Sereno et al. 2022 said Spinosaurus was not aquatic

Summary:
This paper seems to have missed the transitional niche of shallow water, somewhere between dry land and deep water. Even Wikipedia, reports, “It (= Spinosaurus] lived in tidal flats and mangrove forests.”

Figure 1. Spinosaurus from Sereno et al. figures 2a (above) and 2d (below). 2.6m of water is deeper than most civic swimming pools. Why is this not a suitable niche for Spinosaurus?

Sereno et al. report,
“That model shows that on land S[pinosaurus]. aegyptiacus was bipedal and in deep water was an unstable, slow surface swimmer (<1m/s) too buoyant to dive.”

There’s no need to dive. What’s wrong with just shoulder-deep water? Or belly deep water? The Sereno et al. figure 2d (Fig 1 here) shows exactly that. That’s where most humans and other tetrapods spend most of their time when near rivers and beaches.
Too buoyant to dive is: OK! Slow surface swimming is: No problemo!

Figure 2. From March 2015. Aquatic Spinosaurus to scale with contemporary Early Cretaceous giant fish. Note the shallow waters and all that food! Plus a little respite from that tropical sun.

Sereno et al. report,
“Living reptiles with similar spine-supported sails over trunk and tail in living reptiles are used for display rather than aquatic propulsion, and nearly all extant secondary swimmers have reduced limbs and fleshy tail flukes.”

“Secondary swimmers have reduced limbs.” Wait a minute! This is an argument FOR an aquatic niche, as Sereno et al. acknowledge (Fig 1). Hone and Holtz 2021 made the same set of mistakes.

Sereno et al. make no mention of thermal regulation. We looked at that hypothesis for sail evolution back in 2015 (Fig 2).

Figure 3. Diagram from Dal Sasso et al. 2005, colors and overlay added to show dorsal expansion of the maxilla to cover an elongate naris.

Sereno et al. make no mention of the retracted and vestigial external naris
of Spinosaurus (Fig 3). This location and its tiny size are both quite different from most theropods making this yet another overlooked aquatic trait. The narial aperture cannot be closed in most tetrapods, including river and sea turtles. By contrast, hippos, crocs, ‘whales‘ and ‘seals‘ have narial valves to close the naris. Transitional pre-spinosaurs with smaller, more and more retracted nares (Fig 3), likely were not fitted with narial valves based on the evidence of extant birds (which lack narial valves) and the vestige naris of Spinosaurus.

Figure 4. The skull of Xiongguanlong is long and low, like that of spinosaurs and kin, not like that of tyrannosaurs and kin.

The Sereno et al. taxon list fails to include
Xiongguanlong (Fig 4) and several other spinosaur outgroups, so the Sereno et al. tree topology does not match the large reptile tree (LRT, 2104 taxa) due to taxon exclusion.

While this is not pertinent to the aquatic issue,
it does show a too focused view on the part of Sereno et al., rather than a more appropriate panoramic view, examining all pertinent aspects of this issue. These are clues that Sereno et al. were focused only on what they wanted to document, based on their headline, and their lack of considering the spectrum of niches between dry land and the deepest waters. In summary, it’s okay that spinosaurs got wet. After all, they ate fish. Big, slow fish (Fig. 2).

Sereno et al. report what everyone knows,
“Aquatic vertebrates (e.g., bony fish, sea turtles, whales) live exclusively or primarily in water and exhibit profound cranial, axial or appendicular modifications for life in water, especially at larger body sizes.”

Ironically Spinosaurus exhibits profound cranial, axial and appendicular modifications for life in water compared to spinosaur-related theropods (Fig 3) and theropods in general. Not sure why Sereno et al. don’t view Spinosaurus in this way other than by keeping their blinders on. We’ve seen this over and over and over again in vertebrate paleontology, so it’s a pattern.

Figure 5. Jabiru, a stork-like kingfisher that dips its beak in shallow waters seeking fish. This is similar to the morphology of Spinosaurus in figure 3, so this wading bird likely provides the best clues to the niche and lifestyle of Spinosaurus.

What can diving ducks teach us?
According to Ducks.org, “Like other specialized diving birds, diving ducks also have an unusually high tolerance for asphyxia, or lack of air. This “diving reflex” is triggered when water touches special receptors in the birds’ nares (nostrils).”

Duck nares are not tiny nor located back near the eyes. So a diving duck is not a good analog for Spinosaurus.

Jabiru (Fig 5) has tiny retracted nares, like those of Spinosaurus. This wading bird dips its snout in the water to probe for prey and continue breathing with nostrils held high above the surface. Based on such morphological evidence Spinosaurus had a similar lifestyle: hovering its head over belly-deep waters, dipping its snout in from time to time to probe for prey.

A co-author on Sereno et al. 2022
is Don Henderson, curator of dinosaurs at the Royal Tyrrell Museum who earlier (Henderson 2018) challenged the buoyancy, balance and stability of Spinosaurus. Sereno et al. echo many of Henderson’s hypotheses.

References
Henderson D 2018. A buoyancy, balance and stability challenge to the hypothesis of a semi-aquatic Spinosaurus Stromer, 1915 (Dinosauria: Theropoda). PeerJ 6:e5409; DOI 10.7717/peerj.5409
Hone DWE and Holtz TR Jr 2021. Evaluating the ecology of Spinosaurus: Shoreline generalist or aquatic pursuit specialist. Palaeontologica Electronica 24(1):a03 Online Here.  
Sereno PC et al. (8-coauthors) 2022. Spinosaurus is not an aquatic dinosaur. bioRxiv preprint doi: https://doi.org/10.1101/2022.05.25.493395; this version posted May 26, 2022.

Spinosaurus thermoregulation

The near closure of the naris in Spinosaurus

Spinosaurus: Hone and Holtz 2021 minimize the unique traits

Echeneis and tiny Ductor enter the LRT documenting the origin of the remora adhesion disc during the Eocene and Oligocene

According to many studies,
including the large reptile tree, (LRT, 2104 taxa) extant sharksuckers (e.g. Remora, Echeneis, Figs 2–6) evolved from phylogenetically miniaturized extinct transitional taxa descending from the large extant cobia (Rachycentron, Figs 1, 2). These are 2m fish that also follow large sharks, but do not adhere to them.

Figure 1. Cobia (Rachycentron) swimming with a whale shark (R).

The transition from locomotion to hitchhiking took place
in the early Eocene with phylogenetically miniaturized Ductor and early Oligocene Opisthomyzon (Fig 2), demonstrating, once again, this widespread and generally overlooked evolutionary process.

Figure 2. Rachycentron, the cobia, is ancestral to tiny Ductor, Opisthomyzon, Remora and Echeneis in the LRT. Here shown to the same snout-tail size and to the same scale. Note the phylogenetic miniaturization at the genesis of the adhesion disc in Oligocene pre-remoras like Ductor and Opithomyzon. Cobia ancestors may have been smaller in the Paleocene and Eocene. We don’t know.

The adhesion disc in sharksuckers
is not part of the skull, but overlays most of the skull (Fig 3).

Figure 3. The head of a remora shown in three views and animated. The louvers rotate like venetian blinds after the surrounding rim rises against the skin of the host creating a vacuum between the louvers. The adhesion disc makes this fish a ‘shark-sucker.’ Before this vacuum system evolved, small hooks on every other louver were able to cling to shark skin.

Most authors repeat what Wikipedia reports
“the adhesion disc is a modified dorsal fin.”

Precursor taxa, like Cobia, lack that dorsal fin,
but do have a precusor structure, described as, “six to nine independent, short, stout, sharp spines.” These spines also appear in embryo sharksuckers (Fig 5) prior to their metamorphosis into an independent set of bilateral transverse processes, acting as louvers (Fig 3), no longer associated with the vertebral column, extending anteriorly over the skull.

Figure 4. Echeneis skull from Gregory 1933. Colors added here.

Britz and Johnnson 2012 studied the ontogeny of the remora
(1cm to 17.5cm) to revisit the question of the homology of the disc.

Figure 5. From Britz and Johnson 2012 showing a hatchling remora, focusing on the tiny spines in the cervical region that ultimately become the adhesion disc.

Before the remora vacuum system evolved,
small hooks on every other louver were able to cling to rough shark skin.

Figure 6. Phylogenetic evolution of remora adhesion disc. 1. Simple neural spines differentiate into short odd number (1, 3, 5) and long even number (2, 4, 6) lengths. 2. Both sets of neural arches develop wide lateral processes and posterior processes reduce and disappear. 3. Further modification of both sets of lateral processes. Even number neural processes develop posterior spines/hooks while odd number do not. In remoras these sets rise and fall like Venetian blinds, creating vacuum slots between them. The hooks preceded the vacuum system permitting early remoras to cling to rough shark skin.

Britz and Johnnson reported,
“We compared the initial stages of development of the disc with early developmental stages of the spinous dorsal fin in a representative of the morphologically basal percomorph Morone. We demonstrate that the “interneural rays” of echeneids are homologous with the proximal-middle radials of Morone and other teleosts and that the “intercalary bones” of sharksuckers are homologous with the distal radials of Morone and other teleosts.”

The only trouble is,
remoras are not related to perch in the LRT. Remora ancestors in the LRT include Ductor ventenae (Figs 7, 8) and Opisthomyzon glaronensis (Friedman et al. 2013; early Oligocene), which has a small half sucker.

Figure 7. Ductor vestenae, and Early Eocene pre-remora only 9cm long.

Figure 8. Skull of Ductor vestenae. Colors and reconstruction added here. Blue post-cranial elements show the genesis of the adhesion disc from precursor structures in Rachycentron.

Ductor vestenae
(Blot 1969; Early Eocene; 9cm) was considered a perch or a pilot fish. Friedman et al. 2013 nested it basal to remoras, derived from a much larger extant cobia, Rachycentron. That is confirmed by the LRT.

Britz and Johnson continue,
“The “intercalary bones” or distal radials develop a pair of large wing-like lateral extensions in echeneids, not present in this form in any other teleost. Finally the “pectinated lamellae” are homologous with the fin spines of Morone and other acanthomorphs”.

Morone is the striped bass, not related to remoras and kin.
Traditionally acanthomorophs are rayfin fish with spiny rays.

“The main part of each pectinated lamella is formed by bilateral extensions of the base of the fin spine just above its proximal tip, each of which develops a row of spinous projections, or spinules, along its posterior margin. The number of rows and the number of spinules increase with size, and they become autogenous from the body of the lamellae.”

Ductor has short wing-like lateral extensions on dorsal bones. A diagram of these bilateral extensions in sharksuckers is shown in figure 6.

Figure 8. The Iniopterygidae include Iniopteryx, Promexyele, Iniopera and Sibyrhynchus. These reconstructions are from Zangerl and Case 1973 and the captions label them “tentative.” Note the elevated and hooked pectoral fins enabling attachment to larger sharks and other hosts.

PS
Convergent with sharksuckers are the late Carboniferous iniopterygids. These derived ratfish have elevated pectoral fins decorated with hooks (Fig 8), likely for hooking on to larger swimming hosts.

References
Blot J 1969. Les poissons fossiles du Monte Bolca. Classe´s jusqu’ici dans les familles des Carangidae Menidae Ephippidae Scatophagidae. Stud. Ric. Giaciam. Terz. Bolca 1, 1–525.
Britz R and Johnson GD 2012. Ontogeny and homology of the skeletal elements that form the sucking disc of remoras (Teleostei, Echeneoidei, Echeneidae). Journal of Morphology 273(12):1353–1366.
Friedman M, et al. 2013. An early fossil remora (Echeneoidea) reveals the evolutionary assembly of the adhesion disc. Proc. R. Soc. B 280.1766 (2013): 20131200.

wiki/Rachycentron
wiki/Ductor
wiki/Echeneis
wki/Remora
wiki/Opisthomyzon
wiki/Live_sharksucker

Convergent with mysticetes, one of the largest arthrodire placoderms enters the LRT with one of the smallest

Earlier
tiny latest Silurian Bianchengichthys (Fig 1) entered the large reptile tree (LRT, 2102 taxa) as a phylogenetically miniaturized taxon at the base of the arthrodire clade of placoderms.

Figure 1. Bianchengichthys, a tiny basal arthrodire placoderm shown in detail and actual size on a 72dpi monitor.

Today
a very large, rather flat arthrodire placoderm from the Early Devonian, Heterosteus (Asmuss 1856, Fig 2), nests in the LRT alongside tiny Bianchengichthys (Fig 1).

Figure 1. Giant Heterosteus reconstructed with restored soft jugals and preoperculars. These former lateral facial bones may have acted like baleen to filter out each mouthful of plankton-rich water. Placoderms lack the maxilla.

Heterosteus ingens
(= Heterostius Asmuss 1856, Agassiz 1844; Early Devonian, ~6m total length, 60cm skull length; Fig 2) is one of the largest arthrodires. The jugal and preopercular were not preserved and are restored here. These once ossified, now soft tissues may have acted like baleen to filter out each mouthful of plankton-rich water.

A smaller. closely related Early Devonian arthrodire placoderm,
Yinostius major (Wang and Wang 1984; Fig 3) may be reconstructed like Heterosteus (Fig 2) and different than originally reconstructed by restoring the missing (= soft) jugal + preopercular (gray areas).

Yinostius and Hetersteous
both appear to be open water filter feeders, like whale sharks, engulfing vast amounts of sea water and filtering out tiny to large suspended planktonic animals while expelling exhaled water through gills and soft lateral lips, acting like baleen, as the wide mouth opened and closed for respiration and food acquistion.

This appears to be a novel hypothesis
of observation and interpretation. If not, please provide a citation so I can promote it here.

Speaking of ‘whales’…
ResearchGate.net sent a note saying ‘The Triple Origin of Whales” had reached 900 downloads.

References
Asmuss HM 1856. Das vollkommenste Hautskelet der bisher bekannten Thierreiche. An fossilen Fischen des Alten Rothen Sandsteins aufgefunden und aus ihren Resten erläutert: Abhandlung.
Wang JQ and Wang NZ 1984. New Material of Arthrodira from the Wuding Region, Yunnan. Institute of Vertebrate Palaeontology and Palaeoanthropology, Academia Sinica, Beijing.

wiki/Heterosteus
wiki/Bianchengichthys
wiki/Yinostius

Psittacosaurus fossil preserves uropatagia, convergent with Sharovipteryx

Here’s an observation
of convergence you won’t see anywhere else.

Figure 1. Sharovipteryx reconstructed from firsthand study. Note the flattened torso and uropatagia.

It’s well known that pterosaurs,
their ancestors and cousins, like Sharovipteryx (Fig 1) had uropatagia (= extradermal membranes behind each hind limb).

Figure 2. The SMF R 4970 specimen of Psittacosaurus.

On the other hand,
It’s not so well known that a basal ceratopsian, Psittacosaurus (Fig 2, specimen SMF R 4970), also preserves a uropatagium trailing each hind limb.

Figure 3. Still image from YouTube video on Psittacosaurus. Arrow points to uropatagium.

Many artists and scientists say uropatagia enabled Sharovipteryx to glide,
but no one will ever imagine a gliding Psittacosaurus.

So… maybe uropatagia are not gliding membranes in non-pterosaurs.

Of what use are uropatagia in nonvolant tetrapods?
1) heat sink to cool the largest, most active muscles of the body;
2) extradermal areas for decoration;
3) shade/protection over egg clutches.
4) Anything else?

Figure 4. We can imagine Sharovipteryx as a glider, but we know it was a bipdal sprinter with splayed lepidosaur limbs. Here uropatagia provide heat sinks for the largest, most active muscles in the body, additional canvas for decoration and shade for any little ones hiding beneath, just like Psittacosaurus.

Psittacosaurus major
(Osborn 1923, You et al. 2008) is a sister to Yinlong with a larger rostrum and no premaxillary teeth in the LRT. Psittacosaurus is known from a wide variety of specimens with distinct skull shapes.

References
Mayr G, Peters SD, Plodowski G and Vogel O 2002. Bristle-like integumentary structures at the tail of the horned dinosaur Psittacosaurus. Naturwissenschaften. 89 (8): 361–365.
Osborn HF 1923. Two Lower Cretaceous dinosaurs from Mongolia. American Museum Novitates 95: 1–10.
You H−L, Tanou K and Dodson P 2008. New data on cranial anatomy of the ceratopsian dinosaur Psittacosaurus major. Acta Palaeontologica Polonica 53 (2): 183–196.

wiki/Psittacosaurus

Gonorhynchus, a bonefish with sturgeon traits, enters the LRT

Updated March 29, 2223
with novel scoring that nests this taxon with sturgeons, despite the diphycercal tail. Click here to view the update.

Also known as
the beaked salmon, beaked sandfish, ratfish, sand eel and shark whiting, Gonorhynchus gonorhynchus (Linneaus 1766, Fig 1) enters the large reptile tree (LRT, 2100 taxa) today.

Figure 1a. Gonorhynchus skull diagram from Gregory 1933. Colors added here based on tetrapod homologs. The lacrimal/prefrontal is based on Albula in figure 3, but changes in figure 1b.

Figure 1b. Acipenser (sturgeon) larvae compared (not to scale) with an adult Gonorhynchus.

The peculiar fish
is long and cylindrical with a black blotch on the dorsal, anal and caudal fins. It has a pointed snout, a small protrusible mouth on the underside of the head and a long hair-like barbel anterior to the mouth.

That sounds like a reversal back, back, back in deep time to pre-shark, sturgeon (Fig 2) ancestors like Acipenser.

Figure 2. Origin of jaws from the ostracoderm, Hemicyclaspis, Thelodus, Acipenser (sturgeon) and Chondrosteus.

In Gonorhynchus
the maxilla extends anterior to the premaxilla, distinct from all other vertebrates. The labeled lacrimal is instead the prefrontal (Fig 1). Distinct from the bonefish (Albula, Fig 3) the circumorbital bones are absent.

Figure 3. Albula vulpes skull with highly derived facial bones reidentified here. Note the lateral premaxillary processes and ‘floating’ cheek bones. Green vertebrae are caudals.

This nocturnal fish
eats zooplankton and buried invertebrates, then buries itself in the sandy bottom during the day or when threatened.

References
Linneaus C von 1766. Systema naturæ per regna tria naturæ, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. Tomus I. Editio duodecima, reformata. pp. 1–532. Holmiæ. (Salvius)

wiki/Gonorhynchus
fishesofaustralia.net.au/home/species/1853

Palaeospondylus: Does the morphology show affinity to tetrapod ancestors?

Short answer: no.

Hirasawa et al. 2022 re-describe a common Middle Devonian ‘enigma’ taxon
from Scotland, Palaeospondylus (Fig 1). Eight years ago Hirasawa et al. 2016 first described Palaeospondylus as a type of hagfish, a basal chordate. This time they think it is close to Panderichthys (Fig 4), a proximal outgroup to the Tetrapoda.

So the Hirasawa team is really interested in being the first to figure out
what Palaeospondylus really is, but they keep failing due to taxon exclusion. Others have also tried to nest this traditional Middle Devonian enigma (see citations below) without success.

This tiny swimming basal gnathostome
was earlier (2021) resolved by the large reptile tree (LRT, 2097 taxa, subset Fig 6) when Palaeospondylus nested with the torpedo ray Tetronarce fairchildi (originally Torpedo fairchildi). All other competing candidates were tested and continue to be tested.

Figure 1. A specimen of Palaeospondylus in situ with colors added here. Analysis nests this small taxon with the extant torpedo ray, Tetronarce.

Hirasawa et al. 2022 report from their abstract:
“Palaeospondylus gunni, from the Middle Devonian period, is one of the most enigmatic fossil vertebrates, and its phylogenetic position has remained unclear since its discovery in Scotland in 1890. The fossil’s strange set of morphological features has made comparisons with known vertebrate morphotype diversity difficult.“

That has always been due to taxon exclusion. The LRT was able to figure it out last year in just a minutes of computer time given the wide gamut taxon list.

“Here we use synchrotron radiation X-ray micro-computed tomography to show that Palaeospondylus was a sarcopterygian, and most probably a stem-tetrapod.”

No, they don’t show that. And it doesn’t matter what other tools you use to image specimens if your taxon list excludes pertinent taxa. The authors imagine a tadpole-like juvenile form without limbs only because they do not consider or test the actual closest relatives among the omitted ray-like elasmobranchs.

“The skeleton of Palaeospondylus consisted solely of endoskeletal elements in which hypertrophied chondrocyte cell lacunae, osteoids and a small fraction of perichondral bones developed.”

These are traits of elasmobranchs, but no elasmobranchs were tested.

“Despite the complete lack of teeth and dermal bones,“

The authors are confessing: ‘We’re going to ignore these traits.’ The LRT does not ignore these traits.

“the neurocranium of Palaeospondylus resembles those of stem-tetrapod Eusthenopteron and Panderichthys, and phylogenetic analyses place Palaeospondylus in between them.”

Only because closer relatives were excluded from consideration and testing.

“Because the unique features of Palaeospondylus, such as the cartilaginous skeleton and the absence of paired appendages, are present in the larva of crown tetrapods, our study highlights an unanticipated heterochronic evolution at the root of tetrapods.”

Be wary when paleontologists use the term ‘unique features’. All features are inherited from relatives. For instance, pterosaurs also seem to have unique features so long as relatives are excluded. When relatives are included then those ‘unique traits’ become synapomorphies.

The authors note a ‘cartilaginous skeleton’, but do not test elasmobranchs, which also have a cartilaginous skeleton. Unfortunately, this sort of omission of taxa is all too common throughout paleontology. It’s the main reason why it took over a century for birds to be widely recognized as theropod dinosaurs and other similar issues.

The authors describe the absence of paired appendages in the larva of crown tetrapods (e.g. frog tadpoles), but this is a derived trait not found in the young of basal tetrapods and their finned ancestors. No basal tetrapods undergo a frog-like metamorphosis.

Figure 3. Palaeospondylus imagined as a finless osteolepid by Hirasawa et al. 2021. This is based on taxon exclusion. Palaeospondylus is a ray-like elasmobranch.

According to ScienceAlert.com
“A mysterious, extinct creature that has puzzled scientists for more than a century may have finally found its place in the tree of life. The small, fish-like animal is named Palaeospondylus gunni, first discovered in fossils in Scotland in 1890, which lived approximately 390 million years ago during the Middle Devonian. Now, according to a new analysis of well preserved fossils, scientists think that it was one of the earliest ancestors of tetrapods – animals with four limbs, including humans.”

Figure 4. Panderichthys nests with Palaeospondlyis in Hirasawa et al 2022, but only due to taxon exclusion.

Here is the cladogram from Hirasawa et al.
(Fig 5). Note the lack of elasmobranchs, rays and torpedo rays.

Figure 5. Cladogram from Hirasawa et al. 2022 showing their nesting of Palaeospondylus. This cladogram excludes Tetronarce fairchildi and all elasmobranchis despite noting that the skeleton of Palaeospondylus was cartilaginous and without paired appendages. There is no loss of resolution, like this, in the LRT.

Taxon exclusion
remains the number one problem in paleontology. This latest instance could be embarrassing, like the retracted Oculudentavis paper, but likely the Hirasawa et al. paper will float around the literature like so many other studies suffering from taxon exclusion. The editors and referees at Nature are not doing their job, or they are passing on this responsibility to other workers.

Figure 6. Subset of the LRT focusing on sharks from October 2021.

Let it be said,
given the nesting of Palaeospondylus near the base of all gnathostomes in the LRT (Fig 6), it is not that far off the lineage that ultimately produced sharks, bony fish, tetrapods and humans. Contra Hirasawa et al 2022, Paleopondylus does not show affinity to proximal tetrapod ancestors.

Let it also be said,
the skulls of ray- and skate-like elasmobranchs are not typical of vertebrate skulls in that they usually incorporate pectoral fins and other odd structures. Learn these. Add several rays to your own taxon list. Several traditional ‘batoids‘ are unrelated to each other in the LRT, but converge on this shape, as we learned earlier.

… and let’s not forget,
little Devonian Palaeospondylus also gave rise to a larger manta-like Cretaceous fish, Aquilolamna (Fig 7), but only in the LRT (Fig 6), at present.

Figure 7. Aquilolamna in situ from Vullo et al. 2021. Colors added here.

Luckily we all live in an Internet age
where scientific information can be shared worldwide immediately and at no cost. We no longer have to wait for a year or more for a paper critical of invalid published findings. What we do with the original information and the critique that follows is entirely up to each individual reader. At this point there are no umpires or referees, only supporters, critics and the vast majority who ignore and/or forget such studies.

PS
Thank you for your interest in PterosaurHeresies.Wordpress.com. Recent posts have more than doubled the usual number of readers and page views. Those numbers will likely drop again after the current Prehistoric Planet excitement fades. Confirmation, refutation and correction are always welcome as we work together to model actual evolutionary events.

References
Hirasawa T, Oisi Y and Kuratani S 2016. Palaeospondylus as a primitive hagfish. Zoological Letters. 2 (1): 20.
Hirasawa T, Hu Y, Uesugi, K. et al. 2022. Morphology of Palaeospondylus shows affinity to tetrapod ancestors. Nature https://doi.org/10.1038/s41586-022-04781-3
Hutton FW 1872. Catalogue with diagnoses of the species. Ed. Hutton, FW and Hector J (eds), Fishes of New Zealand, pp. 1-88 pls 1-12, Colonial Museum and Geological Survey Department, Wellington.
Joss J and Johanson Z 2007. Is Palaeospondylus gunni a fossil larval lungfish? Insights from Neoceratodus forsteri development. J Exp Zool B Mol Dev Evol. 2007 Mar 15;308(2):163-71.  https://pubmed.ncbi.nlm.nih.gov/17068776/
Johanson Z et al. 5 co-authors 2017. Questioning hagfish affinities of the enigmatic Devonian vertebrate Palaeospondylus. Royal Society Open Science. 4 (7): 170214.
Smith A 1829. Descriptions of new, or imperfectly known objects of the animal kingdom, found in the south of Africa. South African Commercial Advertiser 3: 2.
Thomson KS 2004. A Palaeontological Puzzle Solved?. American Scientist. 92 (3): 209–211.
Thomson KS, Sutton M and Thomas B 2004. A larval Devonian lungfish. Nature 426(6968):833-834.
Traquair RH 1890. On the fossil fishes at Achanarras Quarry, Caithness. Ann Mag
Nat Hist 6th Ser. 1890;6:479–86.
Vullo R, Frey E, Ifrim C, Gonzalez Gonzalez MA, Stinnesbeck ES and Stinnesbeck W 2021. Manta-like planktivorous sharks in Late Cretaceous oceans. Science 371(6535): 1253-1256. DOI: 10.1126/science.abc1490

wiki/Torpedo_fairchildi
wiki/Palaeospondylus
wiki/Aquilolamna

Publicity
https://www.livescience.com/ancient-fishlike-weirdo-tetropod-ancestor
sciencealert.com/this-fish-like-creature-could-be-one-of-your-oldest-known-ancestors

Cretaceous Aquilolamna nests with Devonian Palaeospondylus in the LRT

Middle Devonian Palaeospondylus nests with extant torpedo rays

Prehistoric Planet: Did Velociraptor have feathers?

Thank you, AppleTV+
for providing these clips from Prehistoric Planet.

Click to play. Did Velociraptor have feathers? segment from Prehistoric Planet.

Today’s segment features Velociraptor
and poses the question, “Did Velociraptor have feathers?” Everyone nowadays nods their head and agrees that dromaeosaurids did indeed have feathers. But that wasn’t the case in 1989 when “A Gallery of Dinosaurs” was published by Sierra Club/Alfred A Knopf (Fig 1).

Figure 1. Image from A Gallery of Dinosaurs 1989 showing Deinonychus with feathers.

1989 was not the first time
artists put feathers on dromaeosaurs. Far from it. But it does document how painfully slow paleontology accepts ideas, hypotheses and direct observations. Here Prehistoric Planet asks the same question 33 years later, even if that question has been answered and should be rhetoric by now.

Unfortunately,
here’s yet another current (2022) example of paleontology writhing in slow-motion turmoil. We’ve seen many of these. One, called the Timeline of Pterosaur Origin Studies, awaits the same sort of consensus enjoyed by feathered dinosaurs. We’ve known the answer for 22 years. Likewise, the dual origin of turtles and the triple origin of whales also await confirmation, refutation or correction, among many other novel hypotheses of interrelationships.

A little later,
David Attenborough holds his hand over an excellent fossil cast of Zhenyuanlong (Figs 2–4), a feathered theropod. He reports, “You can probably guess from these huge claws on its feet that it was related to Velociraptor.”

Funny how he put that, putting the onus on the viewer to guess. Evidently no one on the staff wanted to say what Zhenyuanlong was in definite irrefutable terms.

Figure 2. Frame from Prehistoric Planet. Attenborough describes Zhenyuanlong.

By contrast,
when added to the large reptile tree (LRT, 2097 taxa) Zhenyuanlong nests basal to tyrannosaurs (Fig 4), not with dromaeosaurs, in other words, not related to Velociraptor.

Figure 3. Zhenyuanlong in situ with colors applied to bones and feathers. These colors are transferred to create the reconstruction in figure 4.

The feathers are remarkably preserved
In Zhenyuanlong (Figs 3, 4), and they are large, especially on the wing-like forelimbs.

Figure 4. Tyrannosaurus (without feathers) to scale and directly compared to Zhenyuanlong (with feathers).

Attenborough asks “why would flightless dinosaurs have feathers?“
The answer is always, “Because their parents had feathers.” We looked at the Middle Triassic origin of feathers, proto-feathers, bristles, hair, extradermal fibers and tough scales earlier in a three-part series ending here.

Figure 5. From Prehistoric Planet, Velociraptor attacks a pterosaur on a cliff face. A long, dramatic, dangerous way to go for only the slim chance of catching them ‘at home’ with nothing to do. Reward: a little meat and lots of splintery hollow bones. Then there’s the equally dangerous trek home afterward. A flinal thought: I know of no pterosaurs adapted to mountainous dry environs. Most pterosaurs are tied to water. Exceptions include the insectivorous Dimorphodon to Anurognathus clade.

Given the presence of feathers,
perhaps Attenborough and his advisors should have asked, did Velociraptor flap its proto-wings? They never did flap in the video. Some Velociraptors are shown traversing bleak and rocky cliff faces seeking and attacking pterosaurs resting there. The feathered theropod wings are shown extended to help brake the impact of long leaps. None flap like birds do. There is a continuing tradition of portraying basal birds as gliders, despite evidence presented by Dial 2003 experimenting with flapping, non-volant baby chukars demonstrating an ability to climb steep inclines.

Since we know that tetrapods with short round mobile coracoids
do not flap, and tetrapods with elongate, locked-down coracoids do flap, let’s take a good look at the coracoid of Velociraptor from Norell and Makovicky 1999 (Fig 6).

Based on this evidence, Velociraptor flapped. It had an elongate, locked-down coracoid. It was also fused to the scapula, which most birds don’t do. Unfortunately the scientific advisors for Prehistoric Planet missed this one.

Figure 6. Coracoid and anterior scapula of Velociraptor fused to form a scapulocoracoid from Norell and Mackovicky 1999. Colors applied here. The ‘glenoid’ is the shoulder joint, where the humerus articulates.

Granted, the makers and advisors of Prehistoric Planet had so much to cover.
That was probably the reason why they fell back on easy, traditional depictions.

Oddly, when the advisors and producers did venture forth
it was to the polar regions for dino fights, to cliff faces for dromaeosaur attacks, to far off islands the tyrannosaurs had to swim to, to caves for trikes to hide in and to the dry American southwest for ocean-going nyctosaurs. They presented novel geography more often than novel morphology.

References
Norell MA and Makovicky PJ 1999. Important Features of the Dromaeosaurid Skeleton II: Information from Newly Collected Specimens of Velociraptor mongoliensis. American Museum Novitates 3282:1–45.
Dial KP 2003. Wing-assisted incline running and the evolution of flight. Science 299:402-404.

wiki/Velociraptor

Heers et al. 2021 discuss the origin of flight using hatchling birds

Comments on ‘comments on the morphology of the paravian shoulder girdle’

The Locked Down Coracoid and the Origin of Flapping

When true birds, pre-birds and pseudo-birds first started flapping

Flapping before flight

Which theropods were capable of flapping flight?

The African guineafowl enters the LRT with the North American turkey

Yes, they look alike, act alike and eat alike, so…
when the guineafowl, Numida meleagris (Linneaus 1764, Figs 1, 2), was added to the large reptile tree (LRT, 2097, subset Fig 3) it came as no surprise that it nested next to the turkey, Meleagris as part of the chicken clade. What IS surprising is their geographic separation.

Figure 1. Numida meleagris, the helmeted guineafowl in vivo.

Neither the guineafowl, nor the turkey are good flyers,
and yet the former is found in sub-Saharan Africa, while the latter is found in North America, separated by the Atlantic Ocean. How did that happen? Evidently a last common ancestor was present prior to the separation of those continents in the Early Cretaceous.

Figure 2. Skull of Numida meleagris. Note the frontal crest and extended postfrontal.

According to Wikipedia,
“The earliest turkeys evolved in North America over 20 million years ago and they share a recent common ancestor with grouse, pheasants, and other fowl.”

By contrast
the LRT (Fig 3) extends that estimate five to six times deeper into the Early Cretaceous.

Figure 3. Subset of the LRT focusing on birds. According to the LRT, the drect ancestors of many extant birds, including turkeys and guineafowl, were alive and radiating during the Cretaceous.

Numida meleagris
(Linneaus 1764) is the extant helmeted guineafowl. The postfrontal has a descending process beyond the postorbital. The frontal develops a crest that varies in shape (Fig 1).

Figure 4. Phasianus, the common pheasant, in vivo. This game bird relative of the peacock entered the LRT today.

The LRT also nests the pheasant, Phasianus,
(Fig 3) with the peacock Pavo, both derived from the chicken, Gallus. Commonly Phasianus colchicus (Linneaus 1758) is known as the ring neck pheasant. A spur arises from metatarsal 1 as a new structure. Metatarsal 5 is long, representing a reversal.

Figure 5. South America and Africa during the Albian, 100 mya. This is when toucans and hornbills must have separated along with the turkeys and guineafowl.

Members of the wide-ranging pigeon-chicken-pheasant-moa-parrot clade are
chiefly terrestrial (= none swim, dive or soar over seas), seed eaters and rapid, burst flappers that do not migrate. They range in morphology from the plain brown sparrow, to the spectacular peacock and giant Dinornis from New Zealand. The latter is most closely related to the odd South American hoatzin, Opisthocomus. As in turkeys and guineafowl the last common ancestor of these two also had to live before Zealandia split from Antarctica and South America about 100mya during the Cretaceous.

Someday a few more
of those Cretaceous bird fossils will be found. For a long time there were only two that made it to textbooks back then: Ichthyornis and Hesperornis.

References
Linnaeus C 1758. Systema naturæ per regna tria naturæ, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. Tomus I. Editio decima, reformata.
Linneaus C 1764. Museum S:ae R:ae M:tis ludovicae ulricae reginae svecorum, gothorum, vandalorumque &c. &c. &c. In quo animalia rariora, exotica, imprimis insecta & Conchilia describuntur & determinantur prodomi instar editum. Laur. Salvii, Holmiae.

Prehistoric Planet promotes several pterosaur myths in ‘Flamboyant Flyers’

A large, scrappy and disarticulated pterosaur find from Morocco,
Barbaridactylus (Fig. 1), appears center stage in the newest Prehistoric Planet episode called ‘Flamboyant Flyers‘. Unfortunately, traditional myths and problems abound.

Figure 1. At bottom, the KJ2 specimen of Nyctosaurus with crest, to scale with the UNSM 93000 specimen of Nyctosaurus, to scale with the remains of Barbaridactylus and a frame from ‘Flamboyant Flyers’ showing the combination of two pterosaurs to make one imagined pterosaur for Prehistoric Planet.

Problem #1
In ‘Flamboyant Flyers’ male pterosaurs are said to be larger and decorated with cranial crests, distinct from smaller, plainer females.

Fact #1 Phylogenetic analysis shows smaller, plainer specimens are more primitive. Only derived taxa had the time to evolve ornate crests. No male/female traits have ever been supported. Bennett 1992 wondered if a large-basin pelvis represented a female Pteranodon, but did not realize that all Nyctosaurus specimens have a large-basin pelvis. Some rivaled Pteranodon in size (Fig 1).

Figure 2. David Attenborough alongside an imaginary pterosaur skull attributed to Barbaridactylus, a specimen found without a skull, documented in figure 1. The crest is too thick. Pterosaur experts should know this.

Problem #2
In ‘Flamboyant Flyers’ the giant crest is shown to be half as thick as the skull (Fig 2).

Fact #2. In pteranodons and nyctosaurs the crest is typically 1/8-inch (3mm) thick. The imagined skull shown with narrator David Attenborough comes from the model shop, not from the Early Cretaceous sands of Morocco. Only small parts of the rear mandible were found from the head of Barbaridactylus (Fig 1).

Figure 3. Frame one: Blueprint-type image form ‘Flamboyant Flyers’ showing the incorrect deep-chord, bat-wing model for pterosaur wings that has never been found in the fossil record. Frame two: Nyctosaurus images that show the correct shallow-chord wing membrane found in all pterosaur fossils that preserve soft tissue.

Problem #3
In ‘Flamboyant Flyers’ the pterosaurs wings extend to the ankles (Figs 3, 4).

Fact #3 No pterosaurs fossils have ever been found with wing membranes extending to the ankles. I keep looking for one exception that shows this morphology. There are no exceptions. Uropatagia trail each hind limb, missing from the ‘Flamboyant Flyers’ blueprint in figure 3.

Figure 4. Frame from ‘Flamboyant Flyers’ showing the traditional but incorrect pterosaur wing membrane extending to the ankles. Frame two shows the correct morphology for all pterosaur specimens that preserve soft tissue wing membranes, and thus presumed for nyctosaurs. Note the large size of the male with a distinct crest. We have no evidence for larger or more decorative males.

Problem #4
In ‘Flamboyant Flyers’ the pterosaurs are shown to be awkward quadrupeds on land. They over-bend the normally large, stiff wrist far beyond the breaking point in order to make this happen.

Fact #4 Most pterosaur tracks are quadrupedal and these are all attributed to beachcombing clades, not nyctosaurs. A minority of tracks are bipedal, some germanodactylids, basal to nyctosaurs. Due to their long metatarsals nyctosaurs are presumed to be bipeds, balancing over their toes (Fig 1), using their long forelimbs as ski poles when walking. Extended so far anteriorly, the long forelimbs of nyctosaurs can contribute no anterior vector to locomotion.

Figure 5. Barbaridactylus shown taking off by catapulting off the forelimbs, unlike birds or bats and not preserved in the fossil track record. Since pterosaurs could stand bipedally (see figure 4) they could open their wings and start flapping before becoming airborne, not wait until they were set to crash with their wings still below their bodies, creating no thrust or lift. Also note the extreme bending required at the wrist, which is impossible based on examination of the carpals in many pterosaurs.

Problem #5
In ‘Flamboyant Flyers’ the pterosaurs take to the air by bending their forelimbs way past their physical limits, unlike bats and birds.

Fact #5 Pterosaurs were bipeds (Fig 1) when they wanted to be and took to the air by flapping their large wings, like birds do from branches, water and land. No extreme wrist bending or dangerous leaping without the wings already extended and producing thrust is necessary.

Figure 6. Hatchling Barbaridactylus from Prehistoric Planet.

Problem #6
In ‘Flamyboyant Flyers’ the hatchling pterosaurs have a short rostrum and other ‘cute’ features found in mammals and archosaurs (birds + crocodilians).

Fact #6 Several embryo and hatchling pterosaurs have proportions identical to adults. None have a short rostrum, unless the adult also had a short rostrum. This isometric growth strategy is typical of lepidosaurs,, which is where pterosaurs nest in the large reptile tree. Pterosaurs also hatch from leathery eggs, typical of lepidosaurs. They also have elongate manual digit 4 and pedal digit 5, traits absent in archosaurs. We’ve known this since Peters 2000 and 2007, but university students are still taught that pterosaurs are archosaurs.

All these myths made it into ‘Flamboyant Flyers’.

According to Wikipedia,
“Barbaridactylus is a nyctosaurid pterosaur from the Ouled Abdoun Basin of Morocco, a basin that dates back to the Maastrichtian stage of the Late Cretaceous. In the same publication, two other nyctosaurids from the same basin were described: Alcione and Simurghia.”

We looked at Alcione and Barbaridactylus earlier here in 2018. Barbaridactylus is twice the size of most nyctosaurs (Fig 1). Alcione had very short metacarpals, odd for a nyctosaur, unless it was flightless, which is also odd for a nyctosaur.

Figure 7. Darren Naish, lead scientific consultant for Prehistoric Planet. He did a great job on the dinosaurs.

Figure 8. Liz Martin-Silverstone, paleontologist from U of Bristol, home of MJ Benton.

Two English paleontologists,
Darren Naish and Elizabeth Martin-Silverstone helped describe and explain the Flamboyant Flyers episode of Prehistoric Planet. Not sure why they chose to animate a largely imagined nyctosaur based on fragments, rather than animate a more complete specimen (Fig 1), requiring less imagination. Both Naish and Martin-Silverstone have a history of papers supporting pterosaur myths (indexed here and here) taught at the university level from Benton textbooks.

BTW
The rest of the series looks excellent!

Figure 9. Quetzalcoatlus sunning itself, distorted somewhat, according to the skeleton standing beside it.The myth of the bat-wing pterosaur is on display here. So is a wild imagination.

We looked at Prehistoric Planet episodes earlier
here and here.

References
Bennett SC 1992. Sexual dimorphism of Pteranodon and other pterosaurs, with comments on cranial crests. Journal of Vertebrate Paleontology 12: 422–434.
Longrich NR, Martill DM and Andres B 2018. Late Maastrichtian pterosaurs from North Africa and mass extinction of Pterosauria at the Cretaceous-Paleogene boundary. PLoS Biol 16(3): e2001663. https://doi.org/10.1371/journal.pbio.2001663
Peters D 1995. Wing shape in pterosaurs. Nature 374, 315-316.
Peters D 2002. A New Model for the Evolution of the Pterosaur Wing – with a twist. – Historical Biology 15: 277–301.
Peters D 2000b. A Redescription of Four Prolacertiform Genera and Implications for Pterosaur Phylogenesis. Rivista Italiana di Paleontologia e Stratigrafia 106 (3): 293–336.
Peters D 2007. The origin and radiation of the Pterosauria. In D. Hone ed. Flugsaurier. The Wellnhofer pterosaur meeting, 2007, Munich, Germany. p. 27.

wiki/Nyctosaurus
wiki/Barbaridactylus

Zhejiangopterus growth series

Seven problems with the pterosaur wing launch hypothesis

Several pterosaur myths get a boost from Naish, Witton and Martin-Silverstone 2021

New flightless and giant nyctosaurs: Alcione and Barbaridactylus

Early Cretaceous Fengning pterosaur is a large, late-surviving wukongopterid with tiny feet convergent with ornithocheirids

Zhou et al. 2022 found an Early Cretaceous pterosaur
partial wing (Fig. 1) and a tiny complete foot (SDUST-V1006, Figs 2–4) they decided not to name yet. They reported, “The new pterosaur specimen is characterised by an unusual pedal configuration of a short and spread metatarsus with elongate digits, showing a close resemblance to the dentulous Ornithocheiroidea.”

Figure 1. The little SDUST V1006 pterosaur wing shown close to full scale @ 72dpi. Colors added here.

Zhou et al. reported,
“SDUST-V1006 is distinct from all known ornithocheiroids in the pedal proportions, possibly representing a derived condition of the digital elongation. Furthermore, its pedal configuration that the pedal digits are extremely longer than the relevant metatarsals is also distinct from other pterosaur clades.”

Figure 2. Fengning pterosaur right foot, greatly enlarged. Photo and diagram from Zhou et al. 2022. Colors added here. Pedal digit 5 was lost and left a faint mark on the surface.

The Zhou et al. linear-plot diagram
of the second wing phalanx and metatarsal 3 in pterosaurs nested the SDUST specimen close to Haopterus and Boreopterus, two basal ornithocheirids. Their phylogenetic analysis nested the SDUST specimen basal to Istiodactylidae + (Boreopteridae + Ornithocheirae). As it turned out, this was by convergence, something linear-plot diagrams are unable to understand given that only two traits are tested (= Pulling a Larry Martin).

Here, in a competing phylogenetic analysis
both with and without pedal digit 5, the Fengning pterosaur (SDUST-V1006) nests between Wukongopterus and Kunpengopterus (Fig 4) in the large pterosaur tree (LPT, 261 taxa).

Figure 4. Mddle Jurassic Kunpengopterus compared to scale with SDUST-V1006, an Early Cretaceous pterosaur with much larger wings and a smaller pes.

With present data
the Fengning pterosaur (SDUST-V1006) is the first known wukongopterid to survive into the Early Cretaceous. It is convergent with the clade of Late Jurassic scaphognathids that evolved to become Early Cretaceous ornithocheirids. Shifting the Fengnng pterosaur to Boreopterus in the LPT adds 8 steps based on foot traits only. So that’s not trivial. Testing all the available traits, not just a few, even if just a few are available for testing, still remains the best way to identify enigma taxa.

Zhou et al concluded,
“The first pterosaur is described from the Huajiying Formation, the lowest horizon of the Early Cretaceous Jehol Biota, in the northern Hebei Province, China. It is tentatively assigned as an indeterminate ornithocheiroid, showing an unusual pedal configuration with short and spread metatarsus and elongate digits. This pedal configuration is in contrary to the general pattern of the elongate metatarsus and shorter digits in archaeopterodactyloids and pteranodontians, as a derived condition like that of boreopterids and istiodactylids. Functionally, the elongate digits might offset the shortened metatarsus to enlarge the pedal surface for paddling, representing a new strategy in adaptation to the aquatic environment.”

With such tiny feet (Fig. 4), paddling seems unlikely, even with interdigital webbing.

References
Zhou C-F, Zhu Z and Chen J 2022. First pterosaur from the Early Cretaceous Huajiying Formation of the Jehol Biota, northern Hebei Province, China: insights on the pedal
diversity of Pterodactyloidea. Historical Biology, DOI:10.1080/08912963.2022.2079085