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

Pseudictops: what little we know is unique

There are not many mammals with crenulated/serrated teeth.
Pseudictops lophiodon (Matthews, Granger and Simpson 1929, Sulimski 1968, Late Paleocene, 57 mya; Fig. 1; AMNH 21727) is one such mammal. From the start Pseudictops was compared to anagalids like Leptictis (Fig. 2), a basal elephant shrew and ancestor to tenrecs, pakicetids and odontocete whales.

Figure 1. Pseudictops lophiodon compared to the slightly larger Siamotherium.

Figure 1. Pseudictops lophiodon compared to the slightly larger Siamotherium. The mandible is extremely robust and appears to nearly lack a coronoid process, distinct from most mammals.Note the crenulations and and/or robust serrations on the anterior teeth.

Figure 1a. Pseudictops anterior teeth.

Figure 1a. Pseudictops anterior teeth.

The dentary incisors
are deeply rooted in a deep dentary. Not sure why the two dentaries (Fig. 1) have distinct shapes. Perhaps they are not actually related to one another or perhaps some parts are missing from the smaller one and plasterered over.

Figure 2. Leptictis, an early Oligocene elephant shrew.

Figure 2. Leptictis, an early Oligocene elephant shrew.

Now that you’ve met Pseudictops, a quick look at Ictops
reveals a cranium with a double parasagittal crest, as in sister taxon, Leptictis

Figure 6. Rhynchocyon (above) and Macroscelides (below) compared. Though both are considered elephant shrews, they nest in separate major mammal clades in the LRT.

Figure 3. Rhynchocyon (above) and Macroscelides (below) compared. Though both are considered elephant shrews, they nest in separate major mammal clades in the LRT.


References
Matthew WD, Granger W and Simpson GG 1929. Additiions to the fauna of the Gashato Formatin of Mongolia. American Museum Novitates 376:1–12.
Sulimski A 1968. Paleocene genus Pseudictops Matthew, Granger and Simpson 1929 (Mammalia) and its revision. www.palaeontologia.pan.pl/Archive/1968-19–1011-129–10-14.pdf

 

The AMNH animated Jeholopterus

Updated March 3, 2015 with the addition of a dorsal view of Jeholopterus.

About a year ago
the American Museum of Natural History (AMNH) in New York City (NYC) put on a pterosaur display, both in their halls and online.

Their animated portrayal
of the Late Jurassic Chinese pterosaur, Jeholopterus, caught my eye (Fig. 1).

Figure 1. Animated GIF created by the AMNH for their web page on Jeholoopterus. Note the complete lack of an airfoil in the wing, the lack of muscles in the limbs, the presence of a uropatagium between the hind limbs, the lack of a tail, eyes set on the sides of a blockhead skull, and no care to reproduce the wide ribcage. In short, there is little that is accurate about this otherwise wonderfully animated pterosaur. And where is all the long hair that should be there?

Figure 1. Animated GIF created by the AMNH for their web page on Jeholoopterus. Note the complete disregard for its preserved anatomy, the  lack of an airfoil in the wing, the lack of muscles in the limbs, the presence of a uropatagium between the hind limbs, the lack of a tail, eyes set on the sides of a blockhead skull, and no care to reproduce the wide ribcage. In short, there is little that is accurate about this otherwise wonderfully animated pterosaur. And where is all the long hair that should be there? The animator was gifted, but the blueprint was largely imaginary.

One wonders what the animators used for reference… certainly not the fossil.
This animation lacks all the traits that make Jeholopterus unique: the up-curved jawline, the forward angled eyes, the very hairy body, the broad ribcage and belly, the deep chest, the low attachment of the wing, the large-boned limbs, the surgically curved claws, the huge feet with a very large digit 5, a longish tail and longer wings. Also lacking here is a wing with a decent airfoil section, a proper trailing edge stretched between the wing tip and elbow, large limb muscles and paired uropatagia behind each hind limb. And where does that box-like skull come from??

This is an old-school pterosaur cartoon,
lacking almost everything we know about this complete and articulated fossil. For comparison, a reconstruction is offered here (Fig. 2) based on precise tracings.

Figure 3. Click to enlarge. The Jeholopterus holotype (left) alongside the referred specimen (right). No doubt they were related, but were likely not conspecific. The one on the right was an insect eater. The one on the left was specialized for drinking dinosaur blood.

Figure 3. Click to enlarge. The Jeholopterus holotype (left) alongside the referred specimen (right). No doubt they were related, but were likely not conspecific. The one on the right was an insect eater. The one on the left was specialized for drinking dinosaur blood.

Jeholopterus had so many traits distinct from those of other anurognathid pterosaurs, that it deserves more respect than the AMNH gave it. Seems they purposely avoided describing it for what it is… a vampire pterosaur (details here). Would have been a bigger draw and a more accurate presentation had they just paid attention to the details.

The genesis of this post
came from an Ask.MetaFilter.com post on binocular vision in pterosaurs posted by Hactar, who wrote: “I am trying to find any information about binocular vision in pterosaurs. This past weekend, I went to the Museum of Natural History’s exhibition on pterosaurs. Their illustrations for Jeholopterus varied greatly in the placement of they eyes from on the sides of the head to facing forward (third picture on the page). (The second image caused me to dub it “freaky monkey pterosaur.”)  So how much binocular vision did pterosaurs have? I have found a couple of scattered references to family Anurognathus (of which Jeholopterus is a genus) having binocular vision, based on the structure of ear [sic] canals. Were these pterosaurs unique in having binocular vision, or did pteranodons and other pterosaurs have vision like a raptors instead of like a tern or pigeon? Links to academic articles are acceptable, I have confederates who can access articles for me. Please nothing by David Peters. From what I can read, his work on pterosaurs is at best somewhat wrong and generally completely inaccurate, which is a shame as he seems to be the only one who has posted anything online about this. (If the site mentions Jeholopterus as a vampire, skip it).”

Several things jump out here: 

  1. The AMNH did not edit their artwork. As noted above, one piece of artwork had lateral eyes. The other had anterior eyes.
  2. Science is a process that can be repeated by anyone. Therefore, Hactar could have taken a skull photo of Jeholopterus (or any other binocular pterosaur, like Batrachognathus), and traced the elements to arrive at his/her own skull reconstruction.
  3. If my work on pterosaurs varies from “somewhat wrong to completely inaccurate,” then I am at a loss as to how to explain the internal consistency of sister taxa that not only nest in complete resolution, but gradually evolve from one to another, apparently modeling the actual evolution of the group with stone cold logic. I also note that no one else is producing accurate tracings AND reconstructions based on those tracings. The alternative, of course, is to accept hopeful monsters, like Bennett’s anurognathid, or Andres’ hypothesis that anurognathids begat pterodactyloids, or Unwin’s uropatagium and other such fanciful hypotheses.

And like I said earlier,
this is Science, so you don’t have to accept anyone’s word for whatever you’re trying to figure out. You can find out for yourself by tracing the specimen and creating your own reconstruction. If my observations and hypotheses cannot be replicated, please send me your interpretations so they can be repaired here.

Figure 4. Jeholopterus in dorsal view. Here the robust hind limbs, broad belly and small skull stand out as distinct from other anurognathids. Click to enlarge.

Figure 4. Jeholopterus in dorsal view. Here the robust hind limbs, broad belly and small skull stand out as distinct from other anurognathids. Click to enlarge.

Don’t just repeat the propaganda ad nauseum.
The data is set in stone. Go get it and you’ll find the process rewarding.

References
Cheng X, Wang X, Jiang S and Kellner AWA 2014. Short note on a non-pterodactyloid pterosaur from Upper Jurassic deposits of Inner Mongolia, China. Historical Biology (advance online publication) DOI:10.1080/08912963.2014.974038
Kellner AWA, Wang X, Tischlinger H, Campos DA, Hone DWE and Meng X 2010. The soft tissue of Jeholopterus (Pterosauria, Anurognathidae, Batrachognathinae) and the structure of the pterosaur wing membrane. Proc Royal Soc B 277: 321–329.
Peters D 2003. The Chinese vampire and other overlooked pterosaur ptreasures. Journal of Vertebrate Paleontology 23(3): 87A.
Wang X, Zhou Z, Zhang F and Xu X 2002. A nearly completely articulated rhamphorhynchoid pterosaur with exceptionally well-preserved wing membranes and “hairs” from Inner Mongolia, northeast China. Chinese Science Bulletin 47(3): 226-230.

wiki/Jeholopterus