Don’t give up on the origin of pterosaurs!

Evidently it is still widely held
that pterosaurs appeared suddenly without antecedent. As evidence of this failure to follow the data, I came across a blog called Tetrapod Flight in which the author, Leon Linde, writes on Monday, March 16, 2015:

  1. The first tetrapods to evolve powered flight were the pterosaurs. True
  2. These were a group of archosaurs related to the dinosaurs, but not dinosaurs themselves. False. Pterosaurs are lepidosaurs, not related to dinos. 
  3. The earliest known pterosaur was Eudimorphodon, who lived in what is now Italy around 230-220 million years ago, in the late Triassic. True enough
  4. However, while the earliest known pterosaur, Eudimorphodon had specialised multi-cusped teeth not found in any of the later pterosaurs, so it would not have been ancestral to them but rather part of a distinct pterosaur lineage that died out in the Triassic. False. Multicupsed teeth are found in several Triassic pterosaurs AND in their proximal sisters. 
  5. Furthermore, both Eudimorphodon and other late Triassic pterosaurs are “completely” developed, having all the typical pterosaur skeletal characteristics. True. That’s why they are called pterosaurs. They have all ‘the goods’.
  6. This suggests the origins of pterosaurs may lie even further back in the past, in the earlier Triassic or perhaps even in the Permian (Wellnhofer, 1991). Yes to the earlier (Middle) Triassic (Cosesaurus) and No to the Permian. 
  7. No fossils of the pterosaurs’ immediate ancestors are known. False. We have pterosaur proximal and distant ancestors going back to basal tetrapods with fins. Click here
  8. The most likely theory on their origins is that they evolved from arboreal creatures that would leap from branch to branch, flapping their forelimbs to stay airborne longer. Actually we have evidence for this scenario chronicled here.
  9. Pterosaur hips had great freedom of movement, their knees and ankles were hinge-like and their feet were plantigrade. True, True, True and False. Some beachcombers had plantigrade feet, but basal forms did not. 
  10. The knees and ankles did not permit the necessary rotation for them to move bipedally, so pterosaurs were obligate quadrupeds (though they may have had bipedal ancestors). False. Like living bipedal lizards, basal pterosaurs were bipedal and agile. We have their tracks! Later forms, especially beachcombers, were quadrupedal, and we have their tracks, too.
  11. A possible explanation for these features is that the early pterosaurs or proto-pterosaurs were arboreal creatures that evolved powerful leaping from branch to branch as an active mode of transport not dissimilar to that of arboreal leaping primates (Christopher, 1997). This reference should be Bennett 1997. Powerful leaping, fast running, yes, but without the use of the hands, which were flapping like those of birds and getting larger. Hard to develop wings when you’re using your hands on the ground. 
  12. These arboreal leapers would not have been gliders, who merely fall slowly downwards and forwards with the help of special flaps, but rather creatures utilising a quite different form of locomotion, one that led them to eventually having their forelimbs evolve into more and more sophisticated flapping airfoils. True! But not like the image below (which appeared on the blog post). This pretty but bogus image shows no flapping and no reason or benefit to having proto-wings on this dinosaur that should have been a fenestrasaur. 

Click to enlarge. A false series of pterosaur ancestors. Artist: Maija Karala.

Sadly
this state of affairs in pterosaur research shows that the general public and pterosaur artists and workers alike are still stuck in the tail-dragging age. Evidently, they have decided to shun and overlook recent data that chronicles and documents the origin of pterosaurs.  See below and here.

References
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 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
Wild R 1993. A juvenile specimen of Eudimorphodon ranzii Zambelli (Reptilia, Pterosauria) from the upper Triassic (Norian) of Bergamo. Rivisita Museo Civico di Scienze Naturali “E. Caffi” Bergamo 16: 95-120.

wiki/Cosesaurus

 

 

Dr. David Unwin on pterosaur reproduction – YouTube

Dr. David Unwin’ talk on pterosaur reproduction 
was recorded at the XIV Annual Meeting of the European Association of Vertebrate Palaeontologists, Teylers Museum, Haarlem, Netherlands and are online as a YouTube video.
Dr. Unwin is an excellent and engaging speaker.
However, some of the issues Dr. Unwin raises have been solved at www.ReptileEvolution.com
The virtual lack of calcite in pterosaur eggs were compared to lepidosaurs by Dr. Unwin, because pterosaurs ARE lepidosaurs.  See: www.ReptileEvolution.com/reptile-tree.htm
Lepidosaurs carry their eggs internally much longer than archosaurs, some to the point of live birth or hatching within hours of egg laying. Given this, pterosaurs did not have to bury their eggs where hatchlings would risk damaging their fragile membranes while digging out. Rather mothers carried them until hatching. The Mrs. T external egg was prematurely expelled at death, thus the embryo was poorly ossified and small.
Dr. Unwin ignores the fact that hatchlings and juveniles had adult proportions as demonstrated by growth series in Zhejiangopterus, Pterodaustro and all others, like the JZMP embryo (with adult ornithocheirid proportions) and the IVPP embryo (with adult anurognathid proportions).
Dr. Unwin also holds to the disproved assumption that all Solnhofen sparrow- to hummingbird-sized pterosaurs were juveniles or hatchlings distinct from any adult in the strata. So they can’t be juveniles (see above). Rather these have been demonstrated to be phylogenetically miniaturized adults and transitional taxa linking larger long-tailed dorygnathid and scaphognathid ancestors to larger short-tailed pterodactyloid-grade descendants, as shown at: www.ReptileEvolution.com/MPUM6009-3.htm
Thus the BMNH 42736 specimen and Ningchengopterus are adults, not hatchlings. And the small Rhamphorhynchus specimens are also small adults.

Some things you learn are not found in any textbooks…yet.

No current discoveries are found in the latest textbooks. 
That’s because it takes time (years typically) for textbooks to be (in reverse order) assigned, accepted, distributed, printed, edited, written and illustrated, researched and concepted. Textbook publishers are out to sell the maximum number of books, so they write to the current consensus, which may be in flux on several points and hypotheses. The current consensus may also be wrong–but it remains the consensus.

There are no courses
at any colleges entitled, PTEROSAURS 101, 102 or 103. Who would attend? There are only two dozen people in the world who have an interest, who study them, or contribute to what we know about them. And where is the consensus? On some points, there is no consensus!! And all too often “the consensus” is holding on to outmoded, invalid and unverifiable paradigms (see below).

Every new fossil specimen is really a new chapter
in an ever expanding textbook on paleontology. And all paleontologists who publish are contributing authors to that future textbook.

Striiving for veracity
It is important for all workers to see things as they are in specimens, and not to reinterpret them to fit an established paradigm, no matter the temptation to do otherwise. For instance, narrow chord wing preservation in pterosaurs is not the result of ‘shrinkage’ as some workers report. Rather it is what it is, universal. All pterosaur specimens have narrow chord wings. If you know one that is different, please tell me. I know one that appears different, but that’s because part of its arm was ripped away and displaced. Look closely. That’s the way it is.

If Galileo
went to school as a teenager and found the following question on a test: “If object A at ten pounds and object B at 10 ounces both fall from 1000 feet at the precisely the same moment, how many seconds ahead of B will A strike the ground?” He’d would not have even had the opportunity to choose answer E. “zero seconds.” Common knowledge at the time, based on Aristotle, would not have allowed it, no matter the facts of this case, proven by experiment. This went on for centuries.

Similarly,
if you were in college today and were given the multiple choice question, “Which one of the following taxa is most closely related to pterosaurs? A. Dinosaurs. B. Scleromochlus. C. Proterochampsids (including Lagerpeton). D. Euparkeria. E. Erythrosucids. F. We don’t know.” You would have to pick “F” to get a good score, because that’s the current consensus… unless your professor had recently written a paper espousing one of the other answers (see below). “G. None of the above” is the better answer according to the large reptile tree where fenestrasaurs are more closely related to pterosaurs. But each one of the above (A-E) has been proposed by recent authors, not caring if they made sense or not.

Imagine the plight of the poor student in Paleontology 101 today
when he or she asks the professor about that website, “repitleevoluton.com” The professor is going to have to say, “If you want a good grade, you’ll ignore that website and provide the same answers that are in your textbook.” That’s what Dr. Darren Naish  reported online. Don’t consider, test or discuss other possibilities. Best to ignore them — if you want to advance in paleontology and get your Masters or PhD.

Take, as an example,
David Hone’s dissertation that was later published in two papers in which he proposed comparing two competing pterosaur origin hypotheses, one by Peters 2000 (Cosesaurus, Sharovipteryx, Longiasquama) and one by Bennett 1996 (Scleromochlus) using the supertree method of analysis (combining several published analyses without actually examining any fossil specimens). Aware that his professor, Michael Benton, had earlier written a paper (Benton 1999) celebrating Scleromochlus as the sister to pterosaurs, Hone decided to delete and diminish the taxa proposed by Peters. He somehow created several typos in the Peters data and then deleted the entire Peters dataset because of those typos (references and the full story here). Then Hone and Benton (2008) gave credit for both competing hypotheses to Bennett while deleting all reference to Peters 2000. As a result, Hone received his PhD, two associated papers (Hone and Benton 2007, 2008) were published and Hone gained the ability to referee pterosaur manuscripts (like mine) submitted to academic journals. I wrote to Dr. Benton about the inconsistencies and leaps of logic between the two parts of their two part paper. His reply was a sheepish, “whoops. :  )”

See how it works? 
That’s how you crush an opposing hypothesis. And that’s just the tip of the iceberg of current readily solvable problems, as Pterosaur Heresies readers are well aware. No PhD wants to admit he/she was wrong. On some problems consensus will likely never be achieved — because in order to do so all invalid candidate hypothesis writers would have to admit they were wrong.

And that’s just not going to happen.
Not without a fight or a dismissal. Let me know if you know of any instances of someone admitting they were wrong (I know of one semi-wrong situation regarding Dr. Padian and his fight with pterosaur tracks). In the origin of snakes, pterosaurs, turtles and dinosaurs there are lots of ‘right’ answers out there, but few challenges to the weaker hypothesis and no one admits to being wrong.

As history tells us, in paleontology it takes decades to turn the boat around. And paleontologists don’t want anyone else, even other paleontologists, solving their mysteries for them… even when solutions are published in the literature.

Thanks for your interest.
I will continue to study and make informed comment on new fossil specimens, (many that haven’t made the textbooks yet). I will throw a spotlight on problems and celebrate solutions as they are verified or not in the large reptile tree. And I encourage you to do the same. If I can do it, anyone can do it.

There are too many paleontologists who
follow
matrices, textbooks and papers blindly
and not enough paleontologists who have the balls to say, “Hey, there’s something wrong here.”

We’ll help fix the world of paleontology someday.
Unfortunately, it’s not going to happen this year. After four years of working with the large reptile tree, and improving it, and enlarging it year after year, it still has not been accepted for publication or gained intrigue among basal reptile workers. They don’t like it. It rocks the boat.

References
Bennett SC 1996. The phylogenetic position of the Pterosauria within the Archosauromorpha. Zoolological Journal of the Linnean Society 118: 261–308.
Benton MJ 1999. Scleromochlus taylori and the origin of the pterosaurs. Philosophical Transactions of the Royal Society London, Series B 354 1423-1446. Online pdf
Hone DWE and Benton MJ 2007. An evaluation of the phylogenetic relationships of the pterosaurs to the archosauromorph reptiles. Journal of Systematic Palaeontology 5:465–469.
Hone DWE and Benton MJ 2008. Contrasting supertree and total evidence methods: the origin of the pterosaurs. Zitteliana B28:35–60.
Peters D 2000. A Redescription of Four Prolacertiform Genera and Implications for Pterosaur Phylogenesis. Rivista Italiana di Paleontologia e Stratigrafia 106 (3): 293–336.

News on the Origin of Pterosaurs on YouTube

I just uploaded a pterosaur origins video on YouTube. Click here to view it.

Click to view this "Origin of Pterosaurs" video on YouTube.

Click to view this “Origin of Pterosaurs” video on YouTube. 17 minutes long. 

Palaeontology [online]

Header for website paleontology online.

Header for website paleontology online. Click to go to the website.

A website (new to me, but looks like it’s been around for awhile) palaeontologyonline.com is, in their own words,

“Palaeontology [online] is a website covering all aspects of palaeontology. The site is updated with articles about the cutting edge of research, by the researchers themselves. These are usually written by experts in the field, but are aimed at non-specialists. Articles vary widely in their content: some serve as an introduction to palaeontological or interdisciplinary fields, while others outline events in the history of palaeontology. Some contributions include summaries of recent findings and advances in rapidly evolving disciplines, and some focus on a particular geographic region or time period. Finally, some of our articles are based on the experience of being a palaeontologist – what life and work is really like as a fossil worker.  Our online format allows researchers to explain their work with the aid of an unlimited number of figures and videos.”

Commissioning editors (who are responsible for inviting contributions and overseeing the website) are:

Russell Garwood: Invertebrate palaeontologist; Peter Falkingham: Postdoctoral research fellow in the fields of vertebrate palaeontology and ichnology (trace fossils); Alan Spencer: Palaeobotanist; Imran Rahman: Postdoctoral researcher in invertebrate palaeontology and evolutionary genetics.

Some great pages here. Check out this placodont page.

The pterosaur page was written by Dr. David Hone, who states, “The origins and the relationships of the pterosaurs have long been contentious, although a consensus is forming on both issues. Often confused with dinosaurs, pterosaurs are members of their own clade, but are close relatives of their more famous cousins.

Over the years, palaeontologists have hypothesized that pterosaurs originated from various parts of the reptile evolutionary tree. Very early researchers considered them to be the ancestors of birds or even bats, and for a long time it seemed that they were probably basal archosaurs (the clade that contains dinosaurs, birds, crocodilians and some other groups). More recently evidence has begun to stack up that they are a separate group to the dinosauromorphs (dinosaurs and their closest relatives) but that the two groups evolved from a common ancestor. Most researchers now support this position. This makes pterosaurs reasonably close relatives to birds, but they are not bird ancestors as is sometimes wrongly reported.”

Well, par for the course…
Sad to see when there actually is a verifiable better relationship out there, but then that would involve actually acknowledging the literature (Peters 2000, 2002, 2007, 2009, 2011) and/or testing candidates one vs. another. But nobody wants to do this without fudging the data or reducing the inclusion set. It’s time to either recognize the literature or argue with it. The large reptile tree found a long line of pterosaur ancestors between Ichthyostega and Longisquama. Almost any one will do, as we learned earlier with turtles and pterosaurs.

References
Peters D 2000a. Description and Interpretation of Interphalangeal Lines in Tetrapods.  Ichnos 7:11-41.
Peters D 2002. A New Model for the Evolution of the Pterosaur Wing – with a twist. – Historical Biology 15: 277–301.
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.
Peters D 2009. A reinterpretation of pteroid articulation in pterosaurs. Journal of Vertebrate Paleontology 29:1327-1330.
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
http://www.reptileevolution.com/pterosaur-wings.htm

Pterosaur origins according to Wikipedia

Not sure
who has established him/herself as the editor of the “Pterosaur” article in Wikipedia, but there was a falsehood in there that had to be edited.

With regard to the “Origins” section, as I read it, the author reported that I did not view the fossils themselves. However, the author approved the Hone and Benton 2007 supertree analysis and the 2011 Nesbitt 2011 archosaur family tree.

The opposite is actually true. 
I had first hand access to Longisquama, Sharovipteryx, Cosesaurus, Langobardisaurus and Macrocnemus, taxa that are related to pterosaurs in order of  increasing phylogenetic distance (Longisquama is the closest). Hone and Benton, as in all authors of supertree analyses, did not even look at these specimens, but reported they were going to join together previous pertinent trees. Instead they only combined the trees they liked. They deleted Peters (2000) from their analysis and added a few typos to the scores to justify their deletion, as we discussed earlier. So there was no Bennett vs. Peters “contest.” W.C. Fields echoed their feelings when he said, “Go away, boy… you bother me.”

So, kids, this is what we’re dealing with.
No one wants to look at fenestrasaurs and there are people out there who are willing to flip the truth.

Not sure
how long the edit will stand. Wikipedia can edited by anyone. Just thought you should know…

Benton 1985 on pterosaurs

Benton 1985 was an early cladistic analysis done without a published matrix. Benton nested pterosaurs between Rhynchosaurs and Younginiforms + Lepidosaurs (that’s a stretch!). He did not report which pterosaur(s) he used in analysis.

Benton wrote: “Pterosaurs have typically been regarded as archosaurs that had their ancestry among the thecodontians (e.g. Romer, 1966; Wellnhofer, 1978). However, Wild (1978) has described two late Triassic genera on the basis of good material (Eudimorphodon, Peteinosaurus) , and he has made the proposal that the pterosaurs arose directly from ‘eosuchians’ and are not true archosaurs. Pterosaurs possess an antorbital fenestra, but Wild (1978: 247) considered that this may be a convergence. Further, Wild ( 1978: 246-253) reviewed numerous similarities between the early pterosaurs and various ‘eosuchians’ and differences from early thecodontians. The characters shared with Youngina, Prolacerta and others are all primitive to diapsids as a whole, except for the reduced quadratojugal, the ossified sternum, the ‘hooked’ 5th metatarsal, and the 3-pointed teeth seen in Eudimorphodon.

Until Peters 2000, Wild (1978) was the sole voice doubting the affinity of pterosaurs with archosaurs. Neither Wild nor Benton realized that the diapsid configuration arose twice in reptile phylogeny, as shown by the large reptile tree because their test did not include primitive reptiles.

Benton wrote: “Pterosaurs display all of the characters of the Neodiapsida as far as can be determined, except B2 (ventral processes on parietals) and B6 (emarginated quadrate). They show some archosauromorph synapomorphies (C4-10), but lack others: C1-3, 11-14. Pterosaurs share two characters with the Lepidosauromorpha: the single ossified sternum, and specialized sternal attachments for the ribs. The most parsimonious position for the pterosaurs at present is within the Archosauromorpha, as sister-group to all other archosauromorphs. Further work is needed on this question as well as on the suggestion that Pterosauria are the sister-group of Aves (Gardiner, 1982).”

Benton, to his credit, at least gave a nod to the lepidosauromorph traits. He noted pterosaurs shared 6 archosauromorph traits, but lacked 7 others.

According to Benton, archosauromorph traits shared with pterosaurs:

C4. Loss of tabulars. Benton notes they are also lost in lepidosaurs.

C5. Stapes without a foramen. I don’t think stapes have ever been identified in pterosaurs, but living lepidosaurs retain a heavier stapes with a foramen, according to Benton. Huehuecuetzpalli, at the base of the Tritosauria, does not show a foramen, but then it is only partly exposed.

C6. Vertebrae not notochordal. Benton notes that Sphenodon and geckos retain notochordal verts. Reynoso (1998) reports that Huehuecuetzpalli had amphicoelous verts, a trait shared with pterosaurs.

C7. Transverse processs on dorsal vertebrae project as distinct narrow elongate processes. Benton’s samples are all large reptiles. We don’t see these on pterosaur ancestors until Macrocnemus and all of its descendants among the tritosaurs.

C8. Cleithrum absent. Also absent on Huehuecuetzpalli. 

C9. No entepicondylar foramen in the humerus. Benton notes that lizards lose this too. Huehuecuetzpalli retains one. Cosesaurus does not have one.

C10. Loss of foramen in carpus between ulnare and intermedium. Benton notes this is lost in Squamata.

So that’s his list. Not much to say the least. I was hoping for more.

According to Benton, archosauromorph traits lacked in pterosaurs include:

C1. Premaxilla extends behind naris. Benton is wrong here, but Huehuecuetzpalli shares this trait.

C2. Nares elongate and close to midline. Benton is wrong here. Huehuecuetzpalli shares this trait.

C3. Quadratojugal (if present) located mainly behind the lower temporal fenestra. Benton is wrong here, but the same morphology is present in Cosesaurus.

C11. Presence of a lateral tuber on the calcaneum. Benton is correct! But no lateral tuber is found on Huehuecuetzpalli. 

C12. Complex concave-convex articulation between the astragalus and calcaneum. Correct, but the same is found on Huehuecuetzpalli.

C13. Fifth distal tarsal lost. Correct, but the same is found in Huehuecuetzpalli.

C14. Fifth metatarsal hooked without lepidosaur specializations. These include: ‘hooked’ in two planes. According to Benton mt5 bears specialized plantar tubercles, and it passes into the tarsus over the proximal end of the 4th metatarsal. Benton may be right. In any case pterosaurs and Huehuecuetzpalli have the same kind of mt5. In Pteranodon the metatarsus is reduced to being hooked in one plane.

Benton did not realize the rampant homoplasy in the reptilia.
The HI (Homoplasy Index) of the large reptile tree is over 0.90. So, exceptions and convergences abound within the reptilia. Very few traits are found in one and only one clade.

Benton mentioned Cosesaurus briefly, noting in the original description a long antorbital fossa (but he quoted the original French). He lumped it with Malerisaurus in “Prolacertiformes, incertae serdis”, not realizing that Cosesaurus was a tritosaur, along with Macrocnemus, Tanystropheus and Tanytrachelos, which he also considered prolacertiformes. Longisquama and Sharovipteryx, the two taxa closest to pterosaurs, were not considered.

The Gardiner (1982) paper mentioned by Benton has been largely ignored, and for good reason. Not sure why it was even included, but then, we’re talking about 1985 here. We’ll look at Gardiner 1982 tomorrow.

Bottom line:
With wrong, tenuous and convergent evidence Benton 1985 found pterosaurs nested outside the archosauromorpha. Later workers, who merely looked at the conclusions without questioning the evidence, accepted Benton’s conclusion. And look where that has brought us.

Later Hone and Benton (2007, 2009) applied the same lax interest and disposal of data to show that pterosaurs probably nested close to archosauromorphs after deleting the only competing candidate taxa. We looked at those problems in detail here.

I think it all comes down to conservatism. The same sort of conservatism that dismissed Wagner’s (and others) hypothesis on continental drift, Heyerdahl’s hypothesis on western migration to Polynesia and the static, earth-centered universe. Those days are not yet over.

References
Benton MJ 1985. Classification and phylogeny of the diapsid reptiles. Zoological Journal of the Linnean Society 84: 97-164.
Hone DWE and Benton MJ 2007. An evaluation of the phylogenetic relationships of the pterosaurs to the archosauromorph reptiles. Journal of Systematic Palaeontology 5:465–469.
Hone DWE and Benton MJ 2008. Contrasting supertree and total evidence methods: the origin of the pterosaurs. Zitteliana B28:35–60.
Reynoso V-H 1998. Huehuecuetzpalli mixtecus gen. et sp. nov: a basal squamate (Reptilia) from the Early Cretaceous of Tepexi de Rodríguez, Central México. Philosophical Transactions of the Royal Society, London B 353:477-500.