to all who request additional data.