A conodont, thelodont and acanthodian fauna from the Lower Přídolí (Silurian) of the Much Wenlock area, Shropshire

Abstract

Conodonts, thelodonts and acanthodians have previously been collected from the Přídolí of Shropshire (Welsh Borderland) from bone beds such as the Ludlow Bone Bed. In general, specimens collected from these types of deposit are very abraded and make taxonomic studies difficult. This contribution describes well preserved thelodont microelements from two samples from the Downton Castle Sandstone Formation (Přídolí, Silurian) of the Much Wenlock area of Shropshire. Head scales, a wide variety of transitional scales, and pore scales of the lateral line sensory canals of the thelodont Paralogania ludlowiensis (Gross) are described for the first time. A new acanthodian Nostolepis linleyensis sp. nov. and elements from the apparatus of the conodont Ozarkodina?hemensis sp. nov. are documented from the same samples. The thelodonts in both samples are typical of upper Ludlow–Přídolí faunas from across the Welsh Borderland, and are also present in smaller numbers in the Ludlow Series of Gotland, Sweden, Saaremaa Island, Estonia, and in Latvia and Lithuania. The conodont O? hemensis sp. nov. is restricted to the Much Wenlock area of Shropshire. The co‐occurrence of well preserved elements of conodonts and thelodonts suggests that they were deposited fairly rapidly with little or no re‐working and that a restricted marine environment prevailed in the early Přídolí in the Much Wenlock area of Shropshire.

At what stratigraphical level is the mid Ludfordian (Ludlow, Silurian) positive carbon isotope excursion in the type Ludlow area, Shropshire, England?

“…However, this is unlikely because these strata (and those overlying them) contain geographically widespread conodont, thelodont and chitinozoan taxa (e.g. Miller 1995, Miller et al 1997, Miller & Märss 1999, suggesting good connections with the open ocean. Chitinozoan biostratigraphy indicates that this is not the level to look for the mid Ludfordian positive CIE anyway.…”

“…5). Miller & Märss (1999) Based on the presence of the thelodont Paralogonia ludlowiensis not only in the Ludlow Bone Bed Member but also in the Sandstone Member of the Downton Castle Sandstone Formation and the stratigraphical occurrences of this species in Estonia and Latvia, the lower part at least of the Downton Castle Sandstone Formation is probably of mid Ludfordian age.…”

Revision of Silurian vertebrate biozones and their correlation with the conodont succession

“…That paper also presented the first carbon isotope data from the region and correlated δ 13 C variations with those in the Baltic area. The taxonomy and distribution of agnathans and fishes in southern Britain have been investigated, the regional vertebrate zonal scheme has been updated and characteristic vertebrate assemblages have been correlated with the conodont zonation (Miller & Märss 1999;Turner 2000;Märss & Miller 2004). …”

Late Silurian (Ludlow) and Early Devonian (Pragian) conodonts from the Cobar Supergroup, western New South Wales, Australia

“…This taxon, originally based on Early Devonian material from Nevada (Murphy & Matti 1982), is poorly known. Miller & Märss (1999) described some robust ele-ments from the lower Přídolí Downton Castle Sandstone and, although noting some of their similarities to E. divarica, reconstructed them as Ozarkodina? hemensis.…”

“…Both have the diagnostic alternating divergent denticles on both processes. Miller & Märss (1999) tentatively reconstructed similar elements from the Přídolí Downtown Sandstone as an ?ozarkodinid taxon. From the illustrations, however, their S elements do not clearly show alternating divergent denticles (e.g.…”