A Palaeozoic shark with osteichthyan-like branchial arches

  title={A Palaeozoic shark with osteichthyan-like branchial arches},
  author={Alan Pradel and John G. Maisey and Paul Tafforeau and Royal H. Mapes and Jon Mallatt},
The evolution of serially arranged, jointed endoskeletal supports internal to the gills—the visceral branchial arches—represents one of the key events in early jawed vertebrate (gnathostome) history, because it provided the morphological basis for the subsequent evolution of jaws. However, until now little was known about visceral arches in early gnathostomes, and theories about gill arch evolution were driven by information gleaned mostly from both modern cartilaginous (chondrichthyan) and… 

An early chondrichthyan and the evolutionary assembly of a shark body plan

Preliminary phylogenetic results highlight the likely convergent evolution of conventional chondrichthyan conditions among earliest members of this primary gnathostome division, while skeletal morphology points towards the likely suspension feeding habits of Gladbachus, suggesting a functional origin of the gill slit condition characteristic of the vast majority of living and fossil chondRichthyans.

A symmoriiform from the Late Devonian of Morocco demonstrates a derived jaw function in ancient chondrichthyans

A previously undescribed symmoriiform shark, Ferromirum oukherbouchi, from the Late Devonian of the Anti-Atlas is reported, in which the jaw articulation is specialized and drives mandibular rotation outward when the mouth opens, and inward upon closure.

A Silurian maxillate placoderm illuminates jaw evolution

A second Silurian maxillate placoderm is described that more securely bridges the jawless toothlike plates of placoderms to the development of the jawed condition that ultimately led to the three-boned jaw in ancestors of modern vertebrates.

The pharynx of the stem-chondrichthyan Ptomacanthus and the early evolution of the gnathostome gill skeleton

Using computed tomography scanning to image the three-dimensionally preserved branchial apparatus in Ptomacanthus, a 415 million year old stem-chondrichthyan, insight is provided into the skull conditions of early jawed vertebrates through three-dimensional computed tomographic imaging.

A symmoriiform chondrichthyan braincase and the origin of chimaeroid fishes

The results of a computed tomography analysis of Dwykaselachus, an enigmatic chondrichthyan braincase from the ~280 million year old Karoo sediments of South Africa, reveal preconditions that suggest an initial morpho-functional basis for the derived chimaeroid cranium, and shed new light on the chondRichthyan response to the extinction at the end of the Devonian period.

Comparative anatomy of the gill skeleton of fossil Aulopiformes (Teleostei: Eurypterygii)

Micro-computed tomography is applied to visualize and describe gill-arch anatomy in three-dimensionally preserved Late Cretaceous–early Palaeogene remains of seven genera attributed to the eurypterygian clade Aulopiformes (lizardfishes), indicating the potential for the extraction of considerable new morphological data – and phylogenetic information – from suitably preserved fossil specimens.

An exceptionally preserved Late Devonian actinopterygian provides a new model for primitive cranial anatomy in ray-finned fishes

An exceptionally preserved ray-finned fish from the Late Devonian (Middle Frasnian, ca 373 Ma) of Pas-de-Calais, northern France is presented, representing by a single, three-dimensionally preserved skull, with no support found for a monophyletic grouping of Moythomasia with Mimiidae.

A three‐dimensional placoderm (stem‐group gnathostome) pharyngeal skeleton and its implications for primitive gnathostome pharyngeal architecture

An articulated, nearly complete pharyngeal skeleton in an Early Devonian placoderm fish, Paraplesiobatis heinrichsi Broili, from Hunsrück Slate of Germany is described and the three‐dimensional gill arch architecture is resolved and reconstructed and compared with other gnathostomes.

First Shark from the Late Devonian (Frasnian) Gogo Formation, Western Australia Sheds New Light on the Development of Tessellated Calcified Cartilage

The specimen is the first Devonian shark body fossil to be acid-prepared, revealing the endoskeletal elements as three-dimensional undistorted units: Meckel’s cartilages, nasal, ceratohyal, basibranchial and possible epibranchials cartilage, plus left and right scapulocoracoids, as well as teeth and scales.

The early elasmobranch Phoebodus: phylogenetic relationships, ecomorphology and a new time-scale for shark evolution

The first skeletal remains of Phoebodus from the Famennian (Late Devonian) of the Maïder region of Morocco are reported, revealing an anguilliform body, specialized braincase, hyoid arch, elongate jaws and rostrum, complementing its characteristic dentition and ctenacanth fin spines preceding both dorsal fins.



Acanthodes and shark-like conditions in the last common ancestor of modern gnathostomes

A new description of the Acanthodes braincase is presented, yielding new details of external and internal morphology, notably the regions surrounding and within the ear capsule and neurocranial roof that contribute to a new reconstruction that, unexpectedly, resembles early chondrichthyan crania.

A Silurian placoderm with osteichthyan-like marginal jaw bones

A three-dimensionally preserved 419-million-year-old placoderm fish from the Silurian of China is described that represents the first stem gnathostome with dermal marginal jaw bones (premaxilla, maxilla and dentary), features previously restricted to Osteichthyes.

Homology of the Fifth Epibranchial and Accessory Elements of the Ceratobranchials among Gnathostomes: Insights from the Development of Ostariophysans

Developmental series strongly suggest that the so-called epibranchial 5 of actinopterygians does not belong to the epal series because it shares the same chondroblastic layer with ceratobranchial 4 and its ontogenetic emergence is considerably late.

Holocephalan Embryo Provides New Information on the Evolution of the Glossopharyngeal Nerve, Metotic Fissure and Parachordal Plate in Gnathostomes

The anatomical study of an embryo of the holocephalan Callorhinchus milii by means of propagation X-Ray Synchrotron phase contrast microtomography and single distance phase retrieval process shows that, contrary to what was previously inferred for holocephalans, the arrangement of the glossopharyngeal nerve relative to the surrounding structure in holicephalans is more similar to that of elasmobranchs.

The Visceral Skeleton and Jaw Suspension In the Durophagous Hybodontid Shark Tribodus limae from the Lower Cretaceous of Brazil

The Lower Cretaceous hybodontid shark Tribodus limae is considered durophagous, based on presence of ‘trabecular cartilage' struts and a weakly heterodont monognathic pavement dentition of flattened hexagonal teeth, as in extant myliobatoid rays.

Shark Pharyngeal Muscles and Early Vertebrate Evolution

The pharyngeal muscles of bony fishes are considered, and concluded to have evolved from a sharklike condition through an acanthodian-like intermediate, and to have been re-interpretation of the evolutionary history of these muscles.

On the Carboniferous shark Tristychius arcuatus Agassiz from Scotland

  • J. R. F. Dick
  • Environmental Science
    Transactions of the Royal Society of Edinburgh
  • 1978
Synopsis Skeletal remains of Tristychius arcuatus commonly occur in ironstone nodules from the Scottish Upper and Lower Oil Shale Groups. This material is clearly distinguishable from the small shark

Evolution of the vertebrate jaw from developmental perspectives

The neoclassical and heterotopy theories are compared from evolutionary developmental perspectives, in conjunction with the development of nasal and hypophyseal placodes, in the context of the evolutionary acquisition of the jaw.

A New Paleozoic Symmoriiformes (Chondrichthyes) from the Late Carboniferous of Kansas (USA) and Cladistic Analysis of Early Chondrichthyans

A new phylogenetic analysis based on neurocranial characters is presented, which supports the third hypothesis and corroborates the hypothesis that crown-group chondrichthyans (Holocephali+Neoselachii) form a tightly-knit group within the chondRichthyan total group, by providing additional, non dental characters.

A new stethacanthid chondrichthyan from the lower Carboniferous of Bearsden, Scotland

The rudimentary mineralization of the axial skeleton and small size of the paired fins are contrasted with the massive, keel-like, spine and brush complex: Akmonistion zangerli was unsuited for sudden acceleration and sustained high-speed pursuit of prey.