A new look at Jidapterus (basal azhdarchid pterosaur)

Wu, Zhou and Andres 2017
bring us long anticipated details on Jidapterus (Early Cretaceous, Dong, Sun and Wu 2003) which was previously presented as a small in situ photograph lacking details. Even so a reconstruction could be made (Fig. 1). Coeval larger tracks (Elgin and Frey 2011) have been matched to that reconstruction.

Figure 2. Jidapterus matched to the Gansu, Early Cretaceous pterosaur tracks. The trackmaker was one-third larger than the Jidapterus skeleton.

Figure 1. Jidapterus matched to the Gansu, Early Cretaceous pterosaur tracks. The trackmaker was one-third larger than the Jidapterus skeleton.

Of interest today
is the fact that Jidapterus was originally and, so far, universally considered toothless. Its specific name, J. edentatus, refers to that condition. Wu, Zhou and Andres 2017 produced tracings (Figs. 2, 3) of the rostrum that are also toothless. However, they are crude and appear to miss the premaxilla and maxilla sutures, the palatal elements… and maybe some teeth. Those jaw rims are not slippery smooth like those of Pteranodon. Outgroups in the large pterosaur tree (LPT), all have tiny teeth.

Figure 2. Rostrum of Jidapterus (RCPS-030366CY) and traced according to Wu et al. and colorized using DGS to reveal skull sutures and possible teeth.

Figure 2. Rostrum of Jidapterus (RCPS-030366CY) and traced according to Wu et al. and colorized using DGS to reveal skull sutures and possible teeth. See figure 3 for details. What Wu, Zhou and Andres label the  “low ridge of rostrum” is here identified as the rostral margin above the palatal portion. 

The cladogram of Wu, Zhou and Andres
lacks dozens of key taxa found in the LPT that separate azhdarchids from convergent tapejarids and shenzhoupterids. In the LPT giant azhdarchids arise from tiny toothy azhdarchids once considered Pterodactylus specimens… and these, in turn are derived from tiny and mid-sized dorygnathids in the Middle Jurassic.

What Wu, Zhou and Andres label the  “low ridge of rostrum”
is here identified as the rostral margin rim at the edge of the palate.

Figure 3. Focus on the rostral tip of Jidapterus shown in figure 2. Are these teeth?

Figure 3. Focus on the rostral tip of Jidapterus shown in figure 2. Are these teeth? You decide. I present the data. 

As in all pterosaurs
each premaxilla of Jidapterus has four teeth according to this data.

Are these tiny teeth?
Or are they tiny occlusions and/or chisel marks. Let’s get even better closeups to figure this out. Phylogenetic bracketing indicates either tiny teeth or edentulous jaws could be present here.

References
Dong Z, Sun Y and Wu S 2003. On a new pterosaur from the Lower Cretaceous of Chaoyang Basin, Western Liaoning, China. Global Geology 22(1): 1-7.
Elgin and Frey 2011. A new azhdarchoid pterosaur from the Cenomian (Late Cretaceous) of Lebanon. Swiss Journal of Geoscience. DOI 10.1007/s00015-011-0081-1
Wu W-H, Zhou C-F and Andres B 2017. The toothless pterosaur Jidapterus edentus (Pterodactyloidea: Azhdarchoidea) from the Early Cretaceous Jehol Biota and its paleoecological implications. PLoS ONE 12(9): e0185486.

wiki/Jidapterus

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Vesperopterylus (aka: Versperopterylus, Lü et al. 2017) did not have a reversed first toe

And this specimen PROVES again
that anurognathids DID NOT have giant eyeballs in the anterior skull.

Figure 1. Vesperopterylus in situ. There is nothing distinct about pedal digit 1.

Figure 1. Vesperopterylus in situ. There is nothing distinct about pedal digit 1.

Lü et al. 2017 bring us a new little wide-skull anurognathid
Vesperopterylus lamadongensis (Lü et al. 2017) is a complete skeleton of a wide-skull anurognathid. It was considered the first pterosaur with a reversed first toe based on the fact that in digit 1 the palmar surface of the ungual is oriented lateral while digis 2–4 the palmar surfaces of the unguals are medial. That is based on the slight transverse curve of the metatarsus (Peters 2000) and the crushing which always lays unguals on their side. In life the palmar surfaces were all ventral and digit 1 radiated anteriorly along with the others.

Figure 2. Vesperopterylus reconstructed using original drawings which were originally traced from the photo. Manual digit 4.4 is buried beneath other bones and reemerges to give its length. Pedal digit 1 turns laterally due to metacarpal arcing and taphonomic crushing. There is nothing reversed about it. 

Figure 2. Vesperopterylus reconstructed using original drawings which were originally traced from the photo. Manual digit 4.4 is buried beneath other bones and reemerges to give its length. Pedal digit 1 turns laterally due to metacarpal arcing and taphonomic crushing. There is nothing reversed about it.

Lü et al were unable to segregate the skull bones.
Those are segregated by color here using DGS (Digital Graphic Segregation). See below. Some soft tissue is preserved on the wing. Note: I did not see the fossil first hand, yet I was able to discern the skull bones that evidently baffled those who had this specimen under a binocular microscope. Perhaps they were looking for the giant sclerotic rings in the anterior skull that are not present. Little ones, yes. Big ones, no.

Figure 1. Vesperopterylus skull with bones identified by DGS (digital graphic segregation). Lü et al. were not able to discern these bones and so left the area blank in their tracing. Note the complete lack of a giant eyeball in the front of the skull. Radius and ulna were removed for clarity and to show a complete lack of giant eyeballs (sclerotic rings) in the anterior skull. 

Figure 1. Vesperopterylus skull with bones identified by DGS (digital graphic segregation). Lü et al. were not able to discern these bones and so left the area blank in their tracing. Note the complete lack of a giant eyeball in the front of the skull. Radius and ulna were removed for clarity and to show a complete lack of giant eyeballs (sclerotic rings) in the anterior skull.

This skull reconstruction
(Fig. 4) is typical of every other anurognathid, because guesswork has been minimized here. After doing this several times with other anurognathids, I knew what to look for and found it. No giant sclerotic rings were seen in this specimen.

Figure 4. Vesperopterylus skull reconstructed from color data traced in figure 3.

Figure 4. Vesperopterylus skull reconstructed from color data traced in figure 3. Due to the angled sides of the skull some foreshortening was employed  to match those angles. Original sizes are also shown.

With regard to perching
all basal pterosaurs could perch on branches of a wide variety of diameters by flexing digit 1–4 while extending digit 5, acting like a universal wrench (Peters 2000, FIg. 5). This ability has been overlooked by other workers for the last two decades,

Figure 1. The pterosaur Dorygnathus perching on a branch. Above the pes of Dorygnathus demonstrating the use of pedal digit 5 as a universal wrench (left), extending while the other four toes flexed around a branch of any diameter and (right) flexing with the other four toes. As in birds, perching requires bipedal balancing because the medially directed fingers have nothing to grasp.

Figure 1. The pterosaur Dorygnathus perching on a branch. Above the pes of Dorygnathus demonstrating the use of pedal digit 5 as a universal wrench (left), extending while the other four toes flexed around a branch of any diameter and (right) flexing with the other four toes. As in birds, perching requires bipedal balancing because the medially directed fingers have nothing to grasp.

I have not yet added Vesperopterylus
to the large pterosaur tree.

References
Lü J-C et al. 2017. Short note on a new anurognathid pterosaur with evidence of perching behaviour from Jianchang of Liaoning Province, China. From: Hone, D. W. E., Witton MP and Martill DM(eds) New Perspectives on Pterosaur Palaeobiology.
Geological Society, London, Special Publications, 455, https://doi.org/10.1144/SP455.16
Peters D 2000. Description and Interpretation of Interphalangeal Lines in Tetrapods. 
Ichnos, 7: 11-41

 

Smallest Pteranodon: Bennett 2017

Figure 1. The new small Pteranodon wing, FHSM 17956, compared to Ptweety and the adult NMC41-358 specimen.

Figure 1. The new small Pteranodon wing, FHSM 17956, compared to Ptweety and the adult NMC41-358 specimen. At half the size of the adult, the FHSM specimen would have been 4x the size of a hatchling.

A new small partial wing specimen of Pteranodon
discovered by Glen Rockers, was described by Bennett 2017 (Figs. 1-4). It is virtually identical to similar bones in Ptweety (Fig. 1), a specimen now lost to science and half the size of the Triebold specimen NMC41-358, which is similarly gracile. Click here to see more robust Pteranodon adults compared to the new small FHSM specimen.

Figure 2. FHSM 17956 compared to Ptweety. They are virtually identical, though Ptweety looks like a juvenile of a more robust variety of Pteranodon, thus a younger specimen because adults would be larger.

Figure 2. FHSM 17956 compared to Ptweety. They are virtually identical, though Ptweety looks like a juvenile of a more robust variety of Pteranodon, thus a younger specimen because adults would be larger.

Young (small) Pteranodon specimens
were essentially unknown prior to the Bennett paper. So this is important news.

Figure 2. Small Pteranodon, FHSM 17956, carpus insitu and reconstructed. Here several bones were reidentified.

Figure 3. Small Pteranodon, FHSM 17956, carpus insitu and reconstructed. Here several bones were reidentified. See reconstruction in figure 3. It demonstrates that all the newly identified parts fit together.

Unfortunately
a reconstruction based on Digital Graphic Segregation (DGS, Fig. 4) shows that Bennett, widely known as THE expert on Pteranodon going back to his PhD thesis, misidentified several carpal bones here. In his defense, that was easy to do. The distal carpal is beneath the other carpal bones and it has splinters that extend beyond it. Rather than using DGS, Bennett chose to outline bones the old fashioned way. This leads to problems that can be solved when you color each bone and bone splinter THEN test your colors with a reconstruction. Bennett provided no reconstruction that tested his outline tracings. Bennett also overlooked manual digit 5. The fragment (FR) probably comes from the crushed and splintered distal carpal. Bennett reported, “All carpal elements are severely deformed by compression such that they preserve little of their original morphology…” That’s because he misidentified elements that are otherwise identical to those of adult specimens.

Figure 3. Small Pteranodon (FHSM 17956) carpus reconstructed after several bones were reidentified.

Figure 4. Small Pteranodon (FHSM 17956) carpus reconstructed after several bones were reidentified.

 

Bennett also upholds several invalid paradigms

  1. Other small, short crested Pteranodon specimens represent young ones. Actually they represent taxa closer to the outgroup, Germanodacytylus
  2. Short-crested specimens are females. No male/female pairs have ever been documented. Rather short-crested taxa are closer to the crestless outgroup. 
  3. Large pelvis specimens  are females. No, they are large nyctosaurs. 
  4. Small size Rhamphorhynchus were juveniles of larger ones. No, phylogenetic analysis indicates a period of phylogenetic miniaturization followed the genesis of Rhamphorhynchus from larger Campylognathoides ancestors. Bone histology would include juvenile bone tissue in adults of these small, precocial and fast-breeding taxa. It is important that someday Bennett runs a phylogenetic analysis, something he told me decades ago was critical to understanding taxonomy. 
  5. There is no such thing as manual digit 5 in pterosaurs. He overlooked it here. 

Bennett now realizes:
“A new juvenile specimen of Pteranodon collected from the Smoky Hill Chalk Member is so small that it challenges the interpretation of rapid growth to large size before flying and feeding (Bennett, 2014a).” As everyone knows now, hatchling pterosaurs were able to fly shortly after hatching. To his credit, Bennett continues, “The interpretation of rapid growth while under parental care is rejected.”

Bennett examined the specimen under stereo microscope
and made mistakes here re-identified on a computer monitor applying colors to each bone to visually segregate one from another and facilitate accurate reconstruction. This is something that cannot take place using old-fashioned stereo microscopes.

Bennett occasionally
misidentifies small pterosaur bones. This was documented here dealing with the flat-headed anurognathid SMNS 81928, in which he considered the mandible a giant sclerotic ring in the front half the skull, different from all other pterosaurs. Bennett 2008 promoted an invalid hypothesis on the origin of the pterosaur wing based on imagination rather than taxa, documented here. Bennett’s (2007) interpretation of pteroid articulation against the preaxial carpal. was invalidated by Peters 2009 who nested it on the anterior radiale (Fig. 4).

Note
The extensor tendon process is articulated with the rest of m4.1, as in all Pteranodon specimens. Bennett once considered unfused  extensor tendon processes a sign of immaturity. This is not correct. As reported earlier, since pterosaurs are lepidosaurs they display lepidosaur fusion traits, typically not ontogenetic, but phylogenetic. As an example, in Nyctosaurus the extensor tendon process remains unfused, distinct from Pteranodon. Bennett insists that the extensor tendon process in the juvenile specimen is unfused but notes that the fragile cortical bone was lost during preparation. And just think about it.. the carpals, typically wrapped tightly in ligaments were scattered while the extensor tendon process didn’t move during taphonomy. By contrast, in Nyctosaurus the extensor tendon process popped off before the toes disarticulate.

Bennett avoid mentioning or citing
work by Peters 2009, which disputed Bennett 2007, who articulated the pteroid with the preaxial carpal. In order to do so, Bennett 2017 did not cite Bennett 2007, but did manage to cite nearly every other one of his papers. Kids.. sometimes you have to look for what’s not mentioned.

Pteranodon variety
is best seen and appreciated by direct comparison of the skulls and the post-crania. FHSM 17956 is a juvenile of a gracile form, similar to the Triebold specimen NMC41-358 (Fig. 1), a short-crested gracile variety. By contrast, Ptweety appears to be more similar to the more robust long-crested taxa. 

Bennett describes ontogenetic niches
for hatchling, juvenile and adult Pteranodon. This is necessary for 8x smaller hatchlings incapable of handling adult-sized prey.

In Bennett’s Acknowledgements he reports, 
“Constructive reviews from M. Witton and L. Codorniú led to improvements in the manuscript, and an anonymous reviewer disagreed with everything.” That anonymous reviewer was not me. That would be blackwashing. I always try to find something of value in any manuscript I review, even if I disagree with some of what is presented.

Bennett first described this taxon
in a 2014 SVP abstract. See how long traditional studies take to get published? I was just about to call Chris to see if he was okay. I’m glad to see he is still out there publishing important specimens.

References
Bennett SC 2007. Articulation and Function of the Pteroid Bone of Pterosaurs. Journal of Vertebrate Paleontology 27(4):881–891.
Bennett SC 2008. Morphological evolution of the forelimb of pterosaurs: myology and function. Pp. 127–141 in E Buffetaut and DWE Hone eds., Flugsaurier: pterosaur papers in honour of Peter Wellnhofer. Zitteliana, B28.
Bennett SC 2017. New smallest specimen of the pterosaur Pteranodon and ontogenetic niches in pterosaurs. Journal of Paleontology. pp.1-18. 0022-3360/15/0088-0906
doi: 10.1017/jpa.2017.84
Peters D 2009. A reinterpretation of pteroid articulation in pterosaurs. Journal of Vertebrate Paleontology 29:1327-1330.

Tanystropheus: aquatic? or terrestrial?

Beard and Furrer 2017 conclude (or do they?)
that Tanystropheus (Figs. 1–3) was likely terrestrial.

From the abstract
“The Middle Triassic protorosaur Tanystropheus has been considered as both a terrestrial and aquatic taxon based on several lines of biomechanical and distributional evidence, but determining conclusively which habitat was most likely has remained problematic. The preservation of Tanystropheus was found to be more similar to Macrocnemus than Serpianosaurus implying carcasses of Tanystropheus originated in terrestrial or at least marginal and near-shore, shallow marine settings. That these were also the most probable habitats in life is supported by the relatively lower number of Tanystropheus (and also Macrocnemus) compared to Serpianosaurus.”

Tanystropheus underwater among tall crinoids and small squids.

Figure 1. Tanystropheus in a vertical strike elevating the neck and raising its blood pressure in order to keep circulation around its brain and another system to keep blood from pooling in its hind limb and tail.

Unfortunately,
Tanystropheus was not a protorosaur, nor a member of the Archosauromorpha. It was a tritosaur lepidosaur as taxon inclusion would have informed the authors.

Tanystropheus and kin going back to Huehuecuetzpalli.

Figure 2. Tanystropheus and kin going back to Huehuecuetzpalli.

Unfortunately,
the smaller Tanystropheus considered a juvenile by the authors was probably a different genus, based on a long list of distinct traits, including its distinct teeth. Moreover the authors did not realize that several large putative Tanystropheus specimens have distinct skull morphologies that are not congeneric (Fig. 2). But all that is beside the point…

Figure 2. Tanystropheus with skull reconstructions based on two specimens, exemplar i and exemplar m.

Figure 3. Tanystropheus with skull reconstructions based on two specimens, exemplar i and exemplar m.

The authors report:
“An alternative aquatic lifestyle has also been suggested for Tanystropheus (Tschanz 1988). The main argument is the supposed inflexibility of the neck due to the elongated vertebrae and bundled cervical ribs that prevented all but a horizontal position (Tschanz 1988; Renesto 2005).”

Or any aquatic position,
including vertical (Fig. 1). The authors do cite the hooks from squid suckers found in the stomach region (Wild 1973; Fig. 1) and other prior hypotheses, then describe the taphonomy of the skeletons. The authors cite trackway data matched to Tanystropheus, (Fig. 3) ignoring the fact that even sea turtles leave trackways on beaches when they lay eggs.

Figure 3. Tanystropheus specimens matched to Synaptichnium tracks. The match is good in each case, except for one toe or the other.

Figure 3. Tanystropheus specimens matched to Synaptichnium tracks. The match is good in each case, except for one toe in each trackway. So, is this good enough? Or is this cause for dismissal?

Did the authors test the tracks?
No. But that is done here (Fig. 3). In each case there is a pretty good match—except for one toe in each case. The manus and pes have been scaled to match the tracks and thus are not matched to the scale bars which are for the tracks alone. Even so, the scale for the trackmakers’ extremities is a pretty good match! The case is not rock solid, but pretty good, that big and small tanystropheids made those Synaptichnium tracks.

Taphonomy 
The journey from the biosphere to the lithosphere was investigated. The terrestrial Ticinosuchus, a type of archosauriform, was discovered in these beds along with the aquatic Serpianosaurus, a type of pachypleurosaur, according to the authors (a basal thalattosaur in the large reptile tree). So was the tritosaur lepidosaur, Macrocnemus. The authors wondered if the taphonomy of Tanystropheus would be more similar to the terrestrial or the aquatic taxa. Wild (1973) listed and illustrated  over a dozen specimens of Tanstropheus in various stages of completeness and articulation. The water depth of fossil deposition was estimated between 30 and 130m with anoxic bottom conditions. So ALL the specimens were transported horizontally and vertically. Importantly, fragmentary skeletons of Tanystropheus were excluded from this study. From the remaining data the authors compiled articulation and completeness scores.

Why did they throw out competing data?
We’ve seen this before with Hone and Benton (2007, 2008). Given that they used only the more complete specimens (and who knows how many incomplete specimens were never collected), the authors report Tanystropheus specimens exhibited 0-58% articulation and 36–97% completeness. Larger specimens tended to be more complete. The authors also note that Serpianosaurus alone lacks obvious features that promoted buoyancy, like hollow cervicals in Tanystropheus. The authors cite Brand et al. 2003, who noted “lizard skin in water formed a limp but durable bag containing the bones” during water transport.

The authors conclude
“Tanystropheus langobardicus at least died in, but probably also lived in a terrestrial or near-shore marine setting.” The presence of squid hooks in the stomach “does not necessarily preclude a more-normal niche in shallow water.” 

‘Near shore marine’ = aquatic.
So the authors conclusion is no conclusion at all. Contra their headline, they did not ‘determine’ anything. It could have been on the beach, or in shallow water. Is the marine iguana (Amblyrhynchus cristatus) aquatic? or terrestrial? What would you say if you only found its skeleton? Or its footprints?

The good evidence continues to be
the stomach contents as the best evidence for life style (feeding niche) for the giant forms. Let the smaller ones feed in shallower waters. Let both give birth and warm up on land, like marine iguanas.

References
Bassani F 1886. Sui Fossili e sull’ età degli schisti bituminosi triasici di Besano in Lombardia. Atti della Società Italiana di Scienze Naturali 19:15–72.
Beard SR and Furrer 2017. Land or water: using taphonomic models to determine the lifestyle of the Triassic protorosaur Tanystropheus (Diapsida, Archosauromorpha). Palaeobiodiversity and Palaeoenvironments (advance online publication) DOI: https://doi.org/10.1007/s12549-017-0299-7
https://link.springer.com/article/10.1007/s12549-017-0299-7
Diedrich C 2008. Millions of reptile tracks—Early to Middle Triassic carbonate tidal flat migration bridges of Central Europe—reptile immigration into the Germanic Basin. Palaeogeography, Palaeoclimatology, Palaeoecology, 259, 410–423.
Haubold HA 1983. Archosaur evidence in the Buntsandstein (Lower Triassic). Acta Palaeontologica Polonica, 28, 123–132.
Li C 2007. A juvenile Tanystropheus sp.(Protoro sauria: Tanystropheidae) from the Middle Triassic of Guizhou, China. Vertebrata PalAsiatica 45(1): 37-42.
Meyer H von 1847–55. Die saurier des Muschelkalkes mit rücksicht auf die saurier aus Buntem Sanstein und Keuper; pp. 1-167 in Zur fauna der Vorwelt, zweite Abteilung. Frankfurt.
Nosotti S 2007. Tanystropheus longobardicus (Reptilia, Protorosauria: Reinterpretations of the anatomy based on new specimens from the Middle Triassic of Besano (Lombardy, Northern Italy). Memorie della Società Italiana di Scienze Naturali e del Museo Civico di Storia Naturale di Milano, Vol. XXXV – Fascicolo III, pp. 1-88
Peyer B 1931. Tanystropheus longobardicus Bass sp. Die Triasfauna der Tessiner Kalkalpen. Abhandlungen Schweizerische Paläontologie Gesellschaft 50:5-110.
Rieppel O, Jiang D-Y, Fraser NC, Hao W-C, Motani R, Sun Y-L & Sun ZY 2010. Tanystropheus cf. T. longobardicus from the early Late Triassic of Guizhou Province, southwestern China. Journal of Vertebrate Paleontology 30(4):1082-1089.
Wild R 1973. Die Triasfauna der Tessiner Kalkalpen XXIII. Tanystropheus longobardicus (Bassani) (Neue Ergebnisse). – Schweizerische Paläontologische Abhandlungen 95: 1-162 plus plates.

wiki/Tanystropheus

SVP abstracts – Ennatosaurus

Romano et al. 2017
brings us a new reconstruction of Ennatosaurus (Fig. 1, btw – this is not it.)
Figure 1. An old reconstruction of Ennatosaurus, still not a synapsid, closer to millerettids and Eunotosaurus.

Figure 1. An old reconstruction of Ennatosaurus, still not a synapsid, closer to millerettids and Eunotosaurus.

As you read the abstract,
bear in mind the only thing wrong here is the author’s insistence that Ennatosaurus is a pelycosaur and a synapsid. It is neither, as the addition of taxa to a cladistic analysis would have informed the Romano team. Ennatosaurus was derived from the similarly built milllerettids. This was demonstrated several years ago in the large reptile tree by the simple addition of taxa to the inclusion set.

From the abstract:
The Russian caseid Ennatosaurus tecton (Synapsida Caseasauria) is an important member of the group, being among the few “pelycosaurs” occurring in the Middle Permian, thus making caseids among the longest-surviving groups of non-therapsid synapsids. Although the cranial skeleton has been recently restudied in detail, the descriptions currently available for the postcranium are essentially limited to the original short account on the holotype provided by the original description from the 1950s. This contribution represents a new analysis of the postcranium of this taxon, using several different approaches. The postcranium of Ennatosaurus is informative with respect to both the taxonomy and phylogeny, with autapomorphic characters present particularly in the vertebral column. In addition, we conducted eight principal component analyses to investigate the position of the various appendicular elements of Ennatosaurus within the caseid morphospace. Members of all major groups of “pelycosaurs” were included in the morphometric analysis (along with selected outgroup taxa), allowing us to make some broader preliminary inferences regarding postcranial morphospace occupation of these basal synapsids for each individually-considered element. From the results of the principal component analyses, a major decoupling among the morphological patterns of stylopodial and zeugopodial elements is detected. Whereas femora and humeri exhibit a shared common pattern (with a wider overlap in their respective morphospace), the ulnae, radii, tibiae and fibulae show well-separated regions of morphospaces in the different clades. This result indicates the importance of such long bones also for taxonomic differentiation (in addition to their use for classical functional and biomechanical studies). Finally, a 3D photogrammetric model of the mounted specimen at the Paleontological Institute of Moscow has been used to obtain the first in vivo reconstruction of Ennatosaurus tecton, providing for the first time a potentially realistic picture of the Russian caseid in life.

For all this great work
resistance to taxon inclusion doomed any conclusions drawn. Sadly this basic problem is similar to workers who resist adding fenestrasaurs to pterosaurs studies, thalattosaurs to Vancleavea studies, tenrecs and desmostylians to whale studies, etc. etc…

References
Romano M, Brocklehurst N and Fröbisch J 2017. Redescription of the postcranial skeleton of Ennatosaurus tecton (Synapsida, Caseasauria, Caseidae) and its first in vivo restoration. Abstrcts from the 2917 meeting of the Society of Vertebrate Paleontology in Calgary.

SVP abstracts 2017: The earliest lepidosaurs

Simöes 2017 brings us
new insights into the origin and early radiation of lepidosaurs, but seems to focus on the squamate side of that equation. Earlier Simöes brought us new data on Ardeosaurus (late Jurassic proto-snake) and Calanguban (Early Cretaceous, late-surviving basal squamate).

From the abstract:
“The origins and early radiation of lepidosaurs remain largely enigmatic by several factors, including:

  1. the oldest unequivocal fossils currently attributed to the Squamata are from the Middle Jurassic;
  2. available studies of broad level/deep-time diapsid reptile relationships provide very limited sampling of either fossil or living lepidosaurs (often, Squamata being represented as a single terminal unit);
  3. morphological and molecular evidence of squamate relationships disagree on what is the earliest squamate clade (iguanians vs dibamids and geckoes);
  4. among others.”

“Here, I provide a new phylogenetic dataset with a deep sampling of the major diapsid and
lepidosaurian lineages (living and fossil) at the species level in order to identify the
composition and early evolution of lepidosaurs. All taxon scorings were based on
personal observation of specimens and/or 3D CT scans from 51 collections from around
the world, making it the largest species sample ever collected for investigating the origin
of lepidosaurs—over 150 species.”

“The results indicate novel relationships among diapsids and re-shape the lepidosaurian
tree of life. Previously proposed early lepidosaurs are found to belong to other lineages of
reptiles. Importantly, heretofore unrecognized squamate fossils are found as the earliest
squamates, dating back to the Early Triassic, thus filling what was thought to be a fossil
gap of at least 50 million years. In most results (morphology only and combined data)
geckoes are the earliest squamate crown clade, iguanians are always found as later
evolving squamates, and scincomorphs are polyphyletic, thus dramatically differing from
previous morphology based studies, but agreeing with the molecular data.”

Figure 1. Lacertulus, a basal squamate from the Late Permian

Figure 1. Lacertulus, a basal protosquamate from the Late Permian

How does this data compare
to the large reptile tree? The LRT has 140 lepidosaur taxa, but I don’t get the feeling that Simöes included tritosaurs and protosquamates, some of which extend back to the Late Permian (Lacertulus, Fig. 1). If Simöes does not include those clades, the hypothesis needs more taxa. The abstract is enigmatic with regard to which early lepidosaurs now belong to other lineages and which unrecognized squamates are now earliest squamates.

But I like that Simöes is looking at more taxa!!

Unfortunately,
Simöes does not provide outgroup taxa in the abstract. I’m guessing he did not test a wide gamut of taxa, like the LRT, to see if they were lepidosaurs or not. That’s how you recover protosquamates and tritosaurs. In the LRT geckoes are not the basalmost squamates and scincomorphs are not polyphyletic.

I look forward to this paper!!

References
Simöes TR 2017. The origin and early evolution of lepidosaurian reptiles. Abstracts from the Society of Vertebrate Paleontology 2017.

Adding more birds to the LRT

Over the last week or so
more birds have been added to the large reptile tree (LRT, 1074 taxa, subset Fig. 1). Many are still with us. Others are recently extinct. Still others are known only from the Paleocene.

Figure 1. Subset of the LRT focusing on extant birds and their closest kin.

Figure 1. Subset of the LRT focusing on extant birds and their closest kin.

I was surprised to see

  1. the toothed birds, Yanornis, Ichthyornis and Hesperornis nest within the clade of extant birds. That means, like Pelagornis, some sort of teeth came back.
  2. the moa, DInornis and Gastornis (= Diatryma) both nest close to parrots (like Ara) and the hoatzin (Opisthocomus). Here ratites are no longer monophyletic. Wikipedia notes, “The systematics involved have been in flux.”
  3. ducks, like Anas, are close to predatory birds, like Sagittarius
  4. the Solnhofen bird, Jurapteryx (= Archaeopteryx) recurva nests at the base of the clade of extant birds
  5. Details later.