Teyujagua paradoxa: still no paradox in the LRT

Back in 2016 Pinheiro et al.
introduced readers to a small Early Triassic proterosuchid without much of an antorbital fenestra, Teyujagua paradoxa (Fig. 1). Back then a smaller large reptile tree (LRT, subset Fig. 2) nested Teyujagua as one of several smaller descendants of Proterosuchus without an antorbital fenestra. Based on taxon exclusion Pinheiro et al. 2016 mistakenly described Teyujagua as, “transitional in morphology between archosauriforms and more primitive reptiles…as the sister taxon to Archosauriformes.” Evidently they were looking for greater glories than Teyujagua actually represented.

Figure 1. Teyujagua compared to sister taxa, including Youngoides, Proterosuchus and Chasmatosaurus. Teyujagua is a phylogenetic miniature in which the antorbital fenestra became a vestige.

Figure 1. Teyujagua compared to sister taxa, including Youngoides, Proterosuchus and Chasmatosaurus. Teyujagua is a phylogenetic miniature in which the antorbital fenestra became a vestige.

 

This year (2019) Pinheiro et al. returned to Teyjagua
They wrote, “The evolution of the archosauriform skull from the more plesiomorphic configuration present ancestrally in the broader clade Archosauromorpha was, until recently, elusive.”

This is a bogus statement.
The LRT found a series of terrestrial younginiforms basal to archosauriforms and protorosauria. You read about them here in 2011. All the authors had to do was google Teyjagua to find the data needed to overturn their hypothesis.

Pinheiro et al. 2019 continue, 
“This began to change with the discovery and description of Teyujagua paradoxa, an early archosauromorph from the Lower Triassic Sanga do Cabral Formation of Brazil. In addition to providing new details of the anatomy of T. paradoxa, our study also reveals an early development of skull pneumaticity prior to the emergence of the antorbital fenestra.”

This is an backwards statement.
The LRT found Teyujagua was losing an antorbital fenestra, not gaining one. Adding taxa would have solved this problem for Pinheiro et al. 2019, as suggested three years ago.

Pinheiro et al. 2019 continue,
‘The data presented here provide new insights into character evolution during the origin of the archosauriform skull.”

The actual origin of the archosauriform skull
according to the LRT (Fig. 2). occurs in a list of excluded taxa ending with Youngoides romeri FMNH UC1528. As before Teyujagua remains a sister to Chasmatosaurus alexandri NMQR 1484 and is therefore a dead end taxon, basal to nothing.

Figure 2. Cladogram of basal archosauriforms. Note the putative basalmost archosauriform, Teyujagua (Pinheiro et al 2016) nests deep within the proterosuchids. The 6047 specimen that Ewer referred to Euparkeria nests as the basalmost euarchosauriform now.

Figure 2. Cladogram of basal archosauriforms. Note the putative basalmost archosauriform, Teyujagua (Pinheiro et al 2016) nests deep within the proterosuchids. The 6047 specimen that Ewer referred to Euparkeria nests as the basalmost euarchosauriform now.

This should be embarrassing to the authors
when an amateur without a science degree of any firsthand access to  the specimen can tell the PhDs they didn’t included enough taxa to understand what they were dealing with. Sadly, this is not the first time, and it won’t be the last. The LRT is a powerful tool, free for all to use.

Figure 1. Youngoides romeri FMNH UC1528 demonstrates an early appearance of the antorbital fenestra in the Archosauriformes. This specimen is the outgroup to Proterosuchus, the traditional basal member of the Archosauriformes. 

Figure 3. Youngoides romeri FMNH UC1528 demonstrates an early appearance of the antorbital fenestra in the Archosauriformes. This specimen is the outgroup to Proterosuchus, the traditional basal member of the Archosauriformes.

Figure 3. Click to enlarge. Updated image of various proterosuchids and their kin. When you see them all together it is easier to appreciated the similarities and slight differences that are gradual accumulations of derived taxa.

Figure 4. Click to enlarge. Updated image of various proterosuchids and their kin. When you see them all together it is easier to appreciated the similarities and slight differences that are gradual accumulations of derived taxa. Teyujagua is a deadened taxon, less glorious than Pinheiro et al. 2016 and 2019 wish it was.

A paper on Youngoides romeri and the origin of the Archosauriformes
can be read online here at ResearchGate.org. It was rejected by the referees.


References
Pinheiro FL, França MAG, Lacerda MB, Butler RJ and Schultz CL 2016. An exceptional fossil skull from South America and the origins of the archosauriform radiation. Nature Scientific Reports 6:22817 DOI: 10.1038/srep22817.
Pinheiro FL, De Simao-Oliveira D and Butler RJ 2019. Osteology of the archosauromorph Teyujagua paradoxa and the early evolution of the archosauriform skull.
Zoological Journal of the Linnean Society, zlz093
https://doi.org/10.1093/zoolinnean/zlz093
https://academic.oup.com/zoolinnean/advance-article-abstract/doi/10.1093/zoolinnean/zlz093/5585773

https://pterosaurheresies.wordpress.com/2016/03/13/teyujagua-not-transitional-between-archosauriforms-and-more-primitive-reptiles/

 

Mystacina: a walking, climbing, scraping micro-bat

The little New Zealand bat, Mystacina
(Figs. 1, 2), provides a living example for the earlier drop and hover hypothesis for the origin of bat flight. Most bats hang by their feet and observe what is below when they are not flying. This one, not so much.

Figure 1. The false vampire bat hovering before attacking a mouse in dry fallen leaves, listening to locate is prey.

Figure 4. The false vampire bat hovering before attacking a mouse in dry fallen leaves, listening to locate is prey. Flapping is key. Pre-bats were not gliders. Prebats flapped their parachute-like forelimbs.

Distinct from other bats,
Mystacina spends about thirty percent of its time on the ground on all fours (see YouTube video link below), wings folded, digit 2, the ventral one, reduced to a bumper.

Figure 1. Skeleton of Mystacina tuberculata from Digimorph.org and used with permission. The large head size is a derived trait.

Figure 2. Skeleton of Mystacina tuberculata from Digimorph.org and used with permission. The large head size is a derived trait. Note the two large incisors, used for scraping away burrows in soft hollow trees, co-copted by vampire bats to scrape away cattle skin.

The sharp incisor teeth
are used to scrape away soft tree interiors to create arboreal burrows. This trait is co-opted by related and sometimes terrestrial vampire bats to scrape away cattle skin to start  bleeding.

Figure 2. Mystacina skull from Digimorph.org and colorized here.

Figure 3 Mystacina skull from Digimorph.org and colorized here.

The propatagium is small
to aid in terrestrial locomotion. Mystacina has a large brain. A YouTube video (click to view) shows Mystacina in action.

Based on its performance,
and location, I wondered if Mystacina would be one of the most primitive of bats. It is not. So it may have reverted to a more primitive way of getting along (walking on all fours) after earlier achieving inverted bipedality and flight. Perhaps isolation on New Zealand as the only endemic mammal permitted this to happen.

Can you think of another set of animals
that reverted to quadrupedal locomotion after achieving flight? (Answer below).

FIgure 3. Subset of the LRT focusing on bats and kin including Mystacina.

FIgure 4. Subset of the LRT focusing on bats and kin including Mystacina. No, Mystacina does not nest at the base of all bats. Manis is the extant pangolin. Cynocephalus is the extant colugo or flying lemur.

Mystacina tuberculata (Gray 1843; 6-7cm snout-vent length) is the extant New Zealand lesser short-tailed bat. The tail extends beyong the uropatagia. It sometimes feeds on nectar with a long hairy tongue, but is considered omnivorous because it eats beetles and larvae. Today’s post was inspired by the discovery of a fossil relative from the Miocene of New Zealand, Vulcanops jennyworthyae.

Be wary of NatGeo.com stories
with headlines about burrowing bats. Mystacina bats burrow their way into the cores of rotting trees using their scraping incisors, a point missed by the author of the story from 2018, but cited by her in another online story here. Bats did not create small caves in the ground. At best they disturbed or ran into dense leaf litter to locate their prey.

Earlier we looked at the origin of large wings/hands
as holders of fruit hanging from trees (Fig. 5), either for the fruit itself or for the insects boring through it. This allows fruit bats and micro bats to have a phylogenetic common ancestor (Fig. 4 in clawed bats like Icaronycteris and Onychonycteris.

Figure 1. Pteropus and Caluromys compared in vivo and three views of their skulls. Caluromys is in the ancestry of bats and shows where they inherited their inverted posture.

Figure 5. Pteropus and Caluromys compared in vivo and three views of their skulls. Caluromys is in the ancestry of bats and shows where they inherited their inverted posture.

Hanging upside down is something
many, if not all basal placentals did and do (Fig. 5). Those who don’t, like humans, horses and elephants, are derived. In contrast, bats rely only on their feet to hang upside down. The tail is no longer involved and disappears in some taxa.

Figure 1. GIF animation thought experiment on the origin and evolution of bats from a Ptilocercus-like omnivore.

Figure 6. GIF animation thought experiment on the origin and evolution of bats from a Ptilocercus-like omnivore. A change is warranted in this illustration. Abdominal membranes were probably present in pre-bats, extending from the torso to the fingers. These created a flapping steerable  parachute for bat decent to the leaf litter forest floor.

If you’re still wondering about
the other animals that reverted to a quadrupedal configuration after learning how to fly, think of the pterodactyloid-grade pterosaurs, which did so four times by convergence (Figs. 7, 8) according to the large pterosaur tree (LPT). Based on the extreme small size of hatchlings due to phylogenetic miniaturization at the genesis of these clades, these baby pterosaurs were probably relegated to clambering through dense, moist leaf litter until reaching a size that enabled flight without rapid desiccation due to a high surface-to-volume ratio.

Figure 8. Click to enlarge. The descendants of Sordes in the Dorygnathus clade and their two clades of pterodactyloid-grade descendants.

Figure 7. Click to enlarge. The descendants of Sordes in the Dorygnathus clade and their two clades of pterodactyloid-grade descendants.

I have to say,
putting together these cladograms of vertebrates, pterosaurs and therapsids has taught me more about the theory of evolution and the way things work than dissecting a frog ever did in high school, or picking matrix off a fossil later on. Comparative anatomy gives one an appreciation and understanding of micro-evolution, not only what happened, but often why it happened over a wide range of taxa, some of which have never been compared to one another before.

The base of the Scaphognathia

Figure 8. Click to enlarge. The base of the Scaphognathia illustrating the size reduction that preceded the size increase in the transition from Scaphognathus to several later, larger “pterodactyloid”-grade clades.

By contrast,
the focus of paleontology textbooks seems to be showing chapter after chapter of skeletons, too often without making such distant comparisons with a freedom not often enough permitted in academia.


References
Gray JE 1843. List of the Specimens of Mammalia in the Collection of the British Museum, George Woodfall and Son, London.

wiki/Mystacina
wiki/Vulcanops

Hybodus enters the LRT as one of our direct ancestors

Updated January 27, 2020
with new interpretations of Hybodus and many dozen addition taxa helping to settle Hybodus in a node basal to the basal dichotomy that splits most bony fish (see cladogram below, Fig. 3).

It should come as no surprise
that Hybodus (Figs. 1, 2) was basal to the spiny sharks (Acanthodii), but the surprise is there are several intervening taxa between these nodes. Hybodus is also transitional from chimaeras to lobefins + humans in the LRT. So this is a ‘key players’.

Figure 1 (added 01/27/2020 with a current interpretation of skull bones on Hybodus, plus a reconstruction. Note the retention of external gill bars.

Figure 1 (added 01/27/2020 with a current interpretation of skull bones on Hybodus, plus a reconstruction. Note the retention of external gill bars.

Figure 1. Diagram of Hybodus in vivo and skeleton plus teeth.

Figure 2. Diagram of Hybodus in vivo and skeleton plus teeth.

Traditionally considered an odd sort of shark with dorsal spines,
Hybodus (Fig. 1) nests in the large reptile tree (LRT, 1583 (now 1643) taxa; Fig. 2) between sharks + chimaeroids and placoderms leading + two large clades of bony fish. Apparently this hypothesis of interrelationships has been overlooked until now, but it answers so many long-standing questions. Hybodus also greatly resembled the basal placoderm, Coccosteus (Fig. 1) another overlooked hypothesis of interrelationships. And catfish, too.

FIgure 3. Taxa highlighted in today's blog are highlighted here in this subset of the LRT.

FIgure 3. Taxa highlighted in today’s blog are highlighted here in this subset of the LRT.

Hybodus basanus (Agassiz 1837; H. reticulatus (Early Jurassic skull); 2m in length, Permian –Late Cretaceous) nests between sharks + chimaeroids and spiny sharks + bony fish. This relationship was overlooked until now. Note the spines on the dorsal fins. These are homologous with spines on spiny sharks like Diplacanthus (below). Spines are transitional betwen fleshy shark fins and transparent ray fins. The skull is also transitional between sharks and bony fish, despite the presence of large gill bars (yellow) lateral to the jaws.

Figure 3. Diplacanthus, a Mid-Devonian acanthodian with proportions similar to those of a young Hybodus, shorter with longer spines.

Figure 4. Diplacanthus, a Mid-Devonian acanthodian with proportions similar to those of a young Hybodus, shorter with longer spines.

Diplacanthus crassisimus (Miller 1841; Duff 1842; 13cm ; holotype NMS G.1891.92.333, widespread in the Middle Devoinian; Fig. 4). Skull details are vague, so it was not added to the LRT.

According to Davis et al. 2012:
“Acanthodians, an exclusively Palaeozoic group of fish, are central to a renewed debate on the origin of modern gnathostomes: jawed vertebrates comprising Chondrichthyes (sharks, rays and ratfish) and Osteichthyes (bony fishes and tetrapods)… These new data contribute to a new reconstruction that, unexpectedly, resembles early chondrichthyan crania. Principal coordinates analysis of a character–taxon matrix including these new data confirms this impression: Acanthodes is quantifiably closer to chondrichthyans than to osteichthyans. However, phylogenetic analysis places Acanthodes on the osteichthyan stem, as part of a well-resolved tree that also recovers acanthodians as stem chondrichthyans and stem gnathostomes.”

The LRT nests two acanthodians in the stem lobefin clade (Fig. 2).
Earlier we looked at the central nesting of acanthodians between basal taxa and bony fish. Hybodus further confirms this hypothesis of interrelationships now seeking confirmation or refutation from an independent study using a similar taxon list and a new character list.

With more taxa,
and more knowledge of the 137 taxa at hand, note that catfish no longer nest with placoderms, but transitional between placoderms and ray fin fish (Fig. 2).


References
Agassiz L 1837 in Agassiz L. 1833-1843. Recherches sur les Poissons fossiles-I, I, III, Neuchatel, pp 1420.
Burrow C, Blaauwen J, Newman M and Davidson R 2016. The diplacanthid fishes (Acanthodii, Diplacanthiformes, Diplacanthidae) from the Middle Devonian of Scotland. Palaeontologia Electronica 19.1.10A: 1-83.
Davis SP, Finarelli JA and Coates MI 2012. Acanthodes and shark-like conditions in the last common ancestor of modern gnathostomes. Nature 486:247–250.
Duff P 1842. Sketch of the Geology of Moray. Forsyth and Young, Elgin
Maisey JG 1983. Cranial anatomy of Hybodus basanus Egerton from the Lower Cretaceous of England. American Museum Novitates 2758:1–64.
Miller H 1841. The Old Red Sandstone. (first edition). Thomas Constable and Sons, Edinburgh.

wiki/Hybodus
wiki/Diplacanthus

Xiphactinus was a giant, elongate, Cretaceous mahi-mahi

Updated Febrary 6, 2020
When the tarpon, Megalops (Fig. A), was added to the LRT, it nested closer to Xiphactinus. 

Figure 1. Tarpon (Megalops) skeleton.

Figure A. Tarpon (Megalops) skeleton.

Some things are obvious in hindsight.
Previous attempts at understanding the skull of Xiphactinus (Fig. 1) included errors, here corrected using the mahi-mahi (Coryphaneus, Fig. 2) as a guide. Turns out the two not only look alike, and are both large, open-water predators, but they are more closely related. Apparently this is a novel hypothesis of interrelationships. Let me know if there is a prior citation so I can promote it.

Figure 1. Xiphactinus skull revised using Portheus as a guide. The 'shadow' area in the reconstruction indicates a lack of cheek bones, exposing the large pterygoids and quadrate.

Figure 1. Xiphactinus skull revised using Portheus as a guide. The ‘shadow’ area in the reconstruction indicates a lack of cheek bones, exposing the large pterygoids and quadrate.

What about those long teeth?
While Coryphaena (Fig. 2) does not have such long teeth as Xiphactinus (Fig. 1), another elongate extant, related fish, the wolffish (Anarchias) does! In the large reptile tree (LRT, 1583 taxa) Xiphactinus nests between these two extant taxa.

Figure 2. This is where the high forehead of the male mahi-mahi (Corphaena) comes from, one of the very few fish with a frontal crest.

Figure 2. This is where the high forehead of the male mahi-mahi (Corphaena) comes from, one of the very few fish with a frontal crest.

Sometimes scoring is difficult. Mistakes happen.
As I’ve stated before, I never know what I’m going to find with every new taxon. I’m learning as I go. Fish are particularly irksome because they lose, fuse and split facial bones, making homologies troublesome, until properly reviewed with a long list of sister candidates. Plus, I was naive and new nothing about fish skull architecture.  Sometimes quantity is what it takes to sort things out… and a pattern to ‘see’ what is happening.

FIgure 1. Mahi-mahi (Coryphaena) mounted as if in vivo.

Figure 3. Mahi-mahi (Coryphaena) mounted as if in vivo.

Note the longer torso and caudal region in Xiphactinus
elongated with the addition of many more small vertebrae. This moves the pelvic fins rearward, something that does not happen very often in bony ray-fin fish. That elongation enabled the swallowing of longer prey, as documented in stone by the famous ‘fish within a fish’ fossil (Fig. 5).

FIgure 4. Coryphaena skeleton. Note the short torso region with relatively few vertebrae.

FIgure 4. Coryphaena skeleton. Note the short torso region with relatively few dorsal and caudal vertebrae.

Xiphactinus audax (Leidy 1870; Late Cretaceous; up to 6m in length) was a large traditional ray-fin fish. Here nests between the mahi-mahi (Coryphaena) and the wolffish (Anarhichas). The teeth are longer and stronger in the wolffish and Xiphactinus. Prior reconstructions did not indicate a long premaxilla and open cheek. Like the mahi-mahi a parasagittal crest is present. The torso is much longer than in the mahi-mahi, enabling the engulfment of large/long Cretaceous prey (Fig. 5).

Figure 2. Xiphactinus fossil. The famous fish-within-a-fish. Note the posterior pelvic fins.

Figure 5 Xiphactinus fossil. The famous fish-within-a-fish. Note the posterior pelvic fins and long torso with many more dorsal vertebrae enabling the swallowing of elongate prey like this.

 

 

And that’s not all.
Other fish taxa were also recently re-nested after correcting scoring errors. Here are a few:

Figure 6. Three views of the skeleton of Manta, colors added. Green represents the maxilla. Note the terminal mouth, distinct from other rays, skates and guitarfish. The pectoral fins do not reach the orbit. The cephalic fins are highly modified maxillae, still gathering food. Note the attachment to the quadrate. The premaxilla extends across the mouth.

Figure 6. Three views of the skeleton of Manta, colors added. Green represents the maxilla. Note the terminal mouth, distinct from other rays, skates and guitarfish. The pectoral fins do not reach the orbit. The cephalic fins are split form the main fin, like sea robin ‘fingers’. The premaxilla extends across the mouth.

Manta
The wide mouth manta ray (Fig. 6; genus: Manta) now nests with the equally wide mouth whale shark (genus: Rhincodon) overcoming its many similar traits with long-nosed rays (genus: xxx), which continue to nest with long-nosed sharks (genus: Isurus). I suspected this earlier, but the massive convergence between the manta and other rays earlier overwhelmed the scoring. Now just enough traits swing the nesting the other way.

Figure 7. Cheirodus now nests with the similar piranha, Serrasalmus.

Figure 7. Cheirodus now nests with the similar piranha, Serrasalmus.

Cheirodus
The heterocercal tail and ganoid scales nested this taxon (Fig. 7) with some of the earliest ray fin fish, despite overall dissimilarities. Now Cheirodus nests with the overall more similar piranha, Serrasalmus. Scoring for Cheriodus was based on a diagram, but new insights into the splitting and fusing of facial bones changed things enough to move it over.


References
Bronn HG 1858.  Beiträge zur triassischen Fauna und Flora der bituminösen Schiefer von Raibl. Neues Jahrbuch für Mineralogie, Geologie udn Paläontologie 1:1–32.
Leidy J 1870. [Remarks on ichthyodorulites and on certain fossil Mammalia]. Proceedings of the Academy of Natural Sciences, Philadelphia 22:12–13.

wiki/Xiphactinus

Chauliodus, the viperfish, enters the LRT

Figure 1. Cheirolepis, a Middle Devonian ancestor to the viperfish.

Figure 1. Cheirolepis, a Middle Devonian ancestor to the viperfish.

Yes, it’s another great grandson
of Cheirolepis (Fig. 1), one of the earliest known bony fish. Earlier we looked at another great, grandson deep sea fish, Malacosteus.

Figure 1. Chauliodus diagram from xxx 1938. Note the convergent loss of cheek bones in this Cheirolepis clade member.

Figure 2. Chauliodus diagram from Gregory 1938. Note the convergent loss of cheek bones in this Cheirolepis clade member.

Chauliodus sloani (Forster in Bloch and Schneider 1801, up to 60cm in length, subset Fig. 2-4) is the extant viperfish. A tiny glowing lure from the anterior dorsal fin lure deep sea fish to the oversized teeth. Scales and maxillary teeth are retained. Apparently the temporal series (intertemporal, supratemporal and tabular) were not retained, which is almost unique among fish. The anterior dorsal fin is new based on comparisons to Cheirolepis (Fig. 1). Note the evolution of the heterocercal tail to a diphycercal tail, only one of many such convergent instances.

Figure 3. Chauliodus, the viperfish, in vivo.

Figure 3. Chauliodus, the viperfish, in vivo.

Biting is a big deal with Chauliodus
as those jaws go through some gymnastics at maximum aperture (Fig. 4).

Figure 3. Viperfish posed as if biting its prey attracted to its first dorsal fin lure.

Figure 4. Viperfish posed as if biting its prey attracted to its first dorsal fin lure.

This nesting
and several others to come are greatly simplifying the fish family tree. I will list the many exciting changes shortly.


References
Forster JR 1801. in Bloch, ME and Schneider JG editors, Systema Ichthyologiae Iconibus cx Ilustratum. Post obitum auctoris opus inchoatum absolvit, correxit, interpolavit Jo. Gottlob Schneider, Saxo. Berolini. Sumtibus Auctoris Impressum et Bibliopolio Sanderiano Commissum. i-lx + 1-584.

You heard it here in 2011: diadectids are amniotes

Co-author, David S. Berman,
has been saying diadectids are amniotes since the 1990s, but not with a comprehensive taxon list, and, apparently nobody listened. The consensus apparently prefers their diadectids with tadpoles.

Here’s what Wikipedia reports
“Diadectes (meaning crosswise-biter) is an extinct genus of large, very reptile-like amphibians that lived during the early Permian period (ArtinskianKungurian stages of the Cisuralian epoch, between 290 and 272 million years ago[1]). Diadectes was one of the very first herbivorous tetrapods, and also one of the first fully terrestrial animals to attain large size.”

Skeleton of Diadectes. Perhaps unnoticed are the broad dorsal ribs of this taxon, basal to Stephanospondylus, Procolophon and pareiasaurs.

Figure 1 Skeleton of Diadectes. Perhaps unnoticed are the broad dorsal ribs of this taxon, basal to Stephanospondylus, Procolophon and pareiasaurs.

Klembara et al. 2019 report
on the inner ear morphology of diadectids and seymouriamorphs. From the abstract:
“Two pivotal clades of early tetrapods, the diadectomorphs and the seymouriamorphs, have played an unsurpassed role in debates about the ancestry of amniotes for over a century, but their skeletal morphology has provided conflicting evidence for their affinities. Both maximum parsimony and Bayesian inference analyses retrieve seymouriamorphs as derived non‐crown amniotes and diadectomorphs as sister group to synapsids.”

Figure 2. Cladogram from Klembara et al. 2019. Green shows reptile taxa in the LRT.

Figure 2. Cladogram from Klembara et al. 2019. Green shows reptile taxa in the LRT.

Dr. David Marjanovic wrote in the DML:
“Amniota is a crown-group; there’s technically no such thing as a “stem-amniote”, because if it’s on the stem, it’s not an amniote.”

Unfortunately, Klembara et al. don’t have enough taxa
to understand that Amniota is a junior synonym for Reptilia. So Repitilomorpha works well for pre-reptiles. More importantly, for the subject at hand, Diadectes (Fig. 1) and kin have been deeply nested within the large reptile tree (LRT, 1583 taxa) since 2011. This is an online resource you can use to double check your taxon list, just to make sure it is up to date. The Klembara et al. taxon list (Fig. 2) is so inadequate it nests several reptiles apart from one another and omits dozens of others pertinent to this issue.

Figure 2. Subset of the LRT focusing on basal lepidosauromorphs and Diadectes.

Figure 3. Subset of the LRT focusing on basal lepidosauromorphs and Diadectes.

Bottom line, when you add enough taxa
diadectomorphs are not close to synapsids, but arise from millerettids.

At least the Klembara team
moved diadectomorphs inside the Amniota. That’s a minor victory. Add the above taxa to your cladogram (Fig. 2) and see where Diadectes nests. That’s what the LRT is here for… to help workers avoid taxon exclusion.


References
Klembara J, Hain M, Ruta M, Berman DS,  SEPierce and Henrici AC 2019. Inner ear morphology of diadectomorphs and seymouriamorphs (Tetrapoda) uncovered by highâresolution xâray microcomputed tomography, and the origin of the amniote crown group. Palaeontology (advance online publication) Future publication date: August 5, 2020
doi: https://doi.org/10.1111/pala.12448
https://onlinelibrary.wiley.com/doi/full/10.1111/pala.12448

wiki/Diadectes

Spiny sharks (Acanthodii) transitional to lobefins in the LRT

The most recent changes
to the large reptile tree (LRT, 1583 taxa, subset Fig. 1) resolve earlier problems and place two spiny sharks (clade: Acanthodii, Fig. 1) at the base of the newly expanded pre-lobefin clade, all arising from catfish + placoderms, some of which also have spiny pectoral fins.

Figure 1. Classic reconstruction of Cladoselache, a shark-like taxon basal to sturgeons and catfish+placoderms in the LRT.

Figure 1. Classic reconstruction of Cladoselache, a shark-like taxon. Note the robust pectoral fin skeleton. A Silurian sister is the genesis for the spiny sharks, catfish and placoderms.

These in turn
arise from taxa like Cladoselache (Fig. 1), which had strongly supported pectoral fins along with robust anterior spines on the two dorsal fins, homologs of dorsal spines on spiny sharks.

Figure 2. Updated subset of the LRT focusing on basal vertebrates (fish). Arrow points to Hybodus. This tree does not agree with previous fish tree topologies.

Figure 2. Updated subset of the LRT focusing on basal vertebrates (fish). Arrow points to Hybodus. This tree does not agree with previous fish tree topologies.

The tiny size of the basal acanthodian, Brachyacanthus, 
(Fig. 3) documents phylogenetic miniaturization at the genesis of a new major clade. If large eyes, a high forehead and a short rostrum indicate ‘cuteness’ and neotony, then Brachyacanthus is an early example of this. Cladoselache (Fig. 1) has two out of three of these traits.

According to Wikipedia
“Acanthodii or acanthodians (sometimes called spiny sharks) is a paraphyletic class of teleostomefish, sharing features with both bony fish and cartilaginous fish. In form they resembled sharks, but their epidermis was covered with tiny rhomboid platelets like the scales of holosteans (gars, bowfins). They represent several independent phylogenetic branches of fishes leading to the still extant Chondrichthyes.” In the LRT spiny sharks don’t lead to sharks, rays and chimaera, but diverge away from them.

Figure 2. The placoderm/catfish to spiny shark/lobe fin transition. We need more taxa, but here's how the LRT recovers it.

Figure 3. The placoderm/catfish to spiny shark/lobe fin transition. We need more Silurian taxa, but here’s how the LRT recovers it. Brachyacanthus, once again, documents phylogenetic miniaturization at the genesis of new major clades.

So, what is it about the spine fin
that made it a key trait?

Figure 1a. Cheirolepis fossils.

Figure 4. Cheirolepis fossils. Both have a spiny pectoral fin leading edge.

On the ray fin side of the cladogram
basal taxa include Pholidophorus (Fig. 5) and Coccocephalichthys (Fig. 6). This clade embraced open water speedy swimming and predation as their niche from the start. The extant tuna (Thunnus) is an extant relative of these two. Later taxa, like the frogfish (Antennarius) and sea robin (Prionotus), reverted to bottom-dwelling.

Figure 5. Pholidophorus ghosted to highlight the fins.

Figure 5. Pholidophorus fossil ghosted to highlight the fins and eyes.

By contrast, lobefins and their predecessors
appear to have preferred a slower swimming, bottom-dwelling lifestyle. That’s how they readily transitioned into shallow waters, swampy waters, swampy land and dry land in that order.

Figure 2. Coccocephalichthys (formerly Coccocephalus) is a Late Carboniferous transitional taxon between Devonian Strunius and Cretaceous Saurichthys.

Figure 6. Coccocephalichthys (formerly Coccocephalus) is a Late Carboniferous transitional taxon between Devonian Strunius and Cretaceous Saurichthys.

Even so,
some highly derived lobefins learned how to climb trees, fly, and even speed through open waters, with or without fins (Homo, Orcinus, Pavo).

New paper on Plesiadapis suffers from taxon exclusion

Boyer and Gingerich 2019
bring us an excellent and comprehensive review of Plesiadapis (Figs. 1-3), a rodent relative (clade: Glires, Figs. 4, 5) traditionally and wrongly considered a basal primate with rodent-like teeth.

Figure 1. From Boyer and Gingerich 2019, Plesiadapis skeleton and in vivo.

Figure 1. From Boyer and Gingerich 2019, Plesiadapis skeleton and in vivo.

This primate-mimic
nests with another primate mimic, Daubentonia (Fig. 3), the extant aye-aye, a taxon barely mentioned and not analyzed by Boyer and Gingerich.

Plesiadapis

Figure 2. Plesiadapis, formerly considered a basal primate, is here considered a member of Glires close to Carpolestes and Daubentonia. See figure 3.

From the abstract
“Plesiadapis cookei is a large-bodied plesiadapiform euarchontan (and potential stem primate) known from many localities of middle Clarkforkian North American Land Mammal age, late Paleocene epoch, in the Clarks Fork Basin of northwestern Wyoming.”

Figure 1. Ignacius and Plesiadapis nest basal to Daubentonia in the LRT.

Figure 3. Ignacius and Plesiadapis nest basal to Daubentonia in the LRT.

From the abstract
“On a broader scale, cladistic analysis of higher-level taxa… indicates that plesiadapids and carpolestids exhibit a greater number of identical character states than previously thought … Even so, analysis of combined data from dentition, cranium, and postcrania still robustly support a link between plesiadapids, saxonellids, and carpolestids (Plesiadapoidea) and does not contradict previous hypotheses suggesting a special relationship of plesiadapoids to euprimates (Euprimateformes).”

Figure 4. From Boyer and Gingerich 2019, cladograms nesting Plesiadapis.

Figure 4. From Boyer and Gingerich 2019, cladograms nesting Plesiadapis. Too few taxa. Where is Daubentonia? Where are the derived rodents and multitubercuates? Compare to figure 5.

Too few taxa,
alas is the one obvious issue with Boyer and Gingerich 2019 (Fig. 4).

Figure 1. Subset of the LRT focusing on Glires and subclades within.

Figure 5. Subset of the LRT focusing on Glires and subclades within.

Not much else to say.
The large reptile tree (LRT, 1583+ taxa; subset Fig. 5) is an online resource that can and should be employed. Current traditions and textbooks are out of date on this subject. At least consider the taxon list in your more focused studies so you don’t overlook any obvious taxa. Test them yourselves. Don’t make the same mistake.


References
Boyer DM and Gingerich PD 2019. Skeleton of Late Paleocene Plesiadapis cookei (Mammal, Euarchonta): life history, locomotion, and phylogenetic relationships. University of Michigan Papers on Paleontology 38:269pp.

wiki/Plesiadapis

Can you make a living as a paleontologist?

Short one today
as I refer you to professor Donald Prothero’s web page here. This seems to be a precise summary of what you need to know about the profession of paleontology in 2019 — all the practical facts of life for aspiring paleontologists.

Bottom line: Very few aspirants make it to their dream job.
So be nice to the young, wandering PhDs we all know or have heard about. It has to be frustrating for them seeking a position at a university or museum, waiting for an opening. And when they get that job, the duties of the position often take them away from their studies.

Makes me glad that I did not go through the PhD route,
but just started digging and discovering without the tutelage of a traditional professor (Fig. 1). In paleontology, everything you need to know can be found in the textbooks and literature. And you can make contributions as soon as you have something to say.

More changes are coming to the fish portion of the LRT
as taxa currently known by diagram data jump from one node to another. Looking forward to presenting these results.

Kadimakara: holotype and referred specimen reconstructed as protorosaurs

Lately I found more data on Kadimakara
(Bartholomai 1979 ) than I had ever seen before (Figs 1, 2).

Figure 1. What remains of Kadimakara, above, and the referred specimen, below.

Figure 1. What remains of Kadimakara, above, and the referred specimen, below.

Too little data to add to the LRT,
but everyone seems to agree the prolacertiformes (protorosauria) is the clade these taxa belong to. Until further notice, I tend to agree.

Figure 2. Kadimakara holotype restored with Prolacerta, above. Referred specimen restored below.

Figure 2. Kadimakara holotype restored with Prolacerta, above. Referred specimen restored below.

The two taxa do not seem to be conspecific
even though no two parts overlap.


References
Bartholomai A 1979. New lizard-like reptiles from the Early Triassic of Queensland. Alcheringa. 3 (3): 225–234.

wiki/Kadimakara_australiensis