Hone 2020 reviews anurognathid pterosaurs

Here’s a new paper from Dr. DWE Hone (2020).
Quoting Hone’s own publicity sheet regarding the paper, “there’s not a huge amount to talk about here since as it’s a review, it doesn’t contain too much that’s new.”

Even so,
Hone manages to promote invalid pterosaur myths, like the pushup-takeoff (Fig. 1) and the presence of a giant eyeball in the front of the skull (Bennett 2007, Fig. 1). That was repaired here and here (Fig. 1) several years ago. The purported scleral (eyeball) ring is in fact the maxilla in the smaller flat-head SMNS 81928 specimen (Fig. 1) incorrectly referred to the genus Anurognathus (Figs. 3a, b) by Bennett 2007 and repeated by Hone 2020. Correcting the eyeball problem resulted in a traditional dimorphodontid/ anurognathid-type skull (Fig. 1 top figures) despite the skull being flatter than tall, a morphology repeated several times in later anurognathid discoveries.

Bennett presented a unique morphology
(not shared with any other pterosaur) that was copied and embraced by Witton and Hone without question. Both PhDs should have done their own scientific research instead of trusting anyone under this simple rule: “Extraordinary claims require ordinary evidence.” Yes, ordinary evidence. Just confirm or refute Bennett’s bizarre observation with your own tracing of the specimen and compare that with other similar taxa. That’s what PhDs are paid to do. To trust unique claims like Bennett 2007 without a second examination is not scientific.

Figure 1. The SMNS 81928 anurognathid specimen.

Figure 1. The SMNS 81928 anurognathid specimen, two interpretations shown slightly larger than life size. This was the first of several ‘flathead’ anurognathids to be discovered. Let’s hope the blue one can open its wings and start flapping before the eventual face plant. And how did such a take-off configuration evolve from bipedal ancestors?

In summary, Hone 2020
reviews the history of anurognathid research and renames a specimen. Hone promotes previous mistakes (Fig. 1) as valid without support from new, confirming tracings or any tracings whatsoever. Only one taxon is reconstructed (Fig. 1). No phylogenetic analysis appears. The IVPP transitional anurognathid embryo is ignored along with several other basal anurognathids (Fig. 4). Some citations are omitted (see way below). All the above shortcomings and mistakes were resolved online here and at links therein several years ago.

From the Hone 2020 Abstract:
“The anurognathids are an enigmatic and distinctive clade of small, non‐pterodactyloid pterosaurs with an unusual combination of anatomical traits in the head, neck, wings and tail.”

No. After precise tracings and phylogenetic analysis in the large pterosaur tree (LPT, 251 taxa), anurognathids are not enigmas, not all are small, the traditional clade Pterodactyloidea is invalid because it is polyphyletic (Peters 2007, LPT) and there is no reason to trust Hone’s description of the head, neck, wings and tail given his use of M Witton’s invalid illustration (Figs. 1, 2).

Compare Hone and Witton’s published anurognathids
(Figs. 1, 2) with more precise tracings (Figs. 1, 3) of the skeletal and soft-tissue elements of the Anurognathus holotype (Figs. 3a, 3b) distinct from the smaller disc-head SMNS 81928 specimen (Figs. 1, 3b), both from Solnhofen limestones.

Figure 1. From Hone 2020, illustration by M Witton of Jeholopterus. Compare to figure 2.

Figure 2. From Hone 2020, illustration by M Witton of Anurognathus, not the holotype, but the SMNS 81928 as in figure 1.

Witton and Bennett 9007 place the eyeball over the maxilla
in the large antorbital fenestra, rather than further back in the orbit, as in all other pterosaurs, over the jugal (Fig. 3a cyan), behind the lacrimal (Fig. 3a pink).

Figure 2. Click to enlarge. DGS tracing of Anurognathus ammonia. Note the placement of the lacrimals in the skull, behind the large antorbital fenestra. That is not the orbit. The small jugal (bright light blue) also indicates the placement of the small orbit in the back half of the skull, as in all other anurognathids. Also note the disappearance of the cervicals beneath the matrix. That may be an embryo by the tail. More on that tomorrow.

Figure 3a. Click to enlarge. DGS tracing of Anurognathus ammonia. Note the placement of the lacrimals in the skull, behind the large antorbital fenestra. That is not the orbit. The small jugal (bright light blue) also indicates the placement of the small orbit in the back half of the skull, as in all other anurognathids. Also note the disappearance of the cervicals beneath the matrix. That may be an embryo by the tail. More on that tomorrow.

Figure 1. The flat-head pterosaur, a private specimen (on the left) attributed by Bennett (2007) to Anurognathus ammoni (on the right).

Figure 3b. The flat-head pterosaur, a private specimen (on the left) attributed by Bennett (2007) to Anurognathus ammoni (on the right). Pedal digit 5 does not frame a membrane. Rotodactylus and other bipedal Jurassic pterosaur  tracks show how it impresses.

Hone 2020 abstract continues:
“They [anurognathids] are known from very limited remains and few have been described in detail, and as a result, much of their biology remains uncertain.

If pterosaur expert, Dr. Hone, doesn’t want to go to the effort, and wants to ignore workers who have gone to the effort years earlier (Figs. 1-4), before too long Dr. Hone will not be known as the expert he trained to be and thinks he is.

“This is despite their importance as potentially one of the earliest branches of pterosaur evolution or even lying close to the origins of pterodactyloids.

Well, which is it? Basal or transitional? A bit of effort, like creating a cladogram, would have resolved this issue. Hone has a PhD in paleontology. He should not leave things vague and unanswered. This is his passion and his job and he is not doing his job or following his passion.

“This review covers the taxonomy and palaeoecology of the anurognathids, which remain an interesting branch of pterosaurian evolution.”

Hone defined the Anurognathidae,
“as all taxa more closely related to Anurognathus than Dimorphodon, Pterodactylus or Scaphognathus.” That would include all of the taxa (and a few more recent ones) shown in figure 4. Many of these did not appear in the Hone 2020 review, which was intended to be comprehensive.

Figure 2. Click to enlarge. Anurognathids to scale. The adult of the IVPP embryo is 8x the size of the embryo, as in all other tested adult/embryo pairings.

Figure 4. Click to enlarge. Anurognathids to scale. The adult of the IVPP embryo is 8x the size of the embryo, as in all other tested adult/embryo pairings.

See below for comments
on Hone’s self-published publicity statement, which summarizes his paper and arrived a few days before the PDF became available.

Bennett SC 2007. A second specimen of the pterosaur Anurognathus ammoni. Paläontologische Zeitschrift 81(4):376-398.
Hone DWE 2020. A review of the taxonomy and palaeoecology of the Anurognathidae (Reptilia, Pterosauria). Acta Geologica Sinica (English edition)

From DWE Hone’s publication announcement:
“Revising the frog-mouthed pterosaurs: the anurognathids”

Oops. This paper is not a revision. Hone 2020 is titled, “A review of the taxonomy and palaeoecology of the Anurognathidae”. A revision would revise present thinking. Hone himself notes he makes no attempt to do this. Let’s imagine Hone was thinking of the word ‘reviewing’ when he wrote the PR piece, but inserted the more exciting word ‘revising’ by accident.

“The anurognathids are a wonderful group of small non-pterodactyloid pterosaurs known from Europe and various parts of Asia that are perhaps the most distinctive of the early pterosaur groups and probably the latest survivors.

According to the large pterosaur tree (LPT) and simple logic, several clades of Middle and Late Jurassic pterosaurs gave rise to four pterodactyloid-grade clades, some of which extended to the last day of the Cretaceous. You don’t get Cretaceous pterosaurs without Jurassic and Triassic ancestors. Anurognathids also invaded North and South America, according to phylogenetic analysis and footprints.

“They had bizarrely short and broad skulls made of tiny spars of bone and with few teeth and remarkably short tails for non-pterodactyloids. They were mostly small and are interpreted as having been hawking for insect prey on the wing. There are few specimens (even with the recent discoveries) that are hard to tell apart because they are all so similar and yet almost every different specimen has been named as a new species.”

Hone puts no effort (no tracings, a single borrowed reconstruction, no original cladograms) into understanding, reconstructing, modeling, lumping and splitting the several known anurognathid specimens. As in prior studies, Hone stands back when scientific work is required. Hone’s writing is only in service and support to his traditional bias. He avoided citing several peer-reviewed studies that included other anurognathid materials (see below). Bottom line: Hone is supposed to be a scientist, not a journalist. He should be shedding new light on anurognathids, resolving the enigmas, not repeating what others have already published. That’s what journalists do.

“So they are both really unusual and not very well known and that means even if this has taken time to come to fruition, a review of them would be rather handy. And so as you might imagine, this post coincides with a new paper doing exactly that. Somewhat inevitably there’s not a huge amount to talk about here since as it’s a review, it doesn’t contain too much that’s new – the primary role is to bring things together and synthesise them so most of what is there is already known (at least to people who keep up with the pterosaur literature). Reading the review will bring you up speed if you want all the basics, but I do want to talk here about a couple of the more interesting things I have added.”

“The first one is the validity of the various taxa. It’s hardly unknown for pterosaur clades to be made up of lots of species each represented by only a single specimen but the anurognathids are pushing even that. While I can’t immediately think of any calls for synonymy of any taxa, the fact that so few specimens have been described in detail and the poor quality of the preservation of many means that the available lists of diagnoses have been pretty weak to date.

In counterpoint, detailed tracings and reconstructions have been online for every known anurognathid (Fig. 4) for several years. Hone omitted several of these taxa. A cladogram would have helped him separate in-groups from out-groups.

“They are not much better now, but I have at least revised and updated the diagnosis of every taxon. There are two consequences of this that are important. First off, all the current taxa seem valid, and moreover, some of the recently illustrated, but not yet named, specimens also look like they are distinct taxa and there’s probably several new names needed. Secondly, the second species of Dendrorhynchoides, D. mutodongensis is as distinct, if not more so, than many other anurognathid genera and as such needs to be elevated to the genus level… I erected the new genus Luopterus to house the species.

That’s a good name for a specimen needing a new generic name. Well done, Dave!

“Next up, the variation in the different species is quite odd. Anurognathids are weirdly conservative, even compared to other pterosaur groups and while the poor preservation of the specimens hasn’t helped up find distinguishing traits between them, once you sit down and really look it’s hard to find the kinds of traits that you might normally use to separate out genera and species.”

Seeking traits to separate specimens is “Pulling a Larry Martin“. Don’t do that. It leads to madness due to convergence, or, in this case, backing away from what must be done: a comprehensive phylogenetic analysis with all the anurognathid taxa and parts thereof laid out, lumped and separated.

“That said, there are some bits of variation which while commented on before are quite notable in this context (and there is more coming on this in a future paper that I’m involved in). The length of the tail is really variable and while these are as a whole short-tailed (even the longest of them is much shorter than other non-pterodactyloids) there is really quite some difference between the longest and the shortest. I don’t know what this means but it’s an area worthy of greater attention.

Unfortunately, Hone only crudely illustrates the variety found in anurognathid humerus shapes, but omits doing the same for the tails, or any other body parts, especially the skulls. If an amateur can do it (Figs. 1–4), a paid professional and a PhD should be able to do it that much better.

“Similarly, the smaller anurognathids tend to have extraordinarily large heads and the larger ones rather small ones.

This needed to be illustrated and documented. Reconstructions (see Fig. 4) do not reflect and confirm Hone’s observation.

“There could be ontogentic effects here since many of the smaller specimens are juveniles but it stands in contrast with the more general isometry of other pterosaurs, and could be linked to prey sizes or even eye size. If they are, any [sic] many people suspect, nocturnal then juveniles need huge heads to house huge eyes.”

Hone is correct with regard to pterosaur isometry, so why then does he label some pterosaurs ‘juveniles’, rather than small adults of distinct genera? The huge eyes guess is easily resolved by tracing each specimen and locating the eyes, none of which are ‘huge”, with the exceptions of Batrachognathus (Fig. 5) having the most owl-like eyes and most binocular. Even so, those eyes remain in the back half of the skull, as in ALL other pterosaurs.

Dorsal and lateral views of three anurognathid pterosaurs.

Figure 5. Dorsal and lateral views of three anurognathid pterosaurs. From left to right, Dendrorhynchoides, Batrachognathus and Jeholopterus, all crushed dorsoventrally, due to the skull’s greater width.

Hone continues
“Finally, there is the issue of the ‘folded’ wings. While some disarticulation can occur in decaying pterosaurs unless the specimen has disintegrated the various bones of the wing finger stay together. Presumably they are held together by numerous strong ligaments or they would not be able to hold up the forces of flight. It’s a very derived condition since of course all other archosaurs (indeed tetrapods generally) can flex their fingers.

Pterosaurs are not archosaurs. This is yet another myth Hone promotes without citing competing studies. He tried to do so once, but choked on the attempt, kowtowing to the agenda of his professor and mentor, Mike Benton. Hone has not been under the influence of Benton for over a decade, so he should show a little independence now. As a PhD pterosaur expert, knowing what a pterosaur is… that is his job and he is not doing his job. More on the wing issue below.

Anurognathids however, despite having some exquisitely preserved specimens, and nearly all of them being basically articulated, show the joints of the wing finger being flexed. This suggests that they are doing something really rather different with their wings, when flying or even when on the ground.

Not at all. The small size of most anurognathids means the wing finger did not need to be as robust as in the larger clades. That alone could account for the flexion seen in many anurognathid wing phalanges (Figs. 4, 6). There’s also taphonomy. And speaking of wings, no pterosaur fossil shows the wing membrane extending down the thigh to the ankle, as shown in the Witton illustrations (Figs. 1, 2).

Tracing of Jeholopterus using DGS.

Figure 6. Click to enlarge. Tracing of Jeholopterus using DGS. Dorsal view of Jeholopterus based on the tracing. Lower left images include an unidentified pair of semi-circles too large to be embryo upper temporal fenestrae (that was the first guess). The tail is not particularly short when stretched to its full length, despite the reduced length of the individual caudals. The red ellipse represents a hypothetical egg shape. The abdomen was not so wide. The ribs would have had a ventral component and direction, which they do not have here. Note the right angle femoral head, ideal for parasagittal locomotion, like a dinosaur.

“One thing to note is that this is also seen in one other set of pterosaur specimens – embryos. That implies that either anurognathids have inherited this trait from their ancestors (if they are, as some suggest, the first branching group of pterosaurs) or have secondarily acquired what is essentially a paedomorphic trait of wing flexion.”

If Hone had produced a valid cladogram, like the LPT, he would have been able to find a solution to his own problem. See figure 4 for a quick graphic review.

“I’ll leave it there for now. There’s plenty more in the paper that you can read and there is obviously more research to come (indeed I’m working on another anurognathid paper that’s come about in part through this work) so don’t want to go over this in detail when it’s already a review. Hopefully this does sort out a few issues and pave the way for a better understanding of these most interesting of pterosaurs.”

In counterpoint, and allowing for a little verbal showmanship on Hone’s part (e.g. using “revising” instead of “reviewing” in his PR ), all pterosaurs should be equally interesting because taxon omission by PhDs is a traditional sin. Granted, Hone is infatuated with anurognathids, like the proud father of any new paper generally should be. Unfortunately, because this paper is already in print, it is now too late to give it the care and attention it should have had when still in his mind and on his monitor.

David Hone is still a young man.
I hope that someday he will see the light, crawl out of Benton’s shadow, do the work he is paid to do, stop hiding behind taxon and citation omission, and ultimately become the pterosaur expert he trained to be.

Papers and abstracts omitted by Hone 2020
Peters D 1995. Wing shape in pterosaurs. Nature 374, 315-316.
Peters D 2000a. Description and Interpretation of Interphalangeal Lines in Tetrapods.  Ichnos 7:11-41.
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 2002. A New Model for the Evolution of the Pterosaur Wing – with a twist. – Historical Biology 15: 277–301.
Peters D 2003. The Chinese vampire and other overlooked pterosaur ptreasures. ournal of Vertebrate Paleontology, 23(3):87.
Peters D 2007. The origin and radiation of the Pterosauria. In D. Hone ed. Flugsaurier. The Wellnhofer pterosaur meeting, 2007, Munich, Germany. p. 27.
Peters D 2009. A reinterpretation of pteroid articulation in pterosaurs. Journal of Vertebrate Paleontology 29:1327-1330.
Peters D 2010. In defence of parallel interphalangeal lines.
Historical Biology iFirst article, 2010, 1–6 DOI: 10.1080/08912961003663500
Peters D 2011. A Catalog of Pterosaur Pedes for Trackmaker Identification
Ichnos 18(2):114-141. http://dx.doi.org/10.1080/10420940.2011.573605

See a pattern here?
Kids, if you want to get cited, get your PhD and go with the traditional bias and flow. Be willing to ignore competing citations if they come from outsiders who are willing to do the work and go the extra mile without getting paid [heavy on the sarcasm here, for those who are thinking about quote-mining this paragraph].

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