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Abstract

Ischnacanthus gracilis (Egerton, 1861), the only ischnacanthiform acanthodian from the Lochkovian Lower

Old Red Sandstone of Scotland, is known from hundreds of specimens in institutional collections worldwide.

Despite this relative abundance, morphology and histology of its skeletal elements have rarely been investigated.

Surface details of spines, dental elements, and scales are often not visible in specimens because they are

usually split through the middle. We have examined a broad size range of fish, from 35 mm to 250 mm long.

Several intact (not split) specimens have been collected in recent years and acid-prepared to show fine details of

the dermal and dental elements. We have also used scanning electron microscopy of scales, jaws and dental elements,

denticles and fin spines, and serial thin sectioning of articulated specimens, to document their structure.

Some of our notable observations include: identification of ventral lateral lines, double-layered subtessellate

calcified cartilage forming the jaws, and the probable occurrence of extraoral tricuspid denticles on the jaws

of most fish. Examination of the size range, body proportions and dentition of institutional specimens gives no

support for recognising more than one species in the Midland Valley localities.

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Authors and Affiliations

Michael Newman
ORCID: ORCID
Carole J. Burrow
den Blaauwen Jan
Jones Roger
Davidson Robert
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Abstract

Martes wenzensis Stach, 1959 is the only European Pliocene marten and possible ancestor of an evolutionary lineage leading through Martes vetus Kretzoi, 1942 to Martes martes Linnæus, 1758. Its occurrence ranged between c. 3.6–2.2 Ma and its presence is recorded herein from four sites: three Polish and one Bulgarian (Varshets). The oldest record from Węże 1, dated to 3.6–3.2 Ma, is also the most abundant and the type locality for this species. Only isolated teeth came from two other Polish sites, Węże 2 and Rębielice Królewskie 1A, dated to 2.5–2.2 Ma. The visceocranium from Varshets (c. 2.5 Ma) shows intermediate features between the type specimen from Węże 1 and the Early Pleistocene M. vetus, its possible descendant. The palaeontological records corroborate well with molecular data. The comparison of marten crania from Węże 1 and Varshets shows decrease in size and massiveness of teeth during the evolution of the species. Martes wenzensis shows an admixture of features inherent to M. vetus, M. martes, and M. foina Erxleben, 1777. The species resembles more M. vetus and M. martes than M. foina. It is described as a large, robust marten, with a flat forehead, short and broad viscerocranium, wide snout, robust canines, elongated and narrow premolars and enlarged carnassials.
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Authors and Affiliations

Adrian Marciszak
1
ORCID: ORCID
Grzegorz Lipecki
2
ORCID: ORCID
Nikolai Spassov
3
ORCID: ORCID

  1. Department of Palaeozoology, University of Wrocław, Sienkiewicza 21, 50-335 Wrocław, Poland
  2. Institute of Systematics and Evolution of Animals, Polish Academy of Sciences, Sławkowska 17,31-016 Kraków, Poland
  3. National Museum of Natural History, Bulgarian Academy of Sciences, Tzar Osvoboditel 1, 1000 Sofia,Bulgaria

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