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C.G.Miller, T. Marss, H. Blom. New anaspid material from Britain and Estonia
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follows the previous ridge; ridges slightly oblique (Fig. 3J) to perpendicular to the long
axis of the scale (Fig. 3I). One specimen with main scale area of chevron-like, continuous
ridges crossing whole of preserved part of scale (Fig 3K). Articulation facet visible on
most complete scale (Fig. 3I). Single, well-developed, central visceral rib occurs on the
smooth lower surface of the scale (Fig. 3L). On two scales, vascular canals exposed
where sculpture of the main scale area has been worn away (Figs 3J, K).
Histology. Well developed vascular canal system present just below level of the main
scale area (Figs 2B, D; 4B, D). Distinct parallel growth lines of compact structure in
the visceral rib of one specimen (Figs 2D, 4D). Fine fibres present both in the sculpture
ridges and visceral rib. Sharpey’s fibres found in one scale (Figs 2B, 4B).
Remarks. Less material was available from Gardner’s Bank than at Man Brook. The
Gardner’s Bank scales were also broken but it was easier to make thin sections of them.
The broken external surface on one specimen that has now been sectioned (Figs 2D,
3K, 4D) suggests that there were a series of closely spaced fine elements forming each
major ridge on the main scale area. These could have been similar to the ridges on
Rhyncholepis parvula Kiær, 1924 (Blom et al. fig. 26m) or Schidiosteus mustelensis
Pander, 1856 (Blom et al. 2002, fig. 30m). Histological sections (Figs 2B, D; 4B,D)
show a well developed vascular canal system that suggest more of a similarity with the
rhyncholepidids Rhyncholepis, Silmalepis, Vesikulepis, Schidiosteus or Rytidolepis. One
specimen (Fig. 3J) also shows traces of vascular canals in a worn area below the sculpture
on the main scale area. Well developed vascular canal systems are consistent with
members of the Family Rhyncholepididae, which at present is confined to the late
Wenlock to middle Ludlow (Blom et al. 2002). Identification of this material under the
Family Rhyncholepididae extends the range of the family to the late Prídolí. More
material from Gardner’s Bank is certainly needed before the genus can be decided with
any certainty.
Conclusions
1. Trimpleylepis gen. nov. is an anaspid that shows similarities to those from the Family
Septentrionidae. However, there is some doubt that vascular canals are developed, so
at present Trimpleylepis can only tentatively be assigned to this family.
2. Two species have been described; Trimpleylepis juncta gen. et sp. nov. from the
Prídolí of the Welsh Borderland at Man Brook and Trimpleylepis concatenata gen. et
sp. nov. from the Ludlow of Estonia.
3. Material described from Man Brook extends the range of the genus Silmalepis to
Ludlow-latest Prídolí.
4. New material from Gardner’s Bank, Welsh Borderland significantly expands the
range of the Family Rhyncholepididae to mid Wenlock-late Prídolí.
Acknowledgements. - Illustrations of NHM material figured within remain copyright of the
NHM. Sally Young, Natural History Museum, provided useful information about sculptures of
Siluro-Devonian vertebrate microremains. Some SEM images were taken in the Centre of Material
Research at Tallinn Technical University by Dr. Valdek Mikli. T.M. acknowledges the receipt of
an Estonian Science Foundation Grant No. 5726.