Devonian arthrodire embryos and the origin of internal fertilization in vertebrates

  title={Devonian arthrodire embryos and the origin of internal fertilization in vertebrates},
  author={John A. Long and Kate Trinajstic and Zerina Johanson},
Evidence of reproductive biology is extremely rare in the fossil record. Recently the first known embryos were discovered within the Placodermi, an extinct class of armoured fish, indicating a viviparous mode of reproduction in a vertebrate group outside the crown-group Gnathostomata (Chondrichthyes and Osteichthyes). These embryos were found in ptyctodontids, a small group of placoderms phylogenetically basal to the largest group, the Arthrodira. Here we report the discovery of embryos in the… 

Pelvic claspers confirm chondrichthyan-like internal fertilization in arthrodires

The discovery of a completely ossified pelvic clasper in Incisoscutum ritchiei is reported which shows that the basipterygium described previously is in fact unique to females.

A preliminary note of egg-case oviparity in a Devonian placoderm fish

Six enigmatic fossils from the Famennian (Devonian) Cleveland Shale in Ohio, U.S.A., are interpreted here as arthrodiran (Placodermi) egg cases, representing the first record for a non-chondrichthyan producer and suggesting external fertilization as the primitive gnathostome reproductive mode.

Superfoetative viviparity in a Carboniferous chondrichthyan and reproduction in early gnathostomes

The fossilized remains of two specimens of Harpagofututor volsellorhinus from the Upper Mississippian of Montana now provide the first direct evidence of matrotrophic live birth in a Palaeozoic chondrichthyan and of superfoetation in an extinct fish.

Placodermi (Armoured Fishes)

They are the earliest true jawed vertebrates that show a number of anatomical features, illustrating the primitive condition in forthcoming other vertebrates and are the first fish to adapt to different modes of life and to various reproductive strategies.

Pelvic and reproductive structures in placoderms (stem gnathostomes)

The morphology of the pelvic region within the arthrodires and ptyctodonts is reinterpreted and it is suggested that clasper position relative to the pelvic fins was determined by genes responsible for limb position.

Exceptional preservation of organs in Devonian placoderms from the Gogo lagerstätte.

Arthrodires show the earliest phylogenetic evidence for repositioning of the gnathostome heart associated with the evolution of the complex neck region in jawed vertebrates.

Evolution of vertebrate viviparity and specializations for fetal nutrition: A quantitative and qualitative analysis

Phylogenetic analyses indicate that viviparity has originated independently in more than 150 vertebrate lineages, including a minimum of 115 clades of extant squamate reptiles, and substantial matrotrophy has arisen at least 33 times in these v Viviparous clades.

Evolution of vertebrate postcranial complexity: axial skeleton regionalization and paired appendages in a Devonian jawless fish

Find out more about the research and teaching at the UMR CNRS, which aims to provide a “future-proof” view of the natural world through the lens of science and technology.

Fusion in the vertebral column of the pachyosteomorph arthrodire Dunkleosteus terrelli (‘Placodermi’)

The synarcual is described in a subadult specimen of the pachyosteomorph arthrodire Dunkleosteus terrelli, preserving 16 paired vertebral elements showing varying degrees of anteroposterior fusion along the vertebral column.

The erroneous chondrichthyan egg case assignments from the Devonian: implications for the knowledge on the evolution of the reproductive strategy within chondrichthyans.

The presence of the genus Spiraxis in both the USA (east coast) and Belgium reinforces the strong faunal resemblance already observed in both palaeogeographical areas and suggests important faunaal exchanges between these regions of the Euramerica landmass during the Famennian.



Live birth in the Devonian period

The oldest record of a live-bearing vertebrate in a new ptyctodontid placoderm, Materpiscis attenboroughi gen. et sp.

The braincase and jaws of a Devonian ‘acanthodian’ and modern gnathostome origins

The first-known braincase of an Early Devonian acanthodian is presented, andylogenetic analysis resolves Ptomacanthus as either the most basal chondrichthyan or as the sister group of all living gnathostomes, to provide a more detailed picture of the acquisition of early Gnathostome characters.

Unusual preservation of the internal organs of acanthodian and actinopterygian fish in the Middle Devonian of Scotland

Synopsis Relics of internal organs identified as kidney, liver and heart, and also eyes of acanthodian and actinopterygian fishes, have been found in specimens from the Middle Devonian nodule bed

Cowralepis, a new genus of phyllolepid fish (Pisces, Placodermi) from the Late Middle Devonian of New South Wales, Australia

The Cowralepis material has suffered regional tectonism and illustrates why tectonic deformation must be taken into account in the interpretation of fossils from ancient fold belts.

First record of live birth in Cretaceous ichthyosaurs: closing an 80 million year gap

  • E. MaxwellM. Caldwell
  • Environmental Science, Geography
    Proceedings of the Royal Society of London. Series B: Biological Sciences
  • 2003
New fossils of embryonic ichthyosaurs are both the geologically youngest and the physically smallest known ichysosaur embryos, and are located within the body cavity of an adult, presumably the mother.

Supertree analyses of the roles of viviparity and habitat in the evolution of atherinomorph fishes

  • J. MankJ. Avise
  • Environmental Science, Biology
    Journal of evolutionary biology
  • 2006
Despite being correlated with decreased brood size, livebearing has not significantly increased extinction risk in the Atherinomorpha, however, freshwater species were significantly more likely than marine species to be listed as endangered.

The unique fossil assemblage from the Lode Quarry (Upper Devonian, Latvia)

Abstract. The unique fossil fauna from the Lode clay quarry, lower Frasnian, Latvia, includes a diverse ichthyofauna of at least 15 taxa of agnathans and gnathostomes, representing most of the major

Development of the pelvic fins of acipenser ruthenus. New data for the theory of the paired fins of fishes

The adult Chondrosteoidei have retained the primitive fin structure which characterized the elasmobranchs of the Palaeozoic period and which has disappeared in recent forms.

Early growth stages in coelacanth fishes.

  • H. Schultze
  • Geography, Environmental Science
    Nature: New biology
  • 1972
It seems more reasonable to interpret this fossil specimen from the Upper Jurassic of Solnhofen, southern Germany, as a cannibal that had just swallowed two young of its own kind, and this interpretation is favoured by the position of the two specimens.