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82 ADVANCES IN PALAEOICHTHYOLOGY
The following vertebrate remains are preliminarily identified from the Zadonskian
deposits of the Gornostayevka locality: abundant cranial and postcranial remains of
antiarchs “Bothriolepis” zadonica H. Obrucheva, 1983, Bothriolepis sosnensis
Moloshnikov, 2003, B. cf. leptocheira Traquair, 1893 and Remigolepis ? sp.
(Moloshnikov 2001, 2003); numerous acanthodian fin spines of Devononchus cf. laevis
(Gross, 1933); rare isolated bones of the ptyctodontid Chelyophorus sp. and
pachyosteomorph arthrodires; abundant scales and bones of the porolepiform
Holoptychius cf. nobilissimus Agassiz, 1839, osteolepiforms Megapomus markovskyi
Vorobyeva, 1977 and Glyptopomus sp.; numerous tooth plates and rare cranial and
postcranial bones of dipnoans Conchodus sp., Holodipterus sp. and Dipterus sp.
Material and methods
All skeletal fragments were found disarticulated, some of them were broken, while
others, thin and fragile, are complete. The internal (visceral) surface is generally well
preserved. Cranial materials include: the interorbital part of the skull roof, including
the frontals, anterior part of the parietals and almost complete postfrontals preserved in
natural contact (PIN 2657/346) and an incomplete angular (PIN 2657/347). Postcranial
materials consist of the right cleithrum with partly preserved scapulocoracoid fused to
it (holotype PIN 2657/343) and the distal part of the femur (PIN 2657/344). Specimen
PIN 2657/346 is chosen as holotype, all the remaining cranial and postcranial materials
are referred to it, as there is no certainty in whether all remains belong to the same
taxon. The posterior part of the skull roof PIN 2657/348 is questionably assigned to
Jakubsonia livnensis gen. and sp. nov. The material is stored in the collection 2657 of
the Palaeontological Institute of the Russian Academy of Sciences (PIN).
All specimens were prepared manually with mounted needles.
Systematic palaeontology
Superclass TETRAPODA Goodrich, 1930
Family undesignated
Genus Jakubsonia Lebedev, gen. nov.
Derivation of name – to honour O.L. Jakubson, the member of the Livny town Natural
history and Local Lore museum, who enthusiastically helped excavations.
Type species - Jakubsonia livnensis Lebedev, sp. nov.
Diagnosis. An early Famennian tetrapod characterised by short snout (estimated by
frontals which are only 2.4 times longer than wide) and large orbits. The lateral side of
the prefrontal adjoins the lateral margins of the frontal and postfrontal together, the
dorsal process of the postorbital abuts the posterolateral part of the postfrontal, rather
than wedges between it and the parietal.