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Fragments of the head shield of Dunkleosteus sp. A, specimen Muz. PGI-NRI 1809.II.18, back view. B, specimen Muz. PGI-NRI 1809.II.18, visceral view. B1, magnified fragment of fig. B. C, specimen Muz. PGI-NRI 1809.II.18, external view. C1, sketch of the external view of the specimen on C. Abbreviations for Figs 2, 4 and 6: Ce, central plate; d end, opening of the endolymphatic duct; dp. m. cu., cucullaris depression; f.lv, levator pits; laf, lateral articular fossa; m.sept, median septum; Nu, nuchal plate; PNu, paranuchal plate; pap, para-articular process; p.pr, posterior process of the nuchal plate; PrO f., contact face for the preorbital plate; ppt, pineal pit; th.n, nuchal thickening; th.pre, pre-endolymphatic thickening.
Source publication
The arthrodire placoderm, Dunkleosteus sp., is reported from the Upper Devonian (Frasnian) of the Holy Cross Mountains, Poland. The material comprises partially preserved remains of two individuals found in the Kellwasser-like horizon of the P³ucki locality. The remains are preserved as broken bone fragments redeposited from shallower environment i...
Contexts in source publication
Context 1
... material collected comprises therefore putative associations of two individuals. Association 1 consists of the posterior part of a skull roof including the nuchal plate and partly preserved paranuchal (mostly left one) and central plates (Muz. PGI-NRI 1809.II.18, Fig. 2A- C), both partially preserved anterior dorsolateral plates (Muz. PGI-NRI 1809.II.20,21; Fig. 3A, B and the right suborbital plate (Muz. PGI-NRI 1809.II.22; Fig. 3C, D). Association 2 comprises the posterior part of a skull roof including the nuchal plate and partly preserved paranuchal and central plates (MWG UW ZI/43/0053, Fig. 4A, ...
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... and at the Faculty of Geology, University of Warsaw, Warsaw (abbreviated MWG UW). Figs 2B, 6A). The anterior margin of this plate that contacts with the central plates bears a prominent wide V-shaped projection between both central plates. ...
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... transverse occipital thickening of the nuchal plate is continuing that of the paranuchal plates which are preserved on the both sides of the specimen. Internal and external openings of the endolymphatic duct are also preserved (Fig. 6B). The internal opening is located about 1 cm ahead towards levator pits at the base of the occipital thickening (Fig. 2B). The external opening is visible about 1.5 cm from the posterior margin of the paranuchal plate (Fig. 4B). On its outer surface the paranuchal plate carries the sensory line grooves for the main lateral line and posterior pitline. Their connection is not preserved but it seems that they meet at about 80°. Parts of two poorly preserved ...
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... pitline. Their connection is not preserved but it seems that they meet at about 80°. Parts of two poorly preserved anterior dorsolateral plates (Muz. PGI- NRI 1809.II.20 -right, Muz. PGI-NRI 1809.II.21 left; Fig. 3A, B) and the right suborbital plate (Muz. PGI-NRI 1809.II.22) have been found in association with specimen Muz. PGI-NRI 1809.II.18 ( Fig. 2A-C). The suborbital plate comprises the suborbital lamina preserved only in its anteriormost part and the blade which seems to be preserved completely but is strongly eroded. The blade is about 18 cm long and its maximum width reaches 4 cm. The lamina for the posterior supragnathal is well visible, especially on the cross section (Fig. 3D, ...
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... and thin septum (about 0.2 mm). The posterior part becomes thicker and finally forms Fig. 6. A, sketch of specimen Muz. PGI-NRI 1809.II.18 in visceral view. B, restoration of the part of the head shield and the median dorsal plate. Abbreviations: lc, main lateral-line canal; MD, median dorsal plate; ppl, posterior pit line; for the rest see Fig. 2. a carinal process which is broken almost at the base. There are elongated contact faces on the posterolateral margins of the plate for the posterior dorsolateral ...
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... MWG UW ZI/43/0053 (Fig. 4A, B), Muz. PGI-NRI 1809.II.19 ( Fig. 2A, B) and Muz. PGI-NRI 1809.II.23 (Fig. 4C) putatively represent one individual and similarly another association of specimens Muz. PGI-NRI 1809.II.18 ( Fig. 2A, B), Muz. PGI-NRI 1809.II. 20, 21 (Fig. 3A, B) and 22 (Fig. 3C, D). There is of course a possibility that all fragments represent different fishes and species as well. It was one of ...
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... MWG UW ZI/43/0053 (Fig. 4A, B), Muz. PGI-NRI 1809.II.19 ( Fig. 2A, B) and Muz. PGI-NRI 1809.II.23 (Fig. 4C) putatively represent one individual and similarly another association of specimens Muz. PGI-NRI 1809.II.18 ( Fig. 2A, B), Muz. PGI-NRI 1809.II. 20, 21 (Fig. 3A, B) and 22 (Fig. 3C, D). There is of course a possibility that all fragments represent different fishes and species as well. It was one of the reasons why we have decided to leave the identification rather ...
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... nuchal plates are characterized by a similar development of the levator pits areas which show the same thin transverse ridge that is bounding pits posteriorly. In specimen MWG UW ZI/43/0053 (Fig. 4A) this ridge is almost incorporated into the posterior margin of the plate, whereas it is more prominent in specimen Muz. PGI- NRI 1809.II.18 ( Fig. 2A, B). This difference may be ontogenetic because specimen MWG UW ZI/43/0053 (Fig. 4A) is larger and therefore may represent an older stage than PGI-NRI 1809.II.18 ( Fig. 2A, B). Anyway, this feature (pits bounded by the ridge are small posteriorly or almost absent) is unusual for Dunkleosteus (e.g. Carr & Hlavin 2010, fig. 6A, B) and occurs ...
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... MWG UW ZI/43/0053 (Fig. 4A) this ridge is almost incorporated into the posterior margin of the plate, whereas it is more prominent in specimen Muz. PGI- NRI 1809.II.18 ( Fig. 2A, B). This difference may be ontogenetic because specimen MWG UW ZI/43/0053 (Fig. 4A) is larger and therefore may represent an older stage than PGI-NRI 1809.II.18 ( Fig. 2A, B). Anyway, this feature (pits bounded by the ridge are small posteriorly or almost absent) is unusual for Dunkleosteus (e.g. Carr & Hlavin 2010, fig. 6A, B) and occurs not very often. A similar case was illustrated by Lehman (1956, pl. 16F), who identified his fragmentary specimen as Dinichthyidae sensu lato. The shape and morphology of ...
Citations
... Dunkleosteus currently exists as a wastebasket taxon containing a large number of species established upon various isolated, non-overlapping skeletal elements, and many are insufficiently characterized or probably synonymous with other taxa. This is also not considering additional Dunkleosteus material from California [70], Texas [71] and Poland [72] which has been only referred to as Dunkleosteus sp. ...
A new species of Dunkleosteus, D. tuderensis sp. nov., is named based on an infragnathal from the Famennian of the Tver Region, Russia. CT scanning of the holotype revealed two high-density bony constituents comparable in position and interrelations to components described for coccosteomorph arthrodires, supported by the presence of at least two clusters of large vascular canals marking separate arterial supplies. Coccosteomorph and dunkleosteid pachyosteomorphs exhibit similar growth patterns including labio-basal depositions of vascularized bone in the infragnathals and basally in the supragnathals. In contrast to coccosteomorphs, dunkleosteid reinforcement of the occlusal margins occurred via the formation of dense osteonal bone, in parallel with resorption forming extensive lingual fossae. Active bone remodeling proceeded without a complete reworking of the primary osteonal bone structure and the original arrangement of vascular canals. Due to inconsistent anatomical terminology in gnathal elements of dunkleosteid arthrodires, a revised terminology is suggested and new terms are introduced.
... It is difficult to ascertain if the smaller size is merely a regional characteristic or due to the younger ontogenetic stage of the described specimen. It is also noteworthy that the Gorgonichthys from Kowala described herein and the Dunkleosteus from Płucki (Szrek and Wilk, 2018) are the only large marine predators ever found in the Devonian of the Holy Cross Mountains. They appeared during the Late Devonian, correlated with the general submersion of the entire area and the change in placoderm assemblages, with the Early and Middle Devonian demersal assemblages replaced by Late Devonian diversified nektonic-dominated communities (Szrek, 2020). ...
... Numerous vertebrate remains are represented mainly by arthrodire placoderms and show various states of preservation, reflecting their history before subsequent burial (Szrek and Wilk 2018). Most of the fragments are disarticulated and show marks of abrasion (Fig. 7a). ...
Of all the Devonian stratigraphic boundaries, the Frasnian–Famennian transition (372.2 ± 1.6 Ma) preserves the record of one of the most significant crises in the history of life, the final stages of which lie buried in the distinctive Kellwasser limestone. The Kellwasser facies occur in Western and Central Europe and the commonly cited Płucki area of Poland’s geologically rich Holy Cross Mountains is the only site in that region where the Frasnian–Famennian boundary is considered to occur within Kellwasser facies. At this locality, the limestone contains slump structures, comprising contorted beds and folds. Actually the Kellwasser-like limestone from Płucki is composed of a mixture of three distinct types of sediment, occurring as clasts, commonly deformed and sheared, and matrix, rather than being one homogenous bed, as previously considered. Thus, earlier studies and interpretations of this limestone may need revising. This paper documents the evidence for sediment erosion and reworking, debris flows, sliding and soft-sediment deformation on a submarine slope, and suggests that seismic events were the likely triggering mechanism for slumping and resedimentation.
... Regarding many world-wide famous dis- coveries based of fossil record of Łagów, e.g. sex- ual dimorphism of ammonoids (Makowski 1963), record of the 2nd biggest extinction event in the history of life ( Racki et al. 2002), well-preserved big placoderm fish assemblage (Szrek, Wilk 2018), the name of Łagów and its vicinities is becoming to be recognisable among non-geologists tourists. Actually, the marine Devonian strata (419-365 Ma), the most abundant on the described area, are so folded and faulted that the exact nature of the rock succession has not yet been wholly de- termined, and still may bring new discoveries as a 'scientifically open' area. ...
