Reconstructing the palate of Pteranodon in 1910, 1993 and 2024

Eaton 1910
published the first osteological study of Pteranodon, a large Niobrara pterosaur typically found crushed flat. The tall, narrow skull is often (Fig 1), but not always (Fig 2) crushed on its side, making the palate virtually impossible to see and reconstruct.

One possible exception:
the YPM 2594 skull specimen (Fig 1), which Eaton 1910 accurately reconstructed in palatal view without much of a Bauplan to work from back then. Note the absence of the cheek bone (jugal + maxilla) exposing the crushed palate in lateral view.

Or maybe Eaton – did – have a Bauplan to work from…

Figure 1. The YPM 2594 specimen of Pteranodon along with Eaton’s 1910 restoration of the palate. Chen et al used Eaton’s engraving, softened the engraving lines and added a DGS imaginary palatine (red), which is inaccurate to wrong. See figure 2 for corrections.

Only a guess…
perhaps Eaton 1910 was aware of the MHNH 1908-24 specimen (Fig 2), labeled two years earlier (judging by its 1908 museum number). It’s a Pteranodon posterior skull in palatal view illustrated I found in Bennett 1993. Perhaps the Paris museum (MHNH) got this specimen because it was not a real crowd-pleaser, but it is a Pteranodon, a new and exciting taxon from the American prairies and badlands back then. Today the MHNH specimen possibly answers the riddle of how Eaton 1910 and Bennett 1993, 2001 were able to reconstruct the palate of Pteranodon so accurately, when all other specimens crush the palate.

Chen et al 2024 (Fig 1) photoshopped Eaton 1910, apparently overlooking Bennett 1993 and the original MHNH (= Museum National d’Histoire Naturelle, Palenotolgie in Paris) specimen.

Figure 2. The MHNH Pteranodon specimen of the palate compared to Bennett’s 1993 composite palate based on Kansas and Yale specimens that are crushed laterally. I think the Paris specimen is also represented here without credit. Also shown in Germanodactylus cristatus restored in palatal view showing the narrowing of the palatine angle further reduced to 0º in Pteranodon. Here Bennett mislabels the palatal plate of the maxilla as a palatine. DGS colors added here.

Chen et al 2024 reported on the
“new relation established here between the palatine, ectopterygoid, maxilla, and pterygoid suggest some reinterpretation of the main palatal openings.”

More on that paper in the next post.

I’m happy Chen et al 2024 came out.
It offered µCT scans of Dsungaripterus (Fig 3) and other taxa. Even so (and following tradition), Chen et al made several errors (Fig 1), others largely due to taxon exclusion producing an invalid phylogeny. Reviewing Chen et al provided another opportunity to wonder about the pterosaur palate, correct old errors and resolve some interesting evolutionary issues.

Figure 3. Germanodactylus, Phobetor and Dsungaripterus palates compared.

For instance,
the palate of Germanodactylus cristatus (Fig 2) demonstrates how the narrowing of the palatine angle continues until it is reduced to 0º in Pteranodon. The lateral process of the L-shaped palatine is gone = fused. The lateral palatine processes in Germanodactylus revolves anteriorly to become a single strip in Pteranodon. I did not understand that happened until today.

That’s why a valid phylogeny sets the stage for making subtle discoveries in evolutionary morphology, like this one. If you have a question, check out the ancestral condition for clues.

References
Bennett SC 1993 (thesis) 2001 (publication). The osteology and functional morphology of the Late Cretaceous pterosaur Pteranodon. Palaeontogr. Abt. A 260, 1–153.
Chen H, Jiang S, Kellner AWA and Wang X 2024. New insights into pterosaur cranial
anatomy: X-ray imaging reveals palatal structure and evolutionary trends. Nature communications biology 7:456.
Eaton GF 1910. Osteology of Pteranodon. Memoirs of the Connecticut Academy of Arts and Science 2, 1–38.

wiki/Pteranodon

Vaneechoutte et al 2023: Australopithecines Are Probably Not Our Ancestors

You heard that headline here first,
but the authors’ citations indicate the thought has been percolating for decades. However, without a trait-based phylogenetic analysis, like the LRT (subset Fig 2), an alternate hypothesis of human origins remained nebulous coffee talk. If you want to play on this field you have to provide a better set of human ancestors than australopithecines (Fig 1). No cladogram has done that yet – other than the LRT.

Vanneechoutte et al 2023 wrote,
“In summary, hypotheses that attempt to explain how a semi-erect Homo/Pan last common ancestor transitioned into the bipedal  australopithecines as an adaptation to life on the savannah appear to be ill-conceived and moreover seem to have been superfluous from the very start. We review the numerous similarities between australopithecines and extant African apes, suggesting that they are possibly not hominins and therefore not our direct ancestors. We suggest that we may have been  barking up the wrong ancestral tree, for almost a century.”

“It appears that there was never a transition from a semi-erect (diagonograde) Homo/Pan ancestor to orthograde hominins, but instead there were separate transitions from an already orthograde hominine ancestor to the extant semi-erect chimpanzees and gorillas.”

That last common ancestor: (genus: Hylobates, Fig 1), is bipedal whenever terrestrial. That’s the ‘first step.’

“the savannah hypothesis was a narrative conceived to explain a transition that never happened.”

Or maybe it did somewhere else with a different clade of apes.

Figure 2. The gibbon lineage leading to humans. At right is Australopithecus, a bipedal ape by convergence with humans.

The authors explored
historical roots and offered critical considerations, but did not provide a phylogenetic analysis, like the LRT (subset Fig 2 from 2022).

Figure 2. Subset of the LRT focusing on primates after the addition of Australopithecus and Pongo.

The authors cited several earlier reports when they wrote,
“Keith [1923] recognized “the antiquity of orthograde posture”, pointing to hylobatids and to late-Oligocene/early-Miocene dryopithecines. Morton [1926] had also realized that the bipedalism of early hominoids is not in disagreement with the orthograde posture of extant hylobatids: “The gibbon’s primitive position in the anthropoid group has added value in that it strongly suggests the linking of our modern bipedalism with an early stage of erect  arboreal habits in the ancestral anthropomorphous stem.” and that: “Tree life is the only form of environment, and brachiation the only locomotive habit whereby the structures about the hipjoints would be given the opportunity to become gradually modified for an erect posture.” A study of the frequency of bipedalism in almost 500 zoo-housed hominoids and  cercopithecines found that all could move bipedally, with hylobatids engaging most frequently in bipedal locomotion”.

All these studies lacked was a trait-based
phylogenetic analysis (Fig 2).

In their conclusion Vaneechouette et al wrote,
“Furthermore, since orthogrady and, at the very least, facultative/postural bipedalism were already present in the Homo/Pan ancestor, it follows that our bipedalism can no longer be regarded as the initial and necessary condition that made possible our other numerous anomalous characters, including large brain size, also because brain size did not increase significantly during the millions of years that the bipedal—probably nonhominin—australopithecines and their predecessors existed.

Finally, considering australopithecines as possible ancestors of extant African apes, might help to resolve several enigmas,  such as the counterintuitive lack of fossils of the once numerous African apes and the unexpected absence of PtERV-elements in our genome.”

The LRT (Fig 2) nested Australopithecus basal to Pan + Gorilla in 2022.

The LRT is a hypothesis of interrelationships still needing an independent study with a similar taxon list to confirm, refute or modify it.

References
Keith A 1923. Hunterian Lectures on Man’s posture: Its evolution and disorders: Given at the Royal College of Surgeons of England. British Medical Journal 1:451–454.
Morton DJ 1926. Evolution of man’s erect posture (preliminary report). Journal of Morphology 43: 147–179.
Vaneechouette M, Mansfield A, Munro S and Verhaegen M 2023. Have we been barking up the wrong ancestral tree? Australopithecines are probably not our ancestors. Nature Anthropology DOI: 10.35534/natanthropol.2023.10007

Australopithecus enters the LRT with apes, not with humans

The evolution of temnospondyl (amphibian) larvae

In the LRT
(Fig 3) temnospondyls precede lissamphibians, including their extant representatives, frogs and salamanders. On another branch, temnospondyls also precede reptilomorphs (including Amphibamus, Fig 1) which lead to reptiles = amniotes.

PS Apologies for lack of paragraph spacing in WordPress. It’s a coding error on their part.

Schoch and Witzmann 2024 report,
“Most taxa in which small specimens are preserved had aquatic larvae with external gills that superficially resemble larval salamanders.” 

Figure 1 Late Carboniferous Amphibamus is a potential trackmaker for the Grand Canyon latest Early Carboniferous tracks. with medial digits the longest, like the trackmaker.

The authors identified several ontogenetic paths for temnospondyls:

Basal taxa (edopoids, dvinosaurus, eryopiforms):
Skull developed faster than axis and and appendicular elements plus no drastic transformation.

Dissorophoids:
Skull developed slower than limbs.

Micromelerpeton:
long and steady metamorphosis.

Amphibamus:
(Fig 1) rapid metamorphosis.

The authors wrote,
“We distinguish three different types of metamorphosis (morphological, ecological and drastic) that evolved cumulatively in early tetrapods and within temnospondyls.”

The authors do not dive into frog and salamander metamorphosis.
Rather this paper is focused on temnospondyl larvae.

Schoch and Witzmann bring up an interesting set of phylogenetic questions

that were not delved into in their paper.

 

In the LRT
(Fig 3) basal members of Lissamphibia, Microsauria, Amphibamus and Seymouriamorpha are all amniote precursors. Silvanerpeton (Fig 2) is the last common ancestor of reptiles = amniotes. Gephyrostegus and a long list of traditional anamniotes are also on the amniote side of this divide in the LRT.

Is there an unrecognized connection or disconnection
between the two modes of reproduction and ontogeny? Embryo metamorphosis, whether inside or outside of the confines of the egg, appears to be a bifurcation, rather than a gradual evolution. So what happened ecologically to encourage this split? What environment made Silvanerpeton depart from and distinct from its ancestor, Amphibamus?

Embryos in reptile = amniote eggs swim in their own little ponds
within the waterproof amnion until more fully developed than amphibian larvae. Based on the presence of Latest Devonian Tulerpeton just outside the Reptilia = Amniota, all prior phylogenetic splits must be Devonian, not Carboniferous, where all the fossils are.

Figure 2. Eusauropleura to scale with ancestral and descendant taxa including Eucritta, Utegenia, Silvanerpeton and Gephyrostegus, the last common ancestor of all reptiles. Note the loss of lumbar ribs and the addition of gastralia, perhaps to hold larger eggs in gravid females.

The aforementioned reptile = amniote taxa
lose dorsal ribs in the lumbar region (Fig 2). This seems to be (= a guess) useful for storing larger eggs inside the mother’s body, eventually creating a noticeable bulge in certain living gravid lepidosaurs, offering yet another line of protection for the otherwise helpless eggs/embryos. Larger amniote eggs, held longer within the mother, provide their own ‘pond’ for the completion of development = metamorphosis prior to and after maternal egg-laying.

Perhaps the mother became the pond in the first amniotes = reptiles.
Perhaps Late Devonian to Early Carboniferous reptiles = amniotes were viviparous. If true, then only later did certain reptiles make nests and lay developing eggs. If true, then vivparity in some clades is a reversal of a reversal.

Figure 3. Subset of the LRT focusing on basal tetrapods (aka amphibians).

The authors cite Schoch and Milner 2014 when they write,
“The origin of the temnospondyls remains rather obscure, as all other tetrapod groups are separated from them by wide morphological gaps.”

By contrast in the LRT (Fig 3) the origin of temnospondyls is clear and precise. Even so, the LRT is a hypothesis that requires confirmation, refutation or modification by independent workers with a similar taxon list, repeating the experiment.

References
Schoch RR and Witzmann F 2024. The evolution of larvae in temnospondyls and the stepwise origin of amphibian metamorphosis. Biological Reviews doi: 10.1111/brv.13084

‘Systematics of Miocene apes’ excludes certain Miocene apes

In their paper on Miocene apes, Urciuoli and Alba 2024 wrote:
“The hominin status of the Late Miocene genera Ardipithecus and Sahelanthropus has  sometimes been questioned. However, here these genera have been excluded based on the general view further supported by most recent cladistic analyses that they are early hominins.”

According to results from the large reptile tree (LRT, 2318 taxa) these taxa and hominines should not have been excluded. In the LRT these taxa upset traditional systematics (Fig 1) when they are included. Details here and here and here.

Figure 1. The gibbon lineage leading to humans. At right is Australopithecus, a bipedal ape by convergence with humans.

According to the LRT
Australopithecus was bipedal by convergence. You would only learn/discover that by including taxa excluded by Urciuolit and Alba.

Don’t follow the ‘general view‘.
Therein lies mediocrity. Test the general view. You might discover something everyone else overlooks. Taxon exclusion remains the number one problem hampering paleontology.

References
Urciuoli A and Alba DM 2023. Systematics of Miocene apes: State of the art of a neverending controversy. Journal of Human Evolution 175:103309.

Homo longi, aka ‘dragon man’, compared to Hylobates, the gibbon

More gibbon traits: Decide if these seem human-like.

reptileevolution.com/ardipithecus

Toothy Feredocodon enters the LRT just outside the Mammalia

Feredocodon chowi
(Mao et al. 2024a; IMMNH-PV01035; Early Jurassic) was originally considered a tiny shuotheriid (Fig 4) symmetrodont pre-mammal. Five molars and five premolars were present in adults. That’s a lot of teeth! The nasals were wider posteriorly. At least two specimens are known (Fig 1).

The multi-cusped canines were no larger than the other teeth (Fig 3).
Do those make Feredocodon a tiny herbivore? Or a tiny worm-puller?

Figure 1. TWo specimens of Feredocodon in situ from Mao et al 2024.

The basal metatherian/marsupial
Ukhaatherium has similar proportions, but fewer teeth. Anebodon has more molars, but fewer premolars.

Figure 2. Feredocodon µCT scan from Mao et al 2024. DGS colors added here.

Very few cynodont therapsids have a tricuspid canine.
Feredocodon is an exception to that rule. Note the anteriorly narrow mandibles that touch each other along their lengths (Fig 2), convergent with later odontocetes (toothed whales).

Figure 3. Feredocodon dentition from Mao et al 2024. DGS colors added here. The upper molars have three roots. Otherwise they blend gradually with the premolars. Note the canines (orange) have three cusps. This was not a tiny killer, but perhaps a tiny herbivore.

Original comparisons to Shuotherium
seem to be due to similar molar shapes, rather than the molar count or the mandible morphology. In the LRT Shuotherium nests tentatively (too few traits to score) within the Monotremata, not close to Feredocodon.

Figure 4. Medial view of Shuotherium. The last premolar is similar to the first molar, the coronoid process is tiny and the retroarticular process is absent, all distinct from Feredocodon (Fig 2). Not sure how many roots are found in p4 (or is that m1?). The change in morphology indicates the latter is more likely.

Another LRT relative,
Origolestes (Fig 5, Mao et al 2019), was similar in size and morphology, but with a shorter rostrum and thus fewer autapomorphies (= unique traits).

Figure 5. Origolestes in situ with colors added using DGS methods.

Since extant monotremes lack an ear pinna,
these two pre-monotreme and basal monotreme taxa, Feredocodon and Dianoconodon, likewise probably lacked an ear pinna, contra the original publicity illustrations (Fig 6). Living monotremes have an audio slit: vertical in the echidna, horizontal in the platypus.

Figure 6. Dianoconodon and Feredocodon illustrations from the publicity stream had ear pinnae. An alternate illustration without ear pinnae is presented in frame 2.

The most primitive extant marsupials in the LRT
are Caenolestes and Rhyncholestes (Fig 7). Both have an ear pinna and a long, narrow rostrum. Both have a small canine and 3 large molars. A vestigial fourth molar is present. The jaw bones and ear bones are separated and typically mammalian in appearance in these two South American living fossils. The cranium is large and wide, typical for mammals.

Figure 7. Rhyncholestes and Caenolestes are the most primitive living mammals with ear pinnae tested in the LRT.

As mentioned earlier,
I have not read the Mao et al paper, which remains behind a paywall. I am working from data available at ResearchGate.net, which includes many photos and graphics, but does not include a cladogram.

References
Mao F et al (6 co-authors) 2024a. Jurasssic shuotheriids show earliest dental diversification of mammaliaforms. Nature 782(260) online.

wiki/Feredocodon – not yet posted

Publicity
Sci.new.com
earth.com
amnh.org
popsci.com

Dianoconodon enters the LRT as the most primitive mammal

Mao et al 2024b brought us news of
Dianoconodon youngi (Fig 1, IVPP V4257), an Early Jurassic “mammal ancestor”. However, when this taxon was added to the large reptile tree (LRT, 2318 taxa) it nested as the basal-most monotreme, which makes it the most primitive mammal tested by the LRT.

Note: The Mao et al paper is behind a paywall, but the images are available at ResearchGate.net. None of those include a cladogram.

Figure 1. From Mao et al 2024 b images of Dianoconodon (above) compared to Morganucodon (below). DGS colors added here. In the LRT Morganucodon is an early marsupial.

Dianoconodon is much younger
than the oldest known mammals, which appeared in the Late Triassic and radiated widely by the Early Jurassic. So monotremes = mammals had an earlier and as yet undocumented first appearance and radiation than Early Jurassic Dianoconodon.

We looked at Dianoconodon and the mandible/ear transition here yesterday.

References
Mao F et al (8 co-authors) 2024b. Fossils document evolutionary changes of jaw joint to mammalian middle ear. Nature 1759(266):onlline
researchgate.net/publication

wiki/Dianoconodon – not yet posted

New Jurassic fossils reveal (again) that our hearing evolved from reptilian jawbones

Publicity
eurekalert.org/news-releases/1040018
newsweek.com/new-mammal-fossils-ears-teeth-1886471

New Jurassic fossils reveal (again) that our hearing evolved from reptilian jawbones

Unfortunately this is old news. Several decades old.
Everyone knew our hearing evolved from reptilian jawbones at least back to the 1980s following the work of James Hopson and others. Following those earlier discoveries, Peters 1991 included this illustration (Fig 1) in a popular book on evolution (cited below).

Figure 1. Click to enlarge. A series of jaw bones demonstrating the gradual accumulation of traits that changed them into ear ossicles and an eardrum frame. from 2012, copied and pasted from Peters 1991.

Publicity hype from SciTechDaily.com:
“An international team of paleontologists has uncovered important fossils that provide crucial insights into how early mammals transitioned from having jaw joint bones to middle ear bones during their evolution. The findings published today in the prestigious journal Nature provide a clearer insight into the evolution of hearing in mammaliaforms.”

“Important.” “Crucial insights.” “Prestigious.” = new hype + old news.

“Co-author Dr. Thomas Rich of Museums Victoria Research Institute said, “Newly recognized well-preserved fossils from the Jurassic of China significantly clarify how one of the most remarkable transitions in the history of the vertebrates occurred; namely, the transformation of many of the multiple bones in the lower jaws of reptiles became tiny bones in the middle ears of mammals.”

Readers, this is where paleontology is at in 2024: recycling old discoveries (Mao et al 2024 a, b), shunning new discoveries, and creating myths. Just follow the money (see video below).

From the AMNH.org website:
“Scientists have been trying to understand how the mammalian middle ear evolved since Darwin’s time,” said [co-author] Meng. “These new fossils bring to light a critical missing link and enrich our understanding of the gradual evolution of the mammalian middle ear.”

I guess it would not make a great headline to report, ‘Excellent fossils of rare tiny taxa support and confirm earlier hypotheses of middle ear development in mammals.’

Pretending this is a new discovery makes both scientists and publishers look a little desperate for attention. Does this come down to grant procurement (= money for universities)? That trend in that direction is widely reported in several sciences.

I will add these taxa
(Feredocodon and Dianoconodon) to the LRT when high-rez data becomes available. They are wonderfully preserved and should score strongly.

References
Crompton AW and Jenkins FA Jr 1968. Molar occlusion in late Triassic mammals, Biological Review, 43 1968:427-458.
Gow CE 1986. A new skull of Megazostrodon ( Mammalia, Triconodonta) from the Elliot Formation (Lower Jurassic) of Southern Africa. Palaeontologia Africana 26(2):13–22.
Mao F et al (6 co-authors) 2024a. Jurasssic shuotheriids show earliest dental diversification of mammaliaforms. Nature 782(260) online.
Mao F et al. (8 co-authors) 2024b. Fossils document evolutiionary changes of jaw joint to mammalian middle ear. Nature 1759(266):onlline
Peters D 1991. From the beginning – The story human evolution. Wm Morrow PDF

wiki/Megazostrodon

Publicity
scitechdaily.com/our-hearing-evolved-from-reptilian-jawbones/
amnh.org/explore/news-blogs/research-posts/fossil-discoveries-mammal-evolution

Video from an astrophysicist and YouTube personality

Crown and stem amniote problems: resolved by the LRT

Modesto 2024 discusses
Problems of the interrelationships of crown and stem amniotes. Modesto reports, “The oldest amniotes are Late Carboniferous in age (ca. 318 million years ago), and they are preserved in coal beds and lycopod tree stumps that have yielded rich faunas of temnospondyls, anthracosaurs, and other early tetrapods.”

And there’s the problem. Here’s the solution:

Add taxa. Neither Modesto nor any other academic steeped in basal amniotes recognize Early Carboniferous (Viséan) Silvanerpeton (Fig 2) as the last common ancestor of all extant amniotes in the large reptile tree (LRT, 2312 taxa) – becaue they omit it from cladograms.

A basal amniote doesn’t have to look like a reptile. It just has to reproduce like a reptile, by enclosing embryos in an amnion.

Figure 1. Basal Diadectomorpha [from 2011].

Modesto follows out-dated textbooks when he reports,
“the overall picturegenerated by the early-tetrapod research community agrees that Amniota is a clade (monophyletic group) that is divided into Synapsida on one hand and Reptilia on the other hand;”

The LRT nests Synapsida within Archosauromorpha (by definition) and Amniota is a junior synonym for Reptilia. Modesto and others will find this out when they add pertinent taxa to their cladograms.

Figure 2. Eusauropleura to scale with ancestral and descendant taxa including Eucritta, Utegenia, Silvanerpeton and Gephyrostegus, the last common ancestor of all reptiles. (from 2018]

Modesto cites Klembara et al 2021,
who found diadectomorphs are crown amniotes (= reptiles).

The LRT found diadectomorphs (Fig 1) are the sisters of procolophonids on one branch and pareiasaurs + turtles on the other in 2011 and 2013.

Modesto criticized Klembara et al when he wrote,
“Perhaps the greatest weakness in Klembara et al.’s (2021) phylogenetic conclusions is that these authors neglected to include any “microsaurs,” which is surprising in light of numerous previous studies that recover “microsaurs” (with other lepospondyls) closer
to Amniota than to either seymouriamorphs, gephyrostegids, or chroniosuchids.”

The LRT tests all these clades.

Modesto concluded,
“I infer that the researchers were unfamiliar with the literature on early amniotes, resulting in the use of obsolete anatomical information for certain amniote terminal taxa.”

While it is good to hear that at least a few professionals test published studies and matrices, the number one problem affecting paleontology continues to be taxon exclusion.

Don’t let amateurs lead the way. Don’t let amateurs resolve all the issues and enigmas decades before the professionals get around to adding taxa. Build your own LRT before you’re the last one on your block to do so.

References
Klembara J, Ruta M, Hain M and Berman DS 2021. Braincase and inner
ear anatomy of the Late Carboniferous tetrapod Limnoscelis dynatis (Diadectomorpha)
revealed by high-resolution X-ray microcomputed tomography. Front. Ecol. Evol. 9,
709766. doi:10.3389/fevo.2021.709766
Modest SP 2024. Problems of the interrelationships of crown and stem amniotes. Frontiers Earth Science 12:1155806. doi: 10.3389/feart.2024.1155806

You heard it here in 2011: diadectids are amniotes

Diadectes is not an Amphibian. And Procolophon is a diadectid.

Tested lungfish in the LRT

The systematic and scoring problem with lungfish is
their tendency to split (= tessellate) their cranial bones. That makes identification more difficult. Not impossible, just more difficult.

There is also the issue of the naris,
which does not show a migration to the ventral rim – unless lungfish developed a dual system during the transition from having lateral nares to ventral nares. Related clades document a ventral migration of the in-cuirrent and ex-current nares.

Here are the tested lungfish
(clade Dipnoi) in the LRT and their phylogenetic order (Fig 1).

Figure 1. Dipnoi = lungfish taxa tested by the LRT. Here Devonian Grossius is a basal lungfish, perhaps a last common ancestor. Note the presence of the nares in some taxa and the lack of a nares in others.

New DGS identities for several skull bones
are applied to some of the above taxa (Fig 1) based on comparative anatomy. These colors are subject to further updates, of course. Data arrives from several sources, from µCT scans to pen and ink diagrams. All the extinct taxa are from the Devonian. The rest are extant. Nothing here in-between.

References
Boulenger GA 1900. A list of the batrachians and reptiles of the Gaboon (French Congo), with descriptions of new genera and species. Proceedings of the Zoological Society of London 1900: 433–456.
Campbell KSW 1965. An almost complete skull roof and plate of the dipnoan Dipnorhynchus sussmilchi (Etheridge). Palaeontology 8 : 634-637.
Claeson KM, Bemis WE and Hagadorn JW 2007. New interpretations of the skull of a primitive bony fish Erpetoichthys calabaricus (Actinopterygii: Cladistia). Journal of Morphology 268:1021–1039.
Criswell KE 2015. The comparative osteology and phylogenetic relationships of African and South American lungfishes (Sarcopterygii: Dipnoi). Zoological Journal of the Linnean Society, 174, 801-858.
Cuvier G 1829. Le Règne Animal.
Denison RH 1968. Early Devonian lungfishes from Wyoming, Utah and Idaho. Fieldiana, Geology 17:353–413.
Etheridge R 1906. The cranial buckler of a Dipnoan fish, probably Ganorhynchus, from the Devonian Beds of the Murrumbidgee River, New South Wales. Records of the Australian Museum 6(3):129–132.
Giles S, Friedman M and Brazeau MD 2015. Osteichthyan-like conditions in an Early Devonian stem gnathostome. Nature 520(7545):82–85.
Geoffry Saint-Hillaire E 1802. Description d’un nouveau genre de poisson, de l’ordre des abdominaux. Bull. Sci. Soc. Philom., Paris, 3(61):97-98.
Kreft (Krefft) JLG 1870. A short guide to the Australian fossil remains in the Australian Museum.
Long JA 1992. Cranial anatomy of two new Late Devonian lungfishes (Pisces: Dipnoi) from Mount Howitt, Victoria. Records of the Australian Museum 44:299-318.
Romer AS 1946. The early evolution of fishes, Quarterly Review of Biology 21: 33-69.
Sedgwick A and Murchison RI 1828. Trans. Geol. Soc. London 2(3):143.
Smith JA 1865. Notice of a new genus of ganoid fish allied to Polypterus, from Old Calabar. Proc R Soc Edinburgh 3:273–278.
Thomson KS and Campbell KSW 1971. The Structure and Relationships of the Primitive Devonian Lungfish, Dipnorhynchus sussmilchi (Etheridge). Bulletin of the Peabody Museum of Natural History. (38):109pp.
Thomson KS, Sutton M and Thomas B 2004. A larval Devonian lungfish. Nature 426(6968):833-834.

wiki/Lungfish

wiki/Polypterus
wiki/Reedfish
wiki/Howidipterus
wiki/Dipnorhynchus
wiki/Dipterus
wiki/Spotted_lungfish-Protopterus
wiki/Neoceratodus

Basal Amiiformes in the LRT

The bowfin, Amia, usually nests alone
or with unrelated taxa (e.g. Polypterus) in traditional fish phylogenies.

Not here, in the LRT, where Amia has a long list of descendants. These examples (Fig 1) are toothy. long-bodied predators originating in fresh waters then transitioning to marine environs. Some labels have changed from the days of Gregory 1933 based on comparative anatomy shown here in standard DGS colors.

Figure 1. Amia and its phylogenetic descendants in the LRT. Note the change of labels in Esox in Tylosurus where the postorbital (amber) extends further anterior to the orbit and the former palatine is re-identified as a lacrimal (tan). Note the splitting of the supratemporals (green) in Esox creating a ‘scale bone’. These changes have not come easy, but become apparent in charts of comparative anatomy like this one.

Amia looks different
and was classified as different because it is so primitive. Of course, every taxon in the LRT is related, more or less, to every other taxon, even Amia.

Amia calva
(Linneaus 1766; up to 70cm in length) is the extant bowfin, a basal fish able to breathe both water and air. Hatchlings look like tadpoles. Deep lips rim the long teeth. Females produce 2000 to 5000 eggs. Fossil relatives of Amia have a worldwide distribution in fresh and salt waters.

References
Gregory WK 1933. Fish skulls. A study of the evolution of natural mechanisms. American Philosophical Society 23(2) 1–481.
Linneaus C von 1766. Sysema 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) .

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