SVP abstracts 13: Tiny Tiktaalik-like tetrapod

Lembert et al. 2020 bring us
a much smaller Tiktaalik-like tetrapod.

From the Lembert et al. abstract:
“The elpistostegalian stem-tetrapod Tiktaalik roseae (Fig. 1) is known from a single locality (NV2K17) within the Fram Formation of Ellesmere Island, Nunavut Territory, Canada. Specimens from this locality represent subadult to adult specimens, including specimens up to 61% larger than the holotype specimen (NUFV 108) and reaching an estimated 3 meters in length.”

Figure 1. Tiktaalik specimens compared to Ossinodus.

“Here we present fossil material of a much smaller elpistostegalian specimen (NUFV 137) from a second, slightly older locality within the Fram Formation on Ellesmere Island (NV0401), possibly representing a juvenile T. roseae specimen or a new taxon.”

Not mentioned in this abstract, tiny Koilops (Figs. 2, 3) nests basal to Tiktaalik in the large reptile tree (LRT, 1251 taxa).

Figure 2. Koilops is a flat-headed sister to Spathicephalus, but with teeth, larger orbits and a shorter snout

Figure 3. The fin to finger transition in the LRT with the addition of Elpistostege.

Continuing from the Lembert et al. abstract:
“Preserved remains of NUFV 137 include fragmentary lower and upper jaws, gular plates, fragments of the rostrum, articulated body scales, articulated pectoral fin elements, and several other currently unidentified endoskeletal pieces. Linear proportions between homologous landmarks of lower jaws of NUFV 137 and NUFV 108 suggest an animal approximately 61% smaller than the holotype of T. roseae, and, with a reconstructed total jaw length of approximately 12.4 cm, NUFV 137 is similar in size to one of the smallest known elpistostegalian taxa (Rubrognathus kuleshovi).”

Taxon exclusion has evidently excluded the even smaller Koilops (Fig. 2) from the Lembert et al. studies.

“If NUFV 137 represents a juvenile T. roseae individual, it would expand the known size range of T. roseae specimens, with implications for understanding allometric growth in a tetrapodomorph taxon.

Figure 4. Subset of the LRT focusing on basal tetrapods. Colors indicate number of fingers known. Many taxa do not preserve manual digits.

Continuing from the Lembert et al. abstract:
“While lower jaw characters appear to be similar to those in T. roseae, it is uncertain if some features, such as a posteriorly displaced postsplenial pit line, reduced adsymphyseal dentition, and varying postcranial proportions, are the result of differences in ontogeny or warrant a separate taxonomic grouping. These differences, and the presence of a potential operculum, indicate NUFV 137 might represent a distinct but similar, Tiktaalik-like taxon.”

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References
Lemberg JB, Stewart TA, Daeschler E and Shubin NH 2020. Tomography of a tantalizingly tiny Tiktaalik-like taxon. SVP abstracts 2020.

SVP abstracts 12: Conoryctes, still not a taeniodont

Kynigopoulou Z et al. 2020
make another ill-fated attempt at nesting a taxon in a polyphyletic (= invalid) clade. Earlier (part of a 4-part series) the large reptile tree (LRT, subset Fig. 1) split up putative members of the Taeniodonta into several clades, making it invalid due to polyphyly.

Figure 1. Subset of the LRT labeling several traditional taeniodonts in red, indicating the traditional clade Taeniodonta is polyphyletic and should therefore be abandoned.

From the Kynigopoulou Z et al. 2020 abstract:
“Conoryctes belongs to the Taeniodonta, a group of Paleogene mammals with unique dentition, suitable for an abrasive diet, and specialized postcranial skeletons.”

No it doesn’t. There is no monophyletic clade Taeniodonta. Conoryctes (Fig. 2) nests in the LRT as a carnivorous marsupial close to Early Cretaceous Vincelestes.

Figure 2. Conoryctes fossil and drawing from Schoch 1986.

Continuing from the Kynigopoulou Z et al. 2020 abstract:
“Taeniodonts are among few eutherian clades with fossil evidence indicating they crossed the Cretaceous–Paleogene mass extinction boundary. They are traditionally divided into two families: the more ‘generalist’ Conoryctidae and anatomically derived Stylinodontidae.”

Whoa! Stylinodonts aren’t taeniodonts either. They are placental carnivorans.

“Here we report new specimens of Conoryctes from the Paleocene Nacimiento Formation of the San Juan Basin, New Mexico, U.S.A. These consist of numerous vertebrae, a pelvis, sacrum, partial forelimb and hindlimb, with phalanges and unguals, comprising the first relatively complete associated postcranium of the genus.”

Fantastic! Post-crania! Should look like Vincelestes post-crania.

“The new specimens allowed us to add new postcranial characters to a large phylogenetic analysis of early eutherian mammals (622 characters, 125 taxa), which we analysed using parsimony and Bayesian techniques. The results find Onychodectes as a basal taeniodont outside of the sister groups Conoryctidae (Conoryctes, Conoryctella, Huerfanodon) and Stylinodontidae (Wortmania, Psittacotherium, Ectoganus, Stylinodon).”

Missing a TON of taxa here (Fig. 1). I wonder if these taxa were united by teeth traits? If so, don’t do that. The value of quantity (in the LRT) comes up once again. Colleagues: let’s get the overall picture right, then add details.

“We also examined the anatomy and locomotor adaptations of the hindlimb, using multivariate analysis of 11 linear pes measurements to assess foot posture. Three representative taeniodonts (Onychodectes, Conoryctes, Stylinodon) were compared to a suite of extant mammals with known postural grades of the foot, as well as eight Paleogene taxa. Onychodectes and Conoryctes exhibit a more plantigrade posture whereas Stylinodon is more digitigrade, plotting next to the aardvark (Orycteropus).”

Do these authors know the aardvark is an armor-less armadillo?  Did they include Vincelestes (Fig. 3) in their taxon list?

Figure 3. Vincelestes overall.

Continuing from the Kynigopoulou Z et al. 2020 abstract:
“Qualitatively, in Conoryctes, the astragalus features a relatively well-developed trochlear surface indicating cruropedal movement was more limited to the parasagittal plane. The articular surfaces on the astragalus and calcaneum with the navicular and cuboid respectively, show a degree of rotational movement within the middle pes suggestive of moderate supination during pedal flexion. The calcaneal tuber is robust indicative of a powerful foot stroke. These features, in combination with other features of the skeleton, support digging abilities in Conoryctes. Our study suggests that a plantigrade foot posture and digging behaviors are ancestral for Conoryctidae and perhaps all taeniodonts. It is likely their ability to burrow, and feed on tough vegetation, was essential to their survival in the early Paleocene and subsequent radiation.”

The LRT suggests you compare Conoryctes to Vincelestes, if you haven’t done so already. And add more taxa to see if your Taeniodonta remains monophyletic.

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References
Kynigopoulou Z, Shelley S, Williamson T and Brusatte S 2020. The anatomy, paleobiology, and phylogeny of the Paleocene Taeniodont Conorycties. SVP abstracts 2020.

https://pterosaurheresies.wordpress.com/2018/12/24/taeniodonta-is-polyphyletic-part-3-conoryctes/

SVP abstracts 11: Palacrodon returns as a drepanosauromorph?

Jenkins et al. 2020 review
“the phylogenetic placement of an enigmatic reptile from the Early Triassic Transantarctic Mountains.” This reptile has gone through some name changes, but the large reptile tree (LRT, 1751+ taxa) nested it in 2016 with similar, big-eyed, basal placodonts like Palatodonta and Pappochelys (Fig. 1). Co-authors Jenkins and Lewis (2016) nested it with rhynchocephalians, but limited their taxon list to rhynchocephalians and procolophonids. There is no indication that they included basal placodonts in 2020.

Originally
(Broom 1906) considered what little is known of Palacrodon browni (= Fremouwsaurus geludens; Early Triassic; Fig. 1) a member of the Rhynchocephalia.

Figure 1. A comparison of basal placodonts to scale (and Paraplacodus reduced to one-third shows how Fremouwsaurus (Palacrodon) is transitional between the small spike-tooth ancestors like Palatodonta and Pappochelys and the pavement toothed Paraplacodus.

From the Jenkins et al. 2020 abstract:
“The phylogenetic placement of Palacrodon has been contentious since its initial description, with workers naming it as either a rhynchocephalian, lizard, procolophonid, eosuchian, or archosauromorph.”

Taxon inclusion nests it with basal placodonts.

“The uncertainty surrounding the phylogenetic affinity of Palacrodon in large part stems from the fact that nearly all the specimens found are teeth and fragmentary portions of tooth-bearing bone. Palacrodon bears characteristic labio-lingually elongate, molariform, cuspidate teeth reminiscent of herbivorous reptiles like extinct trilophosaurs and polyglyphanodonts and modern shell-crushing lizards.”

“Because previous workers lacked any other skeletal material, Palacrodon has never been placed within a phylogeny.”

Never? The LRT placed it in 2016,

“Though its phylogenetic affinity is uncertain, Palacrodon is a cosmopolitan genus spanning most of the Triassic, with specimens found in the Early Triassic of Antarctica, Early-Middle Triassic of South Africa, and the Late Triassic of Arizona. The only specimen of Palacrodon possessing more than dentition is from the Early Triassic lower Fremouw Formation of Antarctica (specimen number BP/1/5296). That formation is the sedimentary sequence immediately preceding the Permian-Triassic mass extinction boundary in the Transantarctic Mountains and represents the only known Early Triassic paleopolar deposit with abundant tetrapod material. The Antarctic specimen of Palacrodon was described from the impression of a latex peel as a partial small skull belonging to an unknown diapsid reptile initially named Fremouwsaurus geludens, which was later synonymized with Palacrodon.”

“We CT scanned the Antarctic specimen and found that previously undescribed skeletal elements are preserved in BP/1/5296. These include limb bones, ribs, phalanges, caudal vertebrae, ankle bones, and an ilium. Of the cranial elements, portions of the right maxilla, lacrimal, prefrontal, jugal, postorbital, ectopterygoid, and dentary are preserved. Both parsimony and Bayesian analyses found Palacrodon to be a stem saurian with close affinities to drepanosauromorphs.”

See figure 2 for known drepanosaurs (all Late Triassic) and their ancestor, Jesairosaurus (Early to Middle Triassic) in the LRT.

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

From the Jenkins et al. 2020 abstract:
“This finding suggests that Palacrodon is the earliest known drepanosaur, extending the temporal range of the clade by nearly 20 million years. Palacrodon is also the only known drepanosauromorph from the southern hemisphere. Further analysis of these new skeletal elements will now allow a more thorough understanding of the behavior and niche of Palacrodon and primitive drepanosuars generally.”

Excluding far fewer taxa, in the large reptile tree (LRT, 1749+ taxa) moving Palacrodon from the base of the Placodontia to the base of the Drepanosauromorpha adds 8 steps based on very few skull traits. Of course the post-crania could change things, but usually taxon exclusion changes things more.

Figure 2. The head of Palacrodon and the headless body of the Majiashanosaurus compared.

References
Broom R 1906. On a new South African Triassic rhynchocephalian. Transactions of the Philosophical Society of South Africa 16:379-380.
Gow CE 1992. An enigmatic new reptile from the Lower Triassic Fremouw Formation of Antarctica. Palaeontologia Africana 29:21-23.
Gow CE 1999. The Triassic reptile Palacrodon brown Broom, synonymy and a new specimen.
Jenkins K, Lewis P, Choiniere J and Bhullar B-A 2020. The phylogenetic placement of an enigmatic reptile from the Early Triassic Transantarctic Mountains. SVP abstracts 2020.
Jenkins KM and Lewis PJ. 2016. Triassic lepidosaur from southern Gondwana. Abstract from the 2016 meeting of the Society of Vertebrate Paleontology.
Neenan JM, Li C, Rieppel O, Bernardini F, Tuniz C, Muscio G and Scheyer TG 2014. Unique method of tooth replacement in durophagous placodont marine reptiles, with new data on the dentition of Chinese taxa. Journal of Anatomy 224(5):603-613.

https://pterosaurheresies.wordpress.com/2016/10/30/is-palacrodon-a-rhynchocephalian-svp-abstract-2016/

 

SVP abstracts 10: Scottish Middle Jurassic pterosaur, back again this year

This is the second time
the wonderful Skye, Scotland pterosaur has entered the SVP abstracts. The first was in 2019, covered here. Evidently, this specimen is still unnamed and unnumbered, so I wondered, what progress does the new set of authors bring to this specimen this year?

Figure 1. Skye pterosaur from traced from in situ specimens found online.

From the Jagielska et al. 2020 abstract:
“An incomplete fossil record limits understanding of pterosaurian macroevolution during the Middle Jurassic, a period associated with diversification of many major pterosaur clades.”

By contrast, the fossil record in the large pterosaur tree (LPT, 251 taxa) has no large gaps during the Middle Jurassic (Fig. 2) or otherwise. The fossil record is more complete than the authors realize, evidently due to taxon exclusion.

“The European Middle Jurassic pterosaurian record, until now, has consisted of numerous non-taxon specific specimens and included a single named genus, based on a partially preserved dentary.”

Are we forgetting all the many Dorygnathus specimens (Fig. 2)? Several are transitional to higher pterodactyloid-grade taxa, either directly (ctenochasmatids and azhdarchids) or indirectly through Scaphognathus (the rest of them; Peters 2007).

Figure 2. Click to enlarge. The descendants of Sordes in the Dorygnathus clade and their two clades of pterodactyloid-grade descendants.

Continuing from the Jagielska et al. 2020 abstract:
“Here we describe a new three-dimensionally preserved partial skeleton from the Bathonian Lealt Shale Formation of Skye, Scotland, that helps fill the Middle Jurassic pterosaur gap. It is the most complete fossil from the Jurassic sequence of the Scottish Hebrides, which commonly yields ichnofossils but only fragmentary archosaur remains, and the first nearly complete Middle Jurassic pterosaur from outside of China. The new pterosaur is mostly articulated and includes the skull (which retains delicate palatal, hyoid, and neurocranial elements), complete cervical and caudal vertebral series, fully preserved paired forelimbs with partially preserved wing phalanges, a disarticulated dorsal vertebral series and ribcage, and a poorly preserved sacral, pelvis and hindlimb region. It is the largest non-pterodactyloid on record, with an estimated 2 m wide wingspan.”

We also heard this in 2019. Since the authors have changed, perhaps no one told Jagielska et al. that this specimen was featured in an SVP abstract a year ago.

“The specimen represents a new genus and species diagnosed by several autapomorphies, including slender, curved humeral shaft; large teardrop-shaped lower temporal fenestra; a novel “jugo-lacrimal” fossa, and unique palatal arrangement with trident-shaped anterior vomer.”

As Larry Martin was quick to note, most autapomorphies can be found in other tetrapod taxa by convergence. So first, run the analysis. Then start describing some interesting traits.

“We conducted a phylogenetic analysis by combining several published datasets, which placed the new Scottish pterosaur within the paraphyletic array of non-monofenestratans commonly called the Rhamphorhynchinae, where it shares cranial similarities to the similarly-aged Chinese Angustinaripterus longicephalus.”

Sometimes more data nests taxa elsewhere, but their ‘several published datasets’ don’t include the LPT (subset Fig. 3). Borrowing other datasets usually absolves authors from mistakes made by prior authors, especially taxon exclusion issues. Colleagues, students: create your own datasets. Create your own reconstructions. By the way, in 2019 the earlier set of authors nested the Skye pterosaur with Darwinopterus and Wukongopterus, far from Angustinaripterus. The LRT nests the Skye pterosaur basal to the clade of wukongopterids (Fig. 3).

“We imaged the skull using microCT, which reveals a brain endocast with a large cerebellum and floccular region wrapped by thin, curved semi-circular canals of the inner ear, similar to closely related Rhamphorhynchus muensteri.”

The 2019 abstract likewise mentioned µCT scans. None of the above taxa are closely related to R. muensteri.

Figure 3. Subset of the LPT showing the nesting of the Skye pterosaur from available data (Fig. 1).

Continuing from the Jagielska et al. 2020 abstract:
“Along with the highly diverse but fragmentary Tayton Limestone Formation assemblage of England, the new specimen challenges the long-considered notion that the European Middle Jurassic was a time of low pterosaur diversity and anatomical disparity.”

One more specimen that we knew about last year will not challenge a ‘long considered notion’ that was never a notion to begin with. Hate to be snippy here, but hyperbole is not appropriate in science simply to elevate a notion or a cladogram, especially if it lacks dozens of pertinent taxa.

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References
Jagielska N et al. (9 co-authors) 2020. An exceptionally well preserved pterosaur from the Middle Jurassic of Scotland. SVP abstracts 2020.
Martin-Silverstone E, Unwin DM and Barrett PM  2019. A new, three-dimensionally preserved monofenestratan pterosaur form the Middle Jurassic of Scotland and the complex evolutionary history of the scapulo-vertebrael articulation. SVP abstracts 2019. Peters D 2007. The origin and radiation of the Pterosauria. In D. Hone ed. Flugsaurier. The Wellnhofer pterosaur meeting, 2007, Munich, Germany. p. 27.

https://pterosaurheresies.wordpress.com/2019/11/01/svp-abstracts-the-skye-pterosaur/

SVP abstracts 9: Pushing a tiny wading pterosaur into the deep end

Habib, Pittman and Kaye 2020
add laser fluorescence to a tiny pterosaur, the still unnamed Berlin specimen, MB.R.3531 (Figs. 1a, b) we first looked at following Flugsaurier 2018.

From the Habib et al. abstract:
“Water launch capacity has been previously suggested for some marine pterosaurs based on osteological grounds, but robust estimates of specimen-specific performance are difficult without robust estimates of wing area and potential hindfoot webbing. Here, we provide the first estimates of pterosaur water launch performance that take into account preserved soft tissue anatomy.”

FIgure 1a. Reconstruction of MB.R.3531, nesting with Eoazhdarcho, Eopteranodon and Aurorazhdarcho. Shown about actual size, so this pterosaur could have stood upright like this in a 10cm per side box. See figure 1b.

Figure 1b. Aurorazhdarcho primordial and the smaller Aurorazhdarcho micronyx (not a juvenile) to scale. The smaller one had better stay out of deeper waters.

Continuing from the Habib et al. abstract:
“The aurorazhdarchid pterosaur specimen MB.R.3531 from the Upper Jurassic Solnhofen Limestone was imaged using Laser-Stimulated Fluorescence, revealing significant soft tissue preservation. These soft tissues are among the best-preserved of any known Jurassic pterosaur, including for the first time, a complete actinofibrillar complex, an undistorted actinopatagium with the retrophalangeal connective tissue wedge and entire trailing edge, and webbed feet.”

Why the showmanship (= hyperbole, = falsehood)? Most of these traits have been known for several pterosaurs and from less jumbled specimens, including the  Zittel wing specimen of Rhamphorhynchus (Fig. 2), the dark-wing specimen of Rhamphorhynchus and the Vienna specimen of Pterodactylus (Fig. 3).

Figure 2. The Zittel wing from a species of Rhamphorhynchus. This is real. There is no way this wing membrane is going to stretch to the ankles. See figure 3 for comparison and phylogenetic bracketing. This is how pterosaur wings were able to be folded away when not in use. 

Figure 3. Here is the Vienna specimen of Pterodactylus in situ and with matrix removed. Now compare this figure with figure 3, which shows the wings and uropatagia unfolding. There is no way to turn this into a deep chord wing membrane. And it decouples the forelimbs from the hind limbs. This is how pterosaur wings were able to be folded away when not in use. 

Continuing from the Habib et al. abstract:
“These physically validated soft tissues formed the basis for analyzing water launch capability in MB.R.3531. We modeled the water launch as quadrupedal and broadly similar to modern “puddle jumping” anseriform birds that use a combination of their webbed feet and partially folded wings to push against the water surface during takeoff.”

More myth-making. Like the morphologically similar by convergence, Pterodactylus (based on the Vienna specimen; Figs. 3, 4), MB.R.3531 was a quadrupedal wader (note the tiny fore claws), but able to stand bipedally prior to take-off. Waders don’t get themselves into water too deep to touch the substrate. Ask any sandpiper, plover or stilt.

So this is much ado about nothing, based on putting the discredited Habib method of pushup take-off back on the table.

Figure 4. Pterodactylus scolopaciceps (n21) model. Full scale. This is how pterosaur wings were able to be folded away when not in use. 

More from the Habib et al. abstract:
“Under this model, both hind limb and forelimb contact areas are critical. Under conservative assumptions regarding power and range of motion, we predict that MB.R.3531 was capable of rapid takeoff from the water surface.

Yes, of course, but from a bipedal start (Fig. 5). And from shallow ponds, no deeper than knee deep.

FIgure 5. Dimorphodon take off (with the new small tail).

From the Habib et al. abstract:
“Our model predicts that water launch performance in pterosaurs was particularly sensitive to three factors: available propulsive contact area, forelimb extension range, and extension power about the shoulder. MB.R.3531 possessed both osteological and soft tissue features that significantly enhanced these performance characteristics (including, but not limited to, expanded internal rotator/extensor attachments on the proximal humerus, extended humeral length, chordwise distal actinofibril orientation, and webbed pes).”

If you’ll compare one with another, MB.R.3531 (Fig. 1) is convergent in most respects to a typical Solnhofen Pterodactylus (Fig. 4), down to the webbed feet. There was nothing out of the ordinary about MB.R.3531.

“These features would have limited impact on flight performance. We therefore interpret them as likely water takeoff specializations.

Whoa, partner! These traits are typical of most beach combing pterosaurs, so far as they can be determined in fossils and phylogenetic bracketing, even with unrelated clade convergence.

“The osteological specializations in MB.R.3531 are subtle, which may be related to its small size.”

I would agree that the osteological specializations are so subtle they do not exist.

“Larger marine pterosaurs appear to exaggerate these characteristics, which matches expectations from scaling.

This is false. Ornithocheirids have notoriously tiny feet, unsuitable for anything more than standing still and walking slowly. More to come.

“We show that soft tissue data can be used to help validate the dynamic feasibility of water launch in pterosaurs, suggesting it was a regular part of foraging behavior in some taxa.”

This is false. Dr. Habib, just let the pterosaur stand upright, as its ancestors did and as it was designed to do (fused sacrals and fused dorsal vertebrae dorsally, sternum + gastralia + prepubes support ventrally). Quadrupedal pterosaur tracks are more prevalent because they were made by a few clades of small-fingered beach combing pterosaurs, principally pterodactylids, ctenochasmatids and azhdarchids (Peters 2011).

Figure 6. Pelican take-off sequence from water using kicking webbed feet and elevated, then flapping wings simultaneously. Click to enlarge.

From an earlier 2018 assessment of MB.R.3531:
Habib and Pittman 2018 bring us a rarely studied Berlin pterosaur, MB.R.3531 (Fig. 1) originally named Pterodactylus micronyx, then Aurorazhdarcho micronyx. This specimen nests with other wading pterosaurs, Aurorazhdarcho, Eopteranodon and Eoazhdarcho forming  a clade overlooked by other workers, at the transition between germanodactylids and pteranodontids, not related to azhdarchids (Peters 2007).

For those wondering why I don’t publish more.
Why put in the effort if competing studies are ignored? The online way is faster, briefer and can be animated with no color charges. Furthermore, the vetting process prior to publication of hypotheses like the dangerous pushup launch and the bat-wing pterosaur membrane myth, is failing time and again. Editors, professors and researchers who should be earning their paycheck from rigorously testing new hypotheses are instead granting their friends free passes in an effort to keep the status quo in lectures and textbooks.

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References
Habib M and Pittman M 2018. An “old” specimen of Aurorazhdarcho micronyx with exceptional preservation and implications for the mechanical function of webbed
feet in pterosaurs. Flugsaurier 2018: The 6th International Symposium on Pterosaurs. Los Angeles, USA. Abstracts: 41–43.
Habib MB, Pittman M and Kaye T 2020. Pterosaur soft tissues revealed by laser-stimulated fluorescence enable in-depth analysis of water launch performance. SVP abstracts 2020.
Peters D 2000a. Description and Interpretation of Interphalangeal Lines in Tetrapods.  Ichnos 7:11-41.
Peters D 2007. The origin and radiation of the Pterosauria. In D. Hone ed. Flugsaurier. The Wellnhofer pterosaur meeting, 2007, Munich, Germany. p. 27.
Peters D 2010. In defence of parallel interphalangeal lines.
Historical Biology iFirst article, 2010, 1–6 DOI: 10.1080/08912961003663500
Peters D 2011. A Catalog of Pterosaur Pedes for Trackmaker Identification
Ichnos 18(2):114-141. http://dx.doi.org/10.1080/10420940.2011.573605

https://pterosaurheresies.wordpress.com/2018/03/23/pteranodon-quad-hopping-water-takeoff-according-to-the-amnh/

https://pterosaurheresies.wordpress.com/2018/08/12/flugsaurier-2018-web-footed-little-pterosaur-mb-r-3531/

https://pterosaurheresies.wordpress.com/2012/12/16/water-takeoff-in-a-pelican-part-2-with-reference-to-pterosaur-water-takeoffs/

https://pterosaurheresies.wordpress.com/2015/03/23/amnh-animated-pterosaur-takeoffs/

https://pterosaurheresies.wordpress.com/2012/04/07/pterosaur-take-off-from-water/

https://pterosaurheresies.wordpress.com/2013/12/06/pterosaurs-were-unlikely-floaters-hone-and-henderson-2013/

https://pterosaurheresies.wordpress.com/2015/05/23/pterosaur-launch-talk-from-2012-on-youtube/

SVP abstracts 8: µCT studies on Scleromochlus reveal it is a ‘reptile’

Foffa et al. 2020 apply µCT scanning technology
to the tiny Late Triassic Scleromochlus (Fig. 1). This bipedal crocodylomoph with tiny fingers was Michael Benton’s (1999) and Chris Bennett’s (1996) cherry-picked choice to be the taxon closest to pterosaurs (whenever the actual sisters (Peters 2000) were omitted).

Figure 1. Faxinalipterus matched to Scleromochlus. The former is more primitive, like Gracilisuchus, in having shorter hind limbs and more robust fore limbs. The maxilla with fenestra and fossa, plus the teeth, are a good match.

Scleromochlus has become more popular lately.
Earlier this year, Bennett 2020 provided new drawings, but not much new insight. His cladograms failed to recover a single node on which to nest Scleromochlus.

From the Foffa et al. 2020 abstract:
“The herpetofauna of the Lossiemouth Sandstone Formation (Late Triassic) of Elgin (Moray, Scotland) includes several close relatives of key groups such as dinosaurs, pterosaurs, crocodilians and lepidosaurs, although the affinities of some taxa within this assemblage are contentious.”

How contentious?

• Pterosaurs? No.
• Dinosaurs? No.
• Crocodilians (= Crocodylomporha)? Yes: Saltopus and Scleromochlus.
• Lepidosaurs? No, according to Wikipedia and the LRT.

Continuing from the Foffa et al. 2020 abstract:
“The specimens of this assemblage are notoriously challenging to study because of their preservation as voids in sandstone. Historically, the ‘Elgin reptiles’ have been studied primarily using physical molds, which only provide incomplete, and potentially distorted information – an issue that particularly affects small-bodied taxa. Here we use microcomputed tomographic (μCT) techniques as an alternative method to study these important specimens, and access hidden parts of their skeletons.”

“Scleromochlus taylori is one of the most controversial taxa within the assemblage. It is an enigmatic, small-bodied, bipedal reptile that was long hypothesised to be closely related to dinosaurs and pterosaurs, and is represented by several specimens of varying completeness.”

Not an enigma. In the large reptile tree (LRT, 1749+ taxa; subset Fig. 2), and earlier (Peters 2002) nested Scleromochlus as a basal bipedal crocodylomorph. Add pertinent sister taxa (and let’s see your reconstructions and tracings to make sure interpretations are correct) to confirm or refute.

Figure 2. Subset of the LRT focusing on the Crocodylomorpha, dorsal scutes, elongate proximal carpals, bipedality and clades.

Continuing from the Foffa et al. 2020 abstract:
“It was recently reinterpreted as a quadrupedal ‘hopper’, (Bennett 2020) positioned phylogenetically either within doswelliid archosauriforms, or outside of the Archosauria + Erythrosuchidae clade. Neither of these interpretations has been universally accepted, and other aspects of the biology of Scleromochlus are also contentious.

Taxon exclusion is the universal problem with prior studies. Given the proportions of Scleromochlus (Fig. 1) and the proportions of its phylogenetic sisters (Fig. 2), why force it into an awkward quadrupedal posture?

Figure 1. Taxa from the croc subset of the LRT to scale. Click to enlarge.

Continuing from the Foffa et al. 2020 abstract:
“Here we analyse the first μCT scan data collected for Scleromochlus, using all available specimens, and show that historic molding incompletely captured its anatomy. We access and describe previously inaccessible (and thus unaltered) portions of its skeleton including a complete [unintentionally left blank], as well as new details of already described regions. Overall, we clarify previous ambiguous features such as vertebral count, dorsal rib length and curvature, and reveal new details from the neck, tail, girdles, fore and hindlimb (particularly manus, femur and pes). We use this information, alongside that from multiple generations of molds, to shed light on some of the most controversial aspects of its anatomy, phylogenetic relationships, taphonomy, and ecology.”

Well,  that’s a lot of teasing without telling readers what Scleromochlus is. The title of the abstract only refers to Scleromochlus as a ‘reptile/’. No other conclusions are presented.

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References
Foffa D, Barrett P, Butler R, Nesbitt S, Walsh S, Brusatte S, Fraser N 2020. New Information on the Late Triassic reptile Scleromochlus taylori from µCT data. SVP abstracts 2020.

http://reptileevolution.com/scleromochlus.htm

Bennett SC 1996. The phylogenetic position of the Pterosauria within the Archosauromorpha. Zoolological Journal of the Linnean Society 118: 261–308.
Benton MJ 1999. Scleromochlus taylori and the origin of the pterosaurs. Philosophical Transactions of the Royal Society London, Series B 354 1423-1446. Online pdf
Hone DWE and Benton MJ 2007. An evaluation of the phylogenetic relationships of the pterosaurs to the archosauromorph reptiles. Journal of Systematic Palaeontology 5:465–469.
Hone DWE and Benton MJ 2008. Contrasting supertree and total evidence methods: the origin of the pterosaurs. Zitteliana B28:35–60.
Padian K. 1984. The Origin of Pterosaurs. Proceedings, Third Symposium on Mesozoic Terrestrial Ecosystems, Tubingen 1984. Online pdf
Peters D 2002. A New Model for the Evolution of the Pterosaur Wing – with a twist. Hist Bio 15: 277–301.
Senter P 2003. Taxon Sampling Artifacts and the Phylogenetic Position of Aves. PhD dissertation. Northern Illinois University, 1-279.
Sereno PC 1991. Basal archosaurs: phylogenetic relationships and functional implications. Journal of Vertebrate Paleontology 11 (Supplement) Memoire 2: 1–53.
Woodward AS 1907. On a new dinosaurian reptile (Scleromochlus taylori, gen. et sp. nov.) from the Trias of Lossiemouth, Elgin. Quarterly Journal of the Geological Society 1907 63:140-144.

wiki/Scleromochlus

 

Kryptoglanis: a catfish mimic

Workers wondered, where did those big teeth come from?
Catfish don’t have such long, interlocking teeth. No wonder Vincent and Thomas 2011 called Kryptoglanis shajii (Figs. 1–3; 6cm) an ‘enigmatic’ subterranean catfish. No wonder Britz et al. erected a new clade of catfish to put it in.

Figure 1. The uncatfish-like teeth of Kryptoglanis in anterior view.

According to Wikipedia
“[Kryptoglanis] has also been seen in dense vegetation in paddy fieldsThe species strongly avoids light and feeds on small invertebrates.”

“The morphology of K. shajii differs from all other known species of catfish and includes such features as the absence of dorsal fin; the presence of four pairs of barbels; an upwardly directed mouth, with a distinctly projecting lower jaw with 4 set[s] of teeth; subcutaneous eyes; anal fin completely confluent with the caudal fin; anal and caudal fins together carry 70–74 fin rays; and no spines in any of the fins.”

Figure 2. Kryptoglanis in 3 views. Note the catfish-like barbels.

Figure 3. Skull of Kryptoglanis, a knife fish, not a catfish.

Here’s where we put on our lab coats and act like scientists.
Whenever a taxon is described as ‘differs from all other known species’, that’s the time to expand the taxon list. We’ve seen this so many times before. And every time the LRT has found less traditional and more parsimonious sister taxa simply by adding taxa.

Figure 4. Gymnotus carapo in vivo.

Figure 5. Skull of Gymnotus.

According to
the large reptile tree (LRT, 1750+ taxa) those catfish-like barbels on Kryptoglanis developed by convergence on an eel-like knife fish, nesting between the eel, Anguilla and two knifefish, Gymnotus and Electrophorus, the electric eel. This clade of fish DO have large interlocking teeth and a long list of other traits shared with Kryptoglanis. They just don’t have barbels. Seems like prior authors were caught “Pulling a Larry Martin” by focusing on the barbels to the exclusion of all the other traits.

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References
Vincent M and Thomas J 2011. Kryptoglanis shajii, an enigmatic subterranean-spring catfish (Siluriformes, Incertae sedis) from Kerala, India. Ichthyological Research. 58 (2): 161–165. doi:10.1007/s10228-011-0206-6.
Britz R, Kakkassery F and Raghavan R 2014. Osteology of Kryptoglanis shajii, a stygobitic catfish (Teleostei: Siluriformes) from Peninsular India with a diagnosis of the new family Kryptoglanidae. Ichthyological Exploration of Freshwaters. 24 (3): 193–207.

wiki/Kryptoglanis_shajii

SVP abstracts 7: Coombs follows the traditional whale origin myth

Coombs 2020 studied whale skulls
using a traditional, but recently invalidated phylogeny. She did not understand the diphyly of the former clade ‘Cetacea’.

From the Coombs abstract:
“The extant clades of whales, Odontoceti (toothed whales) and Mysticeti (baleen whales), diverged ~39 Ma.”

According to the large reptile tree (LRT, 1749+ taxa) that divergence occurred way back when whale ancestors were still tree shrews. A tiny taxon, Maelestes (Fig. 1; Late Cretaceous, 75-71mya) is near their last common ancestor.

Figure 1. We are very fortunate to have several of these basal placental taxa still living with us, as chronologically long-lived taxa. Starting with the extant Didelphis at the base of the Theria, phylogenetic miniaturization gave us the smaller Monodelphis domestics and the even smaller M. sores and M. kunsi, which gave rise to the larger Nandinia at the base of the Carnivora, Tupaia, at the base of the expanded Glires, Ptilocercus at the base of the expanded Archonta, and Maelestes at the base of the tenrecs + whales and the Condylarthra, aka the rest of the mammals.

Continuing from the Coombs abstract:
“Odontocetes evolved high-frequency echolocation and cranial asymmetry, while mysticetes evolved larger masses and filter feeding.”

Actually odontocete ancestors, represented by extant tenrecs, developed echolocation and cranial asymmetry, by the Paleocene 65mya.

Mysticete ancestors did not develop filter feeding until the Oligocene, 34-23mya at the earliest. Mystacodon (Fig. 2; 36mya) was considered the earliest baleen whale, but this toothy whale nests with the odontocete clade.

FIgure 2. This toothy whale with a tiny pelvis is Mystcodon, originally promoted as the earliest known mysticete (baleen whale).

Continuing from the Coombs abstract:
“Despite an excellent fossil record and unique morphology, there has been little quantitative study of shape evolution spanning cetacean diversity.”

Before making that statement, Coombs should add taxa to start with a valid phylogeny, lacking at present. Ancestors to both whale clades (Fig. 3) have been traditionally overlooked due to taxon exclusion.

“To quantify morphological disparity and evolutionary rate in cranial shape and to identify ecological correlates of shape variation across Cetacea, I gathered 3D scans of specimens representing 84 living (72 odontocetes, 12 mysticetes) and 72 Eocene to Pliocene fossil (45 odontocetes, 17 mysticetes, 10 archaeocetes) cetaceans. I then digitized 123 landmarks and 64 curves on these scans and conducted high-dimensional geometric morphometric and macroevolutionary analyses within a phylogenetic framework.”

The Coombs phylogenetic framework is fatally flawed due to taxon exclusion. Adding pertinent taxa will solve this problem.

Figure 3. Subset of the LRT focusing on the odontocetes and their ancestors.

Continuing from the Coombs abstract:
“The largest component of cranial variation (PC1 = 39.9%) reflects a posterior shift in the nares and separates odontocete and mysticete modes of cranial telescoping. Rostrum length is the major component of variation on PC2 (20.7%) with dolicocephalic [having a long skull] (e.g., Pontoporia blainvillei) and brachycephalic [having a short skull] (e.g., Kogia sima) crania representing the extremes.”

Figure 4. The oreodont-mesonychid-hippo-desmoystlian-mysticete clade subset of the LRT

Continuing from the Coombs abstract:
“Cranial asymmetry in archaeocetes is high in the rostrum, squamosal, jugal, and orbit, possibly reflecting preservational deformation. In odontocetes, it is highest in the naso-facial region. Mysticetes show levels of asymmetry similar to terrestrial artiodactyls.”

In other words: essentially no asymmetry. Why? Because mysticetes and odontocetes had different ancestors. Artiodactyls had nothing to do with whales ever since the LRT pulled hippos out of the artiodactyls and into the mesonychids (Fig. 4).

Figure 5. Taxa in the lineage of right whales include Desmostylus, Caperea and Eubalaena. The tiny bit of jugal posterior to the orbit (in cyan) is found in all baleen whales tested so far. The frontals over the eyes are just roofing the eyeballs in Desmostylus, much wider in Caperea and much, much longer in Eubalaena.

Continuing from the Coombs abstract:
“Significant rate shifts in asymmetry are observed in the stem odontocetes Xenorophidae (∼30 Ma), Physeteroidea (∼27 Ma), Squalodelphinidae (~27 Ma), and Monodontidae (~7 Ma). Rapid evolution of both cranial shape and asymmetry in cetaceans occurred in the Middle-Late Oligocene and peaks in the Middle Late Miocene, largely due to subclade-specific diversification of rostrum and facial morphology.”

Coombs’ results, no matter how carefully measured, are incomplete because they are not recovered within a valid phylogenetic context. Add pertinent taxa to resolve this issue.

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References
Coombs E 2020. Cranial morphology in whales: A study spanning the evolutionary history and diversity of the Cetacean skull. SVP abstracts 2020.

SVP abstracts 6: Dsungaripterus palate

This October 2020 abstract is identical
to one published in April 2020 as Chen et al. described the same Dsungaripterus palate (Fig. 1) in PeerJ. The following is a brief synopsis of that earlier post.

Figure 1. Dsungaripterus palate from Chen et al. 2020 with colors and diagrams (above) from Peters 2000 added. Note only a vestige remains of the lateral process of the palatine. The extent of the jugal is a guess here. Pink = pterygoid. Blue = palatine. Gold = ectopterygoid.  In Chen et al. the line leading toward the abbreviation pl points to the maxilla.

Chen et al. April 2020 cited
Osi et al. 2010, which we looked at earlier here. You might remember, Osi et al. thought they had discovered the true identity of palatal elements, but parenthetically acknowledged that Peters 2000 (Fig. 1) had done so a decade earlier. They did not realize others had also done so over a century before.

Prior to Peters 2000  
and ever since Williston (1902) and continuing through Huene 1914, Wellnhofer (1978, 1991) and Bennett (1991, 2001a,b), the solid palatal plate in pterosaurs had been traditionally considered the palatine. That was the orthodox point-of-view.

Virtually ignored,
Newton (1888), Seeley (1901 and Woodward (1902) reported that the solid palatal plate was an outgrowth of the maxilla, not the palatine. Unfortunately, I did not know those citations when Peters 2000 reported that the palatal plate actually originated from the maxilla. I thought I had discovered something! Rather, I had only confirmed work from a century earlier. Workers: it is important to expand your citation list so future workers will not overlook important papers, be they 20 years old or 120 years old.

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References
Chen et al. (7 co-authors) 2020 (April). New anatomical information on Dsungaripterus weii Young, 1964 with focus on the palatal region. SVP Abstracts
Chen et al. (7 co-authors) 2020 (October). New anatomical information on Dsungaripterus weii Young, 1964 with focus on the palatal region. PeerJ 8:e8741 DOI 10.7717/peerj.8741

https://pterosaurheresies.wordpress.com/2020/04/03/dsungaripterus-palate-news-chen-et-al-2020/

Prior References from April 2020:
Bennett SC 1991. Morphology of the Late Cretaceous Pterosaur Pteranodonand Systematics of the Pterodactyloidea. [Volumes I and II]. – Ph.D. thesis, University of Kansas [Published by University Microfilms International/ProQuest].
Bennett SC 2001a, b. The osteology and functional morphology of the Late Cretaceous pterosaur Pteranodon. Part I and 2. General description of osteology. – Palaeontographica, Abteilung A, 260: 1-153.
Chen et al. (7 co-authors) 2020. New anatomical information on Dsungaripterus weii Young, 1964 with focus on the palatal region. PeerJ 8:e8741 DOI 10.7717/peerj.8741
Newton ET 1888. On the skull, brain and auditory organ of a new species of pterosaurian (Scaphognathus Purdoni) from the Upper Lias near Whitby, Yorkshire. Philosphoical Transaction of the Royal Society, London 179: 503-537.
Osi A, Prondvai E, Frey E and Pohl B 2010. New Interpretation of the Palate of Pterosaurs. The Anatomical Record 293: 243-258.
Peters D 2000. A Redescription of Four Prolacertiform Genera and Implications for Pterosaur Phylogenesis. Rivista Italiana di Paleontologia e Stratigrafia 106 (3): 293–336.
Seeley HG 1901. Dragons of the air. An account of extinct flying reptiles. – London, Methuen: 1-240.
Wellnhofer P 1978. Pterosauria. Handbuch der Paläoherpetologie, Teil 19.– Stuttgart, Gustav Fischer Verlag: 1-82.
Wellnhofer P 1991. The Illustrated Encyclopedia of Pterosaurs. London, Salamander Books, Limited: 1-192.
Williston SW 1902. On the skull of Nyctodactylus, an Upper Cretaceous pterodactyl. Journal of Geology 10:520–531.
Woodward AS 1902. On two skulls of Ornithosaurian Rhamphorhynchus. Annals of the Magazine Natural History 9:1.
Young CC 1964. On a new pterosaurian from Sinkiang, China. Vertebrata PalAsiatica 8: 221-256.

wiki/Dsungaripterus

SVP abstracts 5: New Thalattosauriformes from China

Chai J, Jiang D and Sun Z 2020 introduce
a few new thalattosauriformes (Fig. 1) We looked at thalattosaurs here back in 2011, 2013, when they entered the LRT.

Figure 1. The Thalattosauria and outgroups (Wumengosaurus and Stereosternum) to scale. Do you see why Vancleavea makes a better thalattosaur than an archosauriform?

From the abstract:
“Thalattosaurifomes is one of the important marine reptiles found in Middle to Late Triassic. It can be classified into two clades, namely Askeptosauridae and Thalattosauridae.”

The large reptile tree (LRT, 1749+ taxa) also documents two large clades within Thalattosauria, one that includes Askeptosaurus (Fig. 1) and another that includes Thalattosaurus (Fig. 1).

“They were discovered in North America and Europe, and more recent discovery in Xingyi Fauna, southwest China had provided new information about their evolution. XNGM WS-22-R5, a newly prepared specimen, had a different type of rostrum with the local Xinpusaurus. Its strongly ventrally deflected contour assembles the same type found in North America and Europe, and it’s the first thalattosaur with this design found in China.”

Figure 2. Xinpusaurus suni, a basal thalattosaur sharing many traits with the Rossman specimen.

Figure 3. Xinpusaurus kohi, the swordbill species.

The LRT currently nests two specimens attributed to Xinpusaurus (Figs. 2, 3).

“Phylogenetic analysis indicates that this specimen forms a polytomy with Hescheleria ruebeli and Clarazia schinzi.”

In the LRT Clarazia (Fig. 4) nests close to the Xinpusaurus clade, but closer to other thalattosaurs.

Figure 4. Clarazia, a thalattosaur sister to the new Oregon specimens.

“As the turned-downward rostrum appear in XNGM WS-22-R5, Hescheleria ruebeli and Nectosaurus halius, and the resolution of current phylogenetic tree is low, it’s hard to determine whether this feature is related to phylogeny. It is more likely an adaptation as Nectosaurus did not has a close affinity with this new specimen, as while as the similar design occurred in Proterosuchid.”

Figure 5. Nectosaurus and Hescheleria, two odd hook-nose thalattosaurs

“A complete specimen, XNGM XY-PVR2013-R2, is described. According to the characters of jugal, surangular, angular, humerus, dorsal neural spines and carpals etc, it can be identified as Anshunsaurus cf. A.huangguoshuensis.”

Anshunsaurus is similar to long-snouted Askeptosaurus (Fig. 1), transitional to Miodentosaurus (Fig. 1).

“We compared the currently known three species of Anshunsaurus, and found that the previous diagnosis is not diagnostic enough. The ratio in diagnosis varies among the specimens of the same species. The only distinct diagnostic character is the development of ec- and entepicodylar on the humerus of A,wushaensis. As this is the most unambiguous character among Anshunsaurus and it’s related to the locomotion of forelimbs, we suppose that this difference maybe a sexual dimorphism.”

Try to avoid “Pulling a Larry Martin”. Don’t cherry-pick one to a dozen subtle or stand-out traits. Instead, add taxa, run the analysis and let the software decide. After phylogenetic analysis of several specimens, then decide if any traits are sexually dimorphic or otherwise important as an afterthought.

Wonder if they included Vancleavea (Fig. 1) in their analysis? Among 1749 taxa, Vancleavea would rather nest with thalattosaurs than with archosauriforms.

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References
Chai J, Jiang D and Sun Z 2020. New specimens found in Xingyi Fauna provide evolution information of Thalattosauriformes. SVP abstract