Data denial you can listen to on a podcast

Dr. Mark Witton

Dr. Mark Witton

Dr. Mark Witton is a paleontologist,
author and illustrator, but based on a Liz Martin interview podcast denies the existence of pterosaur ancestors. Like his friends, Dr. David Hone (another data denier), and Dr. Darren Naish, Dr. Witton believes pterosaurs “appeared fully formed in the fossil record. We don’t have the pterosaur Archaeopteryx.”

Sadly this purposefully ignores 
the published literature (Peters 2000 is now 15 years old) online phylogenetic analyses (now 4 years old) and YouTube videos (just a few weeks old) that all provide a long list of pterosaur ancestors that demonstrate a gradual accumulation of pterosaur traits. Why does Dr. Witton prefers to hide his head in the sand rather than examine, test and/or accept published studies? Could this be academic bigotry? (definition: intolerance toward those who hold different opinions from oneself)

Witton believes pterosaurs “are close relatives of dinosaurs.”
If so, then were are the common ancestors that show a gradual accumulation of character traits? Answer: You can’t find them because they are not there. Other taxa share more traits with pteros and dinos than either does with each other. This is the outmoded “Ornithodira” concept.
Witton says he did not expect
that the Jurassic pterosaur, Dimorphodon would be adept at walking on the ground (despite having digitigrade pedes and fully interned femoral heads). Again, published literature demonstrates just the opposite (Padian 1983). Glad to see that Dr. Witton is getting on board with a more terrestrial Dimorphodon.
Dr. Witton waxed on about Solnhofen juvenile and subadult pterosaurs,
agreeing with Bennett (1995) who lumped Rhamphorhynchus into one species by plotting long bone lengths on a graph. Witton thought different species should have a dramatic difference in wing shape. Not so. He didn’t mention foot shape and overall morphology, which varies quite widely and logically when phylogenetic analysis is employed (Fig. 2).
Figure 3. Bennett 1975 determined that all these Rhamphorhynchus specimens were conspecific and that all differences could be attributed to ontogeny, otherwise known as growth to maturity and old age. Thus only the two largest specimens were adults. O'Sullivan and Martill took the brave step of erecting a new species. The n52 specimen is at the lower right. Click to enlarge.

Figure 2 Bennett 1975 determined that all these Rhamphorhynchus specimens were conspecific and that all differences could be attributed to ontogeny, otherwise known as growth to maturity and old age. Thus only the two largest specimens here were adults. Witton agrees that all these are conspecific. Do you agree with Witton? Decide for yourself. Click to enlarge.

Witton follows the Lü et al. (2009) analysis
that nested Darwinopterus as a transitional fossil combination of pterodactyloid skull and basal pterosaur post crania. Other analyses ( Wang et al 2009, Andres 2013, Peters online) do not support that hypothesis. Only Peters online (based on Peters 2007) includes a large selection of sparrow-sized Solnhofen pterosaurs, keys to the origin of all later clades. Along the same lines, Witton believes in Modular Evolution, which is falsified in phylogenetic analysis and apparently occurs only in their vision of Darwinopterus.
Witton reports that some azhdarchids had short necks.
Not sure which azhdarchids he is talking about. Evidently that is sneak preview on unpublished papers. The large pterosaur tree indicates that going back to the Late Jurassic, all azhdarchids and their ancestors had very long necks, even as hand-sized taxa (Fig. 3).
The Azhdarchidae.

Figure 3. The Azhdarchidae. Click to enlarge. No short necks here, except way down toward the left. Not saying they could not evolve. Just saying I haven’t seen them yet. 

Witton reports there are small birds but no small pterosaurs
from the Upper Cretaceous — but no small dinosaurs either — so suggests there may be a preservational bias in the lack of small pterosaurs… but no such bias for small birds. Actually there are small bird fossils from the Late Cretaceous, and they ARE dinosaurs, and no small pterosaurs. Lacking tiny pteros in the Late Cretaceous spelled their doom. Only small and tiny pterosaurs survived the Latest Jurassic extinction event and only these were basal to later giants. So no darwinopterids had descendants in the Cretaceous. Because there were no tiny Late Cretaceous pterosaurs, none survived the Late Cretaceous extinction event.
Can we blame this on a bad mentor?
Dr. Witton has accumulated a great deal of pterosaur knowledge and expresses it wonderfully in his many paintings. Unfortunately, like Hone and Naish, he was ‘raised’ by wrong-minded mentors and continues his false beliefs (= he has not tested his or competing hypotheses in phylogenetic analyses) to this day. Earlier we looked at the many problems in Dr. Witton’s book on pterosaurs.
Dr. Don Prothero

Dr. Don Prothero

Some insight into that sort of thinking…
it’s not that uncommon.
Dr. Don Prothero in a YouTube Video provides great insights into the Creationist mindset that finds strong parallels in the current thinking of Dr. Mark Witton, Dr. David Hone and Dr. Darren Naish.

Notes from the Prothero video
  1. Humans are not rational machines
  2. We all employ motivated (emotional, wants and needs) reasoning, not logical reasoning
  3. We are all belief engines and we all create a world view or core belief
  4. Because of that we don’t like to hear anything that does not fit our world view
  5. AND we use reason to do what we want data to do, not what its telling us. We use ANY tricks to make the evidence of the world fit our beliefs, or twist it to fit, or deny it or ignore it. Michael Shermer, founder of the Skeptics Society and author of “The Believing Brain” writes, “We all support the world we already have.”

Bottom line:
Witton, Hone and Naish don’t like ReptileEvolution.com because it doesn’t support the paleo world they already have. Like Creationists they display the following traits raised by Prothero:

  1. Reduction of cognitive dissonance (= the state of having inconsistent thoughts, beliefs, or attitudes, especially as relating to behavioral decisions and attitude change) when presented with evidence that works against that belief, the new evidence cannot be accepted.
  2. Tribalism = we learn our world from whoever we were raised by. And all three professors are friends of one another.
  3. Deep innate psychological tendencies are genetic = there are some people who readily accept new ideas and there are some people who do not. Unfortunately, all three appear to have the same gene.
  4. Confirmation bias (= the tendency to interpret new evidence as confirmation of one’s existing beliefs or theories.) Thus when Hone and Benton (2007, 2009) come out with the worst paper I have reviewed, Naish and Witton support it anyway.
  5. Cherry picking (= remembering the hits, forgetting the misses). Hone, Witton and Naish like to pick on poor Longisquama, which was difficult, but not impossible to interpret and all three like to ignore the whole point of ReptileEvolution.com, the cladograms, both the large reptile tree and the large pterosaur tree. Note that no other pterosaur worker has produced competing interpretations of Longisquama of equal detail nor competing cladograms that include tiny pterosaurs. In this regard these pterosaur workers are exactly like Dr. Feduccia and the late Dr. Martin (who deny the theropod-bird link and never employ phylogenetic analysis) and also like extant Creationists, who likewise never employ phylogenetic analysis. Remember when Hone and Benton first deleted the taxa that Peters 2000 proposed, then deleted Peters 2000 from the competition? This was cherry picking at its best.
  6. Qiuote mining (= in this case finding images and hypotheses that have been long ago trashed in order to undermine the site. These are essentially ad hominem (directed against a person rather than the position they are maintaining) attacks as they blackwash my methods (which they practice too) and the entire website while they could have gotten specific about one problem or another.
  7. Missing the forest for the trees (= The big picture) is the large reptile tree cladogram. This is created by a huge mass of data and becomes strengthened with every additional taxon – all of which affect every other taxon. In such an analysis you can remove data, remove taxa, remove characters and nothing falls apart. The subsets are just as strong as the dataset itself. But Hone, Naish and Witton refuse to acknowledge that, preferring to continue their thinking that pterosaurs appeared suddenly in the fossil record, like on the fourth day of Creation. Phylogenetic analysis would solve their quandary, if only they would give it a chance.

Dr. Prothero asks: Why is science different?
Prothero answers his own question in this fashion:

  1. Science (like ReptileEvolution.com) is always testing with falsification, prove things wrong, correcting mistakes. Presently I’ve made over 50,000 corrections in drawings and scores and look forward to many more. Getting it right is important.
  2. Science (like ReptileEvolution.com) is always tentative, no claim to final truth. I am always looking for a competing hypothesis. Witton, Hone, Naish, Bennett and other referees are making sure my papers are not getting published. They don’t like it when their claims are disputed here at PterosaurHeresies.
  3. Science (like ReptileEvolution.com) works! It provides answers that make sense, can be replicated, and can provide predictions.
  4. In Science peer review cancels individual biases. Sadly the current pterosaur referees, Hone, Witton, Naish and others, are all from the same school of thought. Every day I hope to change that, to open them up to accept more valid hypotheses that work!
  5. In Science, if you’re not pssing people off, you’re not doing it right. Well, I must be doing something right, because Witton and Naish are never praising my work. It would be great if we could argue about it. I guess we’re doing that here.

Prothero finished with a cartoon
of a professor who was showing his cognitive dissonance: “If P is false, I will be sad. I do not wish to to be sad. Therefore, P is true.”

This is human nature.
We all have it. We all get jealous, ambitious. disappointed. As scientists we have to get over our human nature and let testing and experimentation rise above human nature. We have to be like Galileo, not Aristotle.

References
Bennett SC 1995. A statistical study of Rhamphorhynchus from the Solnhofen limestone of Germany: year classes of a single large species. Journal of Paleontology 69, 569–580.
Lü J, Unwin DM, Jin X, Liu Y and Ji Q 2009. Evidence for modular evolution in a long-tailed pterosaur with a pterodactyloid skull. Proceedings of the Royal Society London B  (DOI 10.1098/rspb.2009.1603.)
Padian K 1983. Osteology and functional morphology of Dimorphodon macronyx (Buckland) (Pterosauria: Rhamphorhynchoidea) based on new material in the Yale Peabody Museum, Postilla, 189: 1-44.
Peters D 2000. 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. Flugsaurier. The Wellnhofer Pterosaur Meeting, Munich 27
Wang X, Kellner AWA, Jiang S, Meng X. 2009. An unusual long-tailed pterosaur with elongated neck from western Liaoning of China. Anais da Academia Brasileira de Ciências 81 (4): 793–812.

Padian on Dinosaur Origin Problems

A recent paper by Kevin Padian (2013) promoted two ideas: “I suggest two changes in thinking about the beginning of the ‘‘Age of Dinosaurs’’: first, the event that we call the (phylogenetic) origin of dinosaurs was trivial compared to the origin of Ornithodira; and second, the ‘‘Age of Dinosaurs’’ proper did not begin until the Jurassic.”

Yes, this is a ‘think piece’,
and it’s a great summary of dinosaur thinking throughout the last 200 years, but it doesn’t represent current thinking. Padian is still trotting out old paradigms parked within this “history of paleontology” article. A couple of problems here:

First, there is no such clade as the Ornithodira. 
Because it contains both dinosaurs and pterosaurs, each of which occupy positions on opposite branches in the large reptile tree, the “Ornithodira” includes the same taxa as the Reptilia (= Amniota). Padian still clings to the unsupportable and falsified hypothesis that pterosaurs are sisters to dinosaurs and also keeps the blinders on with regards to the Fenestrasauria.

Second, Padian’s 3 Reasons for a Jurassic Age of Dinosaurs are not news.

1. Ornithischians do not appear until the Jurassic
Granted, but their poposaur dinosaur sisters are known throughout the Triassic (Lotosaurus = Early Triassic). Padian does not realize that poposaurs were dinosaurs. Neither does Padian recognize that Daemonosaurus nests as a basal ornithischian from the Triassic.

2. Saurischian dinosaurs were larger in the Early Jurassic.
Granted, but this is old news. And they don’t get really big until the Late Jurassic, tens of millions of years later. Even so, factor 3 comes into play…

3. All non-crocodylomorphs “pseudosuchians”(= rauisuchians, phytosaurs, aetosaurs) become extinct prior to the Jurassic.
Granted, but this is old news. Their extinction does indeed clear the slate for the radiation of dinosaurs and, lest we forget… crocs, which invaded marine environs.

Padian reports, “This review began by parsing the question of the origin of dinosaurs into three kinds of problems: dinosaur monophyly and relationships; dinosaurian functional-ecological advances; and the timing and pacing of dinosaur origins and diversification.”

Unfortunately Padian shows up with bad data as he reports, “It was not only dinosaurs but also their closest relatives –lagosuchids, lagerpetids, silesaurids and pterosaurs – that shared a suite of structural, functional and metabolic features that differentiated them considerably from other reptiles before the Late Triassic onwards.”

According to the large reptile tree, lagerpetids and pterosaurs were not related to dinosaurs. So those metabolic features did not differentiate ‘ornithodires’ from other reptiles. Rather, these three disparate clades attained similar abilities and morphologies by convergence. Lagerpetids and their chanaresuchid sisters did not survive into the Jurassic. Neither did the nonvolant relatives of pterosaurs.

To his credit
Padian devotes a page to showing how Rotodactylus (Peabody 1948) ichnites do not fit Lagerpeton feet as Brusatte et al. (2011) tried to force fit. We looked at this earlier here.

To his discredit
Padian ignores prior literature (Peters 2000, 2011) that matched Rotodactylus ichnites to basal fenestrasaurs like Cosesaurus. He kept his blinders on.

Reference
Brusatte SL Niedźwiedzki G and Butler RJ 2011. 
Footprints pull origin and diversification of dinosaur stem-lineage deep into Early Triassic. Proceedings of the Royal Society of London, Series B, 278, 1107-1113.
Padian K 2013. The problem of dinosaur origins: integrating three approaches to the rise of Dinosauria. Earth and Environmental Science Transactions of the Royal Society of Edinburgh, Available on CJO 2013 doi:10.1017/S1755691013000431
Peabody FE 1948.  Reptile and amphibian trackways from the Lower Triassic Moenkopi formation of Arizona and Utah.  University of California Publications, Bulletin of the  Department of Geological Sciences 27: 295-468.
Peters D 2000. Description and Interpretation of Interphalangeal Lines in Tetrapods.  Ichnos 7:11-41.
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

Ornithodira: Avoid this taxon!

One core and basis of the Pterosaur Heresies blog is to demonstrate that, how and why pterosaurs have nothing in common with dinosaurs or their precursors, despite reams of traditional literature promoting that relationship. For example:

“Pterosaurs and dinosaurs have been grouped together for along time, and today, the prevalent view among vertebrate paleontologists is still that they do indeed form a natural group of animals.” — Nick Fraser (2006) in “Dawn of the Dinosaurs.”

If this false paradigm continues another two years that will complete a full three decades of belief in the official, “Ornithodira,” the clade THEY say includes both pterosaurs and dinosaurs. I say ‘belief’ because there’s absolutely no evidence for this relationship — as traditional paleontologists themselves have noted (see below).

“Pterosaurs appear suddenly in the fossil record and in full possession of all their highly derived characters…” — David Hone and Michael Benton (2007, 2008).

“As Figure 4.3 illustrates, paleontologists don’t really know where this group should sit within the diapsid family tree. The reason for this is simple — a complete lack of protopterosaurs that might link this group to other diapsids.” — David Unwin in The Pterosaurs from Deep Time.

Unfortunately, such statements give ammunition to Creationists, because it sounds like pterosaurs were “specially created” and nothing could be further from the truth. So this damages the good names of both Paleontology and Science and can only be repaired by professional paleontologists with PhDs. I’ve done and continue doing my part.

To put the final nail in the coffin
No paleontologist has been able to put forth even a short series of taxa that demonstrate a gradual accumulation of pterosaurian traits within the Archosauria or Archosauriformes.

We also talked about this and solved this problem in the first four PterosaurHeresies.com blogs here, here, here and here.

It’s actually THIS EASY to solve the problem:
If you include several hundred representatives from the gamut of prehistoric reptiles in phylogenetic analysis, at least by default and at best by shared homologies, you will recover some taxa that will nest closer to pterosaurs than to other reptiles. So it’s the shame of paleontology that no one else has attempted this time-consuming, but otherwise relatively easy task by expanding the taxon list to include lepidosauromorphs, lizards, tritosaurs and fenestrasaurs. Actually it can be done with as few as a dozen key taxa if you’re pressed for time, as already shown in an academic publication (Peters 2000). The taxa it promotes continue to be ignored by all other workers* in one of the more interesting feuds/wars in the history of paleontology. I don’t care if you ignore the paper. Don’t ignore the taxa.

*Except Senter 2003, who bungled his observations and provided cartoons for figures. To be fair, I also made freshman mistakes tracing the same difficult taxa, but corrected them here, here and here.

History of the Ornithodira
In the earliest days of phylogenetic analysis, Gauthier & Padian (1985) placed pterosaurs within the clade Ornithosuchidae (Huene 1914) along with Lagosuchus (= Marasuchus (Sereno & Arcucci 1994)), and the Dinosauria.

A tree recovered from Gauthier 1986

Figure 2. A tree recovered from Gauthier 1986 (form Wiki) Pararchosauriformes are in green boxes. Pterosaurs are included within Ornithodira. Pink arrows point to crocs and dinos (which, sans pteros, make up the Archosauria in the large reptile tree.) 

Later, Gauthier (1986, Fig. 2) noted that the position of pterosaurs and Marasuchus with respect to dinosaurs was not resolved, but found the three formed a monophyletic group he called the Ornithodira. Sereno (1991) followed and expanded on this by including Scleromochlus.

While reviewing Sereno (1991), Kellner (1996) concluded that no particular character linked pterosaurs to the Archosauria (sensu stricto), but added that because of several shared derived characters with basal dinosauromorphs, the traditional hypothesis was the best supported at the time.

Peters (2000) added several taxa (Langobardisaurus, Cosesaurus, Sharovipteryx and Longisquama) that had been excluded in prior studies to three prior phylogenetic analyses and recovered trees in which these taxa nested closer to pterosaurs than any included archosaur. Refinements to the observed morphologies and expansion in the taxon list (both chronicled in PterosaurHeresies.com and ReptileEvolution.com) have further cemented these relationships.

Ornithodira Defined
Gauthier (1986) defined “Ornithodira” as all forms closer to birds than to crocodiles. Here, based on the topology recovered by the large reptile tree (with an unmatched gamut) this definition is redundant with an earlier one (Gauthier and Padian 1985) made for Ornithosuchia.

Sereno (1991) re-defined “Ornithodira” as the last common ancestor of the dinosaurs and the pterosaurs, and all its descendants.

Ornithodira Trashed
Here, based on a larger tree that separates the pterosaurs from the dinosaurs on separate branches that divided in the earliest Carboniferous, the definition of Ornithodira is redundant with Reptilia. This can be easily tested with far fewer taxa. Not sure why paleontologists have not done so. Tradition is cozy and comfortable, but no discoveries have ever been made in comfort.

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
Fraser N 2006. Dawn of the Dinosaurs: life in the Triassic. Indiana University Press, 310 pp.
Gauthier JA and Padian K 1985. Phylogenetic, functional, and aerodynamic analyses of the origin of birds and their flight. In M. K. Hecht, J. H. Ostrom, G. Viohl, and P. Wellnhofer (eds.), The Beginnings of Birds: Proceedings of the International Archaeopteryx Conference, Eichstätt 1984. Freunde des Jura-Museums Eichstätt, Eichstätt 185-197
Gauthier JA 1986. Saurischian monophyly and the origin of birds, In Padian K editor. The Origin of Birds and the Evolution of Flight, 1–55. Memoirs Calif Acad Sc 8.
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.
Kellner AWA 1996. Remarks on Brazilian dinosaurs. Memoirs of the Queensland Museum 39(3):611-626
Peters D 2000. A redescription of four prolacertiform genera and implications for pterosaur phylogenesis. Rivista Italiana di Paleontologia e Stratigrafia 106: 293-336
Senter P 2004. 
Phylogeny of Drepanosauridae (Reptilia: Diapsida). J Syst Palaeo 2: 257–268.
Sereno PC 1991. Basal archosaurs: phylogenetic relationships and functional implications. J Vert Paleo 11 (Supp) Mem 2: 1–53.
Unwin, DM 2006. The Pterosaurs From Deep Time. Pi Press. 347 pp.

Nesbitt (2011) and His Characters – Part 6 Ornithodira

Following remarks from fellow paleontologists asking for my study to include more Nesbitt (2011) characters in the large reptile study, I thought we should dive right into them, taking a few days to digest them all — a bite at a time. Earlier we considered more basal clades in parts 1, 2, 3, 4 and 5.

Nesbitt Characters for Ornithodira
Sterling Nesbitt (SN) reported, (1) Distal end of neural spines of the cervical vertebrae unexpanded (191-0). The neural spines of the cervical vertebrae are unexpanded in pterosaurs.
Note: This trait is also found in lepidosaurs, including fenestrasaurs.

(2) Distal expansion of neural spines of the dorsal vertebrae absent (197-0). The expansion of neural spines of the dorsal vertebrae is absent in pterosaurs.
Note: This trait is also found in lepidosaurs, including fenestrasaurs.

(3) Second phalanx of manual digit II (= 2.2) longer than first phalanx (255-1). This character is present in basal pterosaurs and in dinosaurs.
Note: While present in basal pterosaurs, this trait is not present in the dinosaurs, Herrerasaurus, Thecodontosaurus or Scelidosaurus.

(4) Trenchant unguals on manual digits I–III (257-1). Present in basal pterosaurs.
Note: Also present on the fenestrasaur, Longisquama. Not present in quadrupedal dinosaurs.

(5) Tibia longer than the femur (299-1). Present in basal pterosaurs.
Note: Also present in the fenestrasaurs, Sharovipteryx and Longisquama. Not present in quadrupedal dinosaurs. 

(6) Distal tarsal 4 transverse width subequal to that of distal tarsal 3 (347-1). Present in basal pterosaurs.
Note: In pterosaurs distal tarsal 3 is very tiny, never as large as distal tarsal 4. However the centrale, which is typically confused with distal tarsal 3 in character matrices, is usually just as large. 

(7) Size of articular facet for metatarsal V less than half the width of lateral surface of distal tarsal 4 (348-1). Present in basal pterosaurs.
Note: Also present on basal fenestrasaurs. However, the articular facet for mt5 is usually the majority of the lateral surface of distal tarsal 4 in pterosaurs. 

(8) Anterior hollow of the astragalus reduced to a foramen or absent (357-1). Present in basal pterosaurs.
Note: This trait is also present in all tritosaurs, including fenestrasaurs. 

(9) Anteromedial corner of the astragalus acute (361-1). Clearly present in Dimorphodon (fig. 46).
Note: Nesbitt confused the distal tarsals with the proximal tarsals, which are fused to the tibia. 

(10) Compact metatarsus, metatarsals II–IV tightly bunched (at least half of the length) (382-1). Present in pterosaurs.
Note: Also present in most tritosaurs, including the fenestrasaurs (sans Sharovipteryx). 

(11) Osteoderms absent (401-0). Pterosaurs lack osteoderms.
Note: Also absent in tritosaurs, including fenestrasaurs. Osteoderms are present in Scelidosaurus.

(12) Gastralia well separated (412-1). The gastralia of the holotype of Eudimorphodon are well separated as they are in dinosaurs. In contrast, the gastralia of most non-ornithodiran archosauriforms form an extensive, interlocking basket.
Note: The gastralia are also well separated in lepidosaurs, including fenestrasaurs.

Note: The large reptile tree does not recover a monophyletic Ornithodira, but finds pterosaurs and traditional archosaurs separated, evolving several traits by convergence.

Nesbitt (2011) reported, “The character states supporting pterosaurs as members of Archosauria and Ornithodira are not restricted to character states related to locomotion as suggested by Bennett (1996). As demonstrated in the list above, the character states cover features present all over the body, not just in the hind limb.” Unfortunately, Nesbitt (2011), like so many paleontologists before and since, did not even look at the competing candidates within the fenestrasauria, but force fit those square pegs into those round holes. Not sure why everyone is so afraid to let a large tree recover more parsimonious nestings.

Perhaps now you see why there is something terribly wrong with our current pterosaur studies. It’s an Alice-in-Wonderland world out there.

Tomorrow: Lagerpetidae

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
Nesbitt SJ 2011.
 The early evolution of archosaurs: relationships and the origin of major clades. Bulletin of the American Museum of Natural History 352: 292 pp.