Pteranodon quad hopping water takeoff, according to the AMNH

Hopefully this is going to be the last time
the American Museum of Natural History embarrasses itself with bogus pterosaur tricks. We looked at problems from the original 2014 AMNH pterosaur display here and elsewhere. Evidently they have decided to stop using math, physics and modern analogs, alas, to their disgrace… while cartooning (Fig. 1) the bird-like pterosaurs under the guise of a scientific exhibition.

Figure 1. GIF animation from the American Museum of Natural History showing how their Pteranodon managed to hop off the surface of the water until suddenly able to flap and fly. Totally bogus. It won’t develop any lift or thrust with wings folded. …Unless Pteranodon was filled with helium?? Those deep chord wing membranes are likewise not preserved in any fossil. 

Above is how the American Museum of Natural History
(AMNH) imagines the takeoff of Pteranodon from calm seas (Fig. 1, AMNH webpage). Not credible. Not accurate, either with those deep chord wing membranes, not yet found in any fossils.

Figure 2. Pelican take-off sequence from water. Click to enlarge.

Above is how the living pelican
(Pelecanus) actually takes off from gulf waters (Fig. 2 and YouTube video above it in slow motion, click to view). The Pteranodon-like pelican lifts its great wings out of the water to develop lift and thrust. Ground effect keeps it out of the water after one flap. Water is where drag occurs. And legs kicking or hopping has never lifted any pelican out of the water. The wings, fully extended as taut airfoils, do 99% of the work. The foot hops off of wave tops after flight has been initiated, are negligible thrust producers.

Figure 3. Triebold Pteranodon in floating configuration. Center of balance marked by cross-hairs.

Above is how ReptileEvolution.com
imagines Pteranodon floating on the sea (Fig. 4) using its air-filled wing bones as lateral floatation devices. The torso and skull were also lighter than an equal volume of water, as in all floating birds.

Figure 4. Ornithocheirid water launch sequence in the pattern of a pelican launch. LIke ducks, geese and pelicans, pterosaur probably floated high in the water. Here the wings rise first and unfold in an unhurried fashion, keeping dry and unencumbered by swirling waters. Then the legs run furiously, like a Jesus lizard, but with such tiny feet, they were not much help in generating forward motion. The huge wings, however, did create great drafts of air, thrusting the pterosaur forward until sufficient airspeed was attained, as in the pelican.

Earlier we looked at several water take-off scenarios
for pterosaurs using Anhanguera as a model (Fig. 4). Keep those wings out of the water where they can develop thrust and lift with full extension and taut membranes. A sagging wing membrane (Fig. 1) develops neither lift nor thrust.

Figure 5. Click to play. Successful heretical bird-style Pteranodon wing launch in which the hind limbs produce far less initial thrust because the first downstroke of the already upraised wing provides the necessary thrust for takeoff in the manner of birds. This assumes a standing start and not a running start in the manner of lizards. Note three wing beats take place in the same space and time that only one wing beat takes place in the Habib/Molnar model. Compare to a similar number of wingbeats in the pelican.

Above is how the heretical hypothesis
imagines the takeoff of Pteranodon from the ground (Fig. 4): just like a crane, pelican or other large bird. For a water takeoff, just add water and keep the wings off the surface. Flapping so close to the water takes advantage of ‘ground effect’ where lift is increased when the wing is close to the ground.

By contrast,
either the AMNH model is made of helium or hung on a string, or the sea is made of jello, because against all laws of physics somehow those tiny fingers and feet are keeping the head and torso above the watery surface. If anyone can defend the AMNH scenario, please make comment below.

Just found out: The quad fly hypothesis goes back to 1943!
Daffy Duck in “To Duck or Not to Duck” was using the quad style to fly (Fig. 6) back in 1943, just before Elmer Fudd fired a shotgun at him. Compare this technique to Pteranodon in figure 1 and you’ll see convergence on a massive scale.

Figure 8. Daffy Duck in “To Duck or Not to Duck” 1943 uses the quad fly method. See figure 1 for comparable take-off technique.

At the AMNH
Dr. Mark Norell, curator and chair of the Museum’s Paleontology Division, oversaw the pterosaur exhibition with Dr. Alexander Kellner of Museu Nacional in Rio de Janiero.

 

 

Sylviornis: Not a megapode. Not a ratite. Not a giant stem chicken…

In the large reptile tree (LRT, 1080 taxa) the giant recently extinct bird from New Caledonia, Sylviornis (Poplin 1980) nests with basal hook-beak predatory birds, like the seriema (Cariama), the secretary bird (Sagittarius) and the terror birds, like Phorusrhacos.

Figure 1. Sylviornis is not a giant chicken. It’s a giant secretary bird.

It’s a different kind of terror bird
on a small island east of Australia. It was originally considered a ratite, then a megapode, then a stem chicken (Gallus) not quite a meter in length. The premaxilla forms a crest. The narrow rostrum is mobile relative to the wide cranium.

Worthy et al 2016 reported,
“Osteology Supports a Stem-Galliform Affinity for the Giant Extinct Flightless Bird Sylviornis neocaledoniae (Sylviornithidae, Galloanseres).”

Due to convergence,
be very wary of osteology determining relationships. Only cladograms determine relationships. In this case, the authors excluded Cariama and Sagittarius, proximal sisters to Sylviornis in the LRT.

References
Poplin F 1980. Sylviornis neocaledoniae n. g., n. sp. (Aves), ratite éteint de la Nouvelle-Calédonie”. Comptes Rendus de l’Académie des Sciences, Série D (in French). 290: 691–694.
Mourer-Chauviré C and Balouet JC 2005. Description of the skull of the genus Sylviornis Poplin, 1980 (Aves, Galliformes, Sylviornithidae new family), a giant extinct bird from the Holocene of New Caledonia. In Alcover, J. A.; Bover, P. Proceedings of the International Symposium “Insular Vertebrate Evolution: the Palaeontological Approach”. Monografies de la Societat d’Història Natural de les Balears. 12. pp. 205–218.
Worthy TH et al. 2016. Osteology Supports a Stem-Galliform Affinity for the Giant Extinct Flightless Bird Sylviornis neocaledoniae (Sylviornithidae, Galloanseres). PLoS ONE 11(3): e0150871. doi:10.1371/journal.pone.0150871

wiki/Sagittarius
wiki/Llallawavis
wiki/Phorusrhacos
wiki/Sylviornis

Müller et al. discuss Lagerpeton ‘sisters’ without Tropidosuchus

Müller, Langer and Dias da Silva (2018) report:

“Despite representing a key-taxon in dinosauromorph phylogeny, Lagerpertidae is one of the most obscure and enigmatic branches from the stem that leads to the dinosaurs.”

It’s taxon exclusion, yet again.

Lagerpeton (Fig. 1) is obscure and enigmatic because it is NOT in the stem that leads to dinosaurs. We discussed that earlier here in 2011. Langer is aware of the better, more inclusive, option because he sent me the reference for Novas and Agnolin 2016 discussed here.

“Recent new findings have greatly increased our knowledge about lagerpetids, but no phylogenetic analysis has so far included all known members of this group. Here, we present the most inclusive phylogenetic study so far conducted for Lagerpetidae. …Finally, quantification of the codified characters of our analysis reveals that Lagerpetidae is one of the poorest known among the Triassic dinosauromorph groups in terms of their anatomy, so that new discoveries of more complete specimens are awaited to establish a more robust phylogeny.”

Tropidosuchus is known from complete skeletons (Fig. 1) and is the sister to Lagerpeton in the more inclusive large reptile tree (LRT, 1173 taxa).

Problem solved!

Figure 1. The closest kin of Tropidosuchus are the much larger Chanaresuchus (matching Nesbitt 2011) and the smaller Lagerpeton.

Ixalerpeton

Müller et al. nest Ixalerpeton (Fig. 24) with Lagerpeton without testing other candidates. In the LRT Ixalerpeton nests among basal protorosaurs, far from Lagerpeton. And yes, it might have been the only bipedal protorosaur, exciting news that was completely overlooked due to taxon exclusion. Or not. The foot would be helpful, but is not known.

Figure 2. Ixalerpeton bits and pieces reconstructed. This taxon nests with protorosaurs.

Which protorosaur was closest to Ixalerpeton?
Ixalerpeton nests between the AMNH 9502 specimen of Prolacerta and Czatkowiella, (Fig. 3), taxa omitted by the Müller et al. 2018 study.

Figure 3. Czatkowiella harae bits and pieces here reconstructed as best as possible. Note the size difference here between the large maxilla and the small one. This taxon is close to Ixalerpeton. The skull roof and occiput are comparably similar.  Perhaps Ixalerpeton had a longer neck based on this sister.

References

Müller RT,  Langer  MC & Dias-Da-Silva  S 2018. Ingroup relationships of Lagerpetidae (Avemetatarsalia: Dinosauromorpha): a further phylogenetic investigation on the understanding of dinosaur relatives. Zootaxa 4392(1): 149â158

DOI: http://dx.doi.org/10.11646/zootaxa.4392.1.7

http://www.mapress.com/j/zt/article/view/zootaxa.4392.1.7

Novas FE and Agnolin FL 2016 Lagerpeton chanarensis Romer (Archosauriformes): A derived proterochampsian from the middle Triassic of NW Argentina. Simposio. From Eventos del Mesozoico temprano en la evolución de los dinosaurios”. Programa VCLAPV. Conferencia plenaria: Hidrodinámica y modo de vida de los primeros vertebrados. Héctor Botella (Universitat de València, España) 2016

wiki/Lagerpeton

The Early Permian Ascendonanus assemblage

There are five specimens from the same pit
that were assigned to the varanid taxon Ascendonanus. Spindler et al. 2018 thought they were all conspecific.

Given their distinct proportions
(Fig. 1) and the phylogenetic differences recovered in 2 of the 5 so far (earlier one nested as a basal iguanid), we’re going to need some new generic names for at least one of the referred specimens. The others have not yet been tested in the large reptile tree (LRT, 1179 taxa).

The holotype
remains Ascendonanus, but here it’s no longer a varanopid synapsid. Here it nests as a derived prodiapsid and the basalmost tested diapsid (Fig. 2), a little younger than the oldest diapsid, Petrolacosaurus.

Figure 1. The five specimens from the Ascendonanus quarry, all to the same scale, counter plate flipped in every specimen. Most images from Spindler et al. 2018. Some have skulls 3x the occiput/acetabulum length. Others as much as 5x, the first hint that these taxa are no conspecific.

Some of these specimens
(Fig. 1) have an occiput/acetabulum length distinct from the others, ranging from 3x to 5x the skull length, the first clue to their distinct morphologies.

Figure 2. The Prodiapsida now include the holotypes of Ascendonanus and Anningia. Remember, the Diapsida does not include any Lepidosauriforms, which nest elsewhere.

Spindler et al. 2018
did not include several taxa typically included in pelycosaur studies and should not have included any caseasaurs, despite their traditional inclusion. Spindler et al. did not include any diapsids nor did they understand the role of the former varanopids now nesting as ancestors to the Diapsida (sans Lepidosauriformes).

Figure 3. Cladogram from Spindler et al. 2018. Colors refer to clades in the LRT.

The holotype 0924 specimen has more of a varanopid skull
than the 1045 specimen we looked at earlier. Prodiapsid sisters include varanopids ancestral to synapsids. Prodiapsids, as their name suggests, are late-surviving ancestors to diapsids like the coeval Araeoscelis (Early Permian) and the earlier Spinoaequalis (Late Carboniferous).

Figure 3. The Ascendonanus holotype skull as originally traced and as traced here. Whether an upper temporal fenestra was present (as shown in the color tracing), or not (as shown in the drawings, makes no difference as this taxon nests at the transition. 

Not sure yet
where the other three specimens assigned to Ascendonanus nest. Enough muck stirred for the moment.

References
Rößler R, Zierold T, Feng Z, Kretzschmar R, Merbitz M, Annacker V and Schneider JW 2012. A snapshot of an early Permian ecosystem preserved by explosive volcanism:
New results from the Chemnitz Petrified Forest, Germany. PALAIOS, 2012, v. 27, p. 814–834.
Spindler F, Werneburg R, Schneider JW, Luthardt L, Annacker V and Räler R 2018. First arboreal ‘pelycosaurs’ (Synapsida: Varanopidae) from the early Permian Chemnitz Fossil Lagerstätte, SE Germany, with a review of varanopid phylogeny. DOI: https://doi.org/10.1007/s12542-018-0405-9

Problems in the reevaluation of Caseosaurus

Baron and Williams 2018
bring us a new evaluation of a Late Triassic ilium considered to be an enigmatic (because nothing more than an illiim is known) dinosauriform, Caseosaurus crosbyensis.

From their abstract
“Historically, Caseosaurus crosbyensis has been considered to represent an early saurischian dinosaur, and often a herrerasaur. More recent work on Triassic dinosaurs has cast doubt over its supposed dinosaurian affinities and uncertainty about particular features in the holotype and only known specimen has led to the species being regarded as a dinosauriform of indeterminate position. Here, we present a new diagnosis for Caseosaurus crosbyensis and refer additional material to the taxon—a partial right ilium from Snyder Quarry. Our comparisons and phylogenetic analyses suggest that Caseosaurus crosbyensis belongs in a clade with herrerasaurs and that this clade is the sister taxon of Dinosauria, rather than positioned within it.”

Unfortunately
in order to determine which taxa are in and out of the Dinosauria and the Archosauria, you have to include basal bipedal crocodylomorphs, the outgroup for the Dinosauria in the large reptile tree (LRT, 1176 taxa). Baron and Williams omit this vital clade and so come up short in their evaluation. Baron recently made waves when he united Ornithischia with Theropoda to the exclusion of Sauropodomorpha. That error was also due to taxon exclusion, covered earlier here and here.

Worse yet, the authors report, 
“In addition, our analysis recovers the enigmatic European taxon Saltopus elginensis among herrerasaurs for the first time.”

Hopefully that will be the first and only time.
In the LRT, Saltopus nests with Scleromochlus and Gracilisuchus as basal crocodylomorphs.” Again, this is due to taxon exclusion.

Worst yet, the authors report,
“Dimorphodon macronyx was included as an additional outgroup taxon, following its use in the study by Baron et al. (2017a).”

Hopefully this will be the last time
pterosaurs are used in dinosaur phylogenetic analysis. They are not related to each other.

Building on these fails, the authors continue:
“If this hypothesis is correct then this clade of herrerasaurs also represents the first clade of non-dinosaurian dinosauromorphs known to contain large-bodied carnivorous species.”

This hypothesis is not correct.
In the LRT, Herrerasaurus and kin nest as the last common ancestor of all dinosaurs, and so, by definition, Herrerasaurus and kin are dinosaurs, basal carnivorous dinosaurs. Based on the proximity of basal bipedal crocs to dinosaurs, there are no known non-dinosaur dinosauromorphs at this time. The Dinosauromorpha is a junior synonym for Archosauria and should be dropped from usage.

And now, the big reveal:
We only know the ilium from Caseosaurus, the holotype UMMP 8870 and the referred material NMMNH P-35995. Are they conspecific? No (Fig 1). Are they congeneric? No.

Figure 1. GIF animation comparing the holotype pelvis of Caseosaurus (big and red) to the referred material (small and blue). Perhaps you are asking yourself, what were these authors thinking? The two pelves are not even congeneric.

Presently in the LRT
the PVL 4597 specimen (Fig. 2, wrongly attributed to Gracilisuchus) nests as the last common ancestor of dinos and crocs. That’s what the ilium looks like compared to the basalmost dino, Herrerasaurus (Fig. 2).

Figure 1. The PVL 4597 specimen attributed to Gracilisuchus by Lecuona et al. 2017, but nesting at the base of the Dinosauria in the LRT.

According to Wikipedia
Langer (2004) examined the ilium and reassigned it to the genus Chindesaurus, which lived during the same period and geological region.

References
Baron MG and Williams ME 2018. A re-evaluation of the enigmatic dinosauriform Caseosaurus crosbyensis from the Late Triassic of Texas, USA and its implications for early dinosaur evolution. Acta Palaeontologica Polonica 63(1): 129–145.
Langer M 2004. Basal Saurischia. In Weishampel, Dodson and Osmolska. The Dinosauria Second Edition. University of California Press. 861 pp.

https://en.wikipedia.org/wiki/Caseosaurus

Enigmatic Perochelys and a review of soft-shell turtle origins

In short:
Current turtle workers are under the mistaken assumption that Carettochelys (Fig. 1) the tube-nosed soft-shell turtle mimic with a domed hard shell and flippers is the outgroup for soft-shell turtles. That is not supported by the large reptile tree (LRT, 1176 taxa) which nests soft-shell turtles apart from hard-shell turtles, both derived from separate small, horned pareiasaurs like Scerlosaurus and Elginia respectively.

With that in mind,
it’s no wonder that two prior authors don’t know where to nest the Early Cretaceous soft-shell turtle, Perochelys (Figs. 2, 3), as derived or basal in the soft-shell clade. Li et al. 2017 and Brinkman et al. 2017 don’t even mention the basalmost soft-shell turtle, Odontochelys, let alone ancestral  taxa like Scerlosaurus and Arganaceras.

Figure 1. Carettochelys in 3 views from Digimorph.org and used with permission.

“Trionychidae plus Carettochelyidae form the clade Trionychia (Gaffney and Meylan, 1988; Meylan, 1988; Meylan and Gaffney, 1989; Shaffer et al., 1997; Joyce et al., 2004; Joyce,
2007).”

FIgure 2. Carettochelys, the pig-nose turtle, is a freshwater form with flippers, like marine turtles, by convergence.

In the large reptile tree
(LRT, 1176 taxa) where we test as many taxa as possible and let the nodes form where they may, the tube-nosed, dome-shelled fresh water turtle with flippers, Carettochelys, nests with Foxemys in the hard-shell clade as a soft-shell turtle mimic. Only the LRT nests Sclerosaurus, Arganaceras and Odontochelys in the outgroup for soft-shell turtles.

“Molecular studies place this clade at the base of crown group Cryptodira (Shaffer et al., 1997; Krenz et al., 2005; Parham et al., 2006; Shaffer, 2009; Barley et al., 2010; Louren¸co et al., 2012), whereas unconstrained morphological studies support a more derived position nested within Cryptodira (Gaffney and Meylan, 1988; Joyce, 2007; Sterli, 2010; Anquetin, 2011; Sterli et al., 2013).”

Figure 3. The skull of Carettochelys in 5 views. This skull of this dome-shell turtle shares some traits with the soft-shell Trionyx, but more with the dome-shell Foxemys. Comnpare to Trionyx in figure 4 and you’ll see why convergence has confused the issue of soft turtle origins. Don’t try to figure out turtle origins by yourself. Let the software do it without bias.

“The phylogenetic relationships among modern soft-shelled turtle species are still controversial, but it is generally accepted that Trionychidae consists of two clades, Cyclanorbinae and Trionychinae, and that Trionychinae includes some well-supported monophyletic clades (Meylan, 1987; Engstrom et al., 2004). The taxonomy and phylogenetic relationships of fossil trionychid species are far more controversial, and very little is known regarding the origin and early radiation of this group (Gardner et al., 1995; Joyce and Lyson, 2010, 2011; Vitek and Danilov, 2010; Vitek, 2012; Danilov and Vitek, 2013; Joyce et al., 2013).”

As I said… see above.

Figure 4. Trionyx, a softshell turtle with bones colorized.

“The early record of soft-shelled turtles is poor, and most taxa are based either on fragmentary shells or skulls (Yeh, 1994; Hutchison, 2000; Sukhanov, 2000; Danilov and Vitek, 2013). More complete Mesozoic skull-shell-associated materials have been described only for trionychids from the Campanian and Maastrichtian of North America (Gardner et al., 1995; Brinkman, 2005; Joyce and Lyson, 2011; Vitek, 2012) or the Cenomanian–Santonian of Mongolia (Danilov et al., 2014). The new material described herein is a nearly complete skeleton and therefore represents the first complete Early Cretaceous skull shell-associated trionychid worldwide.”

Figure 5. Perochelys (Early Cretaceous) in situ from Li et al. 2015) colors added.

Perochelys lamadongensis (Early Cretaceous)

Figure 6. Perochelys skull in dorsal and ventral views from Li et al. 2015 with colors added.

Brinkman et al. 2017 looked at another specimen of Perochelys.

Here’s the abstract:
“Pan-trionychids or softshell turtles are a highly specialized and widespread extant group of aquatic taxa with an evolutionary history that goes back to the Early Cretaceous. The earliest pan-trionychids had already fully developed the “classic” softshell turtle morphology and it has been impossible to resolve whether they are stem members of the family or are within the crown. This has hindered our understanding of the evolution of the two basic body plans of crown-trionychids. Thus it remains unclear whether the more heavily ossified shell of the cyclanorbines or the highly reduced trionychine morphotype is the ancestral condition for softshell turtles.”

Softshell turtles never had a heavily ossified shell as demonstrated by Odontochelys and Sclerosaurus, taxa excluded from all prior soft-shell turtle studies.

Figure 7. Trionyx, an African soft-shelled turtle with fossil relatives back to the Cretaceous nests with Odontochelys.

“A new pan-trionychid from the Early Cretaceous of Zhejiang, China, Perochelys hengshanensis sp. nov., allows a revision of softshell-turtle phylogeny. Equal character weighting resulted in a topology that is fundamentally inconsistent with molecular divergence date estimates of deeply nested extant species. In contrast, implied weighting retrieved Lower Cretaceous Perochelys spp. and Petrochelys kyrgyzensis as stem trionychids, which is fully consistent with their basal stratigraphic occurrence and an Aptian-Santonian molecular age estimate for crown-trionychids. These results indicate that the primitive morphology for soft-shell turtles is a poorly ossified shell like that of crown-trionychines and that shell re-ossification in cyclanorbines (including re-acquisition of peripheral elements) is secondary.”

That’s what I’ve been trying to tell turtle workers.
And I presented the phylogenetic evidence in Odontochelys and Sclerosaurus. Brinkman et al. do not present these taxa.

Figure 8. Soft shell turtle evolution featuring Arganaceras, Sclerosaurus, Odontochelys and Trionyx.

Distinct from soft-shell turtles, hard-shell turtles have:

1. domed carapace with scutes
2. dorsal rib tips not visible
3. premaxilla and maxilla curved one way or another
4. large quadratojugal, even when fused to the squamosal above it
5. large premaxilla (forming the ventral margin of the confluent nares
6. nasal fused to prefrontal
7. postorbital fused to postfrontal
8. an ancestry with a broad, bony, convex cranium, which erodes convergent with soft-shell taxa

Like soft-shell turtles, soft-shell turtle mimics with domed hard shells often have:

1. orbits visible in dorsal view
2. elongate cervicals
3. posttemporal fenestra at least half the skull length (but never(?) reaching the jugal)
4. slender digits
5. posteriorly elongate supraoccipital with inverted ‘T’ cross-section

Bottom line:
Don’t try to figure out turtle origins by yourself. Let the software do it without bias. 

References
Li L, Joyce WG and Liu J 2015. The first soft-shelled turtle from the Jehol Biota of China. Journal of Vertebrate Paleontology 35(2):e909450. 2015
Brinkman D, Rabi M and Zhao L-J 2017. Lower Cretaceous fossils from China shed light on the ancestral body plan of crown softshell turtles (Trionychidae, Cryptodira). Scientific Reports 2017(7):6719.

Ascendonanus nestleri: an early Permian iguanid, not a varanopid.

Please see:
https://pterosaurheresies.wordpress.com/2018/03/20/the-early-permian-ascendonanus-assemblage/ Which shows that of the five specimens assigned to Ascendonanus at least two are widely divergent. The other three have not yet been tested. One is an iguanid. Another is a basalmost diapsid.

Just out today by Spindler et al. 2018, but previewed earlier
“A new fossil amniote from the Fossil Forest of Chemnitz (Sakmarian-Artinskian transition, Germany) is described as Ascendonanus nestleri gen. et sp. nov., based on five articulated skeletons with integumentary preservation. The slender animals exhibit a generalistic, lizard-like morphology. However, their synapsid temporal fenestration, ventrally ridged centra and enlarged iliac blades indicate a pelycosaur-grade affiliation. Using a renewed data set for certain early amniotes with a similar typology found Ascendonanus to be a basal varanopid synapsid. This is the first evidence of a varanopid from Saxony and the third from Central Europe, as well as the smallest varanopid at all. Its greatly elongated trunk, enlarged autopodia and strongly curved unguals, along with taphonomical observations, imply an arboreal lifestyle in a dense forest habitat until the whole ecosystem was buried under volcanic deposits. Ascendonanus greatly increases the knowledge on rare basal varanopids; it also reveals a so far unexpected ecotype of early synapsids. Its integumentary structures present the first detailed and soft tissue skin preservation of any Paleozoic synapsid.”

Except
Ascendonanus is not a varanopid synapsid. It’s an arboreal lepidosaur, an iguanid squamate in the large reptile tree (LRT, 1176 taxa, subset Fig. 3) with a typical skull, skin, size and niche typical for this clade. Only the torso has more vertebrae than is typical, but the related Liushusaurus also has more than 25 presacral vertebrae.

The Early Permian
is not where we expect to see lizards. No others are known from this period. Perhaps that is why Spindler et al. 2018 chose to restrict their taxon list to synapsids and their outgroups…and to ignore those upper temporal fenestrae, so plainly visible (Fig. 1). And note those slender, vertical epipterygoids. You don’t see those on synapsids.

Figure 1. The skull of Ascendonanus has a diapsid temporal configuration with clearly visible upper temporal fenestra and a typical iguanid skull morphology. Note manual digit 5 preserved beneath the palm of the hand and restored to a lateral position. Not also the two jugal ascending processes, due to the split leaving medial and lateral halves of this bone. Note the two slender epipterygoids inside the temporal openings. Only squamates have such bones.

Ascendonanus nestleri (Spindler 2017, TA1045) is a German iguanid squamate found in vulcanized early Permian (291mya) sediments. It is the oldest lepidosaur known and based on its phylogeny, suggests an earlier radiation of lepidosaurs that earlier presumed. Other early lepidosauriformes include Paliguana and Lacertulus from the Late Permian. Other basal iguanids and pre-iguanids, like Scandensia, Calanguban, Euposaurus and Liushusaurus are late-survivors in the Late Jurassic and Early Cretaceous. Iguana is a late-survivor of an early radiation living today.

Ascendonanus was originally described
as a tree-climbing varanopid synapsid by Spindler et al. (2018), but no lepidosauriformes were tested. The bones are difficult to see through the scaly skin (Fig. 1). Upper temporal fenestra and other lepidosaur traits were overlooked, perhaps because lizards are otherwise unknown from the Early Permian. No other basal synapsids were arboreal, but some Iguana species are also arboreal. No other varanopids are quite as small, but other iguanids are smaller.

By the way, like more paleo workers
Spindler et al. 2018 were unaware of the synapsid/prodiapsid split that removes many former varanopids from the clade Synapsida, despite their having typical synapsid temporal fenestration. One more reason NOT to label taxa based on traits, but to only label taxa after a wide gamut cladistic analysis, like the LRT.

Thus
we no longer call Ascendonanus a diapsid based on its diapsid temporal configuration. True diapsids, like Eudibamus and Petrolacosaurus, all nest within the Archosauromorpha. By convergence, all members of the clade Lepidosauriformes, including Ascendonanus, all have a diapsid temporal configuration or a modification based on that.

Figure 2. Ascendonanus nestler is an Early Permian iguanid squamate lepidosaur, not a varanopid synapsid.

Sorry to say it,
taxon exclusion is once again the problem here. Spindler et al. 2018 were also following tradition when they included caseids and eothyrids in they analysis of synapsids. The Caseasauria nest elsewhere when given the opportunity to do so.

Figure 3. Ascendonanus cladogram, subset of the LRT. Here Ascendonanus nests with iguanids, not varanopids.

Figure 5. Ascendonanus pes.

References
Rößler R, Zierold T, Feng Z, Kretzschmar R, Merbitz M, Annacker V and Schneider JW 2012. A snapshot of an early Permian ecosystem preserved by explosive volcanism:
New results from the Chemnitz Petrified Forest, Germany. PALAIOS, 2012, v. 27, p. 814–834.
Spindler F, Werneburg R, Schneider JW, Luthardt L, Annacker V and Räler R 2018. First arboreal ‘pelycosaurs’ (Synapsida: Varanopidae) from the early Permian Chemnitz Fossil Lagerstätte, SE Germany, with a review of varanopid phylogeny. DOI: https://doi.org/10.1007/s12542-018-0405-9

Agadirichnus elegans pterosaur tracks rediscovered

Yesterday we looked at a recent online paper that expanded the list of pterosaur taxa present at the last days of pterosaurs and dinosaurs in the latest Cretaceous. Absent from that highly publicized work were the Maastrichtian pterosaur tracks made by ctenochasmatids (some quite large) listed below and the tupuxuarid skull described earlier.

Masrour et al. 2018
rediscover Maastrichtian (Late Cretaceous) dinosaurs, birds and enigmatic 8-9 cm pes tracks and 6cm manus tracks tentatively attributed to some sort of ‘Lacertilia’ under the name Agadirichnus elegans, first documented in Ambroggi and Lapparent 1954. The originals are now considered lost. The site in Morrocco was rediscovered. The enigma tracks were retrospectively identified as two pterosaur morphotypes.

Unknowingly,
these were the first pterosaur tracks ever named, preceding Pteraichnus by three years.

Etymology:
named after Agadir, the Moroccan city near the site.

Biggest takeaway:
There was a variety of pterosaurs in the Maastrichtian (Latest Cretaceous) that is presently underrepresented by skeletons (currently just giant azhdarchids and pteranodontids in rare fossiliferous strata worldwide).

Figure 1. A variety of tracks inappropriately labeled Agadirichnus. Here only one pedal track (B) is matched to Middle Jurassic Darwinopterus, perhaps by convergence. Note what appears to be pedal digit 5 beneath the heel.

The catalog of pterosaur pedes
(Peters 2011) was not cited, but I’ll use it to attempt a trackmaker identification.

Figure 1. A Pteranodon pes, UNSM 2062 as reconstructed plantigrade by Bennett (1991, 2001) and as reconstructed digitigrade. PILs added. Black elements are foreshortened during elevation into the digitigrade configuration. Some Pteranodon pedes were indeed plantigrade, depending on the species, but not this one based on PILs analysis. Note the distal and proximal tarsals are fused to each other.

Taxon B with pedal digit 3 the longest matches:

1. Dimorphodon
2. Darwinopterus (certain specimens only)
3. Wukongopterus
4. Ctenochasma elegans
5. Pterodaustro
6. Shenzhoupterus
7. Pteranodon UNSM 2062 specimen only

Taxon B with digit 1 no longer than p2.2 matches

1. Darwinopterus
2. Wukongopterus
3. Ctenochasma elegans
4. Pterodaustro 
5. Pteranodon UNSM 2062 specimen only

Taxon B with p4 subequal to mt 4 matches

1. Pteranodon UNSM 2062 specimen only. Other tested Pteranodon specimens do not extend digit 3 beyond the others, as shown here. The only problem is: the fingers of Pteranodon cannot touch the substrate due to the long metacarpus relative to the short hind limbs. My guess: there was a large, as yet unknown, ctenochasmatid trackmaker in the Late Cretaceous. Ctenochasmatids had a short manual digit 1 and small dull claws on all digits matching the manus impression of Taxon A. Perhaps this was one of the giant ctenochasmatids, like Gegepterus, at present lacking data for both feet and fingers.

Taxon C with pedal digit 2 the longest, toes shorter than metatarsals and a narrow pes matches:

1. Zhejiangopterus (probaby juvenile based on 6cm size)

Taxon D with pedal digit 2=3, toes shorter than metatarsals and metatarsal 4 much shorter than 1-3 matches:

1. Ctenochasma

References
Ambroggi R and de Lapparent  AF 1954. Les empreintes de pas fossiles du Maestrichtien d’Agadir. Notes du Service Geologique du Maroc, 10:43–6.
Longrich NR, Martill DM, Andres B 2018. Late Maastrichtian pterosaurs from North Africa and mass extinction of Pterosauria at the Cretaceous-Paleogene boundary. PLoS Biol 16(3): e2001663. https://doi.org/10.1371/journal. pbio.2001663
Masrour M, Ducla M d, Billon-Bruyat J-P and Mazin J-M 2018. Rediscovery of the Tagragra Tracksite (Maastrichtian, Agadir, Morocco): Agadirichnus elegans Ambroggi and Lapparent 1954 is Pterosaurian Ichnotaxon, Ichnos.  https://doi.org/10.1080/10420940.2017.1386661

New flightless and giant nyctosaurs: Alcione and Barbaridactylus

Scale bar problems
and a lack of reconstructions in the original paper are issues here.

Longrich, Martill and Andres 2018
bring us news of “a diverse pterosaur assemblage from the late Maastrichtian of Morocco that includes not only Azhdarchidae but the youngest known Pteranodontidae and Nyctosauridae. [This] dramatically increases the diversity of Maastrichtian pterosaurs. At least 3 families —Pteranodontidae, Nyctosauridae, and Azhdarchidae — persisted into the late Maastrichtian. These patterns suggest an abrupt mass extinction of pterosaurs at the K-Pg boundary.”

The authors summary starts off with an invalid statement:
“Pterosaurs were winged cousins of the dinosaurs.”  That was invalidated by Peters 2000, 2007 and ignored every since. We looked at that problem earlier here, here and here in a 3-part series testing all candidates. It’s time to realize that no one will ever find pterosaur kin among the dinos. They’ve already been clearly identified among the lepidosaurs.

The authors failed to include the Maastrictian tupuxuarid
found in southern Texas (Fig. 1; TMM 42489-2) and did not consider the Maastrichtian footprints discovered in 1954 and reexamined in 2018 that include two ctenochasmatids we will look at tomorrow.

Figure 1. TMM 42489-2, the tall crested Latest Cretaceous large rostrum and mandible. It’s a close match to that of Tupuxuara, otherwise known only from Early Cretaceous South American strata.

Alcione elainus gen. et sp. nov.
The new 1.5x larger nyctosaurid, Alcione elainus, known from disassociated bones including a shorter radius + ulna, a shorter metacarpal 4, a larger femur, and a tiny sternal complex (identified as a ‘sternum’ in the text) only 40 percent the size of a standard nyctosaur sternal complex (if the scale bars are correct). When placed on a reconstruction of a more complete Nyctosaurus (UNSM 93000; Fig. 2), scaled to the humerus, the result produces a likely flightless nyctosaur. Strangely, the authors called this a “small nyctosaur” even though it is half again larger than UNSM 93000. The authors mislabeled the shorter, straighter scapula as a coracoid, and vice versa.

Figure 2. GIF movie of Nyctosaurus and Alcione showing a likely flightless nyctosaur based on the parts preserved. Three frames change every 5 seconds. The sternum is tiny (assuming the scale bars are correct), the metacarpus and antebrachium are short and the femur is long.

They did not mention the possibility of flightlessness.
They did report, “The abbreviated distal wing elements in Alcione indicate a specialized flight style. The short, robust proportions suggest reduced wingspan and increased wing loading, implying distinct flight mechanics and an ecological shift. Short wings would increase lift-induced drag at low speeds, but reduced wing areas would decrease parasite drag at high speeds, suggesting that Alcione may have been adapted for relatively fast flapping flight compared to other nyctosaurids. Alternatively, reductions in wingspan might represent an adaptation to underwater feeding, i.e., plunge diving of the sort practiced by gannets, tropicbirds, and kingfishers, where smaller wings would reduce drag underwater.”

Not sure why they mentioned
‘distal wing elements’ here. They did not list or discuss distal wing elements elsewhere. Perhaps they meant proximal.

The reconstructed mandible of Alcione
is narrower than the rostrum in UNSM 93000.

Based on the vestigial fingers of UNSM 93000
and the short metacarpus of the new specimen, Alcione might have been the first pterosaur to walk on metacarpal 4, albeit at the very end of the reign of pterosaurs.

Other flightless pterosaurs include:
the basal azhdarchid form the Solnhofen, Jme-Sos 2428 and the Late Jurassic anurognathid PIN 2585/4 from the Sordes slab. They demonstrate that the distal wing elements reduce first. Thus the reconstruction, based on nyctosaur patterns restores a wing that was not volant.

Longrich, Martill and Andres did find a giant nyctosaur
which they named Barbaridactylus grandis based on a large humerus (Fig. 3). The humerus of the more complete UNSM 93000 specimen is 9.5 cm. By comparison the humerus in Barbaridactylus is 22.5 cm. I’m going to trust the text comment that the ulna + radius are 1.3x longer than the humerus. The scale bars indicate about half that length. Similar problem possible in the scapula/coracoid, according to the nyctosaur bauplan.

Figure 3. Barbaridactylus, a giant nyctosaurid. If the wing was like UNSM 93000, then it could fly. If the wing was like Alcione, then it could not. The scale bars did not match the text description on the ulna + radius, so both sizes are shown. Sometimes you have to be prepared for the occasional mistake in a published paper.

Other giant nyctosaurs
Earlier and here we noted giant nyctosaurs were flying over the Niobrara Sea (midwest North America) based on a large wing finger with unfused extensor tendon process (YPM 2501) and a large nyctosaur pelvis (KUVP 993; misinterpreted by Bennett (1991, 1992) as belonging to a female Pteranodon). 

No reconstructions were provided
by Longrich, Martill and Andres 2018. Reconstructions and a nyctosaur blueprint might have helped these paleontologists with firsthand access to the specimens discover the issues they missed.

It’s good to know
more pterosaurs made it to the latest Cretaceous.

References
Bennett SC 1991. Morphology of the Late Cretaceous Pterosaur Pteranodon and Systematics of the Pterodactyloidea. [Volumes I & II]. Ph.D. thesis, University of Kansas, University Microfilms International/ProQuest.
Bennett SC 1992. Sexual dimorphism of Pteranodon and other pterosaurs, with comments on cranial crests. Journal of Vertebrate Paleontology 12: 422–434.
Longrich NR, Martill DM, Andres B 2018. Late Maastrichtian pterosaurs from North Africa and mass extinction of Pterosauria at the Cretaceous-Paleogene boundary. PLoS Biol 16(3): e2001663. https://doi.org/10.1371/journal.pbio.2001663
Peters D 2000b. 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. In D. Hone ed. Flugsaurier. The Wellnhofer pterosaur meeting, 2007, Munich, Germany. p. 27.

Press coverage
Smithsonian
Newswise
PhysOrg

Pre-elasmosaurs out-competed tanystropheids as passive vertical predators

The hyper-elongate neck developed by convergence three times
(Figs. 1, 2) in the known prehistory of marine tetrapods. On land we have giraffes, langobardisaurs and sauropods, but they are not considered here due to their separate terrestrial environs. Based on the similar necks and diets (fish and squid of these three marine tetrapods, perhaps some of the mystery surrounding these taxa can be resolved.

Figure 1. Albertonectes, Tanystropheus and Dinocephalosaurus to scale. With all the other predators assuming a horizontal pose, maybe the vertical neck of these predators in the midst of schools of fish and squid went unnoticed…until it was too late. Maybe those rocks in the belly of the elasmosaur helped keep it anchored.

The three marine taxa with hyper elongate necks
(Fig. 1) are Albertonectes (Elasmosauridae), Tanystropheus (Tritosauria), and Dinocephalosaurus (Tritosauria). We also know of several specimens closely related to each of these taxa, discussed here, here, and here. They all share more than a hyper-elongate neck in common, but that’s the one thing that predominates. They appear to have all been marine vertical predators, passively extending their neck up into schools of prey, essentially unrecognized because they were not horizontal speedsters, like all the other predators out there.

Figure 2. Skulls of Albertonectes, Dinocephalosaurus and two types of Tanystropheus skulls compared, not to scale. Lots of convergence here, it’s plain to see.

Convergent skull traits in vertical feeders:

1. Small skull
2. Long procumbent teeth
3. Large premaxilla
4. Upward facing eyes
5. Dorsally displaced nares
6. Rostrum wider than tall
7. Internal naris migrated posteriorly
8. Flat palate

Renesto 2005 along with Renesto and Saller 2018
presented evidence to show that Tanystropheus had a semi-aquatic horizontal lifestyle.

1. “Tanystropheus was able to lift the body off the substrate when on land,
2. Tanystropheus lacked adaptations for continuous swimming, either tail-based or limb-based,
3. Tanystropheus was able to swim for by rowing with symmetrical strokes of the hind limbs.”

But remember,
Renesto and Saller mistakenly considered Tanystropheus a protorosaur and an archosauromorph. It is neither. In the large reptile tree (LRT, 1175 taxa) Tanystropheus nests with Huehuecuetzpalli and pterosaurs, all in the clade Tritosauria, a clade within Lepidosauria.

Renesto and Saller continue:
“The life style of Tanystropheus,the largest and most bizarre of all tanystropheids, remained uncertain since its discovery… In conclusion, Tanystropheus may have had lived in a shore line environment, where the elongate neck, may have been used to cach preys in shallow water by dashing at the prey propelled by hindlimbs, either starting from the shoreline from a resting positionor, in water, eventually after slowly closing the distance. In water, the long neck would have allowed Tanystropheus to conceal its real size while slowly approaching to fish or squid schools by reducing the disturbance caused by body surrounding water, avoiding to be detected by the prey’s lateral line. When close enough, Tanystropheus may have shifted to fast pursuit for the sudden propulsive final phase, with a series of rapid symmetrical strokes of the hind limbs (Fig. 6).”

Yeah, maybe…
but Renesto and Saller just said Tanystropheus was not a good swimmer. So let’s toss out that shift to fast pursuit.

Imagine a passive predator distinct from
all the other predators assuming a horizontal pose. Maybe the vertical neck of all these predators in the midst of schools of fish and squid went unnoticed by them…until it was too late. Maybe it’s as simple as that. No extant taxa can be used by analogy, so we have to look at extinct taxa with similar traits. We looked at Tanystropheus among the crinoids (Fig. 1), and the evolution to that niche earlier here. The convergent Dinocephalosaurus neck strike hypothesis is from Peters, Demes and Krause 2005. The long-necked limbed ancestors of elasmosaurs were morphologically similar and coeval to long-necked limbed tritosaurs in the Middle Triassic (Fig. 5).

Note added on the vertical neck: 
Peters, Demes and Krause 2005 (actually just Peters, in this case, as there were three comments to the original Dinocephalosaurus paper (Li, Rieppel and LaBarbera 2004), now lumped into one reply) suggested that breathing would have been difficult for long-necked underwater taxa due to changes in pressure with increasing depth, but these taxa could swallow air at the surface then lower the neck to allow the air bubble to rise into the lungs. Just a few degrees of declination would do the trick.

Renesto and Saller report:
“The study focused mostly on the post-dorsal sections of the vertebral column, on the pelvis and hind limb.”  Ignoring the neck in Tanystropheus ignores the biggest clue to its niche. Let’s not do that.

Figure 3. The Middle Triassic world with the tropical shallow San Giorgio area where Tanystropheus is found highlighted. Warm waters enabled Tanystropheus and other Triassic reptiles  to stay submerged continually.

Another dinocephalosaur
was reconstructed here (Fig. 3). The neck in this specimen is so gracile, it is difficult to imagine it in any active mode, so the vertical passive pose remains as the only viable alternative. These are not active predators.

Figure 4. The new Dinocephalosaurus has traits the holotype does not, like a longer neck with more vertebrae, a robust tail with deep chevrons and a distinct foot morphology with an elongate pedal digit 4.

And finally
Note the long neck of the derived nothosaur/pre-elasmosaur, like Wangosaurus (Middle Triassic), preceded the evolution to flippers found in later vertical feeding elasmosaurs (Fig. 5). Like the the coeval vertical predators tanystropheids (Fig. 1) and dinocephalosaurs (Fig. 4) pre-elasmosaurs like Wangosaurus out-competed these similar tritosaur lepidosaurs, which cannot be found after the Triassic. Clearly pre-elasmosaurs were not such great swimmers when they started, and must have been only marginally better swimmers after their small limbs became small flippers. Given this data, the hypothesis of vertical predation of small squid and fish prey in pre-elasmosaurs and their elasmosaur descendants deserves the opportunity to be falsified.

By contrast, pliosaurs,
like Brachauchenius, with their big flippers and large toothy skulls, were excellent horizontal predators and fast swimmers. This contrast is key to the present hypothesis.

Figure 5. Elasmosaurid origins. The long neck preceded the flippers in this clade of vertical feeders.

Additional data:
Albertonectes vanderveldei (Kubo et al. 2012; Upper Campanian, Alberta; TMP 2007.022.0002) is a virtually complete elasmosaur 11.2m in length (the longest of any elasmosaur) lacking only the skull. It had a 7m neck of 76 vertebrae, the most of any vertebrate. Stones in the belly might have kept it anchored. The gizzard in birds is located posteriorly, as seen in this elasmosaur.

Tanystropheus longobardicus (Tanystropheus conspicuus von Meyer 1855,  Tribelesodon longobardicus Bassani 1886,  Tanystropheus longobardicus Peyer 1930) Anisian, Middle Triassic, ~240 mya, ~4.5m in length, was considered a pterosaur before Peyer (1930) established that the long bones were neck bones, not wing bones. Derived from a sister to the the T4822 specimen of Macrocnemus, Tanystropheus was a sister to the much smaller Tanytrachelos and Langobardisaurus, rather than the convergent Dinocephalosaurus. Warm waters enabled Tanystropheus and other Alpine Triassic reptiles  to stay submerged continually.

Dinocephalosaurus orientalis (Li, Rieppel and LaBarbera 2004) Late Ladinian, Middle Triassic ~228 mya, was orginally considered a marine sister to Tanystropheus with limbs nearly transformed into paddles of similar size. Phylogenetic analysis places it closer to a specimen of Macrocemus, T2472. Dinocephalosaurus was not a protorosaur, as originally described. Rather Dinocephalosaurus was a tritosaur lepidosaur The skull was described as crushed, but it was actually quite flat in life with dorsally directed orbits. The ribs were also much wider than deep. Both of these are characters found in bottom dwellers, not free-swimmers. The cervical (25) and dorsal (33) counts are the highest among tanystropheids. The limbs were short but the hands and feet were relatively large, paddle-like and probably webbed.

Figure 6. A squad of squid, food for both tanystropheids and elasmosaurs.

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.
Li C, Rieppel O and LaBarbera MC 2004. A Triassic aquatic protorosaur with an extremely long neck. Science 305:1931.
Liu, J. et al. 2017. Live birth in an archosauromorph reptile. Nature Communications 8, 14445 doi: 10.1038/ncomms14445
Peters D, Demes B and Krause DW 2005. Suction feeding in Triassic Protorosaur? Science, 308: 1112-1113.
Kubo T, Mitchell MT and Henderson DM 2012. Albertonectes vanderveldei, a new elasmosaur (Reptilia, Sauropterygia) from the Upper Cretaceous of Alberta. Journal of Vertebrate Paleontology 32 (3): 557-572. DOI:10.1080/02724634.2012.658124.
Li C 2007. A juvenile Tanystropheus sp.(Protoro sauria: Tanystropheidae) from the Middle Triassic of Guizhou, China. Vertebrata PalAsiatica 45(1): 37-42.
Li C, Rieppel O and LaBarbera MC 2004. A Triassic aquatic protorosaur with an extremely long neck. Science 305:1931.
Liu, J. et al. 2017. Live birth in an archosauromorph reptile. Nature Communications 8, 14445 doi: 10.1038/ncomms14445
Lockley MG 2006. Observations on the ichnogenus Gwineddichnium and  wyneddichnium-like footprints and trackways from the Upper Triassic of the Western United States. In: Harris JD, Lucas SG, Spielmann JA, Lockley MG, Milner ARG. & Kirkland JI (Eds) – The Triassic-Jurassic Terrestrial Transition. New Mexico Museum of Natural History Science Bulletin 37: 170-175.
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
Peters D, Demes B and Krause DW 2005. Suction feeding in Triassic Protorosaur? Science, 308: 1112-1113.
Peyer B 1931. Tanystropheus longobardicus Bass sp. Die Triasfauna der Tessiner Kalkalpen. Abhandlungen Schweizerische Paläontologie Gesellschaft 50:5-110.
Renesto S 2005. A new specimen Tanystropheus (Reptilia Protorosauria) from the Middle Triassic of Switzerland and the ecology of the genus: Rivista Italiana di Paleontologia e Stratigrafia 111(3): 377-394.
Renesto S and Saller F 2018. Evidences for a semi aquatic life style in the Triassic diapsid reptile Tanystropheus. Rivista Italiana di Paleontologia e Stratigrafia 124(1):23-34.
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/Dinocephalosaurus
wiki/Tanystropheus
https://en.wikipedia.org/wiki/Albertonectes