Chen et al. 2020 describe
a perfectly preserved Dsungaripterus palate (Figs. 1, 2) recovered by Young prior to 1964. This is welcome news! Unfortunately, the presentation of their recent ‘discoveries’ perpetuates a few pterosaur myths.
Figure 1. Dsungaripterus palate from Chen et al. 2020 with colors and diagrams (above) from Peters 2000 added. Note only a vestige remains of the lateral process of the palatine. The extent of the jugal is a guess here. Pink = pterygoid. Blue = palatine. Gold = ectopterygoid. In Chen et al. the line leading toward the abbreviation pl points to the maxilla.
Chen et al. 2020 cite
Osi et al. 2010, which we looked at earlier here. You might remember, Osi et al. thought they had discovered the true identity of palatal elements, but parenthetically acknowledged that Peters 2000 (Fig. 1) had done so a decade earlier. They did not realize others had also done so over a century before.
Prior to Peters 2000
and ever since Williston (1902) and continuing through Huene 1914, Wellnhofer (1978, 1991) and Bennett (1991, 2001a,b), the solid palatal plate in pterosaurs had been traditionally considered the palatine. That was the orthodox point-of-view.
Newton (1888), Seeley (1901 and Woodward (1902) reported that the solid palatal plate was an outgrowth of the maxilla, not the palatine. Unfortunately, I did not know those citations when Peters 2000 reported that the palatal plate actually originated from the maxilla. I thought I had discovered something! Rather, I had only confirmed work from a century earlier. Workers: it is important to expand your citation list so future workers will not overlook important papers, be they 20 years old or 120 years old.
Figure 2. Germanodactylus and the Dsungaripteridae. Contra Chen et al. , azhdarchids are not related.
Longtime readers may remember a wide gamut of dozens
of pterosaur and pterosaur ancestor palates (example Fig. 3) illustrated here, and in nine blogposts that followed, so pterosaur palate data has been online for several years.
The diagram illustration by Chen et al. 2020
(Fig. 1) uses the old-fashioned method of identifying bones, with lines leading from somewhere on the bones to outlying abbreviations. No indication of borders or sutures is provided. All the bones in their Dsungaripterus palate appear fused, despite remnants of borders visible in closer view (Fig. 1). More workers are using colors lately because they impart more data.
From the Chen et al. abstract:
“Among the unique features is a lateral process of the pterygoid divided into two parts: an anterior thin, parabolic arc shaped element that separates the secondary subtemporal and the subtemporal fenestrae, followed by a dorsoventrally flattened portion that is directed inside the sub temporal fenestrae.”
Actually there is no lateral process of the pterygoid divided in two parts. The anterior part is the ectopterygoid often fused to the palatine (= ectopalatine) in most, but not all pterosaurs (Fig. 1; exception: the dorygnathid specimen in Osi et al. remained unfused). The posterior portion is a new outgrowth of the pterygoid. Such a lateral ‘split’ is also found in Pteranodon (Fig. 2) and related sharp-rostrum pterosaur taxa.
From the Chen et al. abstract:
“Among all pterosaurs where the palate is known, the posterior configuration of the palate of D. weii is similar to some azhdarchoids, which is consistent with the suggested phylogenetic position of the Dsungaripteridae as closely related to the Azhdarchoidea.”
Actually dsungaripterids nest between germanodactylids and tapejarids (Fig. 2) in the large pterosaur tree (LPT), far from azhdarchids. A traditional error here perpetuated by taxon exclusion nests azhdarchids with tapejarids in the invalid clade (as currently defined) Azhdarchoidea. When more taxa are included in analysis, azhdarchids arise from tiny dorygnathids.
Figure 3. The palates of several Tapejaridae and Pteranodontidae, both evolving from Germananodactylus. Note the yellow tooth at the tip of each sharp premaxilla here.
From the Chen et al. abstract:
“Furthermore, we identify symmetrical grooves on the lateral surface of the upper and lower jaws, that likely represent the impression of the edge of a keratinous sheath that would cover the upturned toothless rostrum during foraging activity, most likely consisting of hard elements, as has been previously assumed.”
Actually those ‘toothless’ jaws are tipped with large, procumbent single teeth. Check them for dentine and enamel. That’s what makes the tips of the jaws so sharp and resistant to abrasion (more resistant than bone), evident on older specimens (Fig. 4) with blunt tooth tips. Sometimes these teeth fall out. These teeth have roots. And they have a phylogenetic history traceable back to germanodactylids and earlier scaphognathids.
Figure 4. Dsungaripterus single teeth at the tips of the jaws. Phylogenetically these began with Germanodactylus (Fig. 4). The groove (gr) is the premaxilla-maxilla suture.
That ‘groove’ (gr) in figure 4 is the premaxilla-maxilla suture, as noted by Young 1964 and Chen et al. 2020. In such cases, it is a better practice to label a suture as a suture, not a groove.
It’s always good to see new specimens,
but the presentation must be up-to-date. Too many pterosaur workers are perpetuating old myths. Color your bones and expand your taxon list. That will clarify most issues.
Bennett SC 1991. Morphology of the Late Cretaceous Pterosaur Pteranodonand Systematics of the Pterodactyloidea. [Volumes I and II]. – Ph.D. thesis, University of Kansas [Published by University Microfilms International/ProQuest].
Bennett SC 2001a, b. The osteology and functional morphology of the Late Cretaceous pterosaur Pteranodon. Part I and 2. General description of osteology. – Palaeontographica, Abteilung A, 260: 1-153.
Chen et al. (7 co-authors) 2020. New anatomical information on Dsungaripterus weii Young, 1964 with focus on the palatal region. PeerJ 8:e8741 DOI 10.7717/peerj.8741
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Wellnhofer P 1991. The Illustrated Encyclopedia of Pterosaurs. London, Salamander Books, Limited: 1-192.
Williston SW 1902. On the skull of Nyctodactylus, an Upper Cretaceous pterodactyl. Journal of Geology 10:520–531.
Woodward AS 1902. On two skulls of Ornithosaurian Rhamphorhynchus. Annals of the Magazine Natural History 9:1.
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