Newly collected and restudied earlier materials on an enigmatic fish Ventalepis ketleriensis Schultze, 1980

from the upper Famennian (postera – ? Lower expansa conodont zones) of Latvia and central and northwestern

Russia support its porolepiform affinities. A new family Ventalepididae fam. nova is established for this genus

upon a peculiar combination of characters, including scale structure and dermal bones ornamentation. New

records extend the distribution of this genus and the Ventalepis vertebrate assemblage on the whole to a vast

geographical zone along the south-eastern coast of the Old Red Sandstone continent. The habitat area of the

Devonian vertebrate assemblage over such a large territory within the zoogeographical province of Baltica is

established for the first time. Palaeozoogeographical analysis suggests Laurentian affinities of the Ventalepis

assemblage demonstrating the major congruency to the Belgian and East Greenland ones. These and Russian

localities are separated by a vast ORS continent. Presence of the dipnoan Jarvikia in all three locations, as well

as an Ichthyostega-like tetrapod in the Belgian one reveals palaeozoogeographical connections, which might

reflect possible dwelling not only in the near-shore continent periphery but also in the river systems of the

continent itself.

Very rare chondrichthyan spines from the Famennian (Upper Devonian) of European Russia are referred here to ctenacanthiforms, euselachians and a chondrichthyan group of uncertain systematic position. Ctenacanthus Agassiz, 1837 is recorded from the lower and middle Famennian of the central and north-western parts of the area. Sculptospina makhlaevi Lebedev gen. et sp. nov. originates from the lower Famennian of the Lipetsk Region. The holotype of ‘Ctenacanthus’ jaekeli Gross, 1933 and a new specimen from the upper Famennian of the South Urals are shown to belong to the same taxon, which is transferred to Acondylacanthus St. John and Worthen, 1875. New specimens of Tuberospina nataliae Lebedev, 1995 from the upper Famennian of Central Russia are described in detail. The newly presented material increases our knowledge of the composition of Famennian marine assemblages from the East European Platform. It is suggested that these assemblages may be classified as chondrichthyan-dominated and dipnoan-dominated. Hypothetically, after the end- Devonian Hangenberg extinction event, which affected numerous secondary consumers in vertebrate communities, some chondrichthyan groups could have encroached to take advantage of previously occupied ecological niches. Ctenacanthus, as well as Acondylacanthus and Amelacanthus survived the end-Devonian mass extinction to continue into the Carboniferous.