SMNS 12352 is a croc, close to Hesperosuchus.

The following has been updated to reflect an error made originally. Adding the associated manus and wrist changes the nesting of SMNS 12352 from theropod to bipedal croc. 

A recent paper by Knoll and Rohrberg (2012) CT-scanned  and rapid-prototyped a partial skull (SMNS 12352) first described by von Huene (1921). Found in 1908, this Late Triassic specimen was originally considered a second specimen of Procompsognathus. Knoll and Rohrberg (2012) considered the skull an indeterminate basal crocodylomorph, close to, but distinct from Saltoposuchus.

Figure 1. SMNS 12352, a basal theropod. Images from Knoll and Rohlberg (2012) with color added here. I don't completely understand the anterior nasals and associate broken shards. Some may belong to a further extension of the maxilla.

Figure 1. SMNS 12352, a basal croc. Its’ surprising how little it takes to change this specimen into a theropod because it has a rather large antorbital fenestra. The manus and wrist, if they indeed belong to the same creature, tip the scales without a doubt to basal crocs.

Tracings of the skull (Fig. 1) and phylogenetic analysis nested SMNS 12352 close to the the basal croc, Hesperosuchus (Fig. 3). Imaginatively restoring the rest of the skull based on the phylogenetic bracketing and continuing lines from broken skull parts creates a basal croc skull with a typical rostrum based on the wide nasals.

Hesperosuchus

Figure 3. Hesperosuchus

Knoll and Rohlberg (2012) based their nesting on the lack of nasal/antorbital fenestra contact. I do not have that trait in my matrix. Neither do the authors delineate their bones by color or line.

Knoll and Rohlberg (2012) discuss, but do not show a separation of the jugal from the antorbital fenestra, which tracings do not duplicate, either in the prototype or the fossil. Here, if I’ve made a mistake, please let me know.

Figure 2. Manus associated with SMNS 12352 compared to other croc manus and wrists.

Figure 2. Manus associated with SMNS 12352 compared to other croc manus and wrists. The digits have been reversed in SMNS 12352 from the original interpretation to match sisters.

Sereno and Wild (1992) assigned SMNS 12352 to Saltoposuchus. Paul (1988, p. 247) proposed that SMNS 12352 resembles the snout of a herrerasaurid dinosaur. The dinosaur/theropod antorbital fenestra is more open than in sister crocs, which reduce the fenestra compared to the fossa.

Basal dinosaurs, like Trialestes, retain elongated wrist bones, but Herrerasaurus does not have this trait. This is assuming that Trialestes is a basal dino from the few scraps that have been published. More data needs to come out on that taxon. Bipedal crocs and basal dinosaurs are their own closest relatives, so they developed in parallel, but decidedly distinct at higher levels.

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
von Huene F 1921. Neue Pseudosuchier und Coelurosaurier aus dem wu¨rttembergischen Keuper. Acta Zoologica, 2, 329–403.
Knoll F and Rohrberg K 2012.CT scanning, rapid prototyping and re-examination of a partial skull of a basal crocodylomorph from the Late Triassic of Germany. Swiss Journal of Geosciences. DOI 10.1007/s00015-012-0094-4.
Paul GS 1988. Predatory dinosaurs of the world (464). New York: Simon and Schuster.
Sereno PC and Wild R 1992. Procompsognathus: theropod, ‘‘thecodont’’ or both? Journal of Vertebrate Paleontology, 12, 435–458.

Turtle molecules link them to archosaurs??

A new paper (Crawford et al. 2012) reports that turtle molecules link them to archosaurs, not lepidosaurs.

Here’s the abstract
We present the first genomic-scale analysis addressing the phylogenetic position of turtles, using over 1000 loci from representatives of all major reptile lineages including tuatara. Previously, studies of morphological traits positioned turtles either at the base of the reptile tree or with lizards, snakes and tuatara (lepidosaurs), whereas molecular analyses typically allied turtles with crocodiles and birds (archosaurs). A recent analysis of shared microRNA families found that turtles are more closely related to lepidosaurs. To test this hypothesis with data from many single-copy nuclear loci dispersed throughout the genome, we used sequence capture, high-throughput sequencing and published genomes to obtain sequences from 1145 ultraconserved elements (UCEs) and their variable flanking DNA. The resulting phylogeny provides overwhelming support for the hypothesis that turtles evolved from a common ancestor of birds and crocodilians, rejecting the hypothesized relationship between turtles and lepidosaurs.

Ahh, but which archosaurs?
That’s what molecules will never tell you.

At the end we can only confirm with fossil bones
We’ve already uncovered a most parsimonious nesting and a series of gradually accumulating turtle traits in a lineage within the lepidosauromorpha. So if molecules tell a different tale, then someone’s got some ‘splaining to do. Not sure why the molecules would take us one way while the bones take us another.

Turtles are weird.

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
Crawford NG, Faircloth BC, McCormack JE, Brumfield RT, Winker K, and Glenn TC 2012. More than 1000 ultraconserved elements provide evidence that turtles are the sister group of archosaurs. Biology Letters (advance online publication) doi:10.1098/rsbl.2012.0331   online

Variation in Rhamphorhynchus gemmingi

Yesterday we looked at phylogenetic variation in Rhamphorhynchus muensteri. Today we’ll tackle their sisters, R. gemmingi. Click to enlarge figure 1, shown to scale and in phylogenetic order from left to right. The outgroup taxon for both clades is the n62 specimen of Rhamphorhynchus. Shown here are n43, n74, n38, n75 and n52 from the Wellnhofer (1975) catalog.

Specimens nesting with Rhamphorhynchus gemmingi

Figure 1. Click to enlarge. Specimens nesting with Rhamphorhynchus gemmingi in phylogenetic order from left to right, n43, n74 (the holotype), n38, n75 and n52, otherwise known as R. megadactylus.

There’s not much more to say that the pictures say all too well. There’s variation here. Less and less as the taxa employed are more similar, but variation nevertheless. Perhaps there’s as much variation here as in several genera of birds from the same suprageneric clade.

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
von Meyer H 1846. Pterodactylus (Rhamphorhynchusgemmingi aus dem Kalkschiefer von Solenhofen”. Palaeontographica 1: 1–20.
von Meyer H 1859. (Zur fauna der vorwelt, Vol. 4, Reptilien aus dem lithographischen Schiefer des Jura in Deutschland und Frankreich.
Wellnhofer P 1975a-c. Teil I. Die Rhamphorhynchoidea (Pterosauria) der Oberjura-Plattenkalke Süddeutschlands. Allgemeine Skelettmorphologie. Paleontographica A 148: 1-33.Teil II. Systematische Beschreibung. Paleontographica A 148: 132-186. Teil III. Paläokolgie und Stammesgeschichte. Palaeontographica 149: 1-30.

wiki/Rhamphorhynchus

Variation in Rhamphorhynchus muensteri

I recently added several Rhamphorhynchus specimens to see if any were identical to any others. They were not. They nested in interesting ways (see newly revised, completely resolved pterosaur family tree). The R. muensteri clade is here represented by these specimens (n62, the darkwing specimen, MTM V 2998.33.1 and n33), all to scale. Click to enlarge.

Rhamphorhynchus muensteri

Figure 1. Click to enlarge. Specimens that nest with Rhamphorhynchus muensteri in the large pterosaur family tree.

There’s some variation here in relative wing length, pedal phalangeal proportions, sternal shape, leg length, etc. The phylogenetic order is from left to right. The outgroup sister is the relative giant R. longiceps (n81). In life would these be distinct enough to separated into several species? Or are we at the point of individual variation within a species? In either case, we’re about at the limit of separation in the current tree.

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.

Tomorrow we’ll look at variation in four R. gemmingi specimens.

References
Wellnhofer P 1975a-c. Teil I. Die Rhamphorhynchoidea (Pterosauria) der Oberjura-Plattenkalke Süddeutschlands. Allgemeine Skelettmorphologie. Paleontographica A 148: 1-33.Teil II. Systematische Beschreibung. Paleontographica A 148: 132-186. Teil III. Paläokolgie und Stammesgeschichte. Palaeontographica 149: 1-30.

wiki/Rhamphorhynchus

More Modern Folklore on Pterosaur Growth Patterns

A recent post by blogger Dr. David Hone described pterosaur growth patterns (= ontogeny) considering those patterns to be very much like those of mammals and archosaurs (=birds and crocs) in which the embryo/hatchling skull is shorter with big eyes, the bone texture is grainy, the sutures are clearly visible, etc.  This is the traditional view upheld by nothing more than tradition.

We’ve covered the alternative view, but since this bit of false propaganda hit the ‘Net (again!) its worthwhile to show the data once again. I have abridged Hone’s remarks to save space. The complete text is linked above.

If you have a pterosaur specimen in front of you, just how do you know if it’s an adult or not?

1. if you have a pterodactyloid with a 20 cm wingspan then it’s going to be a juvenile, and likewise if you have a rhamphorhynchoid coming in close to the 2 m mark it’s very unlikely to be anything but a big adult.

We’ve seen that embryo and juvenile pterosaurs are virtual copies of adults. And this growth trait goes back to the ancestral tritosaur lizard, Huehuecuetzpalli. Moreover, tiny (non-embyro) pterosaurs don’t nest with adults but with other small pterosaurs at the bases of major clades. No one has phylogenetically matched small pterodactyloids to 2x-8x larger adults yet (other than Pterodaustro and Ptweety). Every time that happens, then you’ll have ontogeny demonstrated – and its isometric rather than the traditional allometric.

2. Young animals (and especially very young animals) tend to have big heads compared to their body and especially very big eyes compared to the size of the head.

Pterodaustro embryo

Figure 1. Pterodaustro embryo. There certainly is no short snout/large eye here!

But you don’t find that in juvenile pterosaurs like Pterodaustro (Fig. 1) and the JZMP specimen. Only the IVPP specimen had a short snout, but so did all of its sister taxa among the anurognathids (not the ornithocheirids as originally reported). Only small adults related to other not so small adults with big eyes, especially in the Scaphognathus clade.

3. A bunch of fusions are absent in young pterosaurs that are present in adults too, just as you’d expect for most animals. The sutures between the centrum and neural arch of the vertebrae will be open in juveniles and closed in adults, and similarly the elements of the pelvis and sacrum, and the scapula and coracoid will be separate in young animals and fused together in adults.

a) Haven’t seen anything yet on the centrum/neural arch suture in tiny pterosaurs. If you have, please send references and we’ll cover that later. b) The fusion of the pelvis/sacrum and the scapula/coracoid follows phylogenetic patterns, not ontogenetic ones. Maisano (2002) covers this very well as in lizards fusion may occur long before growth ceases or it may never occur, as in certain clades of large adult ornithocheirids and ctenochasmatids. One of the largest pteranodontids, YPM 2501, lacks fusion in the extensor tendon process.

4.  Very young pterosaurs also tend to have a very grainy texture to the surfaces of their longbones, despite the fact that even embryonic pterosaurs have a pretty ossified set of bones (unlike many young animals).

Interesting conundrum. Embryos well-ossified, but tiny pterosaurs grainy? We earlier discussed the probable short, fast-growth life of tiny pterosaurs, as in other tiny animals (live fast, die young). These tiny adults were rarely smaller than known embryos, all of which would grow to become 8x larger adults that likely lived longer multi-year lives. The grainy texture reflects this fast growth. Tiny pterosaurs, with such little mass as adults, and even less growing up, don’t require the same ossification that larger pteros do.

5. Smaller pterosaurs also tend to have various parts of the skeleton being less ossified and rather amorphous compared to those of adults. The tarsals are often not well ossified and can be missing (well don’t preserve) and if present may be very simple shapes. The carpals tend to look more ‘blobby’ and lack the detailed morphology seen in adults and will be separated into multiple elements whereas in adults the wrist will primarily be formed of just two massive elements (plus the pteroid).

There’s no doubt certain clades of tiny pterosaurs have embryonic proportions, but other clades of tiny pterosaurs don’t. Wellnhofer (1970) described missing tiny pedal elements (p3.2, p4.2 and p4.3) in certain tiny pterosaurs, but these were displaced. I found them off to the side. With regard to the carpals, I wonder if some of this lack of detail could be due to geological factors as the joints tend to accumulate obscuring minerals? Often the proximal carpals will not fuse. This can be seen in the presumed adult Germanodactylus cristatus. The distal carpals are not fused in the rather large ornithocheirid Zhenyuanopterus (I drew them fused, my mistake). On the other hand the tiny pterosaur TM 10341 has syncarpals.

6. Rather like birds, in adult pterosaurs the sutures all but disappear, or even go entirely, such that the skull looks like a single smooth piece of bone.

This happens in some clades. Not others. Crushing makes it difficult to determine sutures from cracks. And pterosaurologists are famous for ignoring sutures in their reconstructions! You’ll see more sutures at reptileevolution.com.

7. Also as in some birds, bigger pterodactyloids have a notarium and this only fuses up and fully develops in adults.

A notarium develops in certain clades and only in the very largest pterosaurs within those clades. So a notarium is both a size and a phylogenetic trait, not an ontogenetic trait. No medium-sized Triassic and Jurassic adult pterosaurs have a notarium.

8. Similar to the point above about absolute size, the presence and development of some form of head crest is indicative, but not a great indicator of age. Yes a massive and elaborate crest in an animal is indicative that it’s an adult, but there could be a fairly well developed crest in an animal that is close to becoming and adult and of course there are taxa without crests and in at least once case it appears that females don’t have crests.

Only one embryo/juvenile crested pterosaur is known in which the crest is preserved and its crest (what we know of it) is just as large as the adult. So, at present there’s no indication that long crested pteros produced long-crested embryos and its difficult to imagine this in an elongated egg. Likely crests developed rather quickly after hatching with present data. We await the data on this interesting question. It’s certainly not set in stone yet.

7. As in mammals, but unlike dinosaurs and birds, pterosaur also have epiphyses. The growing plates at the ends of the long bones physically separate the main shaft of the bone from the proximal and distal ends, so things like the femur can appear to be in three pieces. Obviously as growth slows towards maturity these epiphyses slowly disappear as they fuse into the single element that you would expect to see.

Lizards also have epiphyses. Hmmm. Wonder why this was not mentioned? In any case, I have not seen epiphyses in any pterosaurs nor have I seen epiphyses in the three well-known embryos. Please send references if available. The epiphyses are seen in living lizards.

Summary: As ever with such things these are not absolutes, but merely guides. Good guides, certainly – you simply won’t see a notarium in a very young pterosaur, or open neurocentral arches in a big, old adult. However, in terms of determining more subtle difference in age it will be tricky – one animal may have fused up the notarium, but may have incompletely ossified tarsals and another could have the reverse. Although at least some characters do seem to have a bit of a pattern (the scapulocoracoid seems to fuse pretty early in most things) a general lack of numerous specimens of different ages makes it hard to do any more detailed analysis. Still, in terms of gross age (hatchling – young – adolescent – adult) even for a specimen of a previously unknown species with no obvious close relatives, it should be relatively easy to determine the approximate age of the animal.

Yes, there are exceptions. And when you put enough pterosaurs into a phylogenetic analysis, then the exceptions start to form phylogenetic patterns. That needs to be done by someone other than yours truly, and without excluding the tiny ones. Let’s find out if they are indeed juveniles, as Dr. Hone reports without a corresponding analysis, or if they are tiny adults, as the phylogenetic analysis here indicates. Pterosaurs are more interesting, it turns out, than we thought.

There’s also a difference between ‘show’ and ‘tell.’ Next time someone tells you the tiny Solnhofen pterosaurs are juveniles, ask him to match them up with their putative adults, if possible. Perhaps predicting frustration may be why nearly all pterosaurologists keep away from the tiny ones. There’s a PhD thesis here for the lucky grad student.

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
Maisano JA 2002. Terminal fusions of skeletal elements as indicators of maturity in squamates. Journal of Vertebrae Paleontology 22: 268–275.

Danger: Suprageneric Taxa and the Vague Hopeful Clouds They Produce

In phylogenetic analysis one attempts to find relationships among taxa.
Each taxon may be composed of a single specimen up to a major clade filled with billions of specimens (like the Dinosauria). It has long been recognized that employing single specimens is the ideal.  Employing single species would be next to ideal. Employing a single genus as a taxon is less than ideal. Often with prehistoric animals all we have is a single specimen to represent a particular genus, so that solves that particular problem.

The large reptile tree and the large pterosaur tree employ specimens, chiefly. If a specimen doesn’t have a skull or a post-crania, then that’s a problem, but its not a deal breaker. Most taxa can still be nested even if they are known from only a few parts. So even a fraction of a specimen can represent a taxon.

Suprageneric Taxa
Most recent studies and current paradigms mix specimens, genera and suprageneric taxa (= many to many dozens of specimens within a single clade). The problem for the viewer is always, which specimen or genus represented the suprageneric taxon in the study? Which dinosaur? Which phytosaur? Which synapsid?

Recent papers (Brusatte et al. 2010, Nesbitt 2011) have nested the Pterosauria (Eudimorphodon and Dimorphodon, two fairly good taxa hopefully based on the holotypes alone as several specimens have been attributed to each) with Scleromochlus (a good genus based on several specimens with no discernable distinctions) and the Dinosauromorpha (but which one, Silesaurus? Coelophysis?). These taxa were nested as the sisters to the Phytosauria (but which one?) + an unresolved clade of Aetosauria + Rauisuchia + Crocodylomorpha + Ornithosuchia.

Now we’re talking about a very large group of reptiles.
As you can imagine such a clade encompasses a wide variety of morphologies, quite literally a vague cloud of sizes and shapes. Somewhere in this long list of taxa we should find a sister to the Pterosauria, according to the most widely followed paradigm (Brusatte et al.  2010, Nesbitt 2011). But NONE of these clades produce ANY good candidates. Nothing comes close. Even so, most paleontologists hang their hats on this hope, and that’s all it is, a hope that somewhere, someday in the more derived Archosauria we’ll eventually find a good pterosaur ancestor. 

But Wait…We Already Have Some Great Pterosaur Ancestral Taxa!!
Many established paleontologists have let it be known they’re not happy with (= they prefer to ignore) the basal lizard Huehuecuetzpalli (which has a short list of pterosaurian traits), Cosesaurus (which has a long list of pterosaurian traits), Sharovipteryx (which heads off in its own direction but has additional pterosaurian traits) or Longisquama (which is very nearly a pterosaur itself). All of these are single specimens with Huehuecuetzpalli represented by an adult and juvenile.

They’re Still Pinning Their Hopes on The Cloud
It’s really amazing to witness the resistance put up by so many paleontologists to new insights. They prefer to hope for some undiscovered specimen to sweep them off their feet when there is a perfectly good set of specimens knocking on the door with everything they would ever want. They don’t even want to look at them and they made sure papers describing them were rejected.

There’ s Always Hope
Certain phylogenetic mysteries will continue to remain mysteries through the power of the suprageneric taxon cloud of hope. If you choose to employ suprageneric taxa, by definition you will be in the cloud, able to cherry pick trait scores and thereby cheat or short change your results to suit your preconceived ideas. Worse yet, the viewer who looks only at your results, will not see the specific evolutionary pathway and the gradual accumulation of character traits that are key to understanding evolutionary processes. They, too, will be left in the cloud.

Populate your matrices with specimens. That settles all issues. And you’ll be amazed at the variation and relationships you’ll find.

Trees should be built without prejudice and exclusion. Sure that’s a lot of work in the beginning, but once clades are established by overarching studies (like the big reptile tree), then more focused studies can proceed with greater confidence that all included taxa are indeed sisters and cousins.

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
Brusatte SL , Benton MJ , Desojo JB and Langer MC 2010. The higher-level phylogeny of Archosauria (Tetrapoda: Diapsida), Journal of Systematic Palaeontology, 8:1, 3-47.
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.

Merck 20??

Dr. John Merck has reportedly been working on a very large reptile tree for over a decade. That’s the competing tree one keeps hearing rumors of. The following letter to the DML from Thomas Holtz, 2000 was linked to me earlier as the latest news (alas, now 12 years old) on the subject:

> From: owner-dinosaur@usc.edu [mailto:owner-dinosaur@usc.edu]On Behalf Of
> Ken Kinman
>
> Thomas,
> Is there anything online or in print about Merck’s ideas on
> Euryapsid-Archosauromorph relationships?

At present, just a few JVP abstracts, and a mention and figure in Brochu’s
recent discussion of the “temporal paradox” in bird origins (JVP 20:
197-200; the cladogram is Fig. 1E). John hasn’t gotten around to writing up
the latest version, yet: I’m going to try and force him to do that this
summer.

> Are they sister groups, or are
> euryapsids nested within Archosauromorpha (i.e. closer to prolacertiforms
> than are the rhynchosaurs or trilophosaurs).

Well, by definition Lepidosauromorpha is the sister group to
Archosauromorpha (i.e., Archosauria and all taxa closer to it than to
Lepidosauria). Some have tried to use a compositionally-based definition of
Archosauromorpha, but the stem-based def. above is preferred by me and many
others.

In his latest runs, Merck finds a clade of Euryapsida and Thallatosauria as
the sister taxon to all other archosauromorphs. (He’s been trying to toss
in some taxa not included in his dissertation work, which is the source of
Fig. 1E in Brochu’s paper).

> I assume Euryapsida also includes the placodonts, and perhaps the
> thalattosaurs, but what about choristodera?

As Merck uses the term, Euryapsida = Ichthyopterygia + Sauropterygia.
Thallatosaurs are the sister group to this clade. Yes, placodonts are
sauropterygians, and thus euryapsids.

Merck finds choristoderes are not euryapsids, but are instead the sister
taxon to rhynchosaurs (and outside a protorosaur + (trilophosaurid +
archosauriform) clade).

> —–Cheers, Ken Kinman
> P.S. Do any of the euryapsids have thecodont teeth?

Checked with Merck about this: most euryapsids have a subthecodont condition
(which is the condition found in most non-archosauriform archosauromorphs).
A few ichthyosaurs have a thecodont dentition, developed independently of
archosauriforms.

Thomas R. Holtz, Jr.
Vertebrate Paleontologist

____________________________

Without publication of the Merck (or any other comparable study) the present large reptile tree remains the largest and most recent examination of the reptile family tree. The expanded inclusion set retains two major clades, the Lepidosauromorpha and the Archosauromorpha, that together include all prehistoric and living reptiles (including birds and mammals). In the large study the Lepidosauromorpha and the Archosauromorpha remain, by definition, sister taxa. However now they split near the basalmost reptile, a sister to Cephalerpeton.

Merck (pre 2000) found a clade of Euryapsida and Thallatosauria as the sister taxon to Archosauria (and all taxa closer to it than the Lepidosauria) and the large reptile tree found pretty much the same nesting, but added several clades between the basalmost archosauromorphs and euryapsids, including splitting the Diapsida in two.

Merck’s nesting of Choristoderes as sisters to rhynchosaurs is not supported by the large reptile tree and they don’t look much alike at any level. Choristodere sisters are covered here. And rhynchosaur sisters are covered here.

Sorry, there’s not much more to report on a competing reptile family tree. That’s why I decided to put effort into producing one. If others don’t like the methods or results, then plenty of opportunities have been offered to specify problematic nestings, etc. Hopefully someone will pop out a few bad nestings so we can get this thing fixed.

Inaccuracy? Or Asymmetry?

While gathering data for the TM 6920/21 (No. 38 in the Wellnhofer 1975 catalog), I restored the published tracings of the feet, both left and right,. The PIL patterns were nearly identical, but some of the phalanges did not match left to right. The differences were slight, but certainly present. The question is: does this represent asymmetry? Or inaccuracy? Or both?

The left and right feet of the no. 38 specimen of Rhamphorhynchus

Figure 1. The left and right feet of the no. 38 specimen of Rhamphorhynchus, TM 6920/21. Most of the metatarsals and phalanges were identical, but a few , here colored, were not. Does this represent Wellnhofer’s inaccuracy? Or asymmetry in Rhamphorhynchus? Someone with access to the specimen will have to determine this.

And, yes, this level of detail scrutiny is important.
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
Wellnhofer P 1975a-c. Teil I. Die Rhamphorhynchoidea (Pterosauria) der Oberjura-Plattenkalke Süddeutschlands. Allgemeine Skelettmorphologie. Paleontographica A 148: 1-33.Teil II. Systematische Beschreibung. Paleontographica A 148: 132-186. Teil III. Paläokolgie und Stammesgeschichte. Palaeontographica 149: 1-30.

wiki/Rhamphorhynchus

This shouldn’t take a PhD

A lot of criticism lately. Not much to back it up. Too much work to do so, from what they’re telling me. I mentioned earlier that others should attempt to throw in a few more taxa into their studies to see where the nestings really are. That provoked a comment that such a study or such a test would entail a PhD thesis.

I agree.

Creating a large family tree and hundreds of reconstructions is a lot of work. Imagine, for every 100 taxa and 100 characters, that’s 10,000 potential scores to assess. Double each of those inputs and you’re up to 40,000. And when the results don’t match expectations, that’s cause for either scrutiny or celebration. So…

Here’s an opportunity to be critical without having to put very much work into it. No one has to create a matrix in this test. We’ll do it the easy way.

Darren Naish thinks I’m wrong in most of my work. And he does speak for the establishment. So here’s an opportunity to point out exactly where I am wrong while putting in the minimum effort.

Pick two taxa from the large reptile family tree or the large pterosaur family tree that you think don’t belong together. Tell me which one is the oddball in that pairing, the one that does belong in your opinion. That’s it. We’ll discuss the ramifications afterwards. It would be better if you were to try to come up with some reasons why the two sisters don’t belong together and why one belongs elsewhere. But you don’t have to. We’ll put the pairings together and figure out which one was “separated at birth.” :  )

What could be easier?
Looking forward to hearing from one or all of you. You will be heard if you treat this seriously. I will.

Duplicating Results

A recent reply by the brilliant scientist Darren Naish to one of my posts concluded by saying, “But the fact is you aren’t right: you know full well that the reason we reject your proposals, your hypotheses, your trees, and the observations that all of those things are based on is that you’re using a wholly unreliable technique that cannot be accepted as proper science. You need to stop thinking that everyone is against you because you are heretical. No, it’s because you’re mostly wrong.”

This is pretty harsh criticism, but note that it is lacking in any evidence. Unfortunately, this is typical of what I hear from other paleontologists and frankly, that’s not how scientists should interact. That’s not how I present my hypotheses. I show my work and others should too.  And it better be good evidence. Unassailable. If the “unreliable” technique I’m using is using photographs, well, that’s how scientists share their work — and everyone does that.

The fact is, no one has attempted to duplicate my taxon list, even in their own way or even to a minor extent. All I ask is for someone to add a few lizards, especially those I found to nest close to pterosaurs in the large reptile tree (Huehuecuetzpalli, Sharovipteryx, Cosesaurus, etc), to any of the recent studies that nest pterosaurs close to Scleromochlus and phytosaurs. They can use their own observations, their own character traits, etc. Excluding other candidates a priori is not good science, especially when they appear to be the correct candidates and the alternatives all have major problems (as detailed in the last 300 or so blogs) and recognized by many.

I’m not trying to be right. I’m reporting results. If anyone can produce a valid study that produces different results, I’ll be more than happy to report on them. Shying away from such a test is not good for science. I’m happy to get your comments, especially those that indicate where I and others have made mistakes. That’s how we all correct the errors of the past and come to more valid conclusions.

I am constantly finding errors in my work as new data comes in. Yes, that has always been true. But the corrections of those errors have only served to clarify relationships and anatomy.

I haven’t met a phytosaur yet that even vaguely could ever claim to be a pterosaur uncle. Yet that’s the current paradigm that no one wants to talk about. So, let’s put the shoe on the other foot and imagine that everyone knows that pterosaurs are lizards derived from Cosesaurus and kin. Now imagine the furor that would erupt if I were to propose that phytosaurs were the closest cousins of pterosaurs.

The current situation just doesn’t make any sense.

This is the power of the current paradigm. Charles Darwin had to fight his then current paradigm. So did others. It’s time to see pterosaurs and reptiles in a new light, based on rigorous evidence and large taxonomic studies that leave little room for doubt.

Please, someone, anyone, just give it a try.

My best to you all.

___________________________________

Addendum in Response to Darren Naish’s note from Saturday, May 12.
“I’m only going to say one more thing here… so long as you keep saying that people “link phytosaurs with pterosaurs”, it’s obvious that you do not understand how to interpret phylogenetic trees. And I agree with David M about your use of characters and codings.”

How else can we interpret this tree? There is an unknown sister taxon between phytosaurs and erythrosuchids that is the closest sister to pterosaurs, according to this tree. This is the image posted by Darren Naish in his blog Scientific American – Tetrapod Zoology. This tree reflects trees recovered by Nesbitt (2011) and Brusatte et al. (2010) in which no other closer basal sister taxa are provided for pterosaurs.

phytosaurs basal to pterosaurs.

Figure 1. Phytosaurs basal to pterosaurs. Note there are no closer taxa offered at the base of the Pterosauria than the Phytosauria. The Erythrosuchia + the Phytosauria do not include a gradual accumulation of pterosaurian characters. Image attribution listed above. 

References
Brusatte SL , Benton MJ , Desojo JB and Langer MC 2010. The higher-level phylogeny of Archosauria (Tetrapoda: Diapsida), Journal of Systematic Palaeontology, 8:1, 3-47.
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.