Fish Skeletons Research Articles

Breathing life into fisheries stock assessments with citizen science.

Citizen science offers a potentially cost-effective way for researchers to obtain large data sets over large spatial scales. However, it is not used widely to support biological data collection for fisheries stock assessments. Overfishing of demersal fishes along 1,000 km of the west Australian coast led to restrictive management to recover stocks. This diminished opportunities for scientists to cost-effectively monitor stock recovery via fishery-dependent sampling, particularly of the recreational fishing sector. As fishery-independent methods would be too expensive and logistically-challenging to implement, a citizen science program, Send us your skeletons (SUYS), was developed. SUYS asks recreational fishers to voluntarily donate fish skeletons of important species from their catch to allow biological data extraction by scientists to produce age structures and conduct stock assessment analyses. During SUYS, recreational fisher involvement, sample sizes and spatial and temporal coverage of samples have dramatically increased, while the collection cost per skeleton has declined substantially. SUYS is ensuring sampling objectives for stock assessments are achieved via fishery-dependent collection and reliable and timely scientific advice can be provided to managers. The program is also encouraging public ownership through involvement in the monitoring process, which can lead to greater acceptance of management decisions.

Body form and paleoecology of the large Late Cretaceous bony fish, Pachyrhizodus caninus

Pachyrhizodus caninus Cope is an extinct bony fish found in various Upper Cretaceous marine deposits in North America, but very little has been known about its paleobiology. This paper describes a nearly complete skeleton of P. caninus from the Britton Formation (Cenomanian – lower Turonian) of the Eagle Ford Shale in Texas, USA. The fish specimen is large, measuring 233 cm in total length, and is significant not only because it suggests that P. caninus had a stout tuna-like body with a marlin-like dorsal fin but also because it preserves a partial skeleton of an ichthyodectiform fish representing putative stomach content. This study indicates that P. caninus was a large, active carnivore that swam in open-ocean pelagic environment, much like the comparable-sized, extant tunas and marlins.

Repeated mass strandings of Miocene marine mammals from Atacama Region of Chile point to sudden death at sea

Marine mammal mass strandings have occurred for millions of years, but their origins defy singular explanations. Beyond human causes, mass strandings have been attributed to herding behaviour, large-scale oceanographic fronts and harmful algal blooms (HABs). Because algal toxins cause organ failure in marine mammals, HABs are the most common mass stranding agent with broad geographical and widespread taxonomic impact. Toxin-mediated mortalities in marine food webs have the potential to occur over geological timescales, but direct evidence for their antiquity has been lacking. Here, we describe an unusually dense accumulation of fossil marine vertebrates from Cerro Ballena, a Late Miocene locality in Atacama Region of Chile, preserving over 40 skeletons of rorqual whales, sperm whales, seals, aquatic sloths, walrus-whales and predatory bony fish. Marine mammal skeletons are distributed in four discrete horizons at the site, representing a recurring accumulation mechanism. Taphonomic analysis points to strong spatial focusing with a rapid death mechanism at sea, before being buried on a barrier-protected supratidal flat. In modern settings, HABs are the only known natural cause for such repeated, multispecies accumulations. This proposed agent suggests that upwelling zones elsewhere in the world should preserve fossil marine vertebrate accumulations in similar modes and densities.

An assessment of the long-term effects of simulated microgravity on cranial neural crest cells in zebrafish embryos with a focus on the adult skeleton.

It is becoming increasingly important to address the long-term effects of exposure to simulated microgravity as the potential for space tourism and life in space become prominent topics amongst the World’s governments. There are several studies examining the effects of exposure to simulated microgravity on various developmental systems and in various organisms; however, few examine the effects beyond the juvenile stages. In this study, we expose zebrafish embryos to simulated microgravity starting at key stages associated with cranial neural crest cell migration. We then analyzed the skeletons of adult fish. Gross observations and morphometric analyses show that exposure to simulated microgravity results in stunted growth, reduced ossification and severe distortion of some skeletal elements. Additionally, we investigated the effects on the juvenile skull and body pigmentation. This study determines for the first time the long-term effects of embryonic exposure to simulated microgravity on the developing skull and highlights the importance of studies investigating the effects of altered gravitational forces.

Fish bones, cut marks, and burial: implications for taphonomy and faunal analysis

Willis et al. (2008) demonstrated that butchering fish can result in upwards of 500 cut marks per fish skeleton. However, despite various ethnographic studies that describe fish butchering techniques for consumption and drying, cut marks are rarely observed or described for fish bone from archaeological sites. To test the discrepancy between the experimental results and archaeological observations, we buried 13 butchered fish skeletons for 27 months to observe whether the cut marks are still visible after exposure to post-depositional taphonomic processes. After burial, we observed a general decrease – up to 76%, depending on the species of fish – in the number of cut marks visible on fish bone, accompanied by a shift from cut marks on identifiable elements to cut marks on unidentifiable bones and bone fragments. These results impact the methods for analyzing archaeological fish bone, and contribute to our understanding and interpretation of taphonomy, aquatic faunal assemblages, and prehistoric butchering practices.

Articulated skeletons of Palaeoleuciscus aff. oeningensis (Agassiz) (Teleostean fish, Cyprinidae) in the lower Miocene of Frankfurt on the Main (Germany), with a note on cyprinid pharyngeal teeth found in the lower Miocene of the Mainz basin

Two almost complete skeletons of cyprinid fishes were found in the lower Miocene of Frankfurt on the Main. They have not been studied before. It is demonstrated that they are the oldest record of fishes closely related to the middle Miocene (Badenian) cyprinid species Palaeoleuciscus oeningensis (Agassiz), which is known from the middle Miocene (Badenian). The revision of the pharyngeal teeth described by Kinkelin (Ber Senckenberg Naturforsch Ges 1883–1884:219–257, 1884) in the lower Miocene of Frankfurt-Niederrad shows that the material which had originally been identified as Alburnus miocaenicus Kinkelin probably belongs to the genus Palaeoleuciscus Obrhelova. This genus is also present in the Wiesbaden Formation (formerly Lower Hydrobia beds) of Mainz-Weisenau, together with pharyngeal teeth of the genus Palaeotinca Obrhelova, which is also present in the Niederrad Formation of Frankfurt-Niederrad, of which Kinkelin (Ber Senckenberg Naturforsch Ges 1883–1884:219–257, 1884) had already figured as Tinca francofurtanus Kinkelin.

Organic geochemistry and elements distribution in Dahuangshan oil shale, southern Junggar Basin: Origin of organic matter and depositional environment

The Dahuangshan oil shale, located in the northern Bogda Mountain, on the southern margin of the Junggar Basin, was deposited in a Late Permian lacustrine environment. A combined investigation of element and organic geochemistry was performed to define the source rock potential, the paleoenvironment, and source of the organic matter. Thick sequences of oil shales with an average thickness of 638m were deposited in Lucaogou Formation which mainly consists of oil shale, argillaceous dolomite, silty claystone, tuff, limestone, and dolomitic marl. A spot of plant stem fossils and abundance of pyrite crystals, fishtail and fish skeleton can also be found there.Analyzed oil shale samples from Dahuangshan area are characterized by high total organic carbon (TOC) contents (5.6–34.75%), S2 (22.65–199.25mgHC/g rock), hydrogen index (HI, 359–1068mgHC/g TOC), and oil yield (4.9–26.6%), indicating the oil shales have excellent source rock potential. Tmax values (433–453°C) show an early to medium maturation stage of organic matter, which is supported by organic geochemical maturation parameters. All of the obtained kerogen types are types II and I, with oil prone source rock potential.Dahuangshan oil shale samples are rich in SiO2 (68.59%), followed by Al2O3 (10.18%) and Fe2O3 (5.43%). Compared with average shale and North American Shale Composite (NASC), analyzed oil shale samples are obviously enriched in P (0.71%). There is a significant correlation between Al2O3 and Fe2O3, MgO, K2O, MnO, Cu, Ba, Co, and Ni for their association with clay minerals. Besides, the significant correlations between Fe2O3 and MnO, Co, and Ni are considered to result from their similarity on geochemical behavior. All selected oil shales are characterized by distinctly sloping light rare earth elements (LREE) trends (LaN/SmN=2.70–5.95) accompanied by flat heavy rare earth elements (HREE) trends, with distinct Eu negative anomalies (0.60–0.73). Two slightly different patterns of REEs in the oil shale samples are distinguished by the difference in Ce depletion and Nd anomaly.In addition, Dahuangshan oil shale samples are characterized by short- to middle-chain n-alkanes, low carbon preference index (CPI) values (0.93–1.24), single peak composed of nC20 or nC22, low Pr/Ph (0.41–0.91), relatively high Homohop index (0.061–0.99), and high concentrations of C27 sterane, indicating reducing, deep-water, and moderate saline environment with prevalent contribution of algae and microorganisms to organic matter accumulation.

The enigmas of bone without osteocytes

One of the hallmarks of tetrapod bone is the presence of numerous cells (osteocytes) within the matrix. Osteocytes are vital components of tetrapod bone, orchestrating the processes of bone building, reshaping and repairing (modeling and remodeling), and probably also participating in calcium-phosphorus homeostasis via both the local process of osteocytic osteolysis, and systemic effect on the kidneys. Given these critical roles of osteocytes, it is thought-provoking that the entire skeleton of many fishes consists of bone material that does not contain osteocytes. This raises the intriguing question of how the skeleton of these animals accomplishes the various essential functions attributed to osteocytes in other vertebrates, and raises the possibility that in acellular bone some of these functions are either accomplished by non-osteocytic routes or not necessary at all. In this review, we outline evidence for and against the fact that primary functions normally ascribed to osteocytes, such as mechanosensation, regulation of osteoblast/clast activity and mineral metabolism, also occur in fish bone devoid of these cells, and therefore must be carried out through alternative and perhaps ancient pathways. To enable meaningful comparisons with mammalian bone, we suggest thorough, phylogenetic examinations of regulatory pathways, studies of structure and mechanical properties and surveys of the presence/absence of bone cells in fishes. Insights gained into the micro-/nanolevel structure and architecture of fish bone, its mechanical properties and its physiology in health and disease will contribute to the discipline of fish skeletal biology, but may also help answer questions of basic bone biology.

Regionalization of the axial skeleton in the ‘ambush predator’ guild – are there developmental rules underlying body shape evolution in ray-finned fishes?

BackgroundA long, slender body plan characterized by an elongate antorbital region and posterior displacement of the unpaired fins has evolved multiple times within ray-finned fishes, and is associated with ambush predation. The axial skeleton of ray-finned fishes is divided into abdominal and caudal regions, considered to be evolutionary modules. In this study, we test whether the convergent evolution of the ambush predator body plan is associated with predictable, regional changes in the axial skeleton, specifically whether the abdominal region is preferentially lengthened relative to the caudal region through the addition of vertebrae. We test this hypothesis in seven clades showing convergent evolution of this body plan, examining abdominal and caudal vertebral counts in over 300 living and fossil species. In four of these clades, we also examined the relationship between the fineness ratio and vertebral regionalization using phylogenetic independent contrasts.ResultsWe report that in five of the clades surveyed, Lepisosteidae, Esocidae, Belonidae, Sphyraenidae and Fistulariidae, vertebrae are added preferentially to the abdominal region. In Lepisosteidae, Esocidae, and Belonidae, increasing abdominal vertebral count was also significantly related to increasing fineness ratio, a measure of elongation. Two clades did not preferentially add abdominal vertebrae: Saurichthyidae and Aulostomidae. Both of these groups show the development of a novel caudal region anterior to the insertion of the anal fin, morphologically differentiated from more posterior caudal vertebrae.ConclusionsThe preferential addition of abdominal vertebrae in fishes with an elongate body shape is consistent with the existence of a conservative positioning module formed by the boundary between the abdominal and caudal vertebral regions and the anterior insertion of the anal fin. Dissociation of this module is possible, although less probable than changes in the independently evolving abdominal region. Dissociation of the axial skeleton-median fin module leads to increased regionalization within the caudal vertebral column, something that has evolved several times in bony fishes, and may be homologous with the sacral region of tetrapods. These results suggest that modularity of the axial skeleton may result in somewhat predictable evolutionary outcomes in bony fishes.

Palaeoenvironment and taphonomy of a Late Jurassic (Late Tithonian) Lagerstätte from central Poland

A rich assemblage of exceptionally preserved marine and terrestrial fossils occurs in fine-grained limestones in the upper part of the Late Tithonian (Middle Volgian) shallowing upward carbonate sequence in Central Poland. The richest horizon, a deposit known locally as the Corbulomima horizon, is named after the shallow burrowing suspension feeding bivalve Corbulomima obscura, moulds of which occur in densities of up to 500 per square metre on some bedding planes. The fauna in this bed also includes organic and phosphatic remains of a wide range of other creatures including the exuviae of limulids and decapods, disarticulated fish skeletons and rare isolated pterosaur bones and teeth. There are also perfectly preserved dragonfly wings and beetle exoskeletons. The average stable carbon and oxygen isotope values for ostracod shells and fine-grained sediment from this horizon suggest precipitation of the calcium carbonate from warm seawater of normal marine salinity. The carbonate sediments overlying the fossiliferous horizon have been interpreted as nearshore to shoreface facies. These pass abruptly into coarse reworked intraclastic sediments interpreted as possible tsunami or storm surge over-wash deposits. The clasts in this deposit have more positive oxygen isotope values than those in the underlying limestone, which may indicate that they were lithified in a slightly more evaporative, perhaps intertidal, setting. The succession terminates with silicified fine-grained limestones likely to have formed in extremely shallow lagoonal environments. In contrast with the Solnhofen limestones of Lower Tithonian age in south-central Germany the Corbulomima horizon is interpreted as a transitional deposit formed in a shallow marine setting by rapid burial with elements of both Konservat- and Konzentrat-Lagerstätte preservation. □Konzentrat and Konservat-Lagerstätte, Taphonomy, Palaeoenvironment, Paleogeography, Late Jurassic, Poland.

Palaeobatrachids (Amphibia, Anura) in the Oligocene sediments of the “Pirin” Mine (Brezhani Graben, southwestern Bulgaria)

Skeletons and tadpoles of Anura belonging to the palaeobatrachids have been collected in the freshwater Early Oligocene sediments of the “Pirin” Mine, near the village of Brezhani, southwestern Bulgaria. Skeletons of cyprinid fishes are also present in the same bituminous argillite. The anatomical study of the palaeobatrachid skeletons has shown that they should be determined as Palaeobatrachus cf. grandipes (Giebel). This new find extends the geographical distribution of this species and of the family Palaeobatrachidae to the southeastern Europe.

The caudal skeleton of extant and fossil cyprinodontiform fishes (Teleostei: Atherinomorpha): comparative morphology and delimitation of phylogenetic characters

The caudal skeleton of teleost fishes of the order Cyprinodontiformes is described and compared on the basis of 394 extant and eight fossil species, supporting delimitation of 21 phylogenetic characters, of which 13 are firstly reported. The Cyprinodontiformes are unambiguously diagnosed by the presence of a single, blade-like epural, and by principal caudal-fin rays continuous on upper and lower hypural plates. Monophyly of the suborder Cyprinodontoidei is supported by the widened neural and hemal spines of the preural centrum 3 and presence of a spine-like process on the stegural, and monophyly of the Aplocheiloidei by the absence of radial caudal cartilages. A keel-shaped lateral process on the compound centrum supports monophyly of the Nothobranchiidae. Some characters of the caudal skeleton in combination to other osteological features indicate the cyprinodontiform fossil genus †Prolebias to be a paraphyletic assemblage; †P. aymardi, †P. delphinensis and †P. stenoura, the type species of the genus, all from the Lower Oligocene of Europe, possibly are closely related to recent valenciids; †“P.” meridionalis from the Upper Oligocene of France is an incertae sedis cyprinodontid; and, †“P”. cephalotes, †“P”. egeranus and †“P”. malzi from the Upper Oligocene-Lower Miocene of Europe are closely related to poeciliids, probably closely related to the recent African genus Pantanodon due to they sharing unique derived features of pelvic fin, branchial arches and jaws.

The structure-mechanics relationship and the response to load of the acellular bone of neoteleost fish: a review

Although fish species represent probably about half of all vertebrate species, the structure and material properties of fish skeletons are poorly understood. Since osteocytes (cells within the bone tissue) are believed to orchestrate the modeling and remodeling responses in mammalian bone, the unique lack of these cells in the bones of the majority of extant fishes (neoteleosts), raises several intriguing questions. In particular, how do their bones handle forces, especially those applied repeatedly and over long periods of time. This paper reviews the available information regarding the structure-function relationship of teleost bones – namely their known structural features, mechanical properties and response to load – with a particular focus on the acellular bone of neoteleosts. We present preliminary results of ongoing investigations in these areas and highlight topics (e.g. mechanisms of tissue fatigue, repair and resistance to high strain rates) we believe particularly ripe for and demanding further investigation.

Advantages and limitations of X-ray and computed tomography systems for the study of the skeleton in meagre (Argyrosomus regius)

Several methods and procedures exist for the diagnosis of skeletal disorders in fish. X-ray is one of the most reliable diagnosis technologies for medium-sized and large animals, whereas external examination is only of value in animals with extreme and prominent deformities. In small fish (e.g. juveniles or larvae), whole mount staining with alizarin red and/or alcian blue is advisable, although soft-tissue X-ray may be also used. Under this context, the study of the fish skeleton and its morphological and developmental disorders requires an accurate visualization of three-dimensional structures, but few widely applicable methods exist for non-destructive whole-volume imaging of animal tissues. In this sense, computed tomography (CT) has been recently suggested as an alternative or complementary imaging method for the early diagnosis of skeletal deformities, as well as a valuable tool for the current research on the causes and prevention of these anatomical disorders. In this study, we have analysed the skeleton of a 9.3 kg meagre (Argyrosomus regius) by means of standard X-rays (SEDECAL APR-VET 20 KW) and computerized X-ray tomography (HiSpeed Zx/i, General Electric Healthcare) and compared both imaging methods. The vertebral column of the examined specimen was composed by 24 vertebral bodies (including the urostyle) with a regional variation in the morphology of centrums along the vertebral axis. Both imaging methodologies allowed the clear visualization and identification of bony structures composing the skeleton of the meagre. In addition, the CT also allowed performing axial cuts of the meagre in which it was possible to differentiate tissues of different density (e.g. muscle, fat, bone), due to their different attenuation of the X-rays measured in Hounsfield scale. A general view of the potential of such imaging techniques, considering both their advantages and limitations is discussed.

Research for Fish Motion Model

The fish motion essentially reflects the state of water quality, so it is necessary to study the methods of obtaining the real-time dynamic motion characters of fish body in the field of biological monitoring of water quality. From the point of view of the video, to extract the fish skeleton and to establish the motion model. Based on analysis of the motion model, it is easy to acquire some parameters, i. e. , fish swimming velocity and corner, tail dimensionality and so on. The experimental results show that our model can describe fish swimming, which lie a theory foundation for the fish to participate in the environment pollution research.

Occurrence of Fibonacci numbers in development and structure of animal forms: Phylogenetic observations and epigenetic significance

A survey of zoological literature affirmed the wide occurrence of Fibonacci numbers in the organization of acellular and prokaryotic life forms as well as in some eukaryotic protistans and in the embryonic development and adult forms of many living and fossil remains of metazoan animals. A detailed comparative analysis of the axial skeleton of a fossil fish and humans revealed a new rule of the “nested triad” of bones organized along the proximal to distal axis of limb appendages. This growth pattern and its ubiquity among living vertebrates appear to underlie a profound rule of pattern formation that is dictated in part by the genetics and epigenetic mechanisms of stem cell clonal development.

Fossil isopods associated with a fish skeleton from the Lower Cretaceous of Queensland, Australia – direct evidence of a scavenging lifestyle in Mesozoic Cymothoida

Abstract: A dense assemblage of fossil isopod crustaceans (Brunnaega tomhurleyi Wilson, sp. nov.) from the Lower Cretaceous (Albian) Toolebuc Formation of Queensland, Australia, has been found within the carcass of a large actinopterygian fish, Pachyrhizodus marathonensis (Etheridge). Preservation of fine anatomical details supports referral to the genus Brunnaega Polz, which is herein reassigned to the family Cirolanidae. Furthermore, placement of this taxon within the cirolanid subfamily Conilerinae Kensley and Schotte is significant because the group includes modern species that are well known as voracious scavengers. This isopod–fish association represents the oldest unequivocal evidence of scavenging by Mesozoic cymothoidean isopods on a large vertebrate carcass.

Evolution of vertebrate appendicular structures: Insight from genetic and palaeontological data

The new body of evidence from fossils and comparative-developmental analysis of subset of appendicular patterning genes has revealed that limb elements seen in tetrapods are assembled in fish fin over evolutionary time. However, despite of deep homology in basic structure and underlying developmental system, there remains a large morphological gap between distal elements of tetrapod limb and distal fin skeleton of tetrapodomorph fish. Understanding the genetic basis of major transformations in distal-limb morphology is the next challenge for evolutionary developmental biologists. Here by integrating data from fossils, comparative-developmental and genetic studies, models are proposed describing the evolution of cis-regulatory elements as a basis for diversification of appendicular architecture. Instead of emphasizing the subset of developmental genes, for instance Hoxd genes, the focus here is on the significance of elucidating cis-regulatory elements for multiple other key molecular players of limb/fin development and genetic/molecular interactions among them, for a better understanding of the developmental and genetic basis of limb evolution.

Maximum age for a concretion at Green Creek, Ontario

Wood (? Salix sp.) from a concretionary nodule found at - 43 m a.s.l. at the Green Creek, Ontario, site was dated at 9 960 ± 820 BP (GSC-2498). The carbonate concretion has an apparent age of 14 400 ± 250 BP (GSC-2530). The wood date is a maximum age for the enclosing sediment and for its cementation; the carbonate date appears anomalous. At the time of the upper limit of error for the wood date (10 780 BP) Champlain Sea stood at or above 100 m a.s.l. The true age of the wood probably is compatible with that of freswhater shells at - 53 m a.s.l. at Bourget, Ontario (10 200 ± 90; GSC-1968), and of wood at - 61 m a.s.l. at Hawkesbury, Ontario (9 860 ± 330; BGS-257). Terrace sediments at ~ 43 m a.s.l. probably are of freshwater origin. Terrestrial and freshwater flora and fauna in earlier collections of concretions from Green Creek also suggest an estuarine to freswhater environment for the enclosing sediments. Occurrence of complete skeletons of fish and other vertebrates in concretions is related to chemically induced carbonate cementation during early stages of putrefaction of soft-bodied animals. This could preserve skeletal remains through several cycles of erosion. Therefore some concretions carry fossil remains that may be allochtonous to the sediment in which they now occur.

Cellular morphology and markers of cartilage and bone in the marine teleost Sparus auratus

Modifications have been characterised in terms of cellular organisation and the extracellular matrix (ECM) during bone ontogeny in the sea bream (Sparus auratus). During endochondral development, the agglomeration of matrix-secreting cells gives rise to chondrones; these chondrones frequently contain proliferating-cell-nuclear-antigen-positive cells, which subsequently become large collagen-II-positive cells with the characteristics of chondrocytes. Moreover, the matrix:cell ratio within the perichondrium increases, accompanied by a modification in ECM composition. Mineralisation of cartilage ECM is marked by a rapid fall in cell number, the switching off of collagen II transcription and the switching on of collagen X transcription, followed by collagen I transcription and bone mineralisation. The formation of dermal structures initiated upon the condensation of mesenchyme cells defines the future location of the dermal bone. Subsequent cellular differentiation gives rise to cells on the bone surface; these cells are positive for collagen I and osteonectin transcripts. The fish skeleton, with the exception of vertebrae, tends to comprise flattened bones that are covered by a monolayer of cells, the periosteum. A third type of tissue, present in gills, consists of chondrocyte-like cells embedded in a mineralised matrix resembling chondroid bone in mammals. The results suggest that the cellular organisation and ontogeny of endochondral and dermal bone in the sea bream are similar to those described in other vertebrates.