TABLE 1. Complete list of the fauna known from the Holothurian Bed at the time of writing; a total of ten sponge species and two dendroids are included, although the exact numbers may increase on further study. Abundance notes are semi-quantitative: "rare": encountered on three or fewer occasions; "occasional": encountered on fewer than half of collecting trips; "frequent": encountered in low numbers on most collecting trips; "common": encountered on almost all collecting trips, often with several individuals; "superabundant": encountered on almost every slab.
|
Group |
Taxon |
Notes |
|
Trilobites |
Ogyginus corndensis |
Common, including as complete juveniles |
|
|
Ogygiacarella debuchii |
Moderately common |
|
|
Cnemidopyge parva |
Occasional complete moults |
|
|
Protolloydolithus reticulatus |
Occasional |
|
|
Platycalymene simulata |
Rare – one complete meraspis |
|
|
Rorringtonia kennedyi |
Occasional |
|
|
Geragnostus mccoyii |
Occasional |
|
|
odontopleurid indet. |
Rare – one rib fragment |
|
|
Microparia lusca |
Rare – few near-complete adults |
|
|
Other cyclopygids (indet.) |
Rare fragments |
|
|
Barrandia cordai |
Rare |
|
Brachiopods |
Apatobolus? micula |
Superabundant |
|
|
Palaeoglossa attentuata |
Common |
|
|
Monobolina ramsayi |
Occasional |
|
|
Opsiconidion nudum |
Occasional |
|
|
Schizocrania cf. salopiensis |
Occasional–only encrusting undetermined substrate |
|
|
Meristopacha granulata? |
Rare |
|
|
Dalmanellid indet. |
Rare |
|
Graptolites |
Cryptograptus tricornis |
Frequent |
|
|
Hustedograptus? teretiusculus |
Occasional |
|
|
Dendrograptus spp. |
Rare; at least two species |
|
Echinoderms |
Cystoid indet. |
Rare – one specimen and one possible |
|
|
Anatifopsis? sp. |
Common |
|
|
Galliaecystis? sp. |
Rare – fragments of four specimens |
|
|
Solute undet. |
Rare – one articulated specimen |
|
|
Carpoid indet. |
Rare – one specimen |
|
|
Oesolcucumaria eostre gen. et sp. nov. |
Occasional |
|
Cnidarians |
Sphenothallus sp. |
rare – few specimens |
|
|
Conulariid indet. |
Rare – one specimen |
|
Ostracodes |
Undetermined smooth form |
Common |
|
|
Bullaeferum sp. |
Occasional |
|
|
Nanopsis sp. |
Occasional |
|
Chordates |
Conodonts |
Occasional as isolated elements; rare as clusters (pellets?) |
|
Molluscs |
Bivalve indet |
Rare |
|
|
Gastropod indet. |
Rare – few specimens |
|
|
Nautiloids indet. |
Rare – few specimens |
|
Sponges |
Pirania? sp. |
Rare |
|
|
Wapkia-like form |
Occasional |
|
|
Xylochos? sp. |
Occasional |
|
|
Reticulosan sp. 1 |
Frequent |
|
|
Reticulosan sp. 2 |
Frequent |
|
|
Hexactinellid indet. |
Rare |
|
|
Sponges undet. (several spp.) |
Rare |
|
|
Eiffeliid indet. |
Isolated spicules only |
|
Worms |
Palaeoscolecid gen. et sp. nov. (Botting et al. in press) |
One confirmed specimen; many too poorly preserved to identify |
|
|
Palaeoscolecid undet. |
One specimen with different plating to Palaeoscolecid gen. et sp. nov. |
|
|
Scolecodonts |
One associated pair of elements |
|
Undet. |
Algal remains? |
Remains on which ostracodes are feeding |
TABLE 2. Approximate proportions of the fauna in terms of collected and life abundance, based on largely non-analytical collecting over 10 years; the figures are therefore not rigorous, but instead estimated values from our observations. The correction factor is based on the ratio of articulated to fragmented scleritomes of Anatifopsis?, representing the proportion of individuals affected by rapid burial, which was then applied to other multi-element scleritomes. Deviations from this factor were employed to allow for ecdysis and additional requirements of soft-tissue preservation; see text for more details.
|
|
complete (c) |
disarticulated (d) |
Correction |
Estimated relative |
|
Apatobolus? micula |
>100 |
Many |
|
>>1000 |
|
sponges |
50 |
Not visible |
20 |
1050 |
|
palaeoscolecids |
17 |
2 fragments |
~20 |
357 |
|
trilobites |
10 (non-moult) 50 (moults) |
? |
20 20/5=4 |
<210 <250 |
|
ostracodes |
30 |
Many |
20/4=5 |
180 |
|
holothurians |
8 |
Not visible |
20+ |
>168 |
|
mitrates |
7 |
~140 |
20 |
~147 |
|
other brachiopods |
? |
100 |
- |
100 |
|
graptolites |
80 |
n/a |
- |
80 |
|
solutes |
1 |
Not visible |
20 |
21 |
|
bivalves |
5 |
n/a |
- |
5 |
|
cornutes |
0 |
4 |
- |
4 |
|
nautiloids |
3 |
n/a |
- |
3 |
|
sphenothallids |
3 |
n/a |
- |
3 |
|
gastropods |
2 |
n/a |
- |
2 |
TABLE 3. Expected taxonomic composition of the preserved fauna under different degrees of preservation. "Poor preservation" implies an entirely disarticulated and washed assemblage of shelly fragments. "Moderate preservation" implies a fauna lacking abrupt burial and soft tissue, but without extended sea-floor exposure or winnowing. The observed fauna is extensive, but will inevitably be increased by further collecting, as taxa from the tail of the hollow curve are discovered. The total diversity of macrobiota in the local area at the time of deposition is impossible to ascertain, but it was likely to have been in excess of 100 species, by comparison with major Lagerstätten such as the Fezouata Biota (Van Roy et al., 2010) and the Burgess Shale (Conway Morris, 1986). In these deposits, many taxa are localised, and were found only after extensive collecting.
|
Complete biota |
Holothurian Bed |
Moderate preservation |
Poor preservation |
|
Trilobites (?11 spp) |
Trilobites (11 spp) |
Trilobites (11 spp) |
Trilobites (<11 spp, frag.) |
|
Brachiopods (?7 spp) |
Brachiopods (7 spp) |
Brachiopods (7 spp) |
Brachiopods (?7 spp) |
|
Other shelly taxa (?8 spp) |
Other shelly taxa (8 spp) |
Other shelly taxa (8 spp) |
Other shelly taxa (<8 spp) |
|
Graptolites (?5 spp) |
Graptolites (5 spp) |
Graptolites (5 spp) |
Graptolites (?5 spp) |
|
Sponges (? 10 spp) |
Sponges (10 spp) |
Sponges (spicules only) |
Sponges (spicules only) |
|
Conodonts (?1 sp.) |
Conodonts (1 sp.) |
Conodonts (1 sp.) |
Conodonts (1 sp.) |
|
Carpoids etc. (?3 spp) |
Carpoids ( 3 spp) |
Carpoids (2 spp) |
Anatifopsis? plates only |
|
Cystoids (?1 sp.) |
Cystoids (1 sp.) |
- |
- |
|
Algae (?1 sp.) |
Algae? (1 sp.) |
- |
- |
|
Holothurians (?1 sp.) |
Holothurians (1 sp.) |
- |
- |
|
Palaeoscolecidans (?2 spp) |
Palaeoscolecidans (2 spp) |
- |
- |
|
Unmineralised arthropods |
- |
- |
- |
|
Unmineralised worms |
- |
- |
- |
|
Other soft-bodied taxa |
- |
- |
- |
|
Estimated total: ? |
51 |
35 |
<30 |
