Jesairosaurus and the drepanosaurs leave the Tritosauria :-(

My earlier reconstruction
of the basal lepidosauriform, Jesairosaurus (Fig. 1; contra Jalil 1997, not a protorosaur/prolacertiform) included several errors based on attempting to create a chimaera of several specimens of various sizes based on scale bars. In this case, scale bars should not have been used. Rather fore and hind parts had to be scaled to common elements, like dorsal vertebrae, as shown below (Fig. 2). I think this version more accurately reflects the in vivo specimen, despite its chimeric origins. All of the partial skeletons assigned to this genus were discovered at the same Early to Middle Triassic sandstone site and two were touching one another. A larger skull, ZAR 7, shows the variation in size from the skull to shoulders remains of the ZAR 6 specimen.

Figure 1. New reconstruction of the basal lepidosauriform, Jesairosaurus (Jalil 1997). The wide and flat ribs are interesting traits for a likely arboreal reptile.

Mother of all drepanosaurs
The Drepanosauria is an odd clade of slow-moving arboreal reptiles that includes Hypuronector, Vallesaurus, Megalancosaurus and Drepanosaurus (Figs. 2, 3). Jesairosaurus was not a drepanosaur, but nested basal to this clade before the present revisions. It remains basal to the Drepanosauria now with revisions.

The revised reconstruction of Jesairosaurus 
shifts this clade away from Huehuecuetzpalli, Macrocnemus and the rest of the Tritosauria. Now Jesairosaurus and the drepanosaurs nests between Saurosternon, Palaegama and the so-called “rib” gliders, beginning with Coelurosauravus.

A short history of Jesairosaurus
Shortly after their discovery Lehman 1971 referred the several hematite encrusted specimens to the Procolophonida. Further preparation showed that they were referable to the Diapsida, according to Jalil (1990) and the, more specifically, to the Prolacertiformes (Jalil 1997) as a sister to Malerisaurus with Prolacerta as a common ancestral sister. Jalil did not include the closest sisters of Jesairosaurus as revealed by the present analysis.

With a much larger list of taxa,
the large reptile tree nests Malerisaurus between the Antarctica specimen assigned to Prolacerta (AMNH 9520) and the holotype of Prolacerta. Jesairosaurus, as mentioned above, nests with the basal lepidosauriformes. Any traits shared with protorosaurs are by convergence. Deletion of Jesairosaurus does not affect the nesting of the Drepanosauria as basal lepidosauriformes.

Figure 3. Drepanosaurs and their ancestor sisters, Jesairosaurus and Palaegama to scale.

Arboreal
This new nesting shifts drepanosaurs closer to kuehneosaurs (Figs. 3, 4), another notably arboreal clade.

Figure 3. The new nesting for Jesairosaurus and the drepanosaurs as sisters to the Kuehneosaurs, several nodes away from Huehuecuetzpalli and the tritosaurs.

Certainly
there will someday be more taxa to fill in the current large morphological gaps in and around Jesairosaurus, but here’s what we have at present (Fig. 3) with regard to the origin of the so-called “rib” gliders (actually dermal rods, not ribs, as shown by Coelurosauravus) and the origin of the drepanosaurs.

Figure 4. Jesairosaurus to scale with sisters Palaegama and Coelurosauravus.

The shifting of a clade
like Jesairosaurus + Drepanosauria occurred due to inaccurate reconstructions used for data. Science builds on earlier errors and inaccuracies. I let the computer figure out where taxa nest in a cladogram of 606 possible nesting sites, minimizing the negative effects of bias and tradition.

It’s sad
to see the drepanosaurs leaving the Tritosauria as it contains several oddly Dr. Seuss-ian variations on the tritosaur theme.

Also note the nesting
of the basal Rhynchocephalians, Megachirella and Pleurosaurus, between the palaegamids and the tritosaurs (Fig. 4). In the course of this study, both also received updates to their skull reconstructions. The former was difficult to interpret without knowing where it nested. What appeared to be an odd sort of a squamosal in Megachirella now appears to be a pair of displaced pleurosaur-like premaxillae. For Pleurosaurus I should not have trusted a prior line drawing by another worker. Here I used DGS to create what appears to be a more accurate skull without so many apparent autapomorphies.

References
Jalil N 1990. Sur deux cranes de petits Sauria (Amniota, Diapsida) du Trias moyen d’ Algerie. Comptes Rendus de I’ Academic des Sciences, Paris 311 :73 1- 736.
Jalil N-E 1997. A new prolacertiform diapsid from the Triassic of North Africa and the interrelationships of the Prolacertiformes. Journal of Vertebrate Paleontology 17(3), 506-525.
Lehman JP 1971. Nouveaux vertebres du Trias de la Serie de Zarzai’tine. Annales de Paleontologic (Vertebres) 57 :71-93.

 

 

SVP 19 – Something vague about a new clade: “Archelosauria”

Pritchard 2015
provides a teaser abstract that sets up the situation, but provides no solution.

From the abstract
“Since the earliest Triassic, saurian reptiles have been critical components of terrestrial ecosystems. However, molecular and fossil evidence indicates that the divergence between the two constituent lineages (Lepidosauria, Archelosauria [turtles + archosaurs]) took place deep in the Permian Period. A large number of early-diverging stem-archosaur and stemlepidosaur clades have been described from the Permian and Triassic, exhibiting an extraordinary range of bauplans. However, the interrelationships of these stem taxa are poorly resolved, owing to fragmentary records and poor preservation in many groups. As such, the timing of both the initial taxonomic and morphological diversifications of Sauria remain poorly understood. To resolve this phylogenetic uncertainty and the first radiation of crown reptiles, a new phylogenetic data matrix was constructed from a broad sample of Permo-Triassic diapsids. New, three-dimensionally preserved fossils from a number of poorly understood stem groups (e.g., long-necked Tanystropheidae, chameleon-like Drepanosauromorpha) allowed coding of many previously unknown morphologies. Iterations of this data matrix were subjected to both standard parsimony analysis and Bayesian tip-dating methodologies. The results of this analysis suggest that at least ten distinct lineages of Permo-Triassic diapsids survived the PTE, substantially more than went extinct at that time. They do not form a monophyletic Protorosauria clade, a group traditionally considered to include most long-necked, small-headed early archosauromorphs. Instead, these taxa include no fewer than six separate Permo-Triassic diapsid lineages. Indeed, character optimizations strongly suggest that a long-necked, lizard-like bauplan was ancestral for Archosauromorpha. The inclusion of fragmentary fossil material from Early Triassic archosauromorphs indicates that a great deal of morphological diversity existed in saurian groups within the first five million years of the Triassic.**”

*Archelosauria is not recovered in the large reptile tree. Not sure why the molecules do what they do, nesting turtles with archosaurs (hence the clade name).
** This is a teaser abstract. No conclusions are presented. I cannot compare the data here to the cladogram recovered in the large reptile tree.

References
Pritchard A 2015. Resolving the first radiation of crown reptiles. Journal of Vertebrate Paleontology abstracts

SVP 20 – a Euryodus (microsaur) -like captorhinid, Opisthodontosaurus

We looked at this taxon, Opisthodontosaurus, earlier here.
Reisz et al. 2015 describe a captorhinid basal reptile similar to a microsaur.

Figure 1. Opisthodontosaurus (above) with missing bones in color. Black lines represent the referred specimen, OMNH 77470 scaled to fit the holotype, OMNH
77469, here in ghosted lines. Colors represent missing bones.

From the abstract
“The Lower Permian fossiliferous infills of the Dolese Brothers Limestone Quarry, near Richards Spur, Oklahoma, have preserved the most diverse assemblage of terrestrial vertebrates, including small-bodied reptiles, lepospondyl microsaurs, and dissorophoid temnospondyls. One taxon that was previously only known from isolated jaw elements at the locality was the microsaur Euryodus primus. Although it is known from more complete material elsewhere, other remains of E. primus have remained elusive at the Dolese Brothers Quarry.

Figure 1. Euryodus primus, a microsaur nesting between Scincosaurus and Micraroter. Note the odd posterior canine teeth, much more exaggerated than in Opisthodontosaurus.

The recent discovery of partial articulated skulls and skeletons of a small reptile at Dolese permits the recognition that the dentigerous elements that were previously assigned to Euryodus primus from this locality belong instead to a new captorhinid eureptile. The new captorhinid represents a major departure from other members of this clade in the unique anatomy of its jaws and dentition, which are characterized by their bulbous maxillary and dentary teeth. Three enlarged teeth are present on the maxilla, one in the anterior and two in the posterior region, whereas the premaxillary dentition is homodont and small. In addition, the largest dentary tooth is present along the posterior half of the bone. The dentary is characterized by the presence of a large well-developed coronoid process and deep lateral excavation in the posterior one-quarter of the bone. A phylogenetic analysis of captorhinid eureptiles yields two most parsimonious trees, with one in which the new captorhinid is recovered as the sister taxon to Concordia, this clade in turn being the sister to all other captorhinids, and a second in which the new captorhinid is the sister to all other derived captorhinids, to the exclusion of Concordia and Thuringothyris“

The sisters to captorhinids
also include Saurorictus (actually a basal captorhinid), Romeria primus, Reiszorhinus and Cephalerpeton in the large reptile tree, none of which have enlarged posterior teeth. Cephalerpeton had a complete set of enlarged maxillary teeth with an oddly raised posterior dentary, below the orbit. All of these taxa have a much taller squamosal and a much smaller suptratemporal. The postorbital and postfrontal are triangular. None of these taxa have a dentary with a deep lateral excavation, but otherwise are all quite similar to microsaurs.

Unique among microsaurs
Euryodus is rather unique among microsaurs with its enlarged posterior teeth. So the headline of Reisz, Leblanc and Scott is a little misleading. The large reptile tree nests Euryodus in a separate clade (Microsauria) from Opisthodontosaurus (with Cephalerpeton).

References
Reisz R, Leblanc A and Scott D 2015. A new early Permian captorhinid reptile (Amniota: Eureptilia) from Richards Spur, Oklahoma, shows remarkable dental and mandibular convergence with microsaurs.

New Origin of Birds YouTube Video

Just in time for Turkey Day!
We’ve seen a lot of data coming in recently with news on Archaeopteryx and reconstructions of basal birds together with their addition to the large reptile tree. In an attempt at simplifying the evolutionary process, here is a YouTube video of < 6 minutes that pulls the origin and evolution of basal birds together based on the cladogram recovered at ReptleEvolution.com.

Click to view YouTube video.

Happy Thanksgiving
to my USA readers.

New ichthyosaur family tree by Ji et al. 2015

A recent paper on ichthyosaur systematics
(Ji et al. 2015, Fig. 1) adds newly discovered taxa and the tree is getting nice and big.

Unfortunately,
at the base of their cladogram Ji et al. place a distinctly different proximal outgroup for ichthyosaurs than what was recovered in the large reptile tree (subset shown in Fig. 1, click to enlarge). They appear to be guessing. Apparently they are not sure how ichthyosaurs are related to other reptiles.

Here 
proximal outgroup taxa for ichthyosaurs include Wumengosaurus, Thaisaurus and Xinminosaurus (in ascending order) not Thadeosaurus. These large reptile tree taxa demonstrate a gradual accumulation of basal ichthyosaur traits. The Ji et al taxa, Hovasaurus, Claudiosaurus and Thadeosaurus do not. In the large reptile tree these three are basal younginiformes, related, yes, but much more distantly related to ichthyosaurs.

Figure 1. Click to enlarge. Ichthyosaur family trees compared. Left: subset of the large reptile tree. Right: from Ji et al. 2015. Note the lack of correct outgroups in the Ji et al study. They have no idea which taxa are proximal ancestors. Yellow are taxa found in both trees.

Figure 1. Subset of the LRT focusing on the clade Ichthyosauria updated November 4, 2018 with a shift of the Hupehsuchidae closer to the base of the Ichthyosauria.

So, as an experiment, 
we’ll delete the large reptile tree proximal outgroup taxa in order to match more closely the Ji et al taxon list. What is recovered now?

1. Hovasaurus, Claudiosaurus and Thadeosaurus now nest together in an outgroup clade.
2. Hupehsuchus + Xinminosaurus, Grippia and (Utatsusaurus + (Shastasaurus  pacificus + Shastasaurus alexandrae) now form clades at the base of the Ichythyosauria.
3. Then Chaohusaurus nests at the base of the rest of the Ichthyosauria with the same topology as the subset of the large reptile tree.

A few differences between the two topologies without deletions…
Note the morphological mismatches in the Ji et al. topology not found in the large reptile tree.

1. In the large reptile tree Chaohusaurus nests between two similar taxa, Parvinatator and Besanosaurus. In the Ji et al. tree Chaohusaurus nests between the mismatched and odd Hupehsuchus and a clade of basal ichthyosaurs as the basalmost ichthyosaur, even though it has a derived ichthyosaur shape and traits.
2. In the large reptile tree the derived, but still Triassic, Cymbospondylus petrinus nests between its contemporary, Mixosaurus and several other giant serpentine ichthyosaurs. All have a depressed cranium with a central ridge. The unrelated flat-headed C. buchseri nests elsewhere with similar deep-bodied, high-crested Shonisaurus popularis. By contrast, in the Ji et al. tree C. piscosus (= petrinus) and C. buchseri nest together with the very primitive, very small, Xinminosaurus, which does not have such a depressed cranium with a central crest.
3. Ji et al. have a clade of Shastasauridae that includes only shastasaurs. In the large reptile tree, that clade also includes the odd little hupehsuchids and demonstrates how these little toothless enigmas evolved from larger forbearers. Ji et al. provided several skull reconstructions. Perhaps a few more would help to resolve the distinct topologies.

Those are the major issues.
The rest can be swept up later. I’d like to see the authors either expand their own taxon list or work off the large reptile tree to confidently establish a series of outgroup taxa for the Ichthyosauria that actually demonstrate a gradual accumulation of character traits, instead of doing what they did. Then we might have closer correspondence in tree topology. And we’re going to have to figure out Cymbospondylus… is it derived? or primitive?

References
Ji C, Jiang D-Y,  Motani R, Rieppel O, Hao -C & Sun Z-Y 2015. Phylogeny of the Ichthyopterygia incorporating recent discoveries from South China, Journal of Vertebrate Paleontology, DOI: 10.1080/02724634.2015.1025956

SVP 18 – the pelycosaur Dimetrodon via Dr. Robert Bakker

Bakker et al (2015)
show evidence that Dimetrodon (Fig. 1) fed on aquatic prey as there were too few terrestrial reptilian herbivores to sustain their numbers.

Figure 1. Dimetrodon, a sailback pelycosaur synapsid reptile of the Early Permian.

From the abstract
“In restorations, Dimetrodon often appear feeding upon large land herbivores, e.g., Diadectes and Edaphosaurus. 􀁄􀁑􀀃􀁄􀁏􀁗􀁈􀁕􀁑􀁄􀁗􀁌􀁙􀁈􀀃􀁙􀁌􀁈􀁚􀀏􀀃􀀲􀁏􀁖􀁒􀁑􀂶􀁖􀀃􀀤􀁔􀁘􀁄􀁗􀁌􀁆􀀃􀀩􀁒􀁒􀁇􀀃 Base Theory (AFBT) recognizes non-terrestrial prey as key for dimetrodont food webs. Over 45% of the bones are severely tooth-marked; ubiquitous shed Dimetrodon teeth are mingled with tooth-marked bones in every depositional unit. The CBB lacks any structures that indicate high current energy, so the hydraulic forces probably did not wash in bones from beyond the trough, though bloated whole carcasses could have floated in. There are 39 Dimetrodon, one each of the large herbivores Edaphosaurus and Diadectes, three of the large non-herbivore, non-apex carnivore Secodontosaurus, and three of the semi-terrestrial amphibian Eryops calculated form postcrania. Did benthic amphibians and fish fill the gap in prey? The benthic amphibian Diplocaulus is abundant in every bone-rich unit. Xenacanth sharks are very common in several layers; each shark carried a large, well ossified head spine. AFBT is corroborated: dimetrodonts fed intensively on aquatic prey at the CBB.”

Combine this with what we know of Spinosaurus, and finback reptiles appear to have been largely aquatic in habitat. That’s heresy joining the mainstream.

There is also a good Dimetrodon video (52 min.)
on YouTube featuring Dr. Bakker as he describes how the vast majority of Dimetrodon tails are missing, neatly cut and probably carried away for their meat (because that’s where the most of it is!) by other Dimetrodons.

References
Bakker RT et al. 2015. Dimetrodon and the earliest apex predators: The Craddock bone bed and George Ranch Facies show that aquatic prey, not herbivores, were key food sources. Journal of Vertebrate Paleontology abstracts.

Jim Hopson (U. Chicago) awarded Romer-Simpson Medal

Jim Hopson, Professor Emeritus, University of Chicago, honored with the Romer-Simpson medal at the Dallas 2015 meeting of the Society of Vertebrate Paleontology. Well deserved.

I’m happy to report
that Jim Hopson has been awarded the highest honor the Society of Vertebrate Paleontology can bestow, the Romer-Simpson Medal for a lifetime of achievement.

Hopson focused his research
on the origin of mammals. His work indicated that mammals descended from a single lineage of mammal-like reptiles. His work on tooth replacement in mammal-like reptiles was one of the first to show that growth patterns and dental anatomy can be used to study these extinct species.

On the side
Hopson served as the expert editor for my book, “From the Beginning, the Story of Human Evolution” (Peters 1991). Shortly thereafter, in the late 80s Dr. Hopson was kind enough to host my field trip to Chicago. He showed me the collections there and at the Field Museum. Dr. Hopson also provided reams of photocopies of his work on synapsids. Much of that went into the book, which remains largely accurate today. You can read the book online in PDF form here.

From the Beginning – The Story of Human Evolution published by Little Brown in 1991 and is now available as a FREE online PDF from DavidPetersStudio.com by clicking here.

However, the latest
cladograms and basal mammal studies can be found at ReptileEvolution.com.

Read more
about Jim Hopson and his contributions to vert paleo here.

A note about the Liaoning bird embryo from a few days ago…
Dr. Zhou was kind enough to send a high resolution image of the specimen and I have updated the imagery and conclusions posted here on the Liaoning bird embryo. In short, the embryo now nests with the holotype (London specimen) of Archaeopteryx, which nested and still nests as a basal enantiornithine bird. Happily, this analysis confirms both the original identification of the embryo as an enantiornithine, AND a close relationship to Archaeopteryx. 

High resolution will get you there,
but low resolution can still get you close…

 

Triassic gastric pellet semi-reconstructed, better this time…

A while back
Dalla Vecchia, Wild and Muscio (1989) described a small pellet (MFSN 1891, Fig. 1) of Late Triassic bones from the Dolomia di Forni Formation of Firuli (NE Italy) as a small jumble of pterosaur bones. They tentatively referred it to Preondactylus, the only pterosaur known at the time from that formation. This was an early work for all three paleontologists.

Following the original paper
Earlier I attempted a reconstruction of the elements based on the pterosaur model. I recognized then that it didn’t turn out too well. I was working from the original drawings. Now new data has been published and a new hypothesis has been put forth that makes much more sense.

Figure 1. Several views of the Triassic gastric pellet formerly considered pterosaurian, but now considered langobaridsaurian. Elements from a surface photo, a microCT scan of the opposite side still buried in matrix, and DGS colors. Not all bones have been colored here, but employed colors are assembled in figure 2. The long cervical at upper left is 1 cm long. So is the scale bar. The pellet is about 5 cm wide.

Recently 
Holdago et al. (2015) redescribed the pellet in much greater detail using microCT acquisition. They concluded “The best candidate for the pellet is not a pterosaur, but a protorosaurian like Langobardisaurus.  Therefore, the skeletal remains could belong to a still unknown small reptile with procoelous dorsal vertebrae, rather elongate and probably procoelous cervical vertebrae with low neural arch and spine, filiform cervical ribs, at least some dicephalous dorsal ribs, elongated and hollow limb bones, and no osteoderms.”

They did not attempt a reconstruction,
so I do so here (Fig. 2) following the hypothesis that the elements belong to a langobardisaur (contra Holdgago, et al., not a protorosaur but a tritosaur lepidosaur).

Figure 2. The elements of MFSN 1891 assembled to form a langobardisaur in a bipedal pose. Some langobardisaurs have a very long neck, slender limbs and a short tail. Lots of guesswork here.

Lots of guesswork here. 
Everything is tentative. The toes could be ribs. Lots of slivers and scraps left over. More complete langobardisaurs (Fig. 3) have 8 cervicals, but they are related to tanystropheids, with 13 cervicals. Renesto et al. (2002) considered langobardisaurs as likely facultative bipeds in the manner of the many extant facultative bipedal lizards, all with sprawling hind limbs.

Figure 3. Langobardisaurus tonneloi reconstructed. Note the cosesaur-like pectoral girdle.

MFSN 1891 needs to be dissembled
in high resolution, then reassembled like a puzzle. I’d like to help if possible. Here (Fig. 2) is a first draft lo rez example leading to others of greater detail in the future. Worthwhile taking another look at the pes (Fig. 3) which greatly resembles a basal pterosaur pes with that elongate p5.1. It resembles a pterosaur pes because these two taxa are related (Peters 2000).

Figure 4. Click to view full scale on a 72 dpi screen. Tanystrachelos compared to the gastric pellet lepidosaur. The large hemal arches on the gastric pellet are the genesis of the paddle-like hemal arches on Tanytrachelos and Tanystropheus.

Compared to the tritosaur Tanytrachelos (Fig. 4)
the gastric pellet reptile has a similar number of cervicals, but longer limbs and longer cervicals. Are we seeing the origin of Tanystropheus (Fig. 5) here? Or a hatchling? The large hemal arches appear to have homologs in Tanytrachelos and Tanystropheus.

Figure 5. Tanystropheus and kin going back to Huehuecuetzpalli. Two scales here, one yellow, one white.

Then we have Fuyuanssaurus, 
a tiny tanystropheid (Fig. 6) about twice the size of the gastric pellet reptile. Unfortunately we don’t know if it was long-legged or not. Notably the skull elements of Fuyuansaurus, which we looked at earlier here were all quite slender. This is the model we should use for the gastric pellet lizard until data suggests another model.

Figure 6. Click to enlarge. Reconstruction of Fuyuanasaurus. Fraser et al. identified a strange circular object as the pubis, but no sister taxa have a circular pubis. Here it is tentatively ID’d as an egg because a standard pubis is found nearby.

References
Dalla Vecchia FM, Wild R and Muscio G 1989. Pterosaur remains in a gastric pellet from Upper Triassic (Norian) of Rio Seazza valley (Udine, Italy). Gortania 10: 121–132.
Holgado B, Dalla Vecchia FM, Fortuny J, Bernardini F and Tuniz C 2015. A Reappraisal of the Purported Gastric Pellet with Pterosaurian Bones from the Upper Triassic of Italy. PLoS ONE 10(11): e0141275. doi:10.1371/journal.pone.0141275
Peters D 2000. A Redescription of Four Prolacertiform Genera and Implications for Pterosaur Phylogenesis. Rivista Italiana di Paleontologia e Stratigrafia 106 (3): 293–336.
Renesto S, Dalla Vecchia FM, Peters D. 2002. Morphological evidence for bipedalism in the Late Triassic prolacertiform reptile Langobardisaurus. In: Gudo M, Gutmann M, Scholz J, editors. Concepts of functionalengineering and constructional morphology: biomechanical approaches on fossil and recent organisms. Senckenb Lethaea 82(1): 95–106.

 

Data denial you can listen to on a podcast

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 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).

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

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.

Liaoning bird embryo IS a Chinese Archaeopteryx

Updated 11/22/2015 with high rez data sent by Dr. Zhou. A new analysis nests the embryo with the holotype Archaeopteryx lithographica, the London specimen, a basal enantiornithine bird. 

Zhou and Zhang (2004)
described a small, precocial, final stage bird embryo from the Liaoning Province (Early Cretaceous, 121mya, IVPP V14238). Strangely, no eggshell was preserved (Fig. 1), but the tucked shape of the embryo indicated that it had not yet hatched. Northern China was a forested landscape dominated by active volcanoes and sprinkled with lakes and streams at the time. No adults were closely associated, but enantiornithine birds are common in that formation.

Figure 1. Click to enlarge. Liaoning bird embryo IVPP V14238 reconstructed Egg tracing in DGS compared to original tracing (in olive). Note the universally observed long tail and the continuation of the tail vertebrae past the back of the skull. Note the broken clavicles. When rotated they form more of a U shape with appropriate spacing of the coracoids. The dorsal coracoid is a convex and the ventral scapula is concave, an enanthiornithine key trait.

The Zhou and Zhang Abstract
“An embryo of an enantiornithine bird has been recovered from the Lower Cretaceous rocks of Liaoning, in northeast China. The bird has a nearly complete articulated skeleton with feather sheet impressions and is enclosed in egg-shaped confines. The tucking posture of the skeleton suggests that the embryo had attained the final stage of development. The presence of well-developed wing and tail feather sheets indicates a precocial developmental mode, supporting the hypothesis that precocial birds appeared before altricial birds.”

Figure 2. The Liaoning bird egg IVPP V14238 in situ with DGS tracing in color. This hirez version updates a prior lo rez version. Length of shell is 3.5 cm.

Zhou and Zhang 
did not create a reconstruction (Fig.1) nor attempt to untuck the embryo. Bird embryos shift into a tuck position before hatching as they begin to occupy most of the egg. No egg tooth is present on this specimen.

Figure 3. The Liaoning embryo compared to its closest sister, the London specimen of Archaeopteryx (holotype). The egg is the correct size to pass through the ischia if they were separated distally. like modern birds,

Zhou and Zhang report [with my observations in brackets]:
“The embryo has several enantiornithine apomorphies such as a strutlike coracoid with a convex lateral margin [yes], a V-shaped furcula [maybe], metacarpal III extending well past metacarpal II distally  [no], and metatarsal IV being more slender than metatarsals II or III [no].“ My observations were improved with a high resolution image (Fig. 2). The Liaoning embryo nests with the holotype Archaeopteryx (London specimen), which nests at the base of the Enantiornithes.

This is the first
Cretaceous avian embryo preserved with feathers, sheathed, not open vanes. These indicate the embryo was precocial, able to move and feed independently shortly after hatching. This specimen demonstrates that the genus Archaeopteryx survived into the Early Cretaceous.

Figure 4. The Liaoning embryo bird nests with several Archaeopteryx specimens in the large reptile tree, AND with enanthiornithes. The large reptile tree does not specifically test for the classic enantiornithine traits, but correctly nested the embryo with adult enantiornithines.

Compare this bird embryo to a precocial pterosaur embryo or three
like Pterodaustro, the IVPP embryo or the JZMP embryo. Embryo pterosaurs have the proportions of an adult. They grow isometrically. Hatchling birds, like the Liaoning embryo, had juvenile proportions with a large head, short tibia and short metatarsus. They grew allometrically, but not as allometric as living altricial (helpless) bird hatchlings.

“Several previously known theropod embryos and the late Cretaceous avian embryos all seem to be preocial animals, judged purely from skeletal evidence,” Zhou said.

Nat Geo
reported, “Zhou said several other enantiornithine species are known from the deposit where the latest fossil was found, but that it was difficult to link the embryo to a specific genus or species.” Unfortunately Zhou and Zhang eyeballed the embyro. They did not attempt a phylogenetic analysis (Fig. 4).

Kevin Padian
quoted in NatGeoOnline noted that half of the fossil’s characteristics are not exclusive to enantiornithines. He added that characteristics that would identify the fossil an enantiornithine are “either dubious or not well preserved on the specimen. But then, what else could it be?” Padian asked. I agree, but then neither of us has seen the fossil first hand.

Figure 4.  A selection of Enanthiornithine birds to scale. None of these nest closer to the Liaoning embryo. These taxa all have a shorter tail and a more gracile clavicle and other traits listed in the large reptile tree.

Others have warned me
that juveniles and embryo reptiles, like pterosaurs and tritosaurs, cannot be added to phylogenetic analyses because they tend to nest with other adults*. Actually I’d like to see that happen. At present I’m a skeptic. This was a test of that hypothesis, but it was done with a precocial embryo with a relatively larger head, shorter neck and shorter limbs. I don’t see the problem with adding this embryo (Fig. 1) or precocial pterosaur embryos to analyses. But I’m willing to listen to good arguments with valid data.

*Bennett (2006) considered small adult pterosaurs as juveniles of larger germanodactylids based on long bone lengths rather than phylogenetic analysis. Eyeballing, charts and clouds of data points are no replacements for reconstructions and phylogenetic analysis. Hope you agree…

If this is an enantiornithine
which one is it most like? Archaeopteryx lithographica.

If this is an archaeopterygid
we now have some more ontogenetic clues and patterns to work with. You can see (Fig. 1) which body parts get larger and which get smaller during maturation.

Actually it’s both!

References
Bennett SC 2006. Juvenile specimens of the pterosaur Germanodactylus cristatus, with a review of the genus. Journal of Vertebrate Paleontology 26:872–878.
Zhou Z and Zhang F-C 2004. A Precocial Avian Embryo from the Lower Cretaceous of China. BREVIA Science 22 October 2004: 306 no. 5696 p. 653. DOI: 10.1126/science.1100000. online abstract here

NatGeoOnline