Kujdanowiaspididae, Berg, 1955
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publication ID |
https://doi.org/ 10.4202/app.00395.2017 |
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persistent identifier |
https://treatment.plazi.org/id/566487BD-1672-FFBE-AA58-FEFDFA44F805 |
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treatment provided by |
Felipe |
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scientific name |
Kujdanowiaspididae |
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Kujdanowiaspididae indet.
Fig. 4A–I View Fig .
Material.—MZ-VIII/Vp-485, 487, Muz PGI 1733.II.285, 340, 365, spinal plates ( Fig. 4A–E View Fig ); Muz PGI 1733.II.81, 384, 442, median dorsal plates ( Fig. 4F–H View Fig ); MZ-VIII/Vp- 520, post median dorsal scute ( Fig. 4I View Fig ); Podłazie hill, Lower Devonian, Emsian.
Description.— Spinal plates: All spinal plates are incomplete. MZ-VIII/Vp-485 ( Fig. 4B, D View Fig ) and Muz PGI 1755.II.340 ( Fig. 4E View Fig ) are preserved as a cast of the dorsal side, as indicated by the groove for the insertion of the anterior lateral plate; Muz PGI 1733.II.340 is preserved as cast of the ventral side. Muz PGI 1733.II.365 and Muz PGI 1733.II.285 are preserved as three-dimensional casts of the distal part with broken tips. The largest plate (MZ-VIII/Vp-487, Fig. 4A View Fig ) is 93 mm long and 25 mm wide in its proximal part. The plate is gently curved posteromesially. Its surface (dorsal and ventral) is ornamented with small densely distributed tubercles. The size of tubercles is uniform and does not exceed 1 mm in diametre. The mesial margin of the biggest specimens (MZ-VIII/Vp- 485, 487) is ornamented with one row of anteriorly directed thorn-like spinelets which are bigger than the tubercles, and whose size increases posteriorly. Their amount varies from 6 MZ-VIII/Vp-487, Fig. 4A View Fig ) to 7 (Muz. PGI 1733.II.485, Fig. 4B View Fig ) or are absent (Muz PGI 1733.II.285, Fig. 4C View Fig ; Muz PGI 1733.II.340, Fig. 4D View Fig ), although this absence is most likely a preservational artefact. The numbers of those spinelets does not constitute a maximum because of the fragmentary state of preservation and the broken top of spinal plates.
Median dorsal plates: The median dorsal plate is almost as long as wide and has a rounded?-pentagonal outline. Specimens are similar in size: about 40 mm broad and 45 mm long. Width/length index is 88 (based on Muz PGI 1733.II.384 which is the most complete specimen). The latter possesses a low crest which is almost flattened anteriorly but more arched posteriorly. The entire surface is ornamented with coarse, generally irregularly arranged tubercles of a maximum of 1 mm in diametre. On the Muz PGI 1733.II.384 ( Fig. 4G View Fig ), tubercles in the posterior part are arranged in rows radiating from the center located approximately at the geometric center of the plate.
Posterior median dorsal scute: The plate is partially preserved and represents probably the first posterior median dorsal scute. Its anterior part is broken and missing. It is 24 mm wide, and was at least 20 mm long. In posterior view the triangular overlap area is visible ( Fig. 4I View Fig 2 View Fig ). The anterior area is characterised by pronounced raised area which makes a short ridge falling towards the front. The ornamentation consists of tubercles which vary from small (0.7–0.8 mm), densely arranged and coalesced in ridges in the center to bigger (1 mm) and more widely spaced on distal areas.
Remarks.—The spinal plates vary in sizes but all of them are bigger than the plates described and illustrated by Dupret (2010: 21–22, fig. 16A, B). The distance between the pectoral notch and the tip of the plate in Kujdanowiaspis podolica ( Dupret 2010: fig. 16A, B) is 36 mm, whereas the length of the incomplete MZ-VIII/Vp-487 ( Fig. 4A View Fig ) reaches 68 mm. The described spinal plates differ from their homologues in K. podolica or Kujdanowiaspis buczaczensis by bigger sizes, more comparable with “ Acanthaspis ” armatus ( Heintz 1929: fig. 4B). Thorn-like spinelets are prominent and similar to those described and illustrated by Dupret (2010: fig. 2F) and Dupret et al. (2011: fig. 3I). Features described above allow to identify MZ-VIII/Vp-485, MZ-VIII/Vp-487, and Muz PGI 1733.II.285, Muz PGI 1733.II.340 ( Fig. 4A–E View Fig ) as belonging to Kujdanowiaspis sp. All morphological features fit within the Kujdanowiaspis characters observed within the K. podolica , despite the much bigger sizes compared to that of the Podolian material. The absence of other articulated remains induces us to leave this identification in open nomenclature. Reasons of size differences may be related to regional, stratigraphic, ontogenetic and of course taxonomical/phylogenetic variation. Similar large actinolepids are, however, different in morphology and were described from the Pragian of the northwestern Siberian Platform ( Eukaia elongata Mark-Kurik, 2013 ) and from the Givetian of the East European Platform ( Actinolepis magna Mark-Kurik, 1973 ).
The overall shape of the median dorsal plate reminds the plate of K. podolica ( Dupret 2010: fig. 17A, B) being as wide as long and more or less pentagonal, but the low posterior part and the coarse and dense tuberculation is more reminiscnent of Erikaspis zychi ( Dupret et al. 2007) . The plate is also low, reminding the Erikaspis disposition rather than the roof-shaped one in K. podolica or K. buczacziensis . The blunt posterior tip and the crest as long as the posterior half of the plate is also encoutered in Erikaspis zychi and Actinolepis magna . Moreover, median dorsal plate in K. podolica in the posterior part makes a prominent lobe. This character is absent in the studied Polish specimens and resembles the outline of median dorsal plate in Aleosteus eganensis ( Johnson et al. 2000: fig. 2C) and Erikaspis z ychi ( Dupret et al. 2007). An other difference resides in the Polish specimens being relatively low in comparison with the roof-shaped median dorsal plate in K. podolica ( Dupret 2010: fig. 17C) and Aleosteus eganensis ( Johnson et al. 2000: fig. 2D). In this matter, the studied Polish specimens are very similar to Erikaspis zychi ( Dupret et al. 2007: fig. 9A–C), which possesses the same ornamentation pattern, is low and possesses a low crest on the posterior half of its dorsal side. The only difference is that the specimen Muz. PGI 1733.II.384 ( Fig. 3G View Fig ) is anteriorly elongated when compared with Erikaspis zychi ( Dupret et al. 2007: fig. 9A).
The posterior median dorsal scute plate does not show any exceptionally diagnostic features. Size, shape and ornamentation pattern are similar to those illustrated by Johnson et al. (2000: fig. 2A, B), Dupret (2010: fig. 24C–I), and Dupret et al. (2007: fig. 11 E–G). We think that the plate must belong with certainty to an actinolepidoideid placoderm, probably close or belonging to the Kujdanowiaspididae .
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