Deep sea Notothenia joins open sea Coryphaena in the LRT

Notothenia
(Figs. 1, 3), the extant Antarctic yellow belly rock cod,  nests with Coryphaena, the mahi-mahi (Figs. 2, 4), in the large reptile tree (LRT, 1806+ taxa). The two taxa look alike overall… except for the broad-shape of the fins in the former, vs the narrow fins of the latter. And the lack of color and sexual dimorphism in the former. Plus several other relatively, or presently, inconsequential differences you are free to note. 

Figure 1. Notothenia is a deep sea mahi-mahi in the LRT.

Figure 1. Notothenia is a deep sea mahi-mahi in the LRT.

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.

Figure 3. Notothenia is a Coryphaena sister of the deepest oceans.

Figure 3. Notothenia is a Coryphaena sister of the deepest oceans. Here it converges with the wolf eel, Anarhichas.

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

Figure 4. Mahi-mahi (Coryphaena) mounted as if in vivo.

Notothenia coriiceps (Richardson 1844; 50cm) is the extant Antarctic yellowbelly rockcod. It lacks a swim bladder and the bones are dense, accounting for its reduced buoyancy. The body is adapted to sub freezing temperatures. Here it nests with the mahi-mahi, Corphaena (above), not with traditional perch.

Coryphaena hippurus (Linneaus 1758; 1.5m length) is the extant open seas predator mahi-mahi or dolphinfish, here related to the similar, but deeper Notothenia. The dorsal fin starts at the skull. The caudal fin is deeply forked. The teeth are needle-like. Males have a tall fleshy forehead supported by a bony crest. A smaller-crested female is also shown above.

Figure x. Rayfin fish cladogram. This one represents the latest subset of the LRT.

Figure x. Rayfin fish cladogram. This one represents the latest subset of the LRT.

The yellow belly rock cod nests with the mahi-mahi
and THEY nest close to the Atlantic cod, Gadus (Fig. 5), a taxon added to the LRT earlier here. I guess yellow-belly rock cod sounds better than yellow-belly mahi-mahi.

Figure 5. Atlantic cod, Gadus morhua, in lateral view.

Figure 5. Atlantic cod, Gadus morhua, in lateral view.

 

“The task is…not so much to see what no one has yet seen; but to think what nobody has yet thought, about that which everybody sees.” ~ Erwin Schrödinger


References
Linnaeus C 1758. Systema naturæ per regna tria naturæ, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. Tomus I. Editio decima, reformata.
Richardson J 1844. Ichthyology of the voyage of H.M.S. Erebus & Terror. In: Reptiles, fishes, Crustacea, insects, Mollusca, Longman, Brown,London.: 1-16.

wiki/Mahi-mahi
wiki/Notothenia_coriiceps

Sea horse evolution back to large Cretaceous predators

Another series of taxa pulled from the LRT
focusing on phylogenetic miniaturization (PM) in the lineage of sea horses (Fig. 1). PM starts with 60cm-long Early Cretaceous Notelops and similar extant Scomberoides, the queenfish (Fig. 1), which is also (quite obviously) basal to mackerel and tuna.

Figure 1. Seahorse evolution back to Notelops (Early Cretaceous).

Figure 1. Seahorse evolution back to Notelops (Early Cretaceous).

Less obviously,
in the large reptile tree (LRT, 1806+ taxa) another descendant of Scomberoides is the 10x smaller zebra fish (Danio, Fig. 1).

Here’s where it gets interesting…
The sagittal crest present in Scomberoides (Fig. 1) is absent in Danio and the parietals return to meet each other medially, as in basal bony fish like Amia and Prohalecites. This phylogenetic reversal makes creating a cladogram more difficult, due to convergence, but all the more challenging. Danio descendants remains tiny and crestless. I have no data if Scomberoides hatchlings have crests or not. If so that would be a case of neotony leading to Danio.

Relative to Notelops
larger eyes are first seen, not in tiny Danio, but in big Scomberoides (Fig. 1), prior to PM. That increase in orbit size comes at the cost of a reduction in cheek plates that never comes back in descendant taxa. In Scomberoides the circumorbital ring actually overlaps the preopercular (light yellow) and hyomandibular (dark green). That’s a rare trait that makes it a bit difficult to score.

The jugal
(cyan color) in Danio (Fig. 1) is still large, though disconnected from the circumorbital ring where Gregory 1933 labels it the symplectic. According to Wikipedia, the symplectic is “an additional bone linking the jaw to the rest of the cranium.”  That also makes that bone difficult to score. Seeing this bone in a variety of taxa led to the conclusion that it was homologous to the jugal. Starks 1901 listed several synonymies used by various authors for bones of the fish skeleton. None synonymized the jugal and symplectic. That may have changed in the 120 years since. Let me know, if so.

Stickleback stickles
readily seen in Gasterosteus, are first seen in Scomberoides (Fig. 1), though lost in Danio.

Jaw joint migration from behind the orbit
to way out in front of the orbit in this series of taxa starts with Scomberoides, documents a mid-point in Danio, and reaches a conclusion in Gasterosteus (Fig.1).

Figure x. Rayfin fish cladogram. This one represents the latest subset of the LRT.

Figure x. Rayfin fish cladogram. This one represents the latest subset of the LRT.

That’s the utility of the LRT
and the ready-at-your-fingertips online data with all bones colorized using DGS.


References
Starks EC 1901. Synonymy of the fish skeleton. Proceedings of the Washington Academy of Sciences 3:507-539. PDF here.

The Atlantic cod, Gadus mohua, enters the LRT

Sometimes more common and more ordinary fish,
like the Atlantic cod, Gadus (Figs. 1, 2), also enter the large reptile tree (1806+ taxa).

Figure 5. Atlantic cod, Gadus morhua, in lateral view.

Figure 1. Atlantic cod, Gadus morhua, in lateral view.

Actually
it’s only ordinary on the outside. The skull is unique, but like al vertebrates shares a long list of traits with related taxa.

Figure 4. Skull of the Atlantic cod, Gadus. Note the posterior process of the hyomandibular (dark green).

Figure 2. Skull of the Atlantic cod, Gadus. Note the posterior process of the hyomandibular (dark green).

Gadus morhua (Linneaus 1758) is the Atlantic cod, nesting between two open ocean predators, Coryphaena and Rachycentron. Instead of one long dorsal fin, it is split in three. The anal fin is split in two. The chin has a barbel. The postparietal forms a long crest that divides the parietal. The naris is a long opening from snout tip nearly to the orbit.  Note the elongate postfrontal (orange) and hyomandibular (dark green) with accessory processes.

Figure x. Rayfin fish cladogram. This one represents the latest subset of the LRT.

Figure x. Rayfin fish cladogram. This one represents the latest subset of the LRT.


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/Gadus_Atlantic_cod

Cawley et al. 2020 did not realize Mesozoic pycnodonts were derived from extant bonefish

Cawley et al. 2020
brought us an overview of a clade of Mesozoic fish, the Pycnodontiformes (Fig. 1).

From the abstract
“Two other neopterygian clades possessing similar ecological adaptations in both body morphology (†Dapediiformes) and dentition (Ginglymodi) also occurred in Mesozoic seas.”

Short note: Dapediformes includes Dapedium and kin (taxa related to gars, like Lepisosteus in the LRT). Ginglymodi includes Semionotiformes (Semionnotus) and Lepidotidae (Lepidotes and Lepisosteus (= gars)). These taxa nest basal to catfish + placoderms in the LRT. They are Silurian in origin, not related to Pycnodus (Fig. 2) and Albula (Figs. 1, 3) in the LRT.

From the introduction:
“The overarching goal of this study is to evaluate the success but also final demise of pycnodontiform fishes, which represented the major marine actinopterygian elements from the Late Triassic to Palaeogene.”

Figure 1. Color image from Cawley et al. 2020. Albula added. Taxa below the gray line are Semionotiformes unrelated to pycnodontiformes.

Figure 1. Color image from Cawley et al. 2020. Albula added. Taxa below the gray line are Semionotiformes unrelated to pycnodontiformes.

Unfortunately Cawley et al. fails to mention
the extant pycnodontiform, the bonefish, Albula, which nests with the pycnodontiforms, Flagellipinna and Pycnodus (Agassiz 1835), in the large reptile tree (LRT, 1804+ taxa).

Also unfortunately,
Cawley et al. inappropriately includes several members of the Dapediidae and Semionotiformes (Fig. 1). Due to taxon exclusion the authors don’t realize these taxa nest in the other major clade of bony fish, apart from most ray fins, closer to spiny sharks, placoderms and lobefins, far from Pycnodus and Albula.

Cawley et al. reports, 
“Pycnodontiforms represent a well-defined monophyletic group…”

then admits,
“but the intrarelationships of various taxa and groups remain debated.” The LRT tests virtually all other fish clades.

Figure 2. Pycnodus with bones colorized according to tetrapod homologies. Third frame shows maxilla and lacrimal returned to in vivo positions.

Figure 2. Pycnodus with bones colorized according to tetrapod homologies. Third frame shows maxilla and lacrimal returned to in vivo positions.

Wikipedia reports,
Pycnodontiformes is an extinct order of bony fish. The group evolved during the Late Triassic and disappeared during the Eocene. The group has been found in rock formations in Africa, Asia, Europe, North and South America. The pycnodontiforms were small to middle-sized fish, with laterally-compressed body and almost circular outline. Pycnodontiform fishes lived mostly in shallow-water seas. They had special jaws with round and flattened teeth, well adapted to crush food items. One study links the dentine tubules in pycnodont teeth to comparable structures in the dermal denticles of early Paleozoic fish. Some species lived in rivers and possibly fed on molluscs and crustaceans.”

Figure 1. Albula vulpes skull with highly derived facial bones reidentified here. Note the lateral premaxillary processes and 'floating' cheek bones. Green vertebrae are caudals.

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

Pycnodus according to Wikipedia
“The known whole fossils of Pycnodus are around 12 centimetres (5 in) long, and have a superficial resemblance to angelfish or butterflyfish. The animals, as typical of all other pycnodontids, had many knob-like teeth, forming pavements in the jaws with which to break and crush hard food substances, probably mollusks and echinoderms. These teeth are the most common form of fossil.”

According to Wikipedia
Bonefishes live in inshore tropical waters and moves onto shallow mudflats or sand flats to feed with the incoming tide. The bonefish feeds on benthic worms, fry, crustaceans, and mollusks. Ledges, drop-offs, and clean, healthy seagrass beds yield abundant small prey such as crabs and shrimp. It may follow stingrays to catch the small animals they root from the substrate.”

Apparently no one has reported
that pycnodontiformes is an extinct clade within the extant clade Albulidae. Likewise no one has reported that Semionotifomes are not related to Pycnodontiformes. If so, please send the citation so I can promote it here.


References
Agassiz JLR 1835.Recherches sur les Poissons fossiles, 5 volumes. Imprimerie de Petitpierre et Prince, Neuchaatel, 1420 pp.
Bleeker P 1859. xx
Cawley JJ et al. (5 co-authors) 2020.
Rise and fall of Pycnodontiformes: Diversity, competition and extinction of a successful fish clade. Ecology and evolution DOI: 10.1002/ece3.7168

wiki/Pycnodontiformes
wiki/Pycnodus
wiki/Bonefish

Pycnodontiformes Berg 1937
Albulidae Bleeer 1859

 

Dunyu [Galeaspida] enters the LRT

Updated June 23, 2022 with new data and a new nesting of Dunyu with Drepanaspis.

According to Wikipedia
“Galeaspida lived in shallow, fresh water and marine environments during the Silurian and Devonian times (430 to 370 million years ago) in what is now Southern China, Tibet and Vietnam. Superficially, their morphology appears more similar to that of Heterostraci than Osteostraci, there being currently no evidence that the galeaspids had paired fins. However, Galeaspida are in fact regarded as being more closely related to Osteostraci, based on the closer similarity of the morphology of the braincase.”

This is incorrect. Galeaspids are derived from the basal placoderm, Drepanaspis (Fig 1).

“The defining characteristic of all galeaspids was a large opening on the dorsal surface of the head shield, which was connected to the pharynx and gill chamber, and a scalloped pattern of the sensory-lines. The opening appears to have served both the olfaction and the intake of the respiratory water similar to the nasopharyngeal duct of hagfishes.”

Figure 2. Skull of Dunyu with tetrapod homolog colors applied here. Note the elongated dorsal opening. In other galeaspids the opining is more oval. On a 72 dpi monitor this image is only slightly smaller than life size.

Figure 2. Skull of Dunyu with tetrapod homolog colors applied here. Note the elongated dorsal opening. In other galeaspids the opining is more oval. On a 72 dpi monitor this image is only slightly smaller than life size.

Dunyu longiforus
(Zhu et al. 2012; Late Silurian, 425mya; IVPP V 17681; Fig 2) is a galeaspid without cranial horns. It nests with Drepanaspis. The oral cavity is the long slit between the nasals, extending to the frontals here. The frontals include the pineal opening. The underside does not include the mouth or gill openings, only a gular sac that expands and contracts to draw in nutrient- and oxygen-rich sea water while Dunyu is otherwise buried in the sea floor sediments. The skull shape is otherwise convergent with the osteostracan, Hemicyclaspis.

Here
(Fig. 3) in the large reptile tree (LRT, 1803+ taxa then, 2119 tax on June 23, 2022) Dunyu nests between the thelodont, Thelodus, and the osteostracan, Hemicyclaspis (Fig. 3). The resemblance between the three is readily observed. Phylogenetic bracketing (Fig. 3) provides galeaspids with pectoral fins. Closest living relatives are hagfish and sturgeons.


References
Halstead LB 1985. The vertebrate invasion of fresh water. Philosophical Transactions of the Royal Society London B 309:243–258.
Janvier P 1984. The relationships of the Osteostraci and Galeaspia. Journal of Vertebrate Paleontology 4(3):344–358.
Liu YH 1965. New Devonian aganathans from Yunnan. Vertebrata PalAsiatica 9(2):125–134.
Zhu M and Gai Z-K 2006. Phylogenetic relationships of Galeaspids (Agnatha). Vertebrate PalAsiatica 44:1–27.
Zhu M, Liu Y-H, Jia L-T and Gai Z-K 2012. A new genus of eugaleaspidiforms (Agnatha: Galeaspida) from the Ludlow, Silurian of Qujing, Yunnan, Southwestern China. Vertebrata PalAsiatica. 50 (1): 1–7.

wiki/Galeaspida
wiki/Dunyu

Xiphactinus and its ancestors in the LRT

Short one today
told in pictures.

Here are the taxa
(Fig. 1) in the large reptile tree (LRT, 1803+ taxa; subset Fig. 2) in the lineage of Xiphactinus (Fig. 1) a large Late Cretaceous predator from the Niobrara formation, starting with Calamopleurus, the Early Cretaceous bowfin with long, wicked teeth. Calamopleurus likely had a Late Silurian ancestry based on an Early Devonian relative, Doliodus.

Figure 1. Taxa in the lineage of Xiphactinus going back to Salmo, the salmon.

Figure 1. Taxa in the lineage of Xiphactinus going back to Salmo, the salmon.

As mentioned earlier,
wrestling with data on these 90 or so ray-fin bony fish over the last 2-3 months has been a full-time task. Many, many corrections were made. The present subset of the LRT still needs some polishing, but it is settling into a logical model for evolutionary processes distinct from traditional cladograms that do not recognize the origin of bony fish from hybodontid sharks and Gregorius.

Figure x. Rayfin fish cladogram. This one represents the latest subset of the LRT.

Figure x. Rayfin fish cladogram. This one represents the latest subset of the LRT.

The white notch 
that includes mormyrids and piranha (Fig. 2) was covered earlier here.


 

A tiny goby, Elacatinus, enters the LRT with the mudskipper

Short one today.
Uncontroversial traditional nesting for the neon goby with another, larger goby, the mudskipper.

Figure 1. Elacatinus the neon goby, full scale on a 72 dpi monitor.

Figure 1. Elacatinus the neon goby, full scale on a 72 dpi monitor.

Elacatinus oceanops (Jordan 1904; 5cm; Figs. 1–3) is the extant neon goby from Bahamas coral. It is common in the aquariaum trade. Here in the large reptile tree (LRT, 1802+ taxa, subset Fig. 1) the neon goby nests with the mudskipper, Periophthalmus (Fig. 4). This clade is derived from the frogfish (Antennaris) clade and basal to deep-sea tripod fish (Bathypterois) and anglers (Lophius) in the LRT.

Figure 1. Elactatinus skull from Gregory 1933 ion dorsal and lateral views.

Figure 2. Elacatinus skull from Gregory 1933 ion dorsal and lateral views.

Note the absence of a lacrimal, 
exposing the palatine completely. The postorbital is also missing.

Figure 2. Elacatinus in vivo in dorsal and lateral views.

Figure 3. Elacatinus in vivo in dorsal and lateral views.

Figure 4. The mudskipper, Periophthalmus, nests with the neon goby, Elacatinus, in the LRT.

Figure 4. The mudskipper, Periophthalmus, nests with the neon goby, Elacatinus, in the LRT.

References
Jordan DS 1904. Ichthyology in the ‘Encyclopædia Americana.’ Science. 19: 767.

wiki/Frogfish
wiki/Periophthalmus
wiki/Elacatinus

Freshwater Anableps finds a new home with deep sea Gigantura

Weeks of work on ray-fin fish
continue to produce fascinating results. Unfortunately only one or two taxonomic insights are appearing at a time, as readers have witnessed. Convergence is a frustrating problem. Hundreds of mistakes have been corrected with new data similar to today’s new data.

A problematic taxon, Anableps,
the fresh water four-eyed fish (Figs. 1, 3), finally finds a home with a taxon that shares a long list of previously overlooked traits, a deep-sea predator, Gigantura, the telescope fish (Figs. 2, 3). This match only came about because data on the dorsal view of the skull of Anableps became known. This skull architecture appears in only these two taxa. Perhaps, not surprisingly, but rather obviously, both Anableps and Gigantura have eyeballs that extend beyond the skull boundaries.

LCA
Trachinocephalus, a so-called lizard fish (Fig. 3) is a last common ancestor. It prefers shorelines. Lepidogalaxias, a so-called salamander fish (Fig. 3), is another relative one step removed, but has a similar elliptical caudal fin and prefers fresh water. So we’re getting new clues to the ancestry of these highly derived, yet basal bony fish, Anableps and Gigantura.

If Gigantura and Anableps have ever been nested together
in an academic publication, let me know so I can cite it. Otherwise this appears to be an overlooked hypothetical interrelationship.

Let’s look at these two together,
perhaps for the first time.

Figure 1. Dorsal and lateral views of the skull of Anableps from Perez et al. 2017. Colors added as tetrapod homologs.

Figure 1. Dorsal and lateral views of the skull of Anableps from Perez et al. 2017. Colors added as tetrapod homologs. Note the tiny postorbital here identified for the first time.

Figure 2. Gigantura skull in dorsal and lateral views assembled and colorized here from Konstantinidis and Johnson 2016.

Figure 2. Gigantura skull in dorsal and lateral views assembled and colorized here from Konstantinidis and Johnson 2016. Note their palatine is here a premaxilla. Their vomer is here a maxilla. Their maxilla is here a lacrimal. Their frontal is here divided with a parietal.

Dorsal views of the two skulls
(Figs 1, 2) show nearly identical architecture. In the large reptile tree (LRT, 1801+ taxa) no other taxon nests closer to Anableps than Gigantura and it’s even stranger relative, Stylephorus (Fig. 3). Given that semi-related Doliodus (Fig. 3) comes from the Early Devonian, all these taxa have had plenty of time to go their separate ways from a basal bony fish radiation.

Th interrelationship between Gigantura and Anableps
may have gone unnoticed thus far because lateral views of the skulls differ:

  1. In Gigantura the occiput is far anterior to the jaw joint
  2. In Anableps the occiput is far posterior to the jaw joint
  3. In Gigantura the maxilla is greatly reduced below the nasal
  4. In Anableps the maxilla is not reduced
  5. In Gigantura the nasals are greatly reduced
  6. In Anableps the nasals are larger than typical

Konstantidnidis and Johnson 2016 
discussed the homology of the tooth-bearing upper jaw elements. The authors considered the upper jaw composed of the palatine alone “based on topological evidence.” Anableps was not mentioned in their text. Based on comparative anatomy with Anableps, new identities are assigned to certain bones in the Gigantura skull.

  1. The ‘palatine’ (Fig. 2) is here a premaxilla.
  2. The ‘vomer’ is here a vestigial maxilla, still dorsal to the premaxilla.
  3. The leaf-like ‘maxilla’ is here a lacrimal, as in Anableps.
  4. The frontals include parietals, perhaps fused

Figure 1. Taxa from the LRT on one branch of the bony fish. Doliodus is one of these.

Figure 3. Taxa from the LRT on one branch of the bony fish. Doliodus is one of these.

Anableps tetrophthalmus
(originaly Cobitis anableps Linnaeus 1758, Scopolis 1777; 32 cm) is the extant four-eyed fish (aka: cuatro ojos), a surface predator of insects that fall into fresh waters or are preyed upon on shallow shores where Anableps beach themselves to eat. The short lower jaw enables this. Traditionally Anableps is a member of the pupfish (guppy, killifish, topminnow) family. Here Anableps nests with deepsea telescope fish like Gigantura. The naris is anterolateral. Traditionally the fossil record is unknown, but now see figure 3. Females are much larger than males. Internal fertilization (with a modified tubular anal fin) leads to live birth (viviparity) of up to 14 young. The vertebral number is higher than typical for most ray-fin fish.

Figure x. Rayfin fish cladogram

Figure x. Rayfin fish cladogram

Gigantura indica 
(Brauer A 1901Konstantinidis P and Johnson GD 2016; 20 cm standard length, not counting caudal fin) is the extant telescope fish. This small fish can swallow prey larger than itself.

Stylephorus chordatus 
(Shaw, 1791, Regan 1924) is the extant tube-eye or thread-tail. It was considered an oarfish relative, but here nests with Gigantura. Distinct from Gigantura, but convergent with seahorses and oarfish, the tube-eye feeds on tiny plankton sucked in as its tubular mouth enlarges the oral cavity by 40x.


References
Brauer A 1901. Über einige von der Valdivia-Expedition gesammelte Tiefseefische und ihre Augen. Sitzungsberichte der Gesellschaft zur Beförderung der Gesamten Naturwissenschaften zu Marburg 8: 115–130.
Konstantinidis P and Johnson GD 2016. Osteology of the telescope fishes of the genus Gigantura (Brauer, 1901), Teleostei: Aulopiformes. Zoological Journal of the Linnean Society 179(2):338–353.
Michel KB, Aerts P, Gibb AC and Van Wassenberg S 2015. Functional morphology and kinematics of terrestrial feeding in the largescale foureyes (Anableps anableps). Journal of Experimental Biology (2015) 218, 2951-2960 doi:10.1242/jeb.124644
Perez et al. (9 co-authors) 2017. Eye development in the four-eyed fish Anableps anableps: cranial and retinal adaptations to simultaneous aerial and aquatic vision. Proc. R. Soc. B 284: 20170157.  http://dx.doi.org/10.1098/rspb.2017.0157
Scopoli GA 1777. Introductio ad historiam naturalem sistens genera lapidum, plantarum, et animalium. Wolfgang Gerle, Pragae 3-506.
Regan CT 1924. The morphology of the rare oceanic fish, Stylophorus chordatus, Shaw; based on specimens collected in the Atlantic by the “Dana” expeditions, 1920–1922. Proceedings of the Royal Society B 96(674): PDF
Shaw G 1791. Description of the Stylephorus chordatus, a new fish. Transactions of the Linnean Society of London, 2d Ser: Zoology 1:90–92.

wiki/Anableps
wiki/Telescopefish = Gigantura

wiki/Tube-eye = Stylephourus

Is the early evolution of bony fishes obscured?

Updated February 17, 2021
with the shifting of Anableps to the basal bony fish (Fig. 1).

For readers in a hurry,
the answer to the headline question is, ‘no.’

Romano 2021 reports:
“About half of all vertebrate species today are ray-finned fishes (Actinopterygii), and nearly all of them belong to the Neopterygii (modern ray-fins). The oldest unequivocal neopterygian fossils are known from the Early Triassic.”

Clade membership: According to Wikipedia“Neopterygii is a subclass of ray-finned fish (Actinopterygii). They could move more rapidly than their ancestors. Their scales and skeletons began to lighten during their evolution, and their jaws became more powerful and efficient.” Electroreception is a lost sense, even if it has later been re-evolved within Gymnotiformes and catfishes, which possess nonhomologous teleost ampullae. Better control of the movements of both dorsal and anal fins, resulting in an improvement in their swimming capabilities. 

According to the Wikipedia cladogram, Neopterygii include

  1. Lepisosteifomres (gars)
  2. Amiformes (bowfins)
  3. Teleosts (the rest of the ray-fin fish)

By contrast,
in the large reptile tree (LRT, 1801+ taxa) the earliest unequivocal ray fin fish is Doliodus (Fig. 1)  from the Early Devonian. Gars, bowfins, lobefins, placoderms and spiny sharks nest within the bony fish. Moray eels are among the most primitive taxa, and these are derived from hybodontid sharks. Counterintuititively, some of the more bizarre-looking bony fish, often deep sea forms, are among the most primitive bony fish.

Figure 1. Taxa from the LRT on one branch of the bony fish. Doliodus is one of these.

Figure 1. Taxa from the LRT on one branch of the bony fish. Doliodus is one of these.

Romano 2021 continues:
“In the Middle Triassic neopterygians were already species-rich and trophically diverse, and bony fish faunas were more regionally differentiated compared to the Early Triassic. Still little is known about the early evolution of neopterygians leading up to this first diversity peak. Here, I review the fossil record of Early and Middle Triassic marine bony fishes (Actinistia and Actinopterygii) at the substage-level in order to evaluate the impact of this hiatus on our understanding of their diversification after the largest mass extinction event of the past.”

Figure 1. Taxa from the LRT on the other branch of the bony fish, including spiny sharks, bony tongues, placoderms, catfish and lobefins.

Figure 2. Taxa from the LRT on the other branch of the bony fish, including spiny sharks, bony tongues, placoderms, catfish and lobefins derived from Gregorius.

Taxon inclusion in the LRT
permits the association of taxa that had traditionally not been associated before. Traditional memberships and traditional clades are not supported by the LRT where spines evolve to become fins and vice versa.


References
Romano C 2021. A hiatus obscures the early evolution of modern lineages of bony fishes. Frontiers. Earth Science 8:618853 doi: https://doi.org/10.3389/feart.2020.618853
https://www.frontiersin.org/articles/10.3389/feart.2020.618853/full

Tiny Santanichthys is a bonefish

Updated April 28, 2021
with a closer look at Santanichthys now nesting with bonefish like Albula and Opisthoproctus.

This was a paragraph from the earlier post:
Two very closely related taxa, one 20x times larger,
enter the LRT today. Santanichthys (Silva Santos 1995; Figs. 1, 5) is only 3m in length. Notelops (Woodward 1901; Figs. 2–4) reaches 60cm in length. Both are from the Santana Formation, Early Cretaceous.

Figure 1. Tiny Santanichthys is a phylogenetically miniaturized taxon at the base of the Ostariophysi clade.
Figure 1. Tiny Santanichthys is a phylogenetically miniaturized taxon at the base of the Ostariophysi clade.

Santanichthys diasii 
(Silva Santos 1958; Filleleul and Maisey 2004; Early Cretaceous; 3cm; DGM-DNPM 647P) was a tiny Santana Formation fish considered the oldest characiform and otophysan. Here Santanichthys nests with Albula the extant bonefish (Fig. 2). According to Filleleul and Maisey, this is the earliest appearance of a Weberian apparatus, a sound amplifier that connects the swim bladder to the auditory system.

Figure 2. The skull and diagram of tiny Santanichthys from Filleul and Maisey 2004, colors added.

These taxa are considered members of the Characiformes,
a clade that traditionally includes piranha. Likewise the large reptile tree (LRT, 1801 taxa then, 1839 taxa now; subset Fig. x) nests them together, derived from the piranha clade. Traditionally Characiformes also includes knife fish and catfish. These clades are not related to piranha in the LRT, nor are they related to bonefish.

Figure 1. Albula vulpes skull with highly derived facial bones reidentified here. Note the lateral premaxillary processes and 'floating' cheek bones. Green vertebrae are caudals.
Figure 3. Albula vulpes skull with highly derived facial bones reidentified here. Note the lateral premaxillary processes and ‘floating’ cheek bones. Green vertebrae are caudals.

Santanichthys and Albula
share a long list of traits. Tiny Opisthoproctus (Fig 4) has fewer vertebrae, like Santanitchthys.

Figure 3. Opisthoproctus nests with Santanichthys in the LRT.
Figure 4. Opisthoproctus nests with Santanichthys in the LRT.
Figure x. Rayfin fish cladogram

If your studies dive deep into fish science  
you’ll come across the traditional clade Ostariophysi, in which member taxa all have a Weberian apparatus (see above). The LRT indicates that some fish with this trait evolved it independently, while others later lost it by convergence. Be careful. Lumping taxa together using one trait or a dozen is called “Pulling a Larry Martin.” Try to always determine clades with a phylogenetic analysis that tests hundreds of traits and then determine your clades based on a last common ancestor and all of its descendants. Convergence is rampant.

Membership within the clade
Ostariophysi (Lord 1922) includes

Gonorynchiformes — milkfish, untested in the LRT

Cypriniformes — perch, a clade distally derived from Santanichthys in the LRT.

Characiformes — piranha, a clade that proximally precedes Santanicthys in the LRT

Siluriformes — catfish, a clade unrelated to Santanichthys in the LRT

Gymnotiformes — knife fish, a clade that distally precedes Santanichthys in the LRT


References
Filleul A and Maisey JG 2004. Redescription of Santanichthys diasii (Otophysi,
Characiformes) from the Albian of the Santana Formation and Comments on Its Implications for Otophysan Relationships. American Museum Novitates 3455:21pp.
Forey PL 1977. The osteology of Notelops Woodward, Rhacolepis Agassiz Pachyrhizodus Dixon (Pisces: Teleostei). Bulletin of the British Museum (Natural History) 28(2):123–204.
Silva Santos R 1995. Santanichthys, novo epiteto generico para Leptolepis diasii Silva Santos, 1958 (Pisces, Teleostei) da Formacao Santana (Aptiano), Bacia do Araripe, NE do Brasil. Anais da Academia Brasileira de Ciencias 67:249–258.
Woodward AS 1901. Catalogue of the Fossil Fishes in the British Museum (Natural History), 4. xxxviii + 636 pp., 19 pis, 22 figs. Brit. Mus. (Nat. Hist.), London.

wiki/Santanichthys
wiki/Notelops
wiki/Characiformes
wiki/Ostariophysi