Talivalia undetermined
|
publication ID |
https://doi.org/ 10.5070/P940454153 |
|
publication LSID |
lsid:zoobank.org:pub:58312615-0833-432E-BF5D-3DFFBF361AAA |
|
persistent identifier |
https://treatment.plazi.org/id/B21CD55B-FFC7-FFFA-5872-8C33FA6B2329 |
|
treatment provided by |
Felipe |
|
scientific name |
Talivalia undetermined |
| status |
|
( FIG. 7M–O View Figure 7 ; TABLE 1; SUPPL. 1, FIGS. 4 View Figure 4 , 5 View Figure 5 , 7 View Figure 7 , 30)
Referred specimens —Six scales from BC II; three from level 430.5’ (131.2 m); two broken scales from level 453’ (138.1 m); one scale from 722.5’ (220.2 m): Roberts Mountains Formation.
Description and comparison —Most scales closely resemble the elongate teardrop-shaped trunk scales of Talivalia elongata sensu stricto ( Karatajūtė-Talimaa 1968, 1978). One scale in 430.5’, seen in ventral view has small papillae on the thickened basal torus placed anteriorly (Suppl. 1, fig. 5). Talivalia elongata is well known from many circum-Arctic sites spanning late Přidolí to Lochkovian ( Märss et al. 2007). Turner and Burrow (2018) referred one scale from the late Přidolí Eastport Formation of Moose Island, Maine uncertainly to the genus Talivalia .
“ BARLOWODIDAE ” MÄRSS, WILSON AND THORSTEINS- SON, 2002
BARLOWODUS MÄRSS, WILSON AND THORSTEINSSON, 2002
Type species — Barlowodus excelsus Märss et al., 2002 .
BARLOwODUS TRIDENS MÄRSS, WILSON AND THORSTEINS- SON, 2002
Type material — Holotype scale UALVP 44700 ( Märss et al. 2002, pl. 1, fig. 18), upper Barlow Inlet Formation , southern Read Bay section, Cornwallis Island , Canadian Arctic Archipelago (lowermost Devonian, lower Lochkovian).
BARLOwODUS SP. CF. B. TRIDENS ( FIG. 7 View Figure 7 P- S; TABLE 1; SUPPL. 1, FIG. 4 View Figure 4 )
Referred specimens —one scale from BC II level 430.5’ (131.2 m); one from level 527.25’ (160.7 m); one scale AMF 97874 from BC II level 875’ (266.7 m); this last specimen is missing: Roberts Mountains Formation.
Description and comparison —A scale figured by Parkes (1995, fig. 22.15, 16, captioned as?nikoliviid gen. et sp. indet.; Fig. 7P, Q View Figure 7 ) is c. 0.4 mm long with a broken posterior crown, which rises quite steeply posteriad. The dorsal crown is elongated and subdivided into three with a raised central section with two high flat-topped ridges with a deep central groove anteriorly that flattens poste- riad. Laterally there are expanding lappets,one anteriorly seen to the left, also with a bifurcate dorsal ridge that extends about one-third of the crown, and on the left a series of two broken and one complete ridge that extends about two-thirds of crown length. The posterior points of the lappets tend to be rounded but are also broken. A flattened lateral ridge then extends from the base of the lappets towards the broken posterior tip. The ventral crown is covered with an ultrasculpture of fine parallel striae extending from the anterior crown/neck interface to the posterior tips of the lateral lappets and posterior section of the broken crown. The neck itself is relatively shallow and unornamented. The base is oval, extending about one-quarter of the estimated length of the scale. It is relatively mature with a thick torus surrounding the large central oval pulp opening and with a slight anterior thickening. One small, rounded scale has a strong tripartite crown with deep grooves between the high flat ridges. It is most like the simpler cephalopectoral or trunk of B. tridens (e.g., Märss et al. 2006, text-fig. 65) from the Přidolí Barlow Inlet Formation of Cornwallis Island. The scale from level 527.25’ is tricuspid with clear striated ridges on the sides of the cusps ( Fig. 7R, S View Figure 7 ).
Remarks — Märss et al. (2002, 2006) discovered the thelodont genus Barlowodus in the southern section eastern Cornwallis Island at Read Bay (RBBI and RBBI*), which became the stratotype for the Přidolí Barlow Inlet Formation that is formed from argillaceous carbonate marine rocks. At 59.0 m from only one sample, Märss et al. (2002) identified three taxa, Barlowodus tridens , B. excelsus , and B. floralis , the latter doubtfully. Barlowodus tridens sensu stricto is only known elsewhere from Cornwallis Island. However, scales possibly from this, as well as the other two species of this genus, were recorded from the late Přidolí Barlow Inlet Formation by Märss et al. (2006, pp. 124-126).
The fine microornament on the scale figured by Parkes (1995, fig. 22.15,16; Fig. 7P, Q View Figure 7 ) is similar to that in other Devonian taxa such as Neoturinia spp., Barlowodus flo- rialis and even Boothialepis thorsteinssoni ( Märss et al. 2006, pl. 16). Such fine ridging on the scales might have contributed to drag reduction (e.g., Reif 1985). It is unusual in the Nevadan case being on the ventral surface of the crown; we tentatively refer it to B. sp. cf. tridens . However, it is at a level much higher than the other thelodont scales, in the lower to middle Lochkovian.
BARLOwODUS FLORALIS MÄRSS, WILSON AND THOR- STEINSSON, 2002
Type material — Holotype scale UALVP 44955 ( Märss et al. 2002, pl. 1, fig. 17), upper Barlow Inlet Formation , southern Read Bay section, Cornwallis Island , Canadian Arctic Archipelago (lowermost Devonian, lower Lochkovian).
BARLOwODUS SP. CF. B. FLORALIS ( FIG. 8A–K View Figure 8 ; TABLE 1; SUPPL. 1, FIGS. 4 View Figure 4 , 5 View Figure 5 , 7 View Figure 7 )
Referred specimens — Circa 20 specimens from BC II level 430.5' (131.2 m); two from level 453' (138.1 m): Roberts Mountains Formation .
Description and comparison —Small scales with complex crown sculpture, all with fine ribbed ultrasculp- ture ( Fig. 8A–K View Figure 8 ). One possible head or oral scale has a high multi-ridged crown and high neck with a rounded base and large central pulp opening ( Fig. 8A View Figure 8 ). One possible cephalopectoral scale has a flattened rhombic crown which rises only slightly to a posterior point; fine ultrasculpture as well as borings can be seen on the surface ( Fig. 8B View Figure 8 ). Most scales are trunk scales. The crowns rise gently posteriad with three flat ridges or a system of bifurcating ridges separated by deep or wide grooves. The posterior or posterolateral crown margin is multi-pointed ( Fig. 8A, C–F, H–K View Figure 8 ).
Most scales in level 430.5’ seem affected by fungal damage (as noted for other specimens above). Histology was attempted using anise oil but the structure is disrupted and so we cannot verify the apparent “criss-cross aspidine ‘pegs’” noted as characteristic for the genus and separate family by Märss et al. (2006, p. 121). However, a similar criss-cross pattern of Sharpey’s fiber bundle spaces is found in other deep and swollen old bases of other thelodont scale taxa such as Thelodus laevis (e.g., Bystrow 1957, Gross 1967).
Remarks —Most of the scales from Nevada seem closest to B. floralis . The type locality for the latter is at 34.5* m in the same section where it co-occurs with the other two Barlowodus species ( Märss et al. 2006).
( TABLE 1; SUPPL. 1, FIG. 7 View Figure 7 )
Referred specimens —two scales from BCII section level 453' (138.1 m); two scales from BC II section level 527.25' (160.7 m): Roberts Mountains Formation.
Description —These specimens are not well preserved but might be trunk scales of a species of this genus.
No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.