The foot of Tropidosuchus: Another Lagerpeton sister without a pedal digit 5

This post follows
an earlier one that found fault with Niedzwiedzki et al. (2013) and Brusatte et al. (2011), which attempted to match four-toed Lagerpeton (Fig. 2) to five-toed Prorotodactylus and Rotodactylus ichnites, claiming these tracks represented the earliest examples of dinosauromorphs in the fossil record. Beside the morphological mismatch, which they acknowledged yet based their papers on, the large reptile tree found Lagerpeton was not even a dinosaur ancestor, but nested far afield with another chanaresuchid, Tropidosuchus (Fig. 3). Here we’ll show another Lagerpeton/Tropidosuchus sister with a metatarsal 5 lacking a pedal digit 5 sealing the deal that neither Lagerpeton, nor any close sister, could have made Prorotodactylus or Rotodactylus tracks. Even a further distant sister, Chanaresuchus (Fig. 4), lacks pedal digit 5.

A skeleton attributed to Tropidosuchus, but shares traits with Lagerpeton.

Figure 1. An unidentified skeleton attributed to Tropidosuchus, but shares traits with Lagerpeton. No pedal digit 5 here.

Above is a specimen and its reconstruction attributed to Tropidosuchus (Bonaparte 1994), but notice the difference in the pedal proportions and other proportions. The foot morphology is much closer to Lagerpeton. This specimen also has a smaller humerus than Tropidosuchus. The pelvis is distinct from both genera. Chevrons are missing from this specimen. Chevrons may be missing form this clade, which otherwise shares a relatively wide tail base according to the caudal transverse processes.

Lagerpeton reconstructed.

Figure 2. Lagerpeton reconstructed. No pedal digit 5 here.

Tropidosuchus romeri (Arcucci 1990) Late Triassic was originally considered a lagosuchid like Marasuchus but here derived from a sister to BPI 2871 and Chanaresuchus. The pes of Tropidosuchus was quite similar to that of Chanaresuchus emphasizing digit 2 with a slender metatarsal 4. The tarsals did not have a calcaneal heel.

The holotype of Tropidosuchus retains the narrower digit 4 of Chanaresuchus.

Figure 3. The holotype of Tropidosuchus retains the narrower digit 4 of Chanaresuchus. No pedal digit 5 preserved here.

Chanaresuchus bonapartei (Romer 1971) Anisian, Early Middle Triassic is a sister to Tropidosuchus and Teraterpeton. The most robust metatarsal was mt 2 Digit 3 was the longest. Metatarsal IV was extremely gracile and digit V was absent.

Chanaresuchus a quadrupedal ancestor to Tropidosuchus and Lagerpeton and the third taxon.

Figure 4. Chanaresuchus a quadrupedal ancestor to Tropidosuchus and Lagerpeton and the third Tropidosuchus-like taxon. No pedal digit 5 here.

So, why are professors promoting such mismatches? Why are reviewers approving such mismatches? Better matches to Prorotodactylus and Rotodactylus can be found in several untested taxa, as we saw earlier here. There must be a syndicate operating here, friends helping friends. Sometimes Science needs critics, not friends.

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
Arcucci A 1987. Un nuevo Lagosuchidae (Thecodontia- Pseudosuchia) de la fauna de Los Chañares (edad reptil Chañarense, Triásico Medio), La Rioja, Argentina. Ameghiniana 24, 89–94.
Bonaparte JF 1994. Dinosaurios de America del Sur. Impreso en Artes Gráficas Sagitario. Buenes Aires. 174pp. ISBN: 9504368581
Brusatte SL, Niedz´wiedzki G and Butler RJ 2011. Footprints pull origin and diversification of dinosaur stem lineage deep into Early Triassic. Proceedings of the Royal Society B, 278, 1107–1113.
Niedzwiedzki G, Brusatte SL and Butler RJ 2013. Prorotodactylus and Rotodactylus tracks: an ichnological record of dinosauromorphs from the Early–Middle Triassic of Poland. Geological Society, London, Special Publications, first published April 23, 2013. doi 10.1144/SP379.12.

wiki/Lagerpeton

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The Chronological Origin of Dinosaurs – Nesbitt vs. Peters

Dr. Sterling Nesbitt (2011) recently published his chronological family tree of archosaurs and their ancestors (Fig. 1). It’s too small to read, so please click on it to enlarge it.

The family tree of Archosaurs and their ancestors by Sterling Nesbitt.

Figure 1. Click to enlarge. The family tree of Archosaurs and their ancestors by Sterling Nesbitt, who includes pterosaurs, phytosaurs, and proterochampsids (including lagerpetids) that do not belong here according to the large reptile tree of Peters.

Taking the same chronological data, I rearranged and edited the taxa according to the results of the large reptile tree (Fig. 2).

Figure 2. Click to enlarge. The family tree of Archosaurs and their ancestors according to the large reptile tree by Peters. Note the absence here of phytosauria, proterochampsia (including lagerpetidae) and pterosauromorpha all of which nest far afield in the large reptile tree. A few taxa are added here. As in Nesbitt's tree, the major radiation occurred during the early Triassic and rather quickly. Here most dinosaur groups had a long ghost lineage into the Early Triassic, except, possibly, the Ornithischia evolving from Daemonosaurus

Figure 2. Click to enlarge. The family tree of Archosaurs and their ancestors according to the large reptile tree by Peters. Note the absence here of phytosauria, proterochampsia (including lagerpetidae) and pterosauromorpha all of which nest far afield in the large reptile tree. A few taxa are added here. As in Nesbitt’s tree, the major radiation occurred during the early Triassic and rather quickly. Here most dinosaur groups had a long ghost lineage into the Early Triassic, except, possibly, the Ornithischia evolving from Daemonosaurus

The evolution of dinosaurs and their ancestors is an intriguing question made more puzzling by the early appearance of Lotosaurus and Asilisaurus, two highly derived forms appearing in the early Middle Triassic, much sooner than the rest of the known fossils.

The question of poposaur nesting is the big difference here. Nesbitt finds that Ticinosuchus is basal to poposaurids. The large reptile tree found that Ticinosuchus was basal to aetosaurs and Sacisaurus was basal to poposaurids, despite its late appearance in the fossil record. The addition of Daemonosaurus (Fig. 2) provides a short path toward the Ornithischia. Nesbitt (Fig. 1) has a much longer path to the Ornithischia, close to Pisanosaurus, but running to the Early Triassic.

Poposaurids have been described as extremely convergent with dinosaurs, but their croc-like ankle gives them away. The large reptile tree found the development of a croc-like ankle was convergent in crocs and poposaurids, both developing from ankles without a calcaneal tuber or much of one.

The clade of Eoraptor, Panphagia and Pampadromaeus turns out to be the clade from which all phytodinosaurs (sauropodomorphs, ornithischians and poposaurids) evolved.

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.

Prorotodactylus and Rotodactylus: Produced by a Dinosauromorph Archosaur or a Lepidosaur?

There were some strange footprints
in the Early and Middle Triassic in the Holy Cross Mountains of Poland. These are covered in a new paper by Niedzwiedski et al. (2013). They report, “The first body fossil evidence of dinosauromorphs is a few million years younger than the youngest Polish tracks, so Prorotodactylus and Rotodactylus tracks currently provide the oldest record of dinosauromorph morphology, biology and evolution. Here, in this monographic treatment, we provide a detailed documentation of the Polish Prorotodactylus  and Rotodactylus record from the late Early (Olenekian) early Middle (Anisian) Triassic.”

Peabody (1948) introduced us to Rotodactylus from the Moenkopi formation. Haubold (1966, 1967) cataloged several types.

Prorotodactylus“Diagnosis (based on Ptaszyn´ski 2000a; Brusatte et al. 2011; Klein & Niedz´wiedzki 2012). Long striding trackways with small lacertoid pentadactyl pes and manus imprints. Manus overstepped laterally by the pes. Pes outwardly and manus inwardly rotated with respect to the midline. Digitigrade pes with digits I–IV increasing in length, II–IV subparallel and tightly ‘bunched’ with distinct straight metatarsal–phalangeal axis (i.e. straight posterior margin of the preserved digit imprints), digit I everted. Digit V rarely impressed, and if present, located in a posterolateral position and relatively short in comparison to digits I–IV. Manus semiplantigrade or plantigrade, of chirotheroid shape, compact and rounded with posterolaterally positioned digit V mostly impressed. Digit III longest, followed by IV, II and I, which is shortest. The main difference between Prorotodactylus and Rotodactylus is the position and shape of digits V in both the manus and pes imprints of Prorotodactylus.”

Figure 1. Click to enlarge. Chronology of ichnites, from Niedzwieczki et al. 2013. My notes in red. Blue ichnites have been flipped for consistency (now they're all righties, no lefties). Note the middle traces include a manus in which digit 4 is longer than 3, distinct from the others, but overlooked by Niedzwieczki et al. 2013.

Figure 1. Click to enlarge. Chronology of ichnites, from Niedzwieczki et al. 2013. My notes in red. Blue ichnites have been flipped for consistency (now they’re all righties, no lefties). Note the middle traces include a manus in which digit 4 is longer than 3, distinct from the others, but overlooked by Niedzwieczki et al. 2013.

Unfortunately,
The only derived and small archosauriforms with pedal digit 4 longer than 3 include lagerpetids, like Tropidosuchus and Lagerpeton (Fig. 4), two taxa not related to dinos, according to the large reptile tree. Neither these two nor its closest sister, Chanaresuchus, has pedal digit 5. None of these three preserved the manus. Metatarsal and phalangeal proportions do not match the ichnite either. You have to go all the way back to Proterosuchus to find an archosauriform with pedal digit 4 longer than 3, a plesiomorphic trait of basal reptiles.

The combination of manus digit 3 > 4 and pedal digit 4 > 3 is the key to discovering the trackmaker of Prorotodactylus. Here we’ll find that very few taxa are a good match for Rotodactylus and Prorotodactylus ichnites. Several have that formula, but few have the much smaller manus and short fingers.

Figure 2. Click to enlarge. Among the few taxa that have a longer manual digit 3 than 4 AND a longer pedal digit 4 than 3 include Owenetta, Emeroleter, Sphenodon, Cosesaurus and Tanystropheus.

Figure 2. Click to enlarge. Among the few taxa that have a longer manual digit 3 than 4 AND a longer pedal digit 4 than 3 include Owenetta, Emeroleter, Sphenodon, Cosesaurus and Tanystropheus.

And more here:

More reptiles with the unusual manual digit 3 longer than 4 AND pedal digit 4 longer than 3.

Figure 3. More reptiles with the unusual manual digit 3 longer than 4 AND pedal digit 4 longer than 3 include the basal lizards, Liushusaurus and the Daohougo lizard, plus Lazarussuchus. None of these taxa were even considered by Niedzwiedski et al. (2013).

Niedzwiedski et al. (2013) in their quest for a trackmaker to fit Rotodactylus published this image of Lagerpeton, which is an obvious mismatch that doesn't even have a pedal digit 5.  Plenty of other taxa are better matches (Figs. 3,4) but those weren't published, tested or promoted.

Figure 4. Niedzwiedski et al. (2013) in their quest for a trackmaker to fit Rotodactylus published this image of Lagerpeton, which is an obvious mismatch that doesn’t even have a pedal digit 5. And the pedal digit 5 impression does not include an ungual (Peabody 1948). The ungual impression was added with hope, not data. Plenty of other taxa are better matches (Figs. 3,4) but those weren’t published, tested or promoted.

To their credit,
Niedzwiedski et al. (2013) reported, “As Lagerpeton is only known from South America and the Ladinian, it is unlikely that this particular genus was responsible for the Polish footprints. Furthermore, there are specific differences between the foot skeleton of Lagerpeton and the Prorotodactylus and Rotodactylus footprints. Our argument, however, is not that Lagerpeton itself made the Polish footprints, but rather that the Prorotodactylus and Rotodactylus tracks were made by a non-dinosaurian dinosauromorph closely related to, and sharing derived characters with, Lagerpeton.”

Talk about bad science. 
You can see by the above confession that Niedzwiedski et al. (2013) agreed this was a bad match. So why did they promote this? And only this? This is the core result of their entire paper and its predecessor (Brusatte et al. 2011). They also virtually ignored and dismissed the absolutely perfect match provided by Peters (2000, Fig. 6). They also ignored every other taxon that could have made these tracks (Figs, 2,3) better than Lagerpeton. Evidently, someone had a point to prove, and doggone it, facts were not going to get in the way of this hypothesis!

The best matches to Prorotodactylus and Rotodactylus. In this case, something between a small Tanystropheus and an even smaller Cosesaurus provides the best matches in all regards.

Figure 5. The best matches to Prorotodactylus and Rotodactylus. In this case, something between a small Tanystropheus and an even smaller Cosesaurus in the digitigrade configuration provides the best matches in all regards. These taxa were not even mentioned by Niedwiedcki et al. (2013). Skeletal fossils are known from geographically and chronologically similar sediments. Both of these taxa are tritosaur lizards, not archosaurs and not protorosaurs and certainly not non-archosaur archosauriforms. Other sister candidates include langobardisaurs, which also have a wide distribution.

Niedzwiedski et al. (2013) refer to Brusatte et al. (2011) supplementary materials for further explanations regarding trackmaker selection. Unfortunately they had their bias blinders on. They did not include any lizards, but focused only on their favorite archosaurs.

Niedzwiedski et al. (2013) grant, “Some other recent authors have presented alternative identifications of the Rotodactylus trackmaker. Lockley & Hunt (1995) considered the trackmaker to be a lepidosauromorph with a specialized gait. Peters (1996, 1997) briefly discussed (in abstracts) a potential close relationship between Rotodactylus and pterosaurs, while Peters (2000) identified Rotodactylus as being made by a nonarchosaurian archosauromorph.” (BS! I said it was a perfect match to Cosesaurus, which is not a nonarchosaurian archosauromorph! I’ve never used that term. See how twisted paleontologists can get? (more examples here and here). It’s shameful and creepy.)

Niedzwiedski et al. (2013) report, “Regardless of the precise affinities of Rhynchosauroides, a lepidosauromorph or non-archosaurian archosauromorph would not be expected to possess footprints that formed narrow gauge trackways and are consistently digitigrade, with reduced outer digits and tightly bunched central digits.” [See the bias! The Jayne labs prove that fast-moving lizards are narrow-gauge and digitigrade. And these were no ordinary lepidosaurs. They were well on their way toward bipedal locomotion. This group certainly did not exhaust the possibilities (Figs. 3, 4). They kept their blinders on. Now I know exactly how Branch Rickey felt when others were verbally attacking his best ballplayers!] Just because the taxa I promote come from the other side of reptile family tree doesn’t mean they can’t play.

Cosesaurus matched to Rotodactylus from Peters 2000.

Figuure 6. Cosesaurus matched to Rotodactylus from Peters 2000. This a perfect match with no imagination or excuses added. Why didn’t Niedwiedski et al. (2013) acknowledge this? They obviously had a preset agenda. Their conclusions ruled their data. Dinosaurs are cool, they make the news. Cosesaurus, fenestrasaurs, tritosaurs are bench players in their mind, not worth considering. The proximal pahalanges were elevated because the metatarsophalangeal joint was a butt joint, retained by the pterosaur Dimorphodon(?) weintraubi, among other sister taxa.

Niedzwiedski et al. (2013) report, “Furthermore, a pterosaur identification for the Polish tracks is also unlikely, because the feet of Triassic pterosaurs retain elongate pedal digits I and V, unlike dinosauromorphs, and the digits are splayed distally, unlike the tracks of Prorotodactylus and Rotodactylus and the feet of Lagerpeton (e.g. Wild 1978; Dalla Vecchia 2009).”

The patron saint of "No Respect", Rodney Dangerfield.

Figure 8. The patron saint of “No Respect”, Rodney Dangerfield.

This is a red-herring!
Niedzwiedski et al. (2013) argued against something that wasn’t even promoted. Peters (2000) matched Cosesaurus to Rotodactylus because it is a good match! Yes, pterosaurs descended from Cosesaurus and basal forms made similar tracks (Peters 2011), with pedal digit 5 impressing behind the other four digitigrade digits, sometimes splayed, sometimes not. So, why would good paleontologists turn a blind eye to all the best possibilities and force fit a bad match to their discovery?

I keep asking myself the same thing almost every day I write this blog. Unfortunately, this sort of thing happens all the time. For now it’s just grist for the mill.

ADDENDUM
The following was added after original publication. These are examples of how pedal digit 5 operated in basal pterosaurs. Note the impression varies from a single round knuckle impression far behind the digits to a complete phalanx impression (Peters 2011, will send on request).

Digitigrade pterosaur pedes. This is how pedal digit 5 worked in pterosaur taxa with a pedal digit 5. We have ichnites that match anurognathid pedes. See them in the digitigrade pterosaur pedes post linked in the text.

Addendum figure: Digitigrade pterosaur pedes. This is how pedal digit 5 worked in pterosaur taxa with a pedal digit 5. We have ichnites that match anurognathid pedes. See them in the digitigrade pterosaur pedes post linked in the text. PILs (parallel interphalangeal lines are easy to gauge here).

I also encourage you to check out an earlier post on digitigrade pterosaur pedes.

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, Niedz´wiedzki G and Butler RJ 2011. Footprints pull origin and diversification of dinosaur stem lineage deep into Early Triassic. Proceedings of the Royal Society B, 278, 1107–1113.
Haubold H 1966. Therapsiden- und Rhynchocephalien-Fahrten aus dem Buntsandstein Sudthuringens: Hercynia, N. F., v. 3, p. 147-183.
Haubold H 1967. Eine Pseudosuchier-Fahrtenfauna aus dem buntsanstein Sudthurigens: Hall. Jb. Mitteldt. Erge, v. 8, p. 12-48.
Niedzwiedzki G, Brusatte SL and Butler RJ 2013. Prorotodactylus and Rotodactylus tracks: an ichnological record of dinosauromorphs from the Early–Middle Triassic of Poland. Geological Society, London, Special Publications, first published April 23, 2013. doi 10.1144/SP379.12
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.

The Origin of Dinosaurs, Mortimer vs. Peters and the ‘Zipper Check’ Test

Fellow blogger, Mickey Mortimer, at the Theropod Database Blog, has been pretty rough on yours truly lately. From name calling to finger-pointing to associating me with people who have been kicked off the DML*. I gather from Mortimer’s comments that I am sorely in need of a lesson in phylogenetic analysis.

All true. 
As everyone knows, I’m not classically trained. I don’t have immediate access to fossils, but rely on photos and line drawings for my data. On the plus side, I’ve created a larger gamut reptile family tree than anyone so anyone can trace the origin of any major reptile clade. I’m always interested in receiving data that will improve the sometimes crappy data I sometimes deal with. And I change things like images and data when new data or new insights come along. Science is not immutable. Everyone coming here to the Pterosaur Heresies website has permission to change their mind without fear of being vilified.

(That’s not always the case “out there” as we’ve also seen here).

For instance,
when Mortimer suggested that Silesaurus had gastralia, I found the new paper describing it and I was happy to make that change to the matrix. Behind the scenes, my own studies often include rescoring data, especially when new taxa are added. New insights are always coming along. Mortimer calls me “dishonest” for doing this. However, I think it’s important to remove wrong data and replace it with better data whenever possible.

Getting back to our story
Mortimer has been “correcting” the wording and the scorings of the large reptile tree/dinosaur subsection (2000+ “corrections” so far) and Mortimer’s results are as follows (Fig. 1) in graphic form with Sacisaurus at the base and theropods as derived taxa (derived from Sacisaurus and sauropodomorphs):

Basal dinosaur tree as recovered by Mortimer.

Figure 1. Basal dinosaur tree as recovered by Mortimer. Here Sacisaurus is the most basal dinosaur. A sister to Sacisaurus gives rise to ornithischians (Heterodontosaurus) and to saurischians, which give rise to theropods. Thus, in Mortimer’s view, theropods are derived from beaked planteaters like Sacisaurus, and non-beaked plant-eaters, like Massospondylus. Daemonosaurus, despite its similarity to Heterodontosaurus and Massospondylus nests as a sister to Tawa in Mortimer’s tree. This is pretty much just the opposite of the large reptile tree shown in figure 2.

Mortimer’s results conflict with those of the large reptile tree, which looks like this (Fig. 2) in graphic form where carnivorous Herrerasaurus is primitive and beaked Sacisaurus is derived from Eoraptor:

Figure 2. Dinosaur relations as recovered from the large reptile tree. Here short-faced plant-eaters, like Massospondylus and Heterodontosaurus, are derived from meat-eaters, like Herrerasaurus via Daemonosaurus. Eoraptor has been difficult to classify, perhaps because it is a key taxon at the base of the phytodinosauria, along with Pampadromaeus.

Figure 2. Dinosaur relations as recovered from the large reptile tree. Here short-faced plant-eaters, like Massospondylus and Heterodontosaurus, are derived from meat-eaters, like Herrerasaurus via Daemonosaurus. Eoraptor has been difficult to classify, perhaps because it is a key taxon at the base of the phytodinosauria, along with Pampadromaeus.

Cautionary tale. Why the last minute zipper check is so important!

Figure z. Cautionary tale. Why the last minute zipper check is so important!

The Zipper Check
Before us men go out to face the day we touch our fly (pants zipper) to make sure it’s up, not down. That’s the Zipper Check. It’s that one last simple test to make sure there are not going to be any embarrassing moments in the near future. Lining up basal dinosaur skulls (Fig. 2) represents my zipper check**. This little graphic told me my results were going to be okay. The line-up makes sense. Derived traits are found in derived taxa.

Unfortunately, somehow, and despite best intentions, long hours and many years of experience, Mortimer’s tree (Fig. 1) came out the exact opposite of mine (Fig. 2). I suggested a zipper check before Mortimer published. But, well… now it’s out there.

Data Matrix vs Graphic Presentation
I’m using a series of skulls in today’s blog to quickly get across a point that you could also gather over many hours lingering over either Mortimer’s or my data matrix or both. Ease of use is paramount here.

You be the judge.
It’s difficult for me to agree with the results of Mortimer’s tree, but I may be in the minority. Whatever mistakes that are present in the large reptile tree (and there must be some, but fewer than this morning since I dug into it a bit today), evidently the mistakes were not large enough to create an illogical solution, but, instead, appear to echo actual evolutionary events.

Even if my data is voodoo, I stand by my results (until better data comes in!)

The Reason for the Different Trees
I think the rescorings of Mortimer’s tree gave added weight to traits that would link poposaurids to rauisuchids (an outgroup). That’s why Sacisaurus nested as basal. On the other hand, I used the same characters as are found throughout the rest of the large reptile tree. That’s why poposaurids nested as phytodinosaurs in my tree. Others think poposaurids are convergent with dinosaurs. I think they are dinosaurs and the description of dinosaur traits needs to expand (or contract) to include them. The definition (Passer + Triceratops) still works.

And, as always, if you have better data, please forward it. Changes will be made where necessary. Can you find the change I made this morning to the archosaur portion of the tree? Hint: Adding wrist characters was key.

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.

>>>>

*Come to think of it, I, too, was kicked off the DML too! I had the gall to suggest that we test Digital Graphic Segregation techniques versus actually looking at 2D fossils with the naked eye or microscope. According to published results with JeholopterusVancleavea and Shenzhoupterus, to name a few, DGS definitely has its place in the pantheon of tools that can be used by paleontologists. And DGS is used, especially with fish fossils and anywhere else where the scene can be visually confusing. I don’t encourage the use of one tool over another, but the use of all tools to test one method against another.

** The Zipper Check test would also be useful for taxa like Lagerpeton, Vancleavea, pterosaurs, caseasaurs, Bennett’s anurognathid, parasuchians, Rotodactylus, and any other strange bedfellows that don’t look AT ALL like their purported sisters. Sometimes there are ‘by default’ nestings due to a too small gamut list of included taxa that needs expansion to other possible candidate taxa.

Nesting Eoraptor in the Large Reptile Tree

Eoraptor lunensis (Fig. 1) is an early (Carnian, Triassic, 1 meter long, PVSJ 512) bipedal dinosaur introduced by Sereno et al. (1993). Only the skull has been published, and before being fully prepped. The whole skeleton (Fig. 4), sans the tail tip, is known. I understand a monograph should be out this year. Digimorph published the skull in several views. The post-cranial data I’m working with is from Greg Paul (Fig. 4), published online here.

Figure 1. Eoraptor skull from Sereno et al. 1993.

Figure 1. Eoraptor skull modified from Sereno et al. 1993.

I should have added Eoraptor earlier considering the importance of this taxon.

Figure 2. Eoraptor skull, traced from Digimorph image.

Figure 2. Eoraptor skull, traced from Digimorph image. Here the premaxillary teeth appear to be longer.

The Wiki/Eoraptor entry reports, Eoraptor was one of the world’s earliest dinosaurs. It was a two-legged saurischian, close to the ancestry of theropods and sauropodomorphs” and lacked specialized predatory dinosaur traits. Sereno (195) considered Eoraptor the earliest recorded theropod closest to “the hypothetical dinosaurian condition that any other dinosaurian subgroup.

Figure 3. Archosaur/Dinosaur family tree. Here's where Eoraptor nests in the large reptile tree.

Figure 3. Dinosaur family tree. Here’s where Eoraptor nests in the large reptile tree.

Indeed it is.
The large reptile tree (Fig. 3) nested Eoraptor with Panphagia and Pampadromaeus, a clade basal to the Phytodinosauria, derived from basal Theropoda like Herrerasaurus. According to Sereno et al. (1993), Eoraptor has distinct premaxillary and anterior maxillary leaf-shaped teeth. Currie (1997) also found Eoraptor closer to the hypothetical ancestor of both saurischian and ornithischian dinosaurs. More recently, Sues et al. (2011), in their study of Daemonosaurus, considered Eoraptor a basal theropod.

Eoraptor is a key taxon in the family tree of basal Dinosauria. While close to theropods, the snout is shorter and rounder, the teeth are “leaf-shaped,” and the orbit is larger. These traits continue to evolve in Phytodinosauria.

 

Figure 2. Eoraptor based on tracing illustrations in Sereno et al. 2013, including the in situ composite image.

Figure 2. Eoraptor based on tracing illustrations in Sereno et al. 2013, including the in situ composite image.

Interesting PostScript
When working with Sacisaurus, I thought it strange that the postorbital had an odd convex bump just posterior to the eye. Now I see that it is evidently derived from Eoraptor, which likewise shared that postorbital bump.

Figure 4. Dinosaur relations as recovered from the large reptile tree. Here short-faced plant-eaters, like Massospondylus and Heterodontosaurus, are derived from meat-eaters, like Herrerasaurus via Daemonosaurus.

Figure 4. Dinosaur relations as recovered from the large reptile tree. Here short-faced plant-eaters, like Massospondylus and Heterodontosaurus, are derived from meat-eaters, like Herrerasaurus via Daemonosaurus and Pampadromaeus.

A Key Taxon
The figure above represents the phylogenetic nesting of Eoraptor as a sister to Pampadromaeus, which is descended from a sister to Herrerasaurus and basal to the Phytodinosauria: Ornithischia,  Saurompodomorpha and Poposauridae. Seems to make sense on the face of it. And this is why Eoraptor has been hard to classify into traditional categories.

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
Currie PJ 1997. Theropoda. In Encyclopedia of Dinosaurs (P.J. Currie, and K. Padian, Eds.) pp 731-736. Academic Press, San Diego, California.
Sereno PC, Forster CA, Rogers RR and Moneta AM 1993. Primitive dinosaur skeleton form Argentina and the early evolution of the Dinosauria. Nature 361, 64-66.
Sereno PC 1995. Theropoda: early evolution and major patterns of diversification. Journal of Vertebrate Paleontology 15(3, suppl.):52A-53A
Sues H-D, Nesbitt SJ, Berman DS and Henrici AC 2011. A late-surviving basal theropod dinosaur from the latest Triassic of North America. Proceedings of the Royal Society Bpublished online.

Wiki/Eoraptor

New Bipedal Tapejara Take-Off Video

A bipedal pterosaur video!
Just ran across this Tapejara skeleton take-off, fly and land video from the Huffington Post – and its a bipedal takeoff! The original came from the Sankar Chatterjee lab at Texas Tech in November 2012.

Click to animate. Tapejara take-off, flight and landing by the Sankar Chatterjee lab. Red arrows point to morphology problems. 1. Bend humerus back further. 2 Bend elbow more. 3. Pteroid goes to carpals, not the finger joint, unless that's a metacarpal lacking fingers. 4. Knees should be splayed 5. Extend hind limbs laterally.

Figure 1. Click to animate. Tapejara take-off, flight and landing by the Sankar Chatterjee lab. Nice to see. So many things are right about this animation. Yet, red arrows point to minor morphology problems. 1. Bend shoulder back further. 2 Bend elbow forward more. 3. When the elbow is bent, the pteroid angles out from the radius, framing the propatagium better. 4. Metacarpal lacking free fingers. 4. Knees should be splayed 5. Extend hind limbs laterally in flight.

The Huffington headline reads: Pterosaur ‘Runways’ Enabled Huge Prehistoric Flying Animal To Get Airborne, Study Suggests. By: Douglas Main, LiveScience Contributor
Published: 11/08/2012 03:01 PM EST on LiveScience.

How did pterosaurs takeoff and fly?
According to Main, “A new computer simulation has the answer: These beasts used downward-sloping areas, at the edges of lakes and river valleys, as prehistoric runways to gather enough speed and power to take off, according to a study presented Wednesday (Nov. 7) here at the annual meeting of the Geological Society of America.’First the animal would start running on all fours,'” Texas Tech University scientist Sankar Chatterjee, a co-author of the study, told LiveScience. “Then it would shift to its back legs, unfurl its wings and begin flapping. Once it generated enough power and speed, it finally would hop and take to the air,” said Chatterjee, who along with his colleagues created a video simulation of this pterosaur taking flight.

Unfortunately Chatterjee doesn’t give pterosaurs the credit they deserver when he reports, “This would be very awkward-looking,” he said. “They’d have to run, but also need a downslope, a technique used today by hang gliders. Once in the air, though, they were magnificent gliders.” 

So, a downslope was necessary and flapping was rare, evidently, in Chatterjee’s view. Unfortunately, Chatterjee, like the other pterosaur experts, has a built-in bias regarding pterosaurs in that he sees them too weak to run to take-off speed, except downhill, and too weak to flap sufficiently to create enough thrust without a runway, and too weak to flap with vigor while gaining altitude. The caption (Fig. 1) includes a few reconstruction suggestions.

Bipedal lizard video marker

Figure 2. Click to play video. Just how fast can quadrupedal/bipedal lizards run? This video documents 11 meters/second in a Callisaurus at the Bruce Jayne lab. just think what a pterosaur could attain, even without its wings.

Living bipedal lizards are anything but awkward-looking.
In fact they look incredibly like graceful bullets, faster than a rabbit  and impossible to see on film unless greatly slowed down, as shown here in the Bruce Jayne lab films.

Pterosaurs have what bats and birds have
The ability to flap and fly vigorously. Huge pectoral  and upper arm muscles, fur-covered body, independent wings and legs. Gosh, I feel like I’m looking out for the little guy (pterosaurs) here, having to defend them from pterosaur experts.

Doggone it. 
I realize everyone has their pet ideas and given those its important to trash the ideas of others. But this is Science and we can come to certain agreements. Nice to see Chatterjee showing that Tapejara could run bipedally! That’s a first step. Hopefully the round table at the Pterosaur Symposium in Rio in May will bring forth broad agreements on several issues without resorting to shoe throwing.

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.

Did azhdarchids wade or stalk?

The following was added as a comment to a PlosOne paper on azhdarchid ecology.

Poor waders?
Witton and Naish (2008) reexamined the probable feeding niche employed by the largest pterosaurs, the azhdarchids. I agree with their hypothesis that azhdarchid pterosaurs did not feed while skimming, as other pterosaurs probably did. Instead they argued that azhdarchids were stork- or ground hornbill-like generalists, foraging in diverse environments for small animals and carrion because they were poorly suited for all proposed lifestyles bar terrestrial foraging. They dismissed wading as a niche because footprints show that their feet were relatively small, padded and slender, and thus not well suited for wading.

A black-necked stilt is an example of a wading bird with long legs and slender feet without webbing.

Figure 1. A black-necked stilt is an example of a wading bird with long legs and slender feet without webbing.

Good waders!
Unfortunately, modern long-legged waders, like the black-necked stilt (Himantopus mexicanus) have relatively small, slender toes with virtually no webbing. So such toes and long legs are indeed perfectly suited to wading.

Witton and Naish (2008) reported, “Moreover, other pterodactyloids with larger pedal surface areas (most notably ctenochasmatoids) were almost certainly better adapted waders than azhdarchids.”

The ctenochasmatid clade does have relatively larger feet, but much shorter legs, better suited to shallower waters with shifting sands and surf like those surrounding Solnhofen islands. This is distinctly different from the long-legged wading azhdarchids adapted for deeper quieter inland lake waters.

Other problems are phylogenetic in nature
1. Witton and Naish (2008) mistakenly include Bakonydraco with the azhdarchids. Bakonydraco phylogenetically nests with eopteranodontids/eoazhdarchids (Peters 2007).

2. Witton and Naish (2008) mistakenly nest tupuxuarids with azhdarchids because they share a few convergent traits. Phylogenetic analysis indicates that tupuxuarids are derived from a distinct clade of tapejarids and germanodactylids. Azhdarchids are derived from dorygnathids (Peters 2007).

3. Witton and Naish (2008) also incorrectly nest toothless Pteranodon with toothy Anhanguera (Peters 2007).

Still other problems are morphological in nature
Witton and Naish (2008) report, “Langston [17 (bracketed numbers refer to PlosOne references)], Wellnhofer [24] and Chatterjee and Templin [16] reconstructed azhdarchids with narrow brachiopatagia extending to the top of the hindlimbs, whereas Frey et al. [74] suggested that the membrane extended to the ankle, forming a much broader wing. No fossilised azhdarchid wing membranes are known, but evidence from anurognathids, campylognathoidids, rhamphorhynchids, ctenochasmatoids and non-azhdarchid azhdarchoids [86]–[91] indicates that ankle-attached wing configurations are more accurate.”

My independent examination of the data (Peters 2001, not cited by Witton and Naish 2008) agrees with the Langston, etc. narrow-chord interpretation for all pterosaurs. No pterosaur shows an attachment to the ankle. All pertinent examples (e.g. the Zittel wing of Rhamphorhynchus (BSP 1880 II 8), the Vienna wing of Pterodactylus (NHMW 1975/1756), the holotype of Jeholopterus (IVPP V 12705) (Peters 2001)) show an attachment to the top of the hindlimbs following a fuselage fillet. [not in the PlosOne comments: Even Sordes, the prime example among deep chord devotees has a narrow chord wing, as shown here.] Thus little confidence can be placed with any arguments advanced by Witton and Naish (2008) for hypothetical capabilities based on their fictional wing shape.

Witton and Naish (2008) report, “The size of these forms also dictates that they would need to process enormous amounts of probed invertebrates to sustain themselves.” Unfortunately they failed to note that azhdarchids had the relatively smallest torso of all pterosaurs and that implies they had the smallest stomach as well. Furthermore, it’s not uncommon to see dozens of wading bird (click for image) from several different genera picking at a small patch beneath a shallow body of water. Now, simply exchange dozens of wading birds for a few wading azhdarchids in waters too deep for other waders and there’s undoubtedly enough food to go around, in place and not running away or fighting back like terrestrial tetrapods do.

In summary,
the difference between terrestrial foraging and shallow water wading probably cannot be determined by the factors brought up by Witton and Naish (2008). Deeper water wading seeking buried invertebrates remains a possible niche environment for long-legged giant azhdarchids.

References
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. Flugsaurier. The Wellnhofer Pterosaur Meeting, Munich 27. This pterosaur clade phylogenetic analysis has been expanded at www.reptileevolution.com/MPUM6009-3.htm.
Witton MP and Naish D 2008. A Reappraisal of Azhdarchid Pterosaur Functional Morphology and Paleoecology. PLoS ONE 3(5): e2271. doi:10.1371/journal.pone.0002271