Dyoplax skull under DGS

Today,
the benefits of better data are presented.

Earlier
we nested the sole example of a traditional enigma croc, Dyoplax (Figs, 1, 2; Fraas 1867), in the large reptile tree (LRT 1559 taxa) based on a 19th century drawing (Fig. 1). With that sketchy data, Dyoplax nested basal to the clade(s) of marine crocodiles.

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

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

Maisch et al. 2013
provided a closeup photo and interpretive drawing of the skull (Fig. 2). Their interpretation and analysis tentatively put Dyoplax close to another traditional enigma, the croc with indented jaw margins, Erepetoscuchus. No cladogram was presented. Rather a list of shared traits was proposed by them and by prior authors. Yes, by listing traits, they were ‘Pulling a Larry Martin.’  The keywords ‘Dibothrosuchus‘, ‘Thalattosuchia’ and ‘marine’ were not found in the pdf text. So, yes, evidently they were excluding taxa.

By contrast,
using the new data from the skull published in Maisch et al., together with DGS and the LRT all work together to keep Dyoplax at the base of the marine crocodiles, far from Erpetosuchus. Dibothrosuchus remains the outgroup taxon for the sea crocs + river crocs.

Figure 3. Added 08/09/19 from Maisch et al. 2013. DGS sutures do not match sutures found by Maisch et al. Hypothetical missing parts based on phylogenetic bracketing ghosted on.

Figure 3. Added 08/09/19 from Maisch et al. 2013. DGS sutures do not match sutures found by Maisch et al. (drawing) Hypothetical missing parts based on phylogenetic bracketing ghosted on in color

Sea crocs have a longer rostrum
with maxillae that contact one another dorsally. The nares merge. 

Figure 7. Dibothrosuchus nests basal to all later quadrupedal crocs, including marine crocs, in the LRT.

Figure 4. Dibothrosuchus nests basal to all later quadrupedal crocs, including marine crocs, in the LRT. The hind limbs are unknown.

Subtext to this blogpost:
Several mistakes (using the old etching) need not misdirect the software as it employs hundreds of traits to nest hundreds of taxa. I have employed less than optimal data (Fig. 1) often enough. Taxon inclusion remains the key to understanding systematics. Without relevant taxa, enigmas and apparently unique taxa are more difficult to nest.


References
Fraas O 1867. Dyoplax arenaceus, ein neuer Stuttgarter Keuper-Saurier. Jh. Verein vaterländ. Naturk. Württemberg 23:108-112; Stuttgart.
Lucas SG, Wild R, Hunt AP 1998. Dyoplax O. Fraas, a Triassic sphenosuchian from Germany. Stuttgarter Beiträge zur Naturkunde, B. 263: 1–13.
Maisch MW, Matzke AT and Rathgeber T 2013. Re-evaluation of the enigmatic archosaur Dyoplax arenaceus O. Fraas, 1867 from the Schilfsandstein (Stuttgart Formation, lower Carnian, Upper Triassic) of Stuttgart, Germany. Neues Jahrbuch für Geologie und Paläontologie – Abhandlungen. 267 (3): 353–362.

wiki/Dyoplax

 

Advertisements

Meet Seazzadactylus, the newest Late Triassic pterosaur

Dalla Vecchia 2019 introduces us to
Seazzadactylus venirei (Figs. 1–3; MFSN 21545), a small Late Triassic pterosaur known from a nearly complete, disarticulated skeleton (Fig. 2). The tail is supposed to be absent, but enough is there to show it was very gracile. The gracile feet are supposed to be absent, but they were overlooked. The rostrum was artificially elongated, but a new reconstruction (Fig. 3) takes care of that. A jumble of tiny bones in the throat (Fig. 4) were misidentified as a theropod-like curvy ectopterygoid, but the real ectopterygoid fused to the palatine as an L-shaped ectopalatine was identified (Figs. 3,4). 

Figure 1. Seazzadactylus nests between the two Austriadactylus specimens in the LPT.

Figure 1. Seazzadactylus nests between the two Austriadactylus specimens in the LPT.

Seazzadactylus is a wonderful find,
and DGS methodology (Fig. 1) pulled additional data out of it than firsthand observation, which was otherwise quite thorough (with certain exceptions).

Figure 2. Seazzadactylus in situ and tracing from Dalla Vecchia 2019. Colors added here.

Figure 2. Seazzadactylus in situ and tracing from Dalla Vecchia 2019. Colors added here.

Dalla Vecchia reports

  1. The premaxillary teeth are limited to the front half of the bone. Dalla Vecchia did not realize that is so because, like other Triassic pterosaurs, the premaxilla forms the ventral margin of the naris, dorsal to the maxilla (Fig. 3).
  2. A misidentified theropod-like ectopterygoid and pterygoid. Dalla Vecchia should have known no pterosaur has an ectopterygoid shaped like this. Rather the curvy shape represents a jumble of bones (Fig. 4). The real ectopalatine in Seazzadactylus has the typical L-shape (Figs. 3, 4) found in other pterosaurs.
  3. The scapula is indeed a distinctively wide fan-shape.
  4. The proximal caudal vertebrae are present, as are several more distal causals. All are tiny.
Figure 3. Seazzadactylus reconstructed using DGS methods.

Figure 3. Seazzadactylus reconstructed using DGS methods. No such reconstruction was produced by Dalla Vecchia. This is a primitive taxon precocially and by convergence displaying several traits found in more derived taxa.

Figure 4. Seazzadactylus bone jumble, including the L-shaped ectopalatine (orange + tan).

Figure 4. Seazzadactylus bone jumble, including the L-shaped ectopalatine (orange + tan). No pterosaur has a theropod-like ectopterygoid. That’s a loose jumble of bone spurs and shards.

It is easy to see how mistakes were made.
Colors, rather than lines tracing the bones, would have helped. Using a cladogram with validated outgroup taxa and more taxa otherwise were avoided by Dalla Vecchia for reason only he understands.

Figure 5. Seazzadactylus pectoral girdle.

Figure 5. Seazzadactylus pectoral girdle.

Phylogenetically Dalla Vecchia reports,
Macrocnemus bassaniiPostosuchus kirkpatricki and Herrerasaurus ischigualastensis were chosen as outgroup taxa.” (Fig. 6)

Funny thing…
none of these taxa are closely related to each other or to pterosaurs (Macrocnemus the possible distant exception) in the large reptile tree (LRT, 1549 taxa) where no one chooses outgroup taxa for pterosaurs. PAUP makes that choice from 1500+ candidates.

Figure 5. Cladogram by Dalla Vecchia 2019 showing where Seazzadactylus nests

Figure 6. Cladogram by Dalla Vecchia 2019 showing where Seazzadactylus nests. Their is little to no congruence between this cladogram and the LPT (subset Fig. 7), exception in the anurognathids. This cladogram needs about 200 more taxa to approach the number in the LPT.

Within the Pterosauria,
Dalla Vecchia nests his new Seazzadactylus between Austriadraco and Carniadactylus within a larger clade of Triassic pterosaurs that does not include Preondactylus, Austriadactylus or Peteinosaurus. Dalla Vecchia’s cladogram includes 27 taxa (not including the above mentioned outgroup taxa). In the large pterosaur tree (LPT, 239 taxa) Austriadraco (BSp 1994, Fig. 8) is a eudimorphodontid basal to all but two members of this clade. Carniadactylus (Fig. 8) is a dimorphodontid closer to Peteinosaurus. So there is little to no consensus between the two cladograms.

Figure 7. Subset of the LPT focusing on Triassic pterosaurs.

Figure 7. Subset of the LPT focusing on Triassic pterosaurs and their many LRT validated outgroups.

Publishing in PeerJ may cost authors $1400-$1700 (or so I understand).
Dalla Vecchia asked his Facebook friends for monetary help to get this paper published. I offered $900, but only on the proviso that the traditional outgroup taxa (listed above and unknown to me at the time) not be employed. You can understand why I cannot support those invalidated (Peters 2000) outgroups. Dr. Dalla Vecchia’s rejected my offer with a humorless invective of chastisement that likened my offer to one traditionally made by the Mafia. A more polite, ‘no thank-you,’ would have sufficed. Just today I learned of Dalla Vecchia’s ‘chosen’ outgroups. Kids, that’s not good science.

Figure 6. Seazzadactylus sister taxa in the Dalla Vechhia 2019 cladogram to scale.

Figure 8. Seazzadactylus sister taxa in the Dalla Vechhia 2019 cladogram to scale.

Bottom line:
A great new Triassic pterosaur! We’ll hash out the details as time goes by.


References
Dalla Vecchia FM 2019. Seazzadactylus venieri gen. et sp. nov., a new pterosaur (Diapsida: Pterosauria) from the Upper Triassic (Norian) of northeastern Italy. PeerJ 7:e7363 DOI 10.7717/peerj.7363
Peters D 2000a. Description and Interpretation of Interphalangeal Lines in Tetrapods.  Ichnos 7:11-41.
Peters D 2000b. A Redescription of Four Prolacertiform Genera and Implications for Pterosaur Phylogenesis. Rivista Italiana di Paleontologia e Stratigrafia 106 (3): 293–336.

The salamanderfish and the lizardfish enter the LRT together

Earlier we looked at a new extant deep sea sister for the Devonian basal ray fin fish, Cheirolepis (Fig. 1). Today, we add two more overlooked extant cousins (Figs. 2,3) to the Cheirolepis branch of the the LRT.

Figure 1a. Cheirolepis fossils.

Figure 1a. Cheirolepis fossils from Devonian strata. Note the upper one leans toward acanthodians (spiny sharks).

An overlooked extant saltwater shoreline taxon
Trachinocephalus myops (Fig. 2), the blunt-nosed lizardfish, nests with Cheirolepis in the large reptile tree (LRT, 1527 taxa). A variety of living lizardfish are known. Some are deep sea denizens.

Figure 1. The lizardfish, Trachinocephalus with colors added. Diagram from Gregory 1936. This taxon nests with Devonian Cheirolepis, a basal ray-fin fish.

Figure 2. The lizardfish, Trachinocephalus with colors added. Diagram from Gregory 1936. This taxon nests with Devonian Cheirolepis, a basal ray-fin fish.

Trachinocephalus myops (originally Salmo myops and Saurus myops Forster 1801; 40 cm) is the extant blunt-nosed lizardfish. Traditionally it nests in the clade Synodontidae.

Figure 4. Lepidogalaxias, the salamander fish is not yet tested in the LRT, but the resemblance of this freshwater version of the saltwater lizardfish is apparent.

Figure 3. Lepidogalaxias, the salamander fish is not yet tested in the LRT, but the resemblance of this freshwater version of the saltwater lizardfish is apparent. The bending neck is shown at upper right.

The salamander fish
Lepidogalaxias salamandroides (Mees 1961, 7cm in length) is the extant salamanderfish, the only fish with a neck capable of turning the head nearly at right angles to the torso. Like lungfish, the freshwater salamanderfish is capable of surviving dry seasons by burrowing into the sand.

Molecular studies
consistently recover Lepidogalaxias close to the base of the Telostei where Cheirolepis also nests (when fossils and traits are tested), but the connection has never been made until now (let me know if there is a prior citation I missed).

It is so important to use extant and extinct taxa.
For that reason alone, avoid genetic tests. The second reason is: genetic tests don’t match trait tests over deep time in this and other major clades. The third reason: lots of extant taxa go way, way back phylogenetically.

Figure 3. Subset of the LRT focusing on bony ray fin fish and kin. Here Devonian Cheirolepis nests with extant deep sea Malacosteus.

Figure 4. Subset of the LRT focusing on bony ray fin fish and kin. Here Devonian Cheirolepis nests with extant deep sea Malacosteus. Alongside are Lepidogalaxias and Trachinocephalus.

According to tolweb.org
“Fink (1984) referred to Lepidogalaxias as a ‘potpouri of contradictory and reductive characters’ and placed it in an unresolved trichotomy with the Salmonidae as the sister group of the Neoteleostei. The phylogenetic affinity of this bizarre little fish has been enigmatic since Mees (1961) described it as a galaxiid.”

With about 390 million years between them
it is no wonder that the lizardfish and salamander fish developed traits not seen in Cheirolepis… so did all the other fish that are derived from Cheirolepis! The wonder is, why so few traits evolved to distinguish the extant taxa from the overlooked Devonian sister?


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.
Mees GF 1961. Description of a new fish of the family Galaxiidae from Western Australia. J. Roy. Soc. West. Aust. 44: 33-38.

wiki/Cheirolepis
wiki/Trachinocephalus
wiki/Lepidogalaxias

The primitive arowana (Osteoglossum) enters the LRT

Osteoglossum formosum (Cuvier 1829; up to 2m in length; Figs. 1, 2) is the extant arowana or bonytongue. A facultive air breather, the slow-moving, heavily-scaled arowana feeds on prey just above the water. Fossils extend back to the Late Jurassic. The pelvic fins are reduced to strands. In the large reptile tree (LRT, 1516 taxa, Fig. 3), Osteoglossum nests with Early Jurassic Dapedium.

Figure 1. The arowana, an Amazon River predator, nests with Late Jurassic Dapedium in the LRT.

Figure 1. The arowana, an Amazon River predator, nests with Late Jurassic Dapedium in the LRT. The pink dot indicates the position of the pelvic fins, absent in the skeleton below, present in the specimen above.

I hope the DGS colors added to these fish skulls
make them more accessible for learning. Consider this a starting point on your own academic journey and learn as much as you can on your own.

FIgure 2. Osteoglossum skull with colors added to identify bones.

FIgure 2. Osteoglossum skull with colors added to identify bones.

And if you ever wanted to swim with a Jurassic fish,
you don’t have to start with a drop of blood from a mosquito. Just jump into the Amazon, the Nile or any of the rivers of Borneo and Western Australia. Prior to the split of these exclusively freshwater fish, all these areas were united at Pangaea and Gondwana.

For that matter
the walking catfish (Clarias) will take you back to the Silurian (430 mya), and it will get out of the water to walk with you! Or the headless lancelet (Amphioxous) will take you back to the Cambrian (550mya), about as far back as swimming chordates go.


References
Cuvier GCLD 1829. Le Règne Animal distribué d’apres son organisation, pour servir de base a l’histoire naturelle des animaux et d’introduction a l’anatomie comparée. Avec figures dessinées d’après nature. Nouvelle édition, revue et augmentée. Tome V. Suite et fin des Insectes. Par M. Latreille. Déterville & Crochard, Paris, i-xxiv + 556pp.

The reason the freshwater fish arowana live across the sea

wiki/Dapedium
wiki/Osteoglossum
wiki/Arowana

Triassic Pholidophorus nests with Devonian Strunius

This is another overlooked relationship
assisted by a relabeling of fish skull bones using tetrapod names (Fig. 1).

Figure 1. Pholidophorus in situ + two skull drawings relabeled with tetrapod names.

Figure 1. Pholidophorus in situ + two skull drawings relabeled with tetrapod names.

Pholidophorus sp. (Agassiz 1832; Middle-Late Triassic; 40cm long) was a herring-like fish with primitive ganoid scales and poorly ossified spine. Traditionally considered an early teleost, with large eyes, here it nests with Late Devonian Strunius, but lacks the central process of the tail. Here the skull bones are re-identified with tetrapod labels. The pectoral and pelvic fins were similar in size.

Figure 2. Strunius skull enlarged to show detail. Inset shows the second origin of the dual external naris as the original apparently splits by the addition of a skin bridge creating two openings. Compare to figure 1.

Figure 2. Strunius skull enlarged to show detail. Inset shows the second origin of the dual external naris as the original apparently splits by the addition of a skin bridge creating two openings. Compare to figure 1.

Strunius rolandi (Jessen 1966; originally Glyptomus rolandi Gross 1956; 10 cm in length; Late Devonian) was considered a lobe-fin fish with ray fins. Here it nests with Cheirolepis, a traditional and transitional ray fin fish. The origin of the double naris in this lineage appears here as a split dividing the original single in two. The palate and possible choana are not known.

Figure 4. Subset of the LRT focusing on fish. Note the traditional members of the Holostei do not nest together here largely because they don't look alike, but more like other, more attractive taxa.

Figure 3. Subset of the LRT focusing on fish. Note the traditional members of the Holostei do not nest together here largely because they don’t look alike, but more like other, more attractive taxa.


References
Agassiz L 1832. Untersuchungen über die fossilen Fische der Lias-Formation. Jahrbuch für Mineralogie, Geognosie, Geologie und Petrefaktenkunde, 3, 139–149.
Agassiz JLR 1835. Recherches sur les Poissons fossiles, 5 volumes. Imprimerie de Petitpierre et Prince, Neuchaatel, 1420 pp.
Agassiz JLR 1835. On the fossil fishes of Scotland. Report of the British Association for the Advancement of Science, British Association for the Advancement of Science, Edinburgh.

wiki/Strunius
wiki/Pholidophorus

Mola mola enters the LRT

Unbelievable and unforgettable.
The ocean sunfish (Mola mola; Linneaus 1758; 4.3m tall and 3m long; Fig. 1) nests traditionally and in the large reptile tree (LRT, 1512 taxa) with the pufferfish. Both are traditional members of the order Tetraodontiformes.

Figure 4. Mola mola is a relative of Diodon in the LRT. It has no circumorbital bones, but as a hatchling has pufferfish proportions and spines.

Figure 4. Mola mola is a relative of Diodon in the LRT. It has no circumorbital bones, but as a hatchling has pufferfish proportions and spines.

This slow-moving surface predator
eats small fish, fish larvae, squid and floating crustaceans. The dorsal and anal fins provide propulsion, as in the pufferfish, Diodon.

According to Wikipedia,
“The fish develop their truncated, bullet-like shape because the back fin, with which they are born, never grows. Instead, it folds into itself as the creature matures, creating a rounded rudder called a clavus.” (Fig. 1)

“Their teeth are fused into a beak-like structure, and they are unable to fully close their relatively small mouths.”

“Females of the species can produce more eggs than any other known vertebrate,[3] up to 300,000,000 at a time.”


References
Linnaeus C von 1758. Systema naturæ per regna tria naturæ, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. Tomus I. Editio decima, reformata.

wiki/Diodon
wiki/Tetraodontidae
wiki/Ocean_sunfish
wiki/Mola_(fish)

 

Diodon, the pufferfish, enters the LRT

Diodon the pufferfish
(Fig. 1) offers a vexing problem for phylogenetic scoring. Are those facial spines transformed from circumorbital bones? Ore are they novel dermal ossifications?

Figure 1. Diodon the pufferfish offers a problem. Are those facial spines circumorbital bones? Ore are they novel dermal ossifications?

Figure 1. Diodon the pufferfish offers a problem. Are those facial spines circumorbital bones? Ore are they novel dermal ossifications?

The two cheek spines
are placed like the lacrimal and jugal in the bowfin Amia (Fig. 2).

FIgure 3. The bowfin, Amia calva, is basal to both the electric eel and halibut in the LRT.

FIgure 3. The bowfin, Amia calva, is basal to both the electric eel and halibut in the LRT.

On the other hand,
a traditional sister taxon, Mola mola (Fig. 4), does not have circumorbital bones. As a hatchling Mola has pufferfish proportions and spines. So in the large reptile tree (LRT, 1514 taxa, Fig. 5) the spines of the pufferfish were not scored as circumorbital bones. And the ocean sunfish is an overgrown puffer!

Figure 4. Mola mola is a relative of Diodon in the LRT. It has no circumorbital bones, but as a hatchling has pufferfish proportions and spines.

Figure 4. Mola mola is a relative of Diodon in the LRT. It has no circumorbital bones, but as a hatchling (upper left) has pufferfish proportions and spines.

Pufferfish are traditional members of the Tetraodontiformes
which traditionally nest with Perciformes using genomic scores. That nesting is confirmed by the LRT.  Hughes et al. 2018 nested highly derived Tetraodontiformes with highly derived Lophiformes (angler fish). In the LRT, these clades are also related, though other taxa are closer.

Diodon sp. (Linneaus 1758) is the extant porcupinefish. The teeth are extremely tiny, lining or (perhaps due to tooth fusion), creating beak-like jaws. The spines are distributed all over the body and skull. Pelvic fins are absent. The tail is reduced. The pectoral fins provide thrust distinct from Mola. I do not see dorsal ribs inside the spines (Fig. 1). If present, they would presumably restrict the pufferfish’s ability to expand to a balloon like shape as it fills with water or air when threatened.

FIgure 4. Teleost (bony fish) cladogram. Diodon nests with Mola here.

FIgure 5. Teleost (bony fish) cladogram. Diodon nests with Mola here. Gymnothorax is the moray eel.


References
Linnaeus C von 1758. Systema naturæ per regna tria naturæ, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. Tomus I. Editio decima, reformata.

wiki/Amia
wiki/Diodon
wiki/Tetraodontidae
wiki/Mola