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.

The Shotori Range of east-central Iran (east of Tabas) has yielded Famennian ammonoid assemblages dominated by the family Sporadoceratidae. Four genera Maeneceras Hyatt, 1884, Iranoceras Walliser, 1966, Sporadoceras Hyatt, 1884 and Erfoudites Korn, 1999 are represented. The conodont assemblage of one sample containing Iranoceras revealed an Upper marginifera Zone age. The ammonoid assemblages are characterised by comparatively large specimens; they reach conch diameters of 300 mm (including the body chamber) and the mean size is larger than 100 mm. The preservation of the material from the Shotori Range and size comparison with sporadoceratid assemblages from the Anti-Atlas of Morocco and the Rhenish Mountains of Germany suggest that hydraulic sorting has resulted in a bias towards large conchs, explaining the size distribution, rather than latitudinal differences. The new species Maeneceras tabasense is described; the genus Iranoceras is revised with a new description of the two species Iranoceras pachydiscus (Walliser, 1966) and Iranoceras pingue (Walliser, 1966).

The Cleveland Shale fauna represents a unique view of the time after a major Devonian extinction event

(Frasnian–Famenian) with the recovery of arthrodires (Placodermi) best represented by this most specious

North American fauna. This time was followed by an additional event (Hangenberg Biocrisis) leading to the

extinction of arthrodires (and all other placoderms). An understanding of the diversity and interrelationships of

North American arthrodires can aid our understanding of this critical time in vertebrate evolution. A new aspinothoracid

arthrodire Hlavinichthys jacksoni gen. et sp. nov. is described from the Late Devonian of northern

Ohio, U.S.A., which adds to our knowledge of this group. It provides a point of comparison to other members

of the fauna whose interrelationships are poorly known. A phylogenetic analysis supports an assignment of

Hlavinichthys jacksoni gen. et sp. nov. among the aspinothoracid arthrodires. This work has drawn attention to

the continued need for descriptive and phylogenetic analyses of this unique fauna. Decades old species descriptions

need revision along with preparation and description of new taxa. The work on Hlavinichthys jacksoni

gen. et sp. nov. here is one step in that process.

Six enigmatic fossils from the Famennian (Devonian) Cleveland Shale in Ohio, U.S.A., are interpreted here as

arthrodiran (Placodermi) egg cases. Recognition as egg cases is confirmed based on the observation of layered

collagen fibers. The presence of a tuberculated bone fragment preserved within one case confirms a vertebrate

source. The nature of the tubercles and the unique morphology of the egg cases supports the interpretation of

an arthrodiran source. Reports of Devonian egg cases are limited to either assumed chondrichthyan producers

or a putative ‘egg sac’ with a morphology atypical for any vertebrate. The Cleveland Shale egg cases thus

represent the first record for a non-chondrichthyan producer. Among placoderms, behaviors of a pelagic life

style with obligate nesting sites, reef fishes with live birth, and estuarine and fluvial nurseries, along with eggcase

oviparity testifies to the diversity of reproductive strategies. As with modern fishes these strategies may

be ecologically driven and the derived and variable reproductive biology of extant chondrichthyans is actually

a primitive condition among gnathostomes. One consequence of the diversity of reproductive strategies (dependent

on the topology of relationships) is the independent origin of internal fertilization within placoderms,

possibly suggesting external fertilization as the primitive gnathostome reproductive mode.