The little noticed connection between swordfish and gars

Gars are traditionally considered primitive fish.
We invalidated that earlier when the clade Holostei was dismantled by the LRT and even earlier when the LRT nested the garfish (Lepisosteus, Fig. 3) with sticklebacks and sea horses.

In the large reptile tree (LRT, 1516 taxa, subset Fig. 1) swordfish and gars are sister taxa at the base of the seahorse clade, derived from the barracuda clade. Swordfish and gars seem to differ quite a bit from one another, but currently there are no tested transitional taxa between them.

Figure 3. Subset of the LRT focusing on ray fin fish and showing a hatchling swordfish and an adult gar.

Figure 1. Subset of the LRT focusing on ray fin fish and showing a hatchling swordfish and an adult gar.

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

Figure 3. Subset of the LRT focusing on bony ray fin fish and kin. Here Devonian Cheirolepis nests with extant deep sea Malacosteus. More taxa here. The flying fish, Exocoetus, nests with the swordfish, Xiphias, close to Lepisosteus, the gar.

No one has ever put gars and swordfish together before.
Because they really do not look alike overall (Figs. 1, 2). Someday some taxon might come between them, but presently none do.

Figure 1. Extant swordfish (Xiphias) to scale with Eocene swordfish (Blochius).

Figure 2. Extant swordfish (Xiphias) to scale with Eocene swordfish (Blochius). Note the longer, more gracile swordfish ancestor, Blochius.

It might help
if you saw a swordfish (Xiphias) hatchling which has two elongate jaws with teeth (Figs. 3,4), not just a toothless sword and toothless mandible as seen in the adult (Fig. 2).

Figure 3. Adult gar fish (Lepisosteus) compared to look-alike swordfish (Xiphias) hatchling.

Figure 3. Adult gar fish (Lepisosteus) compared to look-alike swordfish (Xiphias) hatchling.

The Florida Museum reports,
“Gars are slow growing fishes that are relatively long lived. Newly hatched gars are 8 to 10 mm in length. Hatchlings attach themselves to vertically to submerged objects by an adhesive disc on their snout. Young remain attached by the adhesive disc until the yolk sac is absorbed (about 9 days). After the absorption of the yolk sac the young are able to remain horizontal, take their first aerial breath and begin feeding.”

Xiphias gladius (Linneaus 1758; Gregory and Conrad 1937; up to 4.5m in length) is the extant swordfish, derived from the barracuda, Sphyraena. 1cm long hatchlings more closely resembled little barracudas, then little sailfish before reducing the long dorsal fin. The sword is not used to spear, but to slice and maim smaller fish traveling in schools. The pelvic fins are absent. Larger females produce more eggs, up to 29 million.

Lepidosteus osseus (also Lepisosteus Lacepéde 1803) is the extant longnose gar. Note the jaw joint is in front of the orbit, similar to the stickleback, Gasterosteus. The longest teeth arise from the inside the of jaws, the long vomer. The rostrum is lined by the premaxilla. The maxilla is absent. The traditional jugal is the lacrimal.

First impressions can be misleading.
Score the traits and let the software nest the taxa. If there are no closer sisters, two apparently distinct taxa can nest together.


References
de Lacepéde BG 1803. Histoire naturelle des poissons. Tome Cinquieme. 5(1-21):1-803 + index.
Linnaeus C 1758. Systema naturæ per regna tria naturæ, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. Tomus I. Editio decima, reformata.

https://www.floridamuseum.ufl.edu/discover-fish/species-profiles/lepisosteus-osseus/

Advertisements

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

New origin of dinosaurs video by Dr. Sterling Nesbitt

There’s a new YouTube video
featuring Dr. Sterling Nesbitt describe his version of dinosaur origins.

Unfortunately
Dr. Nesbitt ‘pulls a Larry Martin‘ by concentrating on key dinosaurian traits and not concentrating on the last common ancestor (Fig. 2) in a wide gamut phylogenetic analysis, like the large reptile tree (LRT, 1515 taxa, subset Fig. 3). Nesbitt is great at finding bones in the field, and describing new taxa, but Nesbitt 2011 and Nesbitt 2017 omitted key proximal outgroups to the Dinosauria (Figs. 2, 3) and so he keeps missing ‘the big picture.’

Continuing an invalid tradition
Dr. Nesbitt nests the tropidosuchid proterochampsid, Lagerpeton, as a close dinosaur outgroup. He also nests pterosaurs close to the base of the Dinosauria, which has been a big mistake for nearly 20 years. Dr. Nesbitt omits bipedal crocodylomorphs (Figs. 2, 3) from his dinosaur cladograms, another traditional academic mistake.

Nesbitt’s taxon exclusion issues
are repaired in the LRT (subset Fig. 3) where the last common ancestor of every included taxon back to Silurian fish is documented and validated by minimizing taxon exclusion.

Figure 2. The origin of dinosaurs to scale. Gray arrows show the direction of evolution. This image includes Decuriasuchus, Turfanosuchus, Gracilisuchus, Lewisuchus, Pseudhesperosuchus, Trialestes, Herrerasaurus, Tawa and Eoraptor.

Figure 2. The origin of dinosaurs to scale in the LRT. Gray arrows show the direction of evolution. This image includes Decuriasuchus, Turfanosuchus, Gracilisuchus, Lewisuchus, Pseudhesperosuchus, Trialestes, Herrerasaurus, Tawa and Eoraptor.

Figure 1. Revision to the LRT with a focus on the Archosauria. Here taxa with a long carpus all nest within the Crocodylomorpha, following traditional thinking. Dinosaur outgroups are reduced. PVL 4597 is still the basalmost archosaur.

Figure 1. Revision to the LRT with a focus on the Archosauria. Here taxa with a long carpus all nest within the Crocodylomorpha, following traditional thinking. Dinosaur outgroups are reduced. PVL 4597 is still the basalmost archosaur.


References
Nesbitt SJ 2011. The early evolution of archosaurs: relationships and the origin of major clades. Bull. Am. Mus. Nat. Hist. 352, 1–292.
Nesbitt et al. 2017. The earliest bird-line archosaurs and the assembly of the dinosaur body plan. Nature (online here).

https://pterosaurheresies.wordpress.com/2017/04/13/teleocrater-a-sister-to-yarasuchus-not-the-earliest-bird-line-archosaur/

https://pterosaurheresies.wordpress.com/2018/02/22/redefining-what-makes-a-dinosaur/

Goodbye to another traditional clade: ‘Holostei’

‘Holostei’ is a traditional clade with just a few members,
(Figs. 1-4) now widely scattered in the large reptile tree (LRT, 1515 taxa; Fig. 5). Two are extant. They are considered midway or transitional between sharks (with no bones) and bony fish (with bones).

Figure 1. Taxa that make up the traditional but invalidated clade, Holostei include Lepisosteiformes, Ammiformes and the Triassic Polidophorus. They appear in distinct clades in the LRT. Image from Encyclopedia Brittanica needs to be updated.

Figure 1. Taxa that make up the traditional but invalidated clade, Holostei include Lepisosteiformes, Ammiformes and the Triassic Polidophorus. They don’t look alike here and they appear in distinct clades in the LRT. Image from Encyclopedia Brittanica needs to be updated.

According to Wikipedia
“Holostei
are eight species divided among two orders, the Amiiformes (the bowfin Amia calva) and the Lepisosteiformes (the garpike Lepisosteus).” Encyclopedia Brittanica added the Triassic xx, Pholidophorus (Fig. 2).

Figure 2. Pholidophorus in situ + two skull drawings relabeled with tetrapod names.

Figure 2. 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 posterior process of the tail. Here the skull bones are re-identified with tetrapod labels. The pectoral and pelvic fins were similar in size. This iconic fish shape is indeed plesiomorphic for ray-fin fish according to the LRT.

Figure 3. Cladogram from wiki/Holostei showing traditional interrelationships among other vertebrate taxa.

Figure 3. Cladogram from wiki/Holostei showing traditional interrelationships among other vertebrate taxa. In the LRT bichirs nest with lungfish, sturgeons with ratfish.

My guess is
taxon exclusion is once again the culprit, followed closely by ‘Pulling a Larry Martin‘, followed more distantly by a lack of consistency in skull bone names. Here (Fig. 2) fish skull bones are colored as homologs to tetrapod skull bones, a long needed suggestion first promoted by Schultze 2007.

Though distinct in overall appearance,
traditional members of the Holostei are united by a few traits. The late Dr. Larry Martin was famous for challenging the nesting of taxa based on a few traits, because most traits can also be found elsewhere on the family tree by convergence. In the LRT hundreds of traits nest every taxon, reducing the influence of convergence and exposing the convergence that appears in traditional Holostei.

Figure 4. Cladogram of the Pachydormidae and outgroups among traditional Holostei (yellow boxes).

Figure 4. Cladogram of the Pachydormidae and outgroups among traditional Holostei (yellow boxes) from Wikipedia

The LRT tree topology
is distinctly different from prior cladograms. It has a wider gamut than in figure 4, but does not include as many partial or poorly known taxa. Note the disbursement of Amia, Pholidophorus and Lepisosteus.

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 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.

Amia calva (Linneaus 1766; up to 70cm in length) is the extant bowfin, a basal fish related to gars, able to breathe both water and air. Rather than two dorsal fins, an single elongate undulating fin is present. Hatchlings look like tadpoles or miniature placoderms. The squamosal an quadratojugal are absent. The postfrontal is fused to the frontal + parietal. In contrast, the lacrimal and jugal break apart into several bones. Females produce 2000 to 5000 eggs. Fossil relatives of Amia have a worldwide distribution in fresh and salt waters.

Lepisosteus osseus (Lacepéde 1803) is the extant longnose gar. Note the jaw joint is in front of the orbit, similar to the stickleback, Gasterosteus. The longest teeth arise from the inside the of jaws, the long vomer. The rostrum is lined by the premaxilla. The maxilla is absent. The traditional jugal is the lacrimal. Compare Lepisosteus with the juvenile swordfish, Xiphias, which nests as a sister and shares many traits, including long toothy jaws and an elongate body.

Wikipedia reports,
“The thick ganoid scales of the gars are more primitive than those of the bowfin.” That is refuted by the LRT, which nests gars as derived taxa along with sticklebacks, pipefish and seahorses, all of which have a bony elements in the dermis.

Wikipedia reports,
“The spiracles are reduced to vestigial remnants and the bones are lightly ossified.” In derived fish with external skeletons, like the placoderms, sturgeons, puffers, gars and seahorses, the internal skeletons tend to be poorly ossified.

This is not the first time the LRT has split apart traditional clade members.
Over the last eight years the LRT invalidated several other traditional clades including Ornithodira, Parareptilia, Cetacea, Pinnipedia, Pterodactyloidea, Monofenestra, Scrotifera, Euarchontaglires, Scandentia, Pseudosuchia, Notoungulata, etc. This is what a wide gamut phylogenetic analysis can do. Links to the above traditional clades can be accessed by using the ‘keywords’ box above.


References
Agassiz L 1832. Untersuchungen über die fossilen Fische der Lias-Formation. Jahrbuch für Mineralogie, Geognosie, Geologie und Petrefaktenkunde, 3, 139–149.
de Lacepéde BG 1803. Histoire naturelle des poissons. Tome Cinquieme. 5(1-21):1-803 + index.
Friedman M, Shimada K, Martin LD, Everhart MJ, Liston J, Maltese A and Triebold M 2010. 100-million-year dynasty of giant planktivorous bony fishes in the Mesozoic seas. Science. 327 (5968): 990–993.
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)
Schultze H-P 2008 (2007). Nomenclature and homologization of cranial bones in actinopterygians. Nomenclature and homologization of cranial bones in actinopterygians. In Mesozoic Fishes 4 – Homology and Phylogeny. Editors: Arratia G, Schultze H-P and MVH Wilson, Verlag Dr. F. Pfeil.

wiki/Holostei
wiki/Amiiformes
wiki/Lepisosteiformes
wiki/Pachycormiformes
wiki/Lepidosteus
wiki/Amia
wiki/Pholidophorus

eptileevolution.com/cheirolepis.htm
reptileevolution.com/amia.htm
reptileevolution.com/gasterosteus.htm

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