Fig 25 - uploaded by Gloria Arratia
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Dorsal fin and dorsal pterygiophores of the catfish Diplomystes camposensis (after ARRATIA 2003). A, dorsal fin of a specimen of 24 mm total length. B, dorsal view of 1 st to 3 rd pterygiophores showing details. C, anterior view of base of second dorsal spine. D, posterior view of base of second dorsal spine. B-D specimen, 103 mm standard length. Abbreviations: ant.pr, anterior process; art.f, articular foramen; art.pr, articular process; dl.ar, dorsolateral articular area. 1 st , 2 nd , 3 rd dpt, first, second, and third pterygiophores; dm.pr, dorso-medial processes; d.sp, dorsal spine; l.dpt. last dorsal pterygiophore; l.pr, lateral processes; m.pr, medial process; md.pr, median process.
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The actinopterygian postcranial skeleton is not as well known as its cranial counterpart, and consequently it is less represented in phylogenetic analyses. Due to this incomplete knowledge, it is often difficult to postulate hypotheses about homologous structures. Fin rays, scutes, fulcra, and spines have been traditionally interpreted as modified...
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... The vertebral column is one of the furthermost imperative informants of characteristics utilized in phylogenetic analysis of teleost (Arratia, 2008(Arratia, , 2009). In the linked osteological investigations, numerous features of the clupeid species have been explored. ...
This paper presents the conclusions of a comparative analysis of six osteological features:
the Structure of the vertebral column, the morphology of the predorsal bones,
the vertebral column regionalization, the pterygiophore interdigitation with neural
spines of dorsal fin, the pterygiophores interdigitation of with the haemal spines
of the anal fin, and the intermuscular bones (IMB) and hypomerals (HM) of 12 clupeid
species of the families Alosidae, Dorosomatidae, Dussumieridae and Ehiravidae.
... The method of counting vertebrae follows Tintori et al. (2007), an approach followed by Arratia (2022), to ensure that the results are comparable. The terms fin rays, scutes, fulcra and its different types, procurrent rays, and principal rays follow definitions provided by Arratia (2008Arratia ( , 2009). ...
A new species ( Marcopoloichthys mirigioliensis ) of the stem teleosteomorph genus Marcopoloichthys is described from the lower Besano Formation (late Anisian at Monte San Giorgio, southern Switzerland), making this new species distinct from Marcopoloichthys furreri from the Prosanto Formation (early Ladinian at Ducanfurgga, southeastern Switzerland). Marcopoloichthys mirigioliensis n. sp. is smaller (ca. 32 mm standard length) than M. furreri (ca. 40 mm standard length), and in addition, the two species have some important differences in the caudal endoskeleton and fin, e.g., number of epaxial and hypaxial basal fulcra, uroneural structure, size of hypurals, and presence versus absence of urodermals. Marcopoloichthys mirigioliensis n. sp. is the smallest member of Marcopoloichthyidae which is currently known from at least five species living in the Triassic of China (one species), Italy (two and others that remain undescribed), and Switzerland and according to current information, with its ca. 32 mm standard length is candidate to be considered a miniature fish. Additionally, this size makes it the smallest known stem teleost. As in other marcopoloichthyids, the buccal and suspensorium anatomy of M. mirigiolensis n. sp. corresponds to that of suction-feeder fishes.
... S4a-b, but were not further considered in Brito et al. (2024). These are dorsal fringing fulcra of the caudal fin (see our Fig. 1 and Fig. 479B in Grande, 2010), structures typical for the leading edges of fins of many basal actinopterygians (Arratia, 2008). Also the elements considered odontodes in Brito et al.'s (2024) Supplementary Data Fig. ...
... Principal rays (labeled in red, Fig. 1, B and C) are the central and longest rays, including all bifurcated rays and the first nonbifurcated ray of each fin lobe. Procurrent rays (dark blue) consist of two series of smaller, nonbifurcated rays anterior to the principal rays (36). The c13a −/− mutants had significantly fewer caudal rays than their WT siblings in both caudal fin lobes, losing a total of three principal and three procurrent rays ( Fig. 2D and fig. ...
Ancient bony fishes had heterocercal tails, like modern sharks and sturgeons, with asymmetric caudal fins and a vertebral column extending into an elongated upper lobe. Teleost fishes, in contrast, developed a homocercal tail characterized by two separate equal-sized fin lobes and the body axis not extending into the caudal fin. A similar heterocercal-to-homocercal transition occurs during teleost ontogeny, although the underlying genetic and developmental mechanisms for either transition remain unresolved. Here, we investigated the role of hox13 genes in caudal fin formation as these genes control posterior identity in animals. Analysis of expression profiles of zebrafish hox13 paralogs and phenotypes of CRISPR/Cas9-induced mutants showed that double hoxb13a and hoxc13a mutants fail to form a caudal fin. Furthermore, single mutants display heterocercal-like morphologies not seen since Mesozoic fossil teleosteomorphs. Relaxation of functional constraints after the teleost genome duplication may have allowed hox13 duplicates to neo-or subfunctionalize, ultimately contributing to the evolution of a homocercal tail in teleost fishes.
... Although a full ontogenetic appraisal is outside the scope of the present study, a few observations are noteworthy: (1) at 80 mm SL, the relative proportions of the body are similar to those of the sub-mature cannibal individuals, possibly implying a strong degree of proportionate isometry in their development from small to large juveniles. (2) The vertebral column is incompletely ossified in the smallest juveniles, with the characteristic dorsal expansion of the haemal arcocentra (Arratia, 2008;Cawley et al., 2018), which is well developed in sub-mature and larger individuals, being absent in the prey fishes. These elements are evidently not ossified during the small juvenile stage, instead first developing in individuals with a standard length closer to 250 mm (based on NHMUK PV 23425; Table 1). ...
Cannibalism (conspecific predation) is a surprisingly common and widespread behavior in modern ecosystems; however, direct evidence for cannibalism is strongly lacking in the fossil record. Identifying cannibalism is important to help better understand recondite trophic interactions between extinct species, as well as to detect potential resource pressures and competition in their ecosystems. Here, I describe the first direct evidence for a cannibalistic diet in a pachycormiform fish, based on three exceptionally well-preserved specimens of Pachycormus macropterus (de Blainville, 1818) with conspecific gut contents from the Early Jurassic (Toarcian) of Normandy (France). The generalist diet of Pachycormus is proven to be more complex than previously considered, which has recently been shown to include vampyropod squids, belemnoteuthids, ammonites, and small teleosts. All of the prey fishes were ingested whole in a longitudinal orientation, revealing that Pachycormus actively hunted juveniles of its own kind and was an indiscriminate opportunistic predator. The cannibal individuals themselves are also juveniles, further supporting previous findings for a dietary shift in Pachycormus from piscivorous to teuthophagous over ontogeny. Despite a widespread European distribution of Pachycormus, only specimens from the Normandy area show evidence for cannibalism, suggesting that the more conventional prey resources were either scarce or restricted at the site, prompting Pachycormus juveniles to indiscriminately predate on one another.
... The infraorbital bones that are located posterior to the antorbital and do not contribute to the orbital margin in Ticinolepis and more derived ginglymodians are termed as anterior infraorbitals (Wenz 1999, López-Arbarello 2012. The segmented and unbranched rays anterior to the principal fin ray are termed as procurrent rays, following the nomenclature used by Arratia (2008). Although we accept that actinopterygian frontals and parietals are the homologues of sarcopterygian parietals and postparietals, respectively (Schultze 1993), we nevertheless use the traditional actinopterygian nomenclature, for ease of comparison with most existing literature. ...
Ginglymodians (e.g. gars) are a group of holostean fishes with a rich fossil history in the Mesozoic. The resolution of interrelationships among extinct ginglymodians is central to the problem of understanding the origin of this clade. Here, a new fossil ginglymodian, Diandongichthys ocellatus gen. et sp. nov., is described based on 13 well-preserved specimens from the Early-Middle Triassic (Anisian) marine deposits exposed in Luoping, eastern Yunnan, China. The discovery documents one of the oldest and smallest ginglymodians hitherto known from the Middle Triassic, with a maximum standard length of 41 mm. Diandongichthys, although displaying several synapomorphies of ginglymodians, retains some primitive states with respect to other early ginglymodians (e.g. a short snout without anterior infraorbitals, a maxilla ending below the orbit, and a median gular); consequently, it is nested at the base of the Ginglymodi in this phylogenetic study. Besides body shape, some autapomorphies on the cranial bones and caudal fin easily distinguish Diandongichthys from other members of this clade. The discovery provides new insights into the origin and early diversification of ginglymodian fishes.
... The 145 inner 16 principal rays branch at least once, while the peripheral principal rays 1 and 18 remain unbranched. (Fig. 1B; Arratia et al., 2008;Coates, 1994). The caudal fin skeleton of fras1 -/fish ( Fig. 1C-F) showed a range of abnormalities (Fig. 1B). ...
... Fin rays are dermal bone, unlike the fully endochondral skeleton of extant tetrapod limbs (Arratia et al., 2008;Coates, 1994). Therefore, we examined if zebrafish fras1 also was required for endochondral fin skeletal pattering. ...
Fraser Syndrome is a rare, multisystemic autosomal recessive disorder characterized by disrupted epithelial-mesenchymal associations upon loss of Fraser Complex genes. Disease manifestation and affected organs are highly variable. Digit malformations such as syndactyly are common but of unclear developmental origins. We explored if zebrafish fraser extracellular matrix complex subunit 1 ( fras1 ) mutants model Fraser Syndrome-associated appendicular skeleton patterning defects. Approximately 10% of fras1 mutants survive to adulthood, displaying striking and varied fin abnormalities, including endochondral bone fusions, ectopic cartilage, and disrupted caudal fin symmetry. The fins of surviving fras1 mutants frequently have fewer and unbranched bony rays. fras1 mutant fins regenerate to their original size but with exacerbated ray branching and fin symmetry defects. Single cell RNA-Seq analysis, in situ hybridizations, and antibody staining show specific Fraser complex expression in the basal epidermis during regenerative outgrowth. Fras1 and Fraser Complex component Frem2 accumulate along the basal side of distal-most basal epidermal cells. Greatly reduced and mislocalized Frem2 accompanies loss of Fras1 in fras1 mutants. The Sonic hedgehog signaling between distal basal epidermis and adjacent mesenchymal pre-osteoblasts that promotes ray branching persists upon Fraser Complex loss. However, fras1 mutant regenerating fins exhibit extensive sub-epidermal blistering associated with a disorganized basal epidermis and adjacent pre-osteoblasts. We propose Fraser Complex-supported tissue layer adhesion enables robust integrated tissue morphogenesis involving the basal epidermis and osteoblasts. Further, we establish zebrafish fin development and regeneration as an accessible model to explore mechanisms of Fraser Syndrome-associated digit defects and Fraser Complex function at epithelial-mesenchymal interfaces.
... The anal fin measures 130 mm and is located immediately close to the caudal fin, with only a short (70 mm) caudal peduncle width separating the two fins. Based on the cross section, the anal fin comprises 6 basal anal fulcra (see Arratia, 2008Arratia, , 2009) and at least 8 lepidotrichia. The original shape of the dorsal and anal fins is uncertain. ...
... The epaxial (upper lobe) basal fulcra number at least five and are of a similar morphology. All fulcra are unpaired and parallelly arranged e a condition shared between many holosteans, non-holostean neopterygians and some stem-teleosts (Arratia and Lambers, 1996;Arratia, 2008;Grande, 2010). ...
Ganoine-scaled fishes belonging to the superfamily Lepisosteoidea, more commonly known as gars, are an ancient lineage with origins in the Mesozoic, first appearing in the Kimmeridgian, Late Jurassic. The Mesozoic gar fossil record is patchy, mostly consisting of disarticulated remains, with only a few partially or mostly complete specimens being extremely rare. Extant gars typically occur in freshwater and brackish environments, with rare observations of a few species frequenting saline waters although little is known of their marine ancestors. Here we describe a new genus and species, Grandemarinus gherisensis gen. et sp. nov., an unusually short-snouted gar from the Upper Cretaceous (Turonian) Akrabou Formation of Morocco. The short-snouted cranial bauplan is superficially convergent with the Eocene freshwater genera Cuneatus and Masillosteus, although a phylogenetic analysis resolves the new gar as the sister taxon to the Lepisosteini (Oniichthys, Lepisosteus, Atractosteus), falling outside of Masillosteinae (Masillosteus, Cuneatus). Gars likely originated as fully marine fishes during the Late Jurassic, and during Early Cretaceous times successfully invaded freshwater ecosystems. The new gar described here is likely a late surviving member of this early marine lineage. The new lepisosteiform is the first complete gar described from a Cretaceous marine deposit; representing a vital clue to help decipher the early evolution and ecology of Lepisosteidae. The taphonomy of the specimen is discussed within the context of a fully marine carbonate Konservat Lagerstätte.
... The platyfish caudal fin has a rounded shape supported by approximately 18 principal rays ( Figures 1A, B). Among them, 16 rays are branched plus one unbranched at the dorsal and the ventral side, as defined by anatomical conventions (Schultze and Arratia, 1989;Arratia, 2008;Schultze and Arratia, 2013;Arratia, 2015). Ray branches, also called bifurcations, are formed through dichotomous splitting of the source ray during their distal growth, which occurs at the tip of the fin. ...
Fin regeneration has been extensively studied in zebrafish, a genetic model organism. Little is known about regulators of this process in distant fish taxa, such as the Poeciliidae family, represented by the platyfish. Here, we used this species to investigate the plasticity of ray branching morphogenesis following either straight amputation or excision of ray triplets. This approach revealed that ray branching can be conditionally shifted to a more distal position, suggesting non-autonomous regulation of bone patterning. To gain molecular insights into regeneration of fin-specific dermal skeleton elements, actinotrichia and lepidotrichia, we localized expression of the actinodin genes and bmp2 in the regenerative outgrowth. Blocking of the BMP type-I receptor suppressed phospho-Smad1/5 immunoreactivity, and impaired fin regeneration after blastema formation. The resulting phenotype was characterized by the absence of bone and actinotrichia restoration. In addition, the wound epidermis displayed extensive thickening. This malformation was associated with expanded Tp63 expression from the basal epithelium towards more superficial layers, suggesting abnormal tissue differentiation. Our data add to the increasing evidence for the integrative role of BMP signaling in epidermal and skeletal tissue formation during fin regeneration. This expands our understanding of common mechanisms guiding appendage restoration in diverse clades of teleosts.
... To avoid confusion, the first time that the parietal and postparietal bones are cited in the text, as well as in figures, the traditional terminology is shown in square brackets, e.g., parietal bone [=frontal]: pa [=fr]. The terms for fin rays, scutes, and fulcra follow Arratia [23,24] and that for urodermals follows Arratia and Schultze [25]. Figures 2A and 3), head and anterior trunk, including squamation. ...
Fishes from the uppermost Norian Fuchsberg Quarry near Seinstedt are represented by two taxa that we interpret as a teleosteomorph (complete specimens) and actinistian (scales). Seinstedtia parva gen. et sp. nov. is described; although it was proposed as a possible semionotiform, this study reveals that Seinstedtia possesses a combination of teleosteomorph features, for instance: characteristic pholidophoriform-shaped cranial roof; fusion of skull roof bones; three dorsoposterior infraorbitals, including an enlarged infraorbital 3; one suborbital bone; movable premaxilla; and characteristic-shaped preopercle. In parallel, Seinstedtia possesses a head gently curved anteriorly, with lower jaw protruding slightly in front of upper jaw; supraorbital 1 forming most of anterodorsal margin of circumorbital ring; one supramaxilla; three extrascapulae; cleithrum with short and broad lower arm; and enlarged clavicle. This character combination places Seinstedtia as a teleosteomorph, family incertae sedis. This fish (total length ca. 50 mm) and some pholidophorids (ca. 70 mm or less; Parapholidophorus nybelini and Pholidoctenus serianus) represent the known smallest teleosteomorphs that inhabited Europe during the Norian. The isolated scales are elasmoid of amioid type ornamented with the elongated ridges of actinistians. This diversity of teleosteomorphs and actinistians in Fuchsberg Quarry during the Triassic indicates a connection to a marine environment.
