0000000000132890
AUTHOR
Ervīns Lukševičs
The earliest evidence of host-parasite interactions in vertebrates
Luk s evics, E., Lebedev, O. A., Mark-Kurik, E. and Karataj u te-Talimaa, V. 2009. The earliest evidence of host‐parasite interactions in vertebrates. — Acta Zoologica (Stockholm) 90 (Suppl. 1): 335‐343 Traces of parasite action have been discovered in the Middle‐Upper Devonian fish from Estonia, Latvia and European Russia. Such traces are known in heterostracan Psammolepis venyukovi , antiarchs Asterolepis radiata and Bothriolepis ciecere , sarcopterygians Holoptychius sp., Ventalepis ketleriensis and Eusthenodon sp. nov. The traces include evidence of parasitic fixation and penetration as well as dwelling traces. Pathologies are developed as (1) round fossulae on the external surface of b…
The orbito-nasal area ofAsterolepis ornata, a Middle Devonian placoderm fish
The structure of the orbito-nasal cavity in the antiarchan placoderm fish Asterolepis ornata has been studied, providing a detailed description of the premedian, rostral, and pineal plates, and bones of the sclerotic ring. Both eyes and nostrils were directed antero-latero-dorsally in Asterolepis. Eyes were enclosed within the sclerotic capsule. Nasal cavities were not opened into a so called “prenasal slit,” but directly above the head of fish. A new reconstruction of the nasal openings and position of the nasal sacs shows broader similarities between various antiarchs than was previously claimed, and allows the evaluation of the differences in the structure of the orbito-nasal cavities in…
The biostratigraphical and palaeogeographical framework of the earliest diversification of tetrapods (Late Devonian)
International audience; The earliest diversification of tetrapods is dated as Late Devonian based on 10 localities worldwide that have yielded bone remains. At least 18 different species are known from these localities. Their ages span the "middle"-late Frasnian to latest Famennian time interval, with three localities in the Frasnian, one at the F/F transition (though this one is not securely dated) and six in the Famennian. These localities encompass a wide variety of environments, from true marine conditions of the nearshore neritic province, to fluvial or lacustrine conditions. However, it does not seem possible to characterize a freshwater assemblage in the Upper Old Red Sandstone based…
The Devonian Stratigraphic Succession and Evolution of the Baltic Sedimentary Basin
Facies analysis, biostratigraphic and taphonomic studies, a re-evaluation of signatures of worldwide events, and a new mathematical model of the Baltic sedimentary basin (BSB) have together enabled a better understanding to be gained of the development of the Devonian basins in the Baltic area. We have established four stages of basin evolution: (a) remnant basin stage (Lochkovian); (b) shallow epeiric basin stage, with mainly siliciclastic sedimentation (Pragian–early Frasnian); (c) shallow epeiric basin stage, with mainly carbonate sedimentation (Frasnian); and (d) infilling stage of the progressively narrowing shallow epeiric basin, with mixed sedimentation (Famennian).
Taphonomy of the vertebrate bone beds from the Klūnas fossil site, Upper Devonian Tērvete Formation of Latvia
Combined sedimentological and taphonomical study of the siliciclastic sequence of the Tērvete Formation in the stratotypical area was aimed at revealing the formation of the three oryctocoenoses discovered and related structural and textural features of the deposits, as well as at detailed observation of the taphonomical peculiarities of the obtained palaeontological material. The fossil vertebrate assemblage is represented by 14 taxa comprising placoderms, acanthodians, sarcopterygians and actinopterygians. The three oryctocoenoses, first recognized in 2010, differ in the proportions of repeatedly buried material, in the number and degree of preservation of small and fragile skeletal eleme…
Ventastega curonica and the origin of tetrapod morphology.
The gap in our understanding of the evolutionary transition from fish to tetrapod is beginning to close thanks to the discovery of new intermediate forms such as Tiktaalik roseae. Here we narrow it further by presenting the skull, exceptionally preserved braincase, shoulder girdle and partial pelvis of Ventastega curonica from the Late Devonian of Latvia, a transitional intermediate form between the 'elpistostegids' Panderichthys and Tiktaalik and the Devonian tetrapods (limbed vertebrates) Acanthostega and Ichthyostega. Ventastega is the most primitive Devonian tetrapod represented by extensive remains, and casts light on a part of the phylogeny otherwise only represented by fragmentary ta…