SVP 2021 abstracts – 24: Archaeopteryx flight reduced? No.

Habib and Pittman 2021 report:
“The flight capabilities of Archaeopteryx continue to be highly contentious. We addressed locomotor performance in this iconic animal using ratios of forelimb to hind limb bone cross-sectional properties.”

Which one of the 13+ Solnhofen birds did Habib and Pittman look at? Every fossil is different (Fig. 1). PhDs need to address these differences and not employ nebulous wastebasket nomenclature.

Figure 1. Most of the complete Solnhofen birds, including Archaeopteryx and the eleventh specimen to scale.

Habib and Pittman continue:
“We compared these results to the same ratios in living birds and the dromaeosaurid, Rahonavis, which provided a critical paravian out-group.”

In the large reptile tree poorly-represented, Rahonavis (Fig. 2), is a small Late Cretaceous (70mya) therizinosaur close to Jianchangosaurus (Fig. 2) from the land of oddball taxa, Madagascar. Both of these therizinosaurs look superficially like dromaeosaurids.
Both have a big toe two ungual.

The problem is: neither are paravian out-group taxa. So, what were these two PhDs thinking when they cherry-picked an incomplete Late Cretaceous taxon and said it was ‘a critical paravian out-group’ of a Late Jurassic radiation?

Why not choose a valid and coeval out-group taxon like Almas? Sinovenator? Anchiornis? The Daiting specimen attributed to Archaeopteryx? Xiaotingia? Ostromia? Eosinopteryx?
Or all of them?

Figure 2. Rahonavis nests with the therizionosaur, Jianchangosaurus ,in the LRT.

Habib and Pittman continue:
“Our analysis recovered Rahonavis as a capable powered flyer.”

No relatives of Rahonavis fly. Only the radius and ulna are preserved in Rahonavis (Fig. 2), not the entire forelimb. Habib and Pittman are guessing what the humerus and manus looked like.

Advice: Choose a more complete and coeval taxon to work with.

A little backstory: Co-author Habib invented the quad-launch in pterosaurs hypothesis by cheating the morphology to suite his vision. Habib also co-authored a soaring azhdarchid hypothesis (Witton and Habib 2010) to suite his vision. This latest abstract does not repair his reputation as Habib continues to overlook inconvenient facts.

“Conversely, we found Archaeopteryx to be a less proficient long-distance flyer than Rahonavis, despite being closer to crown group birds.”

Conclusions like this, based on incomplete data, should be ignored.

“Archaeopteryx was highly cursorial and a short-ranged flyer, at most. The scaled humeral/ femoral section modulus ratio in Rahonavis was 1.49, more than four times higher than the ratio of 0.32 recovered for Archaeopteryx.”

The humerus is not known for Rahonavis (Fig. 2). Neither is the manus. The authors guessed based on imagination and produced a conclusion on that guess. Cherry-picking like this invites criticism. Habib and Pittman could have avoided criticism by using coeval pre-bird taxa, but they ignored published cladograms.

BTW, Rahonavis was also ‘higly cursorial’. Just look at those long slender legs.

“The bone strength ratios in Rahonavis are close to (within 99% Confidence Interval) those measured for falcons, pheasants, and egrets: birds that have strong hind limbs but retain excellent flight abilities (sustained in falcons and egrets, short-range bursts in pheasants).”

Bone strength ratios again. Habib used similar statistics and bone strength ratios to introduce the pterosaur quad-launch hypothesis. That’s fine so long as you don’t short-change or cheat morphology and avoid systematics.

Advice: Dr. Habib and Dr. Pittman, please use a cladogram next time. Don’t cherry-pick invalid outgroup taxa separated in time by tens of millions of years and omit closely related taxa.

Maybe Rahonavis was a capable flyer by convergence. Maybe not. Always start with a valid phylogeny to avoid problems like these two authors have dug themselves into.

“Archaeopteryx compares closely in its humeral/femoral strength ratios with secondarily flightless cursorial birds (99% CI).”

That is to be expected as Solnhofen birds were just learning to fly.
Again, Habib and Pittman need to show that phylogenetic precursors were more flight capable. And which Archaeopteryx (Fig. 1) did they test? Did they pick one to suit their narrative?

“It seems to have possessed a combination of femora that were moderately stronger than expected for its size and humeri that were much more gracile than predicted from regressions of section modulus against body mass for extant birds. Our results are indicative of secondary flight reduction or loss in Archaeopteryx, especially when combined with the existing literature data on this legendary taxon.”

Solnhofen birds became legends because 1) they were considered the first theropods capable of flight; 2) they were considered the first dinosaurs with feathers. Comparing one Late Jurassic Solnhofen bird to one incomplete Late Cretaceous (70mya) therizinosaur does not indicate ‘secondary flight reduction or loss in Archaeopteryx.’

“In a secondary flight reduction model, seemingly conflicting results of prior research regarding the flight capabilities of Archaeopteryx are explained as variably detecting volant ancestry versus flightless life history.”

Habib and Pittman are painting a picture with taxa that are not related to one another, either phylogenetically or chronologically.

“We suggest that Archaeopteryx might have had an ecology and locomotor profile like that of living island rails, many of which are secondarily flightless or flight-reduced hunters that use a wide range of wing-assisted behaviors.”

That’s not a novel suggestion.

“Archaeopteryx may have been a similarly capable island hunter, relying on its exceptionally long and robust hind limbs to chase down small animals and its reduced wings to assist with especially acrobatic terrestrial maneuvers. Our new picture for Archaeopteryx is not one of an animal that was “suboptimal” in any respect. Instead, we reconstruct Archaeopteryx as a specialized, fast, and agile island endemic.”

First straighten out the phylogeny, then the chronology, then avoid the bad habit of cherry-picking incomplete taxa far too late in time in order to suit a narrative. Instead: build a cladogram. Use valid outgroup taxa. Draw conclusions from those.

References
Habib MB and Pittman M 2021. Going up or coming down? Archaeopteryx as the earliest known secondarily flight-reduced vertebrate. Journal of Vertebrate Paleontology abstracts.
Witton MP and Habib MB 2010. On the Size and Flight Diversity of Giant Pterosaurs, the Use of Birds as Pterosaur Analogues and Comments on Pterosaur Flightlessness. PLoS ONE 5(11): e13982. https://doi.org/10.1371/journal.pone.0013982

Figure 3. The flightless pterosaur, Sos 2428, along with two ancestral taxa, both fully volant. Note the reduction of the wing AND the expansion of the torso. We don’t know the torso of Q. northropi. It could be small or it could be very large.

‘Earliest secondarily flight-reduced vertebrate?‘ No.
That accolade goes to the flightless pterosaur, SOS 2428 (Fig. 3), also from Solnhofen limestones, chronicled here and at Researchgate.net.

SVP 2021 abstracts – 23: Plesiadapiformes are still not stem primates

Hovatter, Chester and Wilson Mantilla 2021 report:
“Plesiadapiforms (stem primates) appear in the fossil record shortly after the Cretaceous /Paleogene (K/Pg) boundary and subsequently radiated throughout the Paleocene into a taxonomically and ecomorphologically diverse group.”

This myth has persisted too long due to taxon exclusion. In the large reptile tree (LRT, 1991 taxa) plesiadapiformes (Fig. 1) nest with the extant aye-aye (Daubentonia) within Glires, between rodents and multituberculates. Call them ‘primate-like rodents’ because that’s what they are.

Figure 1. Plesiadapis, formerly considered a basal primate, is here considered a member of the gnawing clade, Glires.

Hovatter, Chester and Wilson Mantilla continue:
“The spatiotemporal patterns surrounding the plesiadapiform radiation are thus important for
understanding their evolutionary history and the post-K/Pg recovery and diversification of placental mammals more broadly.”

The LRT subset of placental mammals (Fig.s 2) documents that more precisely.

Figure 2. Subset of the LRT focusing on placental mammals. Note that Plesiasapis and Daubentonia precede certain Jurassic relatives.

Hovatter, Chester and Wilson Mantilla continue:
“The oldest confirmed occurrences of plesiadapiforms come from deposits in northeastern
Montana dated to the earliest Puercan (Pu1) North American Land Mammal ‘age’ (NALMA), and all records of Puercan plesiadapiforms are taxonomically restricted to members of the Purgatoriidae and two species of the enigmatic plesiadapiform Pandemonium (family incertae
sedis).”

Purgatorius looks more like Palaechthon, a tree shrew and basal member of Volitantia (colugos, bats and kin). Those are close to primates, but not primates in the LRT.

“Plesiadapiform diversity substantially increased in the Torrejonian NALMA with the appearance of five families that exhibit a wide range of dental morphologies. However, the sparse record of compositionally intermediate faunas between the Puercan and the more well-known middle and late Torrejonian NALMAs has hampered our understanding of this crucial interval of
diversification in primate evolutionary history. Here we report a large sample of plesiadapiform dental fossils recovered from the To1 Farrand Channel and Horsethief Canyon localities in the uppermost part of the Tullock Member of the Fort Union Formation in
northeastern Montana. This assemblage includes over 100 isolated teeth and dentigerous dentary fragments and records members of the Purgatoriidae, Paromomyidae, and provisionally the Palaechthonidae.”

There they are, together last: Purgatorius and Palaechthon (Fig. 3).

Figure 3. Purgatorius compared to other basal and often Paleocene mammals from 2017, to scale in the left column, to a common length in the right column.

Hovatter, Chester and Wilson Mantilla continue:
“Notably, these new records provide further evidence that the temporal range of the Purgatoriidae extended into the Torrejonian. Large sample sizes also allowed us to document
intraspecific variability and one previously unknown tooth position of the earliest known paromomyid, Paromomys farrandi. New observations shed light on changes in dental morphology within the Purgatoriidae and Paromomyidae that occurred in the earliest
Torrejonian, which might also help clarify evolutionary relationships with at least some members of the likely non-monophyletic Palaechthonidae. Further, this assemblage records a key interval in the evolutionary history of plesiadapiforms that bridges the gap between their relatively low taxonomic richness in the Puercan and their comparatively higher taxonomic richness and range of morphologies in the middle and late Torrejonian.”

First: Add rodents, Daubentonia, Carpolestes and multituberculates. Then tell us where plesiadapiformes nest in your cladogram.

References
Hovatter B, Chester SG and Wilson Mantilla G 2021. New records of earliest Torrejonian (TO1) plesiadapiformes from Northeastern Montana, USA, provide window into the early diversification of stem primates.

Purgatorius and Plesiadapis are still not primates contra Wilson et al. 2021

Purgatorius: What is it?

SVP 2021abstracts – 22: Snake origins

Hilan, Criswell and Head 2021 report:
“The fossil record demonstrates an abrupt change from limbed lizard ancestors to the snake-like body form in the evolutionary history of Squamates.”

There was nothing abrupt about it in the large reptile tree (LRT, 1991 taxa).

Figure 1. Dolichosaurus added to the lineage of snake origins from 2015. This was prior to the publication of Tetrapophis and Barlochersaurus (figure 2).

Hilan, Criswell and Head continue:
“Little anatomical information is available for intermediate forms, so hypotheses surrounding this transition have previously been based in developmental data.”

The LRT has a long list of intermediate forms (Fig. 3).

Figure 2. Tetrapodophis and Barlochersaurus at full scale when seen on a monitor at 72 dpi.

Hilan, Criswell and Head continue:
“Postulated mechanisms involved axial deregionalization or expansion of a single morphological domain. Recently, retention of axial regionalization in the snake vertebral column has been
demonstrated. However, the squamate rib cage has not yet been examined in this context, despite the key role of ribs in limbless locomotion beyond the ventilatory function seen in limbed taxa.”

Figure 3. Subset of the LRT focusing on geckos and their sister snake ancestors.

Hilan, Criswell and Head continue:
“Using anatomical data from extant taxa, we hypothesise and test a more complex history of
evolutionary modification of patterning mechanisms in the evolution of limbless Squamate body forms.”

No need to used extant taxa and imagine what happened when extinct taxa (Fig. 3) will tell you what happened in the origin of snakes.

“Using CT scan data from the skeletons of over 50 species of snakes and snake-like squamates as well as limbed taxa, we developed a landmarking scheme that captures shape data of all individual free, pre-cloacal, non-bifid ribs.”

So this is more about squamate ribs than snake origins.

“Using segmented linear regression, we analyzed these shape variables to identify axial regions, as gradients of shape morphologies describe axial regions. Clear morphological regionalization of the dorsal ribs is seen in all squamate taxa studied. Across taxa, there is remarkable consistency in both the number and relative positioning of regional boundaries. When mapped on to molecular and morphological time-calibrated phylogenies, we see clade-specific changes at the base of Lacertoidea and Serpentes, however. The same changes to regional boundaries are not seen consistently across independent instances of the snake-like body form, corroborating the hypothesis that this evolutionary change is not the result of a single patterning shift, but a more complex set of steps.”

That set of steps is clearly present in the ancestors of snakes (Fig. 1), but the authors will never know that unless they study the pertinent fossils.

“Analysis of the landmark data also allowed examination of changes in rib shape and intracolumnar heterogeneity across the clade. In each of the multiple instances of the snake-like body form, we see convergence of rib shape, reflecting shared functional requirements. Additionally, axial heterogeneity sharply drops compared to limbed relatives. We conclude that all squamate species retain axial regionalization. The abrupt evolutionary transitions seen in the fossil record are therefore not consistent with loss of function of the patterning genes known to be expressed during development.”

Perhaps the next step in this study will take this new insight back to the fossils in the evolution of the snake body form.

References
Hilan EJ, Criswell K and Head J 2021. Regionalization of the squamates ribcage in the evolution of the snake body form. Journal of Vertebrate Paleontology abstracts

SVP 2021 abstracts – 21: Barbourofelis is ‘a unique cat’ because it’s not a cat

Naples and Haji-Sheikh 2021 report:
“The sabertooth adaptation has appeared at least five times (twice in true felids, twice in pseudofelids and once in synapsids) in the evolution of carnivorans.”

What is a pseudofelid? A keyword search in Google comes back to this paragraph, the only time in the history of paleontology that it was used.

The family Barbourofelidae (= false saber-tooth cats).

“Many hypotheses have been advanced to explain the iterative appearance of this extremely specialized adaptation. Each sabertooth taxon that is discovered in the fossil record shows unique aspects of morphology that reflect different biomechanical considerations for the use of these canines.”

Figure 1. Barbourofelis skull. Compare to Thyloacoemilus in figure 2.

Figure 2. Thylacosmilus skull. Colors added here. Compare to Barbourofelis in figure 1.

Naples and Haji-Sheikh 2021 continue:
“Among the most specialized sabertooths is Barbourofelis fricki, the largest bodied and most recently evolved taxon belonging to the pseudocat barbourofelin lineage.”

By contrast the large reptile tree (LRT, 1991 taxa) nests Barbourofelis (Fig. 1) with the South American marsupial sabertooth, Thylacosmilus (Fig. 2). Not sure why this interrelationhship has been overlooked until now. Barbourofelis entered the LRT a week ago.

“Our work is focused on explaining these anatomical differences and why they are important. This lion-sized sabertooth had the longest upper canines in absolute and relative terms among all taxa so far discovered with exaggerated upper canines. Barbourofelis fricki is distinguished by its elongated canines that are the most slender and highly recurved upper canines among
sabertooths.”

Similar to those in Thylacosmilus, though.

“Although strong and sharp-edged, the narrow shape and tapering anterior and poster edges of these canines renders them brittle, therefore requiring the highest possible precision in biting behavior to avoid breakage. This priority is reflected in many other cranial anatomical features, including a foreshortened rostrum, increased skull depth, in combination with a vertical occiput and a mandible with a reduced coronoid process and robust dependent flange.

Similar to those in Thylacosmilus, though.

“Concomitant with these cranial features is a reorientation of the masticatory muscles reflecting an increase in the dorsoventral component and the reduction of mediolateral mandibular movements.”

Similar to those in Thylacosmilus, though.

“Reconstruction of the cranium of this predator demonstrated that this animal had a larger head than would have been predicted, and that modifications of the anterior cervical vertebrae also contribute to enhanced dorsoventral movements of the head on the neck in B. fricki. Our work demonstrates that this animal probably showed body proportions that differed significantly from previous reconstructions as well as from other sabertooths.”

Funny how Naples and Hajii-Sheikh failed to mention Thylacosmilus.

References
Naples V and Haji-Sheikh MH 2021. Barbourofelis fricki — The head bone is connected to the neck bone or hoe to rebuild a unique cat.

htwiki/Barbourofelis

https://pterosaurheresies.wordpress.com/2021/10/28/barbourofelis-enters-the-lrt-as-a-sabertoothed-marsupial-not-a-big-cat/

SVP 2021 abstracts – 20: Origin of placental mammals

Carlisle et al. 2021 reports:
“Recent molecular clock analyses have suggested that placental mammals originated in the mid to late Cretaceous, before the Cretaceous–Paleogene (K–Pg) mass extinction.”

Don’t trust deep time gene studies. Too often they deliver false positives.

“However, there are no unequivocal fossils of placental mammals from the Cretaceous to
support this.”

The LRT recovered many unequivocal Cretaceous and Jurassic placentals (Fig. 1).
Add taxa to find your own.

Figure 1. Subset of the LRT focusing on placentals. Despite their rarity in the Mesozoic, several are known from Jurassic and Cretaceous strata.

Carlisle et al. continues:
“Definitive fossils of placental mammals only appear after the K–Pg boundary, at which point they rapidly radiate leading into the ‘Age of Mammals’.

Carlisle et al. should add taxa and discontinue promoting this myth.

“Here we use the Bayesian Brownian Bridge model to estimate the age of origin of placental mammals based on the fossil record.”

No need to estimate. Use the last common ancestor method.

“The model uses fossil diversity through time to inform a random walk from the clade’s present day diversity back to the estimated origin of the clade within a Bayesian framework. This model works well with clades that have poor fossil records, such as the early placental mammals, and does not require a phylogeny, thereby mitigating the lingering uncertainty over the branching pattern at the root of the placental tree of life.”

“Does not require a phylogeny?” These workers need to change their mind on this topic.

“Our results support a Cretaceous origin for placental mammals, in agreement with the molecular data, and demonstrate that the group was already present before the K–Pg mass
extinction and experienced a radiation during the Paleogene.”

The LRT origin of placentals is in the Jurassic… the Early Jurassic.

“The Bayesian Brownian Bride model can therefore help to reconcile paleontological data with
molecular data when estimating the origin of clades.”

No. The Carlisle et al. method was falsified by the LRT.

References
Carlisle E et al. 2021. The origin of placental mammals according to the fossil record. Journal of Vertebrate Paleontology abstracts.

SVP 2021 abstracts – 06: Multituberculate bone histology more similar to placentals

Placentals in the Mesozoic? Clues from continental drift.

University textbook, Vertebrate Paleontology, by Michael J Benton: a focused review p2 – placentals

SVP 2021 abstracts – 19: A new (unnamed) basal sea croc

Wilberg et al. 2021 describe
a new basal thalattosuchian, the clade that ultimately produced crocodilians with flippers instead of toes (Fig. 1).

Figure 1. Several Jurassic sea crocs, apparently derived from Late Triassic Dyoplax.

Willberg et al. report,
“Among archosaurs, thalattosuchian crocodylomorphs experienced the most extensive adaptations to the marine realm. Despite significant attention, the phylogenetic position of the group remains uncertain.”

Add Middle Triassic Dyoplax (Fig. 2). Look for the last common ancestor. Added taxa might not have the traits you are looking for, but this is how the LRT recovered the origin of pterosaurs, turtles, snakes, cephalopods, reptiles, tetrapods, ichthyosaurs, etc.

Figure 1. Dyoplax arenaceus Fraas 1867 is a mold fossil recently considered to be a sphenosuchian crocodylomorph. Here it nests as a basal metriorhynchid (sea crocodile) in the Late Triassic.

Willberg et al. report,
“Thalattosuchians are either the sister-group to Crocodyliformes, basal mesoeucrocodylians, or form a group with longirostrine neosuchians. The earliest definite thalattosuchians are known from the Toarcian (c.180 Ma), and already possess many synapomorphies of the group.”

In the LRT the third option is supported. Gavialis is the closest living sister to extinct thalattosuchians in the LRT.

Wilberg 2015 reported,
“This study is the first to demonstrate the great effect of outgroup sampling on the phylogenetic structure of Crocodylomorpha. It seems prudent to sample numerous outgroup taxa especially where large-scale relationships between clades remain an active question. Future efforts at resolving these issues should carefully consider both outgroup sampling and character construction.”

In the LRT every outgroup taxon for every ingroup taxon back to Ediacaran worms is documented. Wilberg has been cherry-picking taxa that look promising.

Figure 2. Subset of the LRT focusing on Crocodylomorpha and Thalattosuchia. Many of these taxa are not employed in various cladograms listed in Wilberg 2015.

Willberg et al. continue:
“All phylogenetic hypotheses imply a ghost lineage extending at least to the Sinemurian (c. 199 Ma), and a lack of older or more plesiomorphic forms may contribute to the uncertain phylogenetic placement of the group.

Dyoplax needs to be added.

“Fragmentary postcranial material from the Sinemurian and Pliensbachian of South America, Europe, and India has been attributed to Thalattosuchia, but lacks thalattosuchian apomorphies.”

Perhaps only the plesiomorphic parts are preserved.

“Here we describe new material from the early Pliensbachian (c. 190 Ma) Belemnite Marl Member of the Charmouth Mudstone Formation (Dorset, UK). The specimen includes partially articulated cranial, mandibular, axial, and appendicular elements. It can be attributed to Thalattosuchia based on the presence of a distinct fossa on the posterolateral corner of the squamosal, a broad ventrolateral process of the otoccipital broadly covering the dorsal surface of the quadrate body, large supratemporal fenestrae that lack a flattened skull table, a broadly exposed prootic, and an orbital process of the quadrate lacking bony attachment with the braincase. This specimen therefore represents the earliest thalattosuchian currently known from diagnostic material.”

So this specimen has thalattosuchian apomorphies. Good. I still wish workers would add this taxon to their cladogram and then announce that this taxon is the last common ancestor of thalattosuchians. Traits can converge. Their is only one last common ancestor (until a better one comes along, of course).

“To determine the phylogenetic position of the new taxon, we performed two separate analyses based on different published datasets.”

So they are borrowing and trusting. That’s not good science.

“Both analyses recover the new taxon as the earliest diverging thalattosuchian, sister to Teleosauroidea + Metriorhynchoidea.”

Does ‘earliest diverging thalattosuchian’ = last common ancestor? If so, good!.
No name was applied. For that we’ll wait for the paper.

“We also performed Bayesian time-scaling analyses using a fossilized birth-death model to investigate the impact of the inclusion of the new specimen on estimates of divergence times of Thalattosuchia within Crocodylomorpha. The results show a likely Late Triassic origin for Thalattosuchia (median age=211 Ma), which is constrained between 224.33 and 196.70 Ma (95% highest posterior density). The new specimen extends the fossil record of Thalattosuchia, but the time-scaling analyses demonstrate that a significant ghost lineage remains.”

Figure 3. Is the similarity of these two taxa homologous? Or analogous? That’s the question.

Figure 4. Pelagosaurus in several views.

First author Wilberg 2015 wrote:
“Outgroup sampling is a central issue in phylogenetic analysis. However, good justification is rarely given for outgroup selection in published analyses.”

This was insightful. The ideal is to have so many outgroup taxa that the software tells the scientist the short list of proximal outgroup taxa, as a large number of taxa do in the LRT.

Wilberg 2015 continues:
“A new analysis of crocodylomorphs with increased outgroup sampling recovers Thalattosuchia as the sister group to Crocodyliformes, distantly related to long-snouted crocodyliforms.”

Various borrowed analyses from that paper omitted Dyoplax (Fig. 1) and considered Pelagosaurus an ingroup thalattosuchian, rather than an outgroup relative of Gavialis. which nests with Crocodylus in the Wilberg 2015 borrowed studies. This is distinct from the LRT (Fig. 2) where Gavialis nests apart from other living crocodilians.

References
Wilberg E, Godoy PL, Griffiths E, Turner AH and Benson RB 2021. A new basal thalattosuchian crocodylomorph from the Early Jurassic (Pliensbachian) of Dorset, UK, and implications for the origin of the group. Journal of Vertebrate Paleontology abstracts.
Wilberg E 2015. What’s in an Outgroup? The Impact of Outgroup Choice on the Phylogenetic Position of Thalattosuchia (Crocodylomorpha) and the Origin of Crocodyliformes. Syst. Biol. 64(4):621–637.

wiki/Dyoplax

SVP 2021 abstracts: 18 – Arcticodactylus under the synchotron

Fitch et al. 2021 took a third look
at the Greenland Triassic eudimorphodontid pterosaur, Arcticodactylus (Fig. 1; Kellner 2015, originally Eudimorphodon Jenkins et al. 1999; MGUH VP 3393).

Fitch et al. wrote:
“Pterosaurs represent the earliest-appearing of only three clades of flying vertebrates, the pioneers of aerial vertebrate ecospace, and the lineage to produce the largest known flying organism.”

Once again, the largest pterosaurs, the azhdarchids, only became large AFTER they became flightless due to having vestigial distal wing phalanges.

It’s also an unnecessary trope that workers feel like they have to explain what pterosaurs are and what they did first. The audience for these abstracts KNOWS what pterosaurs are and what they did first.

“The origins of the pterosaurian flight apparatus have been difficult to ascertain, in part due to incomplete or two-dimensional preservation of the earliest (Triassic–Jurassic) pterosaur remains.”

Not difficult to ascertain. This is something we’ve known for twenty years. For reasons I still cannot fathom, pterosaur workers still don’t want to review or acknowledge Peters 2000 who presented four pterosaur precursors tested by adding these taxa to four prior phylogenetic analyses. Subsequently the large reptile tree (LRT, 1991 taxa) confirmed these taxa as pterosaur precursors. Peters 2002 explored the origin of pterosaur wings. Peters 2007 moved pterosaurs and kin to Lepidosauria.

For more information on pterosaur wing evolution, click here.

Figure 1. Articodactylus is evidently NOT the smallest pterosaur. That honor still goes to an unnamed specimen (not a Pterodactylus kochi juvenile) B St 1967 I 276.

Fitch et al. 2021 continue:
“An exceptional early pterosaur specimen that is preserved in three dimensions, the holotype and only known specimen of Arcticodactylus cromptonellus (Upper Triassic; Fleming Fjord Formation, Greenland) may help address these problems. However, it has remained mostly encased within matrix to protect the delicate elements, obscuring external study.”

What you see here (Fig. 1) is all that was originally published by Jenkins et al. 1999.

“Here we present new synchrotron tomographic scan data of the forelimb (wing-forming)
elements of Arcticodactylus cromptonellus. The forelimb of Arcticodactylus possesses a number of features plesiomorphic to Ornithodira (birds+pterosaurs),”

Ornithodira = dinosaurs + pterosaurs and all their descendants. Since pterosaurs don’t nest with dinosaurs in the LRT, Ornithodira is a junior synonym for the clade Reptilia (= Amniota).

“…including the extension of the phalangeal articular surfaces onto the dorsal surface of metacarpals II–III and manual asymmetry (metacarpal I/metacarpal II length ≤ 0.80), the latter of which is absent in all but two other Triassic pterosaur taxa (Carniadactylus and Seazzadactylus).”

Nobody seems to care that pterosaurs had a longest digit 4, which is not found in Archosauria, but is found in Lepidosauria. Additionally, the most primitive pterosaur in the LRT and large pterosaur tree (LPT, 260 taxa), Bergamodactylus (Fig. 2), likewise preserves manual asymmetry.

Figure 2. Bergamodactylus compared to Cosesaurus. Hypothetical hatchling also shown.

Fitch et al. 2021 continue:
“Arcticodactylus also possesses several hallmarks of the early pterosaurian wing: a deltopectoral crest that is wider than the humeral mediolateral midshaft width, a fourth digit that is longer than the rest of the forelimb, a fourth metacarpal possessing a ‘roller joint’ articulation with the fourth digit, and a crista metacarpi present on the posterior face of this metacarpal. Notably, the humeral deltopectoral crest of Arcticodactylus possesses a straight proximal margin and is separated from the humeral head by a distinct, laterally-facing margin, features found in early ornithodirans but absent in other pterosaurs.”

Which ‘early ornithodirans’? Herrerasaurus (Fig. 3)? Does Fitch et al. know they are cherry-picking traits without an overall phylogenetic analysis that includes a wide gamut of taxa?

Figure 3. Herrerasaurus, the other basal ‘ornithodiran.’ Look at the fingers.

Fitch et al. 2021 continue:
“The presence of a mosaic of anatomical features found in the forelimbs of early-diverging
ornithodirans and of winged pterosaurs (including some found in only the very earliest-diverging pterosaurs) demonstrates that, rather than possessing a “fully developed” pterosaur wing, Arcticodactylus is a structural intermediate between early archosaurs and derived pterosaurs.”

In the LPT Arcticodactlyus nests with Eudimorphodon ranzii (Fig. 4),
five nodes from the base of the Pterosauria.

Figure 4. Lateral, dorsal and cross-sectional views of Eudimorphodon ranzii. Note the overlap of the posterior ribs over the hind limbs and the very wide torso. The cross section shows the 2nd dorsal ribs and the 23rd. Note the small ischium which could only produce small eggs. A little taller and wider than we thought before. The forelimbs are pretty short relative to the torso.

Fitch et al. 2021 continue:
“Other Triassic pterosaur specimens, similarly assumed to represent irrelevant “developed” forms, may also preserve distinct, intermediate morphologies that inform the evolution of the pterosaur forelimb from that of terrestrial archosaurs.”

Irrelevant? Developed? Intermediate? Why not just add all these taxa to a phylogenetic analysis. Then you’ll have that cladogram for the rest of your career and you can use it with authority. It’s evidence, not conjecture, not opinion. It shows you did the work and understand relationships from evidence, without bias.

Figure 5. Click to enlarge. The origin of the pterosaur wing and whatever became of manual digit 5?

References
Fitch AJ, Bhullar B-A, Pritchard AC, Bevit J, Lovelace DM and Nesbitt S 2021. The forelimb of Articodactylus cromptonellus (Pan-Aves; Pterosauria) and the assembly of the pterosaur wing. Journal of Vertebrate Paleontology abstracts.
Jenkins FA Jr, Shubin NH, Gatesy SM and Padian K 1999. A diminutive pterosaur (Pterosauria: Eudimorphodontidae) from the Greenlandic Triassic. Bulletin of the Museum of Comparative Zoology, Harvard University 155(9): 487-506.
Peters D 2000. A Redescription of Four Prolacertiform Genera and Implications for Pterosaur Phylogenesis. Rivista Italiana di Paleontologia e Stratigrafia 106 (3): 293–336.
Peters D 2002. A New Model for the Evolution of the Pterosaur Wing – with a twist. – Historical Biology 15: 277–301.
Peters D 2007. The origin and radiation of the Pterosauria. In D. Hone ed. Flugsaurier. The Wellnhofer pterosaur meeting, 2007, Munich, Germany. p. 27.

SVP 2021 abstracts – 17: Bristol’s pterosaur quad launch study from 2019 returns

Remember 2016
when Rayfield, Palmer and Martin-Silverstone of Bristol University created the following advertisement for a budding paleontologist/engineer student? “The main objective of this proposal is to investigate the effectiveness of the quadrupedal launch [of pterosaurs] and by comparing it with the bipedal launch of birds, test if it was one of the factors that enabled pterosaurs to become much larger than any bird, extant or extinct.”

The Bristol pterosaur workers
did not want to test a quad launch (Fig. 1) vs bipedal launch (Fig. 2) in pterosaurs. Rather this team assumed that pterosaurs took off on all fours based on the ability of tiny 1.2 oz vampire bats to leap and then unfold their wings, then flap, then fly.

Figure 1. Unsuccessful Pteranodon quad launch based on Habib (2008) in which the initial propulsion was not enough to permit wing unfolding and the first downstroke prior to crashing. A push-up is not enough to do this even with the elastic snap effect. The smallest bats manage this by starting with open wings.

Figure 2. Click to play. Successful heretical bird-style Pteranodon wing launch in which the slender hind limbs and huge wings provide 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 shown in figure 1.

Worse yet,
the Bristol team assumed giant azhdarchids could fly, ignoring the vestigial distal phalanges that made azhdarchids flightless before becoming giants. Engineer and inventor, Paul Macready, had to shorten the neck and lengthen the wings of his model Quetzalcoatlus to make it fly (Fig. 3).

Figure 3. Paul MacCready’s flying pterosaur model had longer wings than Q. sp., with its vestigial distal wing phalanges. Here the model and its inspiration are shown to the same length.

I think the Bristol pterosaur team found the student they advertised for in 2016,
If so, he’s now a PhD: Benjamin W Griffin. This guess is based on the observation that this is the second time Griffin and his Bristol team have presented an abstract for pelvic range of motion during a hypothetical quad launch in pterosaurs.

From the Griffin et al. 2021 abstract:
“Pterosaurs were the first vertebrates to develop powered flight as a method of locomotion and subsequently attained sizes unseen in any other flying group.”

Only after becoming secondarily flightless, as described earlier here.

“Launch is the most power intensive aspect with regards to flight, requiring the generation of a launch impulse that will provide sufficient velocity and height to safely begin the flapping cycle. As flying animals increase in size, their capacity for muscular force generation does not increase at the same rate, making this launch impulse harder to generate.”

So far, that sounds sensible. That’s why birds combine a wing flap with a leg launch (Fig. 2). Unfortunately, the quad launch hypothesis separates these two methods for becoming airborne. Between the hind limb leap and the first flap of the pterosaur wing there is a long period of time in which there is no thrust and no lift (Fig. 1), only momentum.

“One hypothesis for how pterosaurs circumvented this issue is that they utilized a quadrupedal
launch, allowing them to incorporate the flight muscles in the launch cycle.”

The tiny bats that can leap into the air like this weigh only 1.2 ounces. Things are different when you are not so tiny (see video of fruit bat below). By contrast, birds the size of pterosaurs incorporate flight muscles in the launch cycle, combining the initial leap with energetic flapping to produce maximum thrust (Figs. 2, 4).

Griffin et al. continued:
“Ornithocheiraeans were a clade of Cretaceous pterosaurs including both Anhanguera and
Ornithocheirus. The largest members of this clade reached wingspans of 6 m. By using Range of Motion (ROM) mapping of the pectoral and pelvic girdles of a generalised 5 m wingspan ornithocheiraean model, we tested the ability of ornithocheiraeans to assume the poses required for quadrupedal launch.”

As the Griffin team did in 2019.

“Additionally, we were able to simulate the effects of soft tissues on the joint mobility of the girdles. This facilitates expansion of the ROM through cartilaginous offsets and restriction of the
ROM by constrictive soft tissues including ligaments and muscles. The ROM maps were then compared against published poses hypothesised to be used in pterosaur launch.”

Published poses? From paleoartists? Why not start from scratch and test quad poses against bipedal poses matched to tracks? See animated figure 4.

Figure 4. Pterodactylus animated matched to tracks. The stick figure in the background is also matched to tracks and this is another source for the Bristol team’s awkward and dangerous hypothesis.

Wonder if the Griffin team ever got rid of the morphological cheats employed by Witton and Habib 2010 (Fig. 5), chronicled here in 2011. You might remember Habib’s idea was to plant the wing finger into the substrate, then roll over it to develop an elastic slingshot effect. The problem is: the wing finger never touches the substrate in any pterosaur track. To make pterosaurs do this Habib and Witton 2010 reduced the three free fingers and put them on top of the wing digit to get them out of the way (Fig. 5). That’s also called cheating. Strangely, no one else noticed as this hypothesis became adopted by museums and artists worldwide.

Figure 5. Errors in the Habib/Molnar reconstruction of the pterosaur manus.

Griffin et al. continued:
“Over 197,000 potential poses were tested for the ball-and-socket joint of the pelvic girdle, and over 591,000 potential poses were tested for the more complex semihellar joint seen in the pectoral girdle.”

Methinks Griffin is ‘milking’ that 2016 offer made by co-authors Rayfield, Palmer and Martin-Silverstone and confessing to it! That is more poses than I would be interested in testing by about 196,900. BTW, the word ‘semihellar’ appears nowhere else in the English language according to a keyword search on Google.

“The ROM maps generated show that the ornithocheiraean model can assume the poses required for a quadrupedal launch.”

Apparently that is the resting (= pre-launch) pose (Fig. 6) for a quadrupedal ornithocheirid. Meanwhile, in the bipedal pose, the center of gravity remains over the extremely tiny (= vestigial) feet, which the animated version (Fig. 6 at left) illustrates much larger, again cheating morphology.

Figure 6. NHM Anhanguera compared to skeletal image in a more upright pose. Free fingers elevated and rotated to show the size and shape of the unguals. Note the tiny feet in the actual Anhanguera, overdeveloped in the NHM model, which also rotates the wing finger away from the plane of the wing.

Griffin et al. continued:
“Additionally, the ROM maps indicate that the model is incapable of using a bipedal posture to generate a launch impulse, even with the largest cartilage offset.”

This will have to be demonstrated, not just said. Methinks they are cheating again in order to make the bipedal model invalid (or to keep their paychecks coming). Note how the model (Fig. 6 left) directs the femora nearly straight down, as if pterosaurs were archosaurs. The femora should be directed much more laterally, as in lepidosaurs, keeping the axis of the femoral head aligned with the axis of the acetabulum.

“This study demonstrates that medium sized pterosaurs could assume the postures required for quadrupedal launch. Next steps will estimate whether sufficient muscular leverage and
power could be generated through a quadrupedal launch cycle.”

Since this 2021 presentation repeats the one presented in 2019, the only cycle apparent here is the recycling of old myths and reconstructions. Scientists should want to falsify their hypotheses in order to get rid of those idea that don’t stand up to scrutiny. That’s when the harshest critics become the greatest allies, whether that feels good or not.

PS
Sharp-eyed readers will note that the university-level textbook “Vertebrate Paleontology” was written by another Bristol University professor, Michael Benton. In addition, David Unwin, who mistakenly imagined a single uropatagium between the hind limbs and lateral toes of Sordes from a displaced wing membrane, also taught at Bristol from 1991 to 1997. So if you wonder why myths persist in paleontology, look no further than this center of influence.

References
Griffin BW, Martin-Silverstone E, Demuth O, Pegas R, Palmer C and Rayfield E 2021. Pectoral and pelvic range of motion constraints on Ornithocheiraen quadrupedal launch. Journal of Vertebrate Paleontology abstracts.
Griffin BW, Demuth OE, Martin-Silverstone E and Rayfield EJ 2019. Simulated range of motion mapping of different hip postures during launch of a medium-sized ornithocheirid pterosaur. Journal of Vertebrate Paleontology abstracts.
Witton MP and Habib MB 2010. On the Size and Flight Diversity of Giant Pterosaurs, the Use of Birds as Pterosaur Analogues and Comments on Pterosaur Flightlessness. PLoS ONE 5(11): e13982. https://doi.org/10.1371/journal.pone.0013982

Here’s a pterosaur proposal doomed to a crashlanding

SVP abstracts – Ornithocheirid hip range of motion (ROM)

SVP 2021 abstracts – 16: Stem gekko? Stem skink? Or neither?

Meyer, Brownstein and Gauthier 2021 report:
“Squamates, with more than 11,000 species, are a major portion of extant tetrapod biodiversity. However, their phylogenetic relationships remain highly contested between hypotheses generated from morphological versus molecular data.”

There is a long history of other workers are also seeing this difference.
Don’t trust genes in deep time studies. Use the hard evidence of traits and fossils.

“This may be due in part to poor sampling of stem members of disparate crown clades, particularly from the Jurassic, when most of the crown ‘backbone’ clades are estimated to have originated.”

No. We have a good sampling in the LRT. Add extant taxa to fossil cladograms, as in the large reptile tree (LRT, 1991 taxa, subset Fig. 2) to make your ‘poor sampling’ better.

Figure 1. Originally pictured as a generic lizard (below), here Eichstattsaurus scaled to the track size walks upright. This taxon nests in the lineage of snakes in the LRT.

Meyer, Brownstein and Gauthier 2021 continued:
“Here, we identify a stem gekkotan from the Kimmeridgian Brushy Basin member of the Morrison Formation. This new species replaces the Tithonian Eichstaettisaurus as the oldest
stem gekkotan currently known.”

Neither is a stem gekkotan. In the LRT Eichstaettisaurus (Fig. 1) is in the snake lineage (Fig. 2), a sister clade to the gekko clade. Just add pertinent taxa to find this out for yourself.

Figure 2. Subset of the LRT focusing on Squamata and the new addition: Paramacellodus (yellow).

Meyer, Brownstein and Gauthier 2021 continued:
“This identification is based on a reexamination of specimen DINO 19514. It consists of a disarticulated partial skull including the maxillae, prefrontals, frontals, parietal, left jugal, right postfrontal and squamosal, partial braincase, both dentaries, and the fused left postdentary
bones. Previous examination of DINO 19514 assigned it to the scincomorph Paramacellodus.”

DINO 19514 (Fig. 3) was described earlier by Evans and Chure 1998.

Figure 3. The DINO 19514 specimen of Paramacellodus from Evans and Chure 1998. Colors, layering, animation and DGS reconstruction added here.

In the LRT the DINO 19514 specimen of Paramacellodus nests with two other Early Cretaceous small to flat-headed lizards, equally small Tepexisaurus and tiny Retinosaurus (Fig. 4). These three are in their own clade basal to the large clade that includes Heloderma + varanids + mosasaurs + skinks + amphisbaemids (Fig. 2).

So Paramacellodus is neither gekko nor skink.

Figure 4. Tepexisaurus and Retinosaurus at full scale on a 72 dpi monitor. Skull of Tepexisaurus enlarged at right. Paramacellodus is similar in size to Tepexisaurus.

Meyer, Brownstein and Gauthier 2021 continued:
“We utilize μCT to re-examine the morphology of DINO 19514 in previously inaccessible detail and find it to be a new taxon that is neither Paramacellodus nor a scincomorph. This new taxon is diagnosed by an enlarged pineal foramen, a relatively wide inter-orbital portion of the frontals (more than 50% of the width of the frontoparietal suture), a postfrontal fused to the postorbital, and a wide parietal nuchal fossa. We incorporated DINO 19514 into a large squamate dataset (165 out of 791 characters x 169 species). Unconstrained maximum- and implied-weights (K=12) parsimony infer it as the earliest-diverging stem gekkotan, sister to a clade containing Eichstaettisaurus, Norellius and crown gekkotans.”

In the LRT (subset Fig. 2) Norellius is another lizard closer to snakes than gekkos. Meyer et al. make no mention of two basal gekkotans in the LRT: Tchingisaurus and Chometokadmon, so one wonders whether or not taxon exclusion is a problem here.

“DINO 19514 grants insight into the condition at the base of Pan-Gekkota. As in other stem gekkotans, it has paired frontals, in contrast to the fused condition of the crown. While incomplete, it is apparent that the subolfactory frontal processes are like those of other stem gekkotans in being intermediate between the ancestral squamate condition and the crown gekkotan condition in which they meet and fuse on the ventral midline. Likewise, the elevated marginal tooth count of DINO 19514 is intermediate between the low ancestral count and the high count of crown gekkotans. A lack of palatal dentition unites it with stem and crown gekkotans, pushing this loss to the Jurassic. The posterior teeth are unicuspid, a feature that it shares with other stem and basal crown-gekkotans.”

Evans and Chure 1998 published on DINO 19514 before the descriptions of and Tepexisaurus (2020). So they had no idea these two would someday be related. Meyer, Brownstein and Gauthier 2021 do not mention these taxa, so they may have omitted them, and the stem gekkotans and stem snakes listed above (Fig. 2). Wait for the paper.

References
Evans SE and Chure DJ 1998. Paramacellodid lizard skulls from the Jurassic Morrison Formation at Dinosaur National Monument, Utah. Journal of Vertebrate Paleontology. 18 (1): 99–114.
Hoffstetter R 1967. Coup d’oeil sur les Sauriers (=lacertiliens) des couches de Purbeck (Jurassique supérieur d’Angleterre). Coloques Internationaux du Centre National de la Recherche Scientifique 163:349–371.
Meyer D, Brownstein CD and Gauthier J 2021. Computed tomography reveals a Jurassic stem-gekkotan from the Morrison Formation. Journal of Vertebrate Paleontology abstracts.

wiki/Paramacellodus
wiiki/Tepexisaurus – not yet posted

SVP 2021 abstracts – 15: The Tetrapod Crown

This is a long abstract,
covering many bases, so hang in there.

Otoo and Coates 2021 report:
“Since its initial description, Whatcheeria [Fig. 1] has become the poster child of post-Devonian stem tetrapods.”

According to the LRT (Fig. 2), this is an inappropriate accolade
because Whatcheeria (Fig. 1) is not a stem tetrapod.

Figure 1. Whatcheeria fossil.

Stem tetrapods = Taxonomic proximal outgroup taxa to frogs, salamanders, caecilians.

Figure 2. Subset of the LRT focusing on basal tetrapods. Colors indicate number of fingers known. Many taxa do not preserve manual digits.

Simply by employing more taxa, in the Large Reptile Tree (LRT, 1991+ taxa; Fig. 2) Early Carboniferous Whathcheeria is a derived taxon with no known descendants. Therefore it is not a good ‘poster child’. It would be better to pick Tersomius (Fig. 3) the last common ancestor of all extant tetrapods.

Figure 3. Tersomius texensis, an amphibamid lepospondyl close to Dendrerpeton.

Otoo and Coates continue:
“But this consensus is matched by uncertainty about the broader membership of the apical stretch of the stem lineage: Whatcheeria, in general, is the ‘safe’ pick while other genera and families flip in and out of the crown.”

See figure 2 above. Taxa don’t flip in and out of the crown Tetrapoda in the LRT.

“Here, we take advantage of the new postcranial redescription of Whatcheeria to re-examine these relationships and explore patterns of tetrapod clades and characters close to the crown node. A new dataset assembled around Whatcheeria provides strong corroboration of the sister group relationship with Pederpes, and that this clade, the Whatcheeriidae, is, in turn, the sister group to all post-Devonian tetrapods (excluding finned relatives).”

The LRT (Fig. 2) does nest Whatcheeria with Pederpes,
but these are taxa without descendants.

“However, the Visean genus Ossinodus, although often presented as a whatcheeriid, is likely not a member of the same group and instead provides a glimpse of an as-yet undersampled
Mississippian- or earlier- tetrapod radiation.”

Ossinodus (Fig. 5) is not related to Whatcheeria (Fig. 1) in the LRT. Instead, Ossinodus is a more basal tetrapod closer to Trypanognathus and Greererpeton (Fig. 4)
the basalmost tetrapods in the LRT (Fig. 2).

Figure 4. Basal tetrapods are all flat, long and with short limbs. Ossinodus is derived in having a shorter body and large limbs.

Figure 5. Ossinodus and Gogonasus to scale with Tiktaalik and Elpistostege.

Otoo and Coates continue:
“Further to this, we find no close links between Whatcheeria and another group of putative close relatives, the anthracosaurs.”

By contrast, in the LRT the Whatcheeria clade is a sister clade
to the Anthracosaurus clade.

The definition of Anthracosauria has varied over time. If often includes Diadectes and kin, which are considered pre-amniotes by most prior workers. By contrast, the LRT nests Diadectes and kin within Reptilia (= Amniota). In the LRT (Fig. 2) Anthracosaurus nests in the clade that starts with Ichthyostega, a clade that left no descendants.

“Anthracosaurs (whole or in part), ‘lepospondyls’ (whole or in part), and colosteids are clustered with early members of the amniote and amphibian total groups. In summary, our results increase crown membership at the expense of the stem, and the baphetids remain as the only limbed clade other than the whatcheeriids excluded from the tetrapod crown.”

In the LRT the first three clades are all widely separated. Baphetids nest with anthracosaurs and whatcheeriids.

“In these trees, support for the tetrapod crown node remains weak and the branching structure throughout much of the tree is unstable.”

That’s what happens with taxon exclusion.

“In our estimates, Caerorhachis and the colosteids might not be far removed from conditions at the crown node.”

The LRT does not rely on ‘estimates’. The LRT does not use the word, “might.” In the LRT Caerorhachis (Fig. 6) nests as a reptilomorph within the Crown Tetrapoda, far from the much more fish-like colosteids, far from the crown group.

Figure 6. Caerorhachis is a reptilomorph and a member of the Crown Tetrapoda.

Otoo and Coates continue:
“Their current placement implies fewer steps between the basal branching members of the crown group and the most crownward stem members.”

The authors fail to mention ‘the most crownward stem members’ (yellow taxa in figure 2).

“Of particular interest, in results of reweighted analyses, colosteids are joined by Aytonerpeton, previously mooted as a colosteid, and these are coupled with the temnospondyls.”

Aytonerpeton (Fig. 7) entered the LRT (Fig. 2) as a collosteid. You heard that here in 2019. These are not related to temnospondyls in the LRT.

Figure 7. Aytonerpeton parts from Clack et al. 2016, restoration added. This taxon nests with Collosteus, Gogonasus in a clade that developed limbs in parallel to those in the Tetrapoda and left no extant descendants.

Otoo and Coates continue:
“The Tournaisian age of Aytonerpeton suggests that this more inclusive crown group is older than previous Visean dates, pegged by the diversity of tetrapod clades known from East Kirkton.”

Except that when taxa are added, Aytonerpeton is not related to Tetrapoda. It’s a tetrapod mimic from a more basal node.

“Correspondingly, this earlier, albeit tentative, minimum date implies a much greater range of Tournaisian tetrapods than currently recognized.”

Perhaps Otoo and Coates need to add taxa.

References
Otoo BK and Coates MI 2021. Old things are new again, Whatcheeria, Aytonerpeton and a Tournasian tetrapod crown. Journal of Vertebrate Paleontology abstracts.

Aytonerpeton enters the LRT as a derived collosteid