# Eyam Limestone

The Eyam Limestone (formerly known as the Cawdor Group, Cawdor Limestone or Eyam Group) is a geologic formation in the Peak District, England. It preserves fossils dating back to the Viséan stage of the Carboniferous period, and represents a marine environment.

## Depositional environment

At the time of deposition, Britain was just south of the equator (<5° S) and part of the Euramerica continent. Study of the growth rings of fossil wood from other localities indicate that the British Isles had a monsoonal climate during the early Carboniferous, with tropical rainfall seasonality. The Eyam Limestone was deposited on an extensive, thick carbonate ramp and platform on the northeast margin of the Widmerpool Gulf (an extensive basin which existed as an area of open water during the time of deposition). Reefs and their associated fore-reef and lagoonal environments are represented in the Eyam Limestone, with crinoids dominating the reef and providing habitats for other animals. The presence of photosymbiotic coral and micritic envelopes on some crinoid ossicles indicates the formation was deposited within the photic zone in a marine environment of normal salinity. The presence of the xenacanth Bransonella has been suggested to imply freshwater influence as xenacanths live mainly in freshwater habitats, however its presence in other marine formations suggests that Bransonella was a marine animal unlike its relatives.
Apatite crystals formed by the recrystallization of phosphatic overgrowths are present on some conodont elements from the formation. As phosphatogenesis only occurs in the anoxic-oxic boundary while apatite precipitation occurs in the top few centimeters of the sediment column, this reveals that shallow sediment with low geothermal temperatures and dysoxic conditions were present in the Eyam Limestone.

## Fossil content

| Color key Taxon Reclassified taxon Taxon falsely reported as present Dubious taxon or junior synonym Ichnotaxon Ootaxon Morphotaxon | Notes Uncertain or tentative taxa are in small text; crossed out taxa are discredited. |

### Cartilaginous fish

Cartilaginous fish reported from the Eyam Limestone :
| Genus | Species | Presence | Material | Notes |
| Acanthorhachis | A. cf. spinatus | Steeplehouse Quarry. | Basal body & spines. | A listracanthid. |
| Anachronistes | A. fordi | Steeplehouse Quarry. | Teeth. | Junior synonym of Cooleyella. |
| Bransonella | B. nebraskensis | Steeplehouse Quarry & Cawdor Quarry. | Teeth. | A xenacanth. |
| Carcharopsis | C. prototypus | Steeplehouse Quarry & Coleshill Quarry. | Teeth. | A squatinactiform. |
| Cladodus | C. sp. | Steeplehouse Quarry. | 4 teeth. | A cladoselachid. |
| Cooleyella | C. fordi | Steeplehouse Quarry & Cawdor Quarry. | Teeth. | An anachronistid. |
| "Ctenacanthus" | "C." costellatus | Steeplehouse Quarry. | Partial tooth. | A ctenacanth. |
| Ctenoptychius | C. lobatus | Steeplehouse Quarry. | 3 teeth. | A petalodont. |
| Cypripediodens | C. cristatus | Once-a-week Quarry. | Teeth. | A petalodont. |
| Denaea | D. cf. fournieri | Steeplehouse Quarry & Cawdor Quarry. | Teeth. | A falcatid. |
| Euchondrocephali gen. et. sp. indet. | Indeterminate | Cawdor Quarry. | Teeth. | Somewhat similar to orodontid teeth. |
| Euselachii gen. et. sp. indet. | Indeterminate | Cawdor Quarry. | Tooth. | An indeterminate euselachian. |
| Ginteria | G. fungiforma | Cawdor Quarry. | Teeth. | An anachronistid. |
| Lissodus | L. wirksworthensis | | Teeth. | Reassigned to the genus Reesodus. |
| Petalorhynchus | P. psittacinus | Steeplehouse Quarry. | Crown & smaller tooth fragment. | A petalodont. |
| Petrodus | P. patelliformis | Steeplehouse Quarry. | Thousands of dermal denticles. | A symmoriid and the most abundant vertebrate in the formation. |
| Reesodus | R. wirksworthensis | Steeplehouse Quarry. | Tooth. | A hybodont. |
| Saivodus | S. striatus | Steeplehouse Quarry. | Tooth. | A ctenacanth. |
| Squatinactis | S. caudispinatus | Cawdor Quarry. | 4 teeth. | A squatinactiform. |
| Thrinacodus | T. dziki | Steeplehouse Quarry & Cawdor Quarry. | Teeth. | A phoebodont. |

### Conodonts

Conodonts reported from the Eyam Limestone :
| Genus | Species | Presence | Material | Notes |
| Gnathodus | G. girtyi | Steeplehouse Quarry. | Partial S element. | An idiognathodontid. |
| ?Hindeodus | ?H. sp. | Steeplehouse Quarry. | P1 element fragment. | An anchignathodontid. |
| ?Idioprioniodus | ?I. sp. | Steeplehouse Quarry. | Two P1 element fragments. | A prioniodinid. |
| Kladognathus | K. sp. | Steeplehouse Quarry. | M element. | A coelodontid. |
| Lochriea | L. commutata | Steeplehouse Quarry. | Two P1 elements. | A spathognathodontid. |
| Lochriea | L. mononodosa | Steeplehouse Quarry. | P1 element. | A spathognathodontid. |
| Lochriea | L. sp. | Steeplehouse Quarry. | Two P2 elements. | A spathognathodontid. |

### Invertebrates
#### Arthropods

Arthropods reported from the Eyam Limestone :
| Genus | Species | Presence | Material | Notes |
| Cummingella | C. cf. carringtonensis | Monyash. | | A phillipsiid trilobite. |
| Cummingella | C. sampsoni | Stoney Middleton & near Hassop. | Multiple specimens. | A phillipsiid trilobite. |
| Cummingella | C. cf. tuberculingenata | Monyash. | | A phillipsiid trilobite. |
| Griffithides | G. whitewatsoni | Stoney Middleton. | Multiple specimens. | A proetid trilobite. |

#### Brachiopods

Brachiopods reported from the Eyam Limestone :
| Genus | Species | Presence | Notes |
| Acanthoplecta | A. mesoloba | Monyash. | A productid. |
| Alitaria | A.? panderi | Monyash. | A productid. |
| Alitaria | A. sp. | Monyash. | A productid. |
| Antiquatonia | A. hindi | Monyash. | A productid. |
| Antiquatonia | A. cf. hindi | Monyash. | A productid. |
| Antiquatonia | A. cf. insculpta | Monyash. | A productid. |
| Antiquatonia | A. sulcata | Monyash. | A productid. |
| Antiquatonia | A. sp. | Monyash. | A productid. |
| Avonia | A. aculeata | Monyash. | A productid. |
| Avonia | A. davidsoni | Monyash. | A productid. |
| Avonia | A. youngiana | Monyash. | A productid. |
| Avonia | A. cf. youngiana | Monyash. | A productid. |
| Avonia | A. sp. | Monyash. | A productid. |
| Brachythyris | B. ovalis | Monyash. | A spiriferid. |
| Brachythyris | B. cf. ovalis | Monyash. | A spiriferid. |
| Buxtonia | B. sp. | Monyash. | A productid. |
| Coledium | C. sp. | Monyash. | A rhynchonellid. |
| Dictyoclostus | D. sp. | Monyash. | A productid. |
| Echinoconchus | E. punctatus | Monyash. | A productid. |
| Echinoconchus | E. subelegans | Monyash. | A productid. |
| Eomarginifera | E. cf. lobata | Monyash. | A productid. |
| Eomarginifera | E. longispinus | Monyash. | A productid. |
| Fluctuaria | F. undata | Monyash. | A productid. |
| Fusella | F. sp. | Monyash. | A spiriferid. |
| Girtyella | G. sacculus | Monyash. | A terebratulid. |
| Hustedia | H. ulothrix | Monyash. | An athyridid. |
| Kochiproductus | K. sp. | Monyash. | A productid. |
| Krotovia | K. spinulosa | Monyash. | A productid. |
| Linoproductoidea indet. | Indeterminate | Monyash. | A productid. |
| Linoprotonia | L. sp. | Monyash. | A productid. |
| Marginicinctus | M. sp. | Monyash. | A productid. |
| Marginiferoidea indet. | Indeterminate | Monyash. | A productid. |
| Martinia | M. sp. | Monyash. | A spiriferid. |
| Orthoidea indet. | Indeterminate | Monyash. | An orthid. |
| Overtonia | O. fimbriata | Monyash. | A productid. |
| Pleuropugnoides | P. pleurodon | Monyash. | A rhynchonellid. |
| Pleuropugnoides | P. sp. | Monyash. | A rhynchonellid. |
| Productina | P. margaritacaea | Monyash. | A productid. |
| Productina | P. sp. | Monyash. | A productid. |
| Productus | P. productus | Monyash. | A productid. |
| Productus | P. sp. | Monyash. | A productid. |
| Pugilis | P. cf. pugilis | Monyash. | A productid. |
| Pugilis | P. sp. | Monyash. | A productid. |
| Pugnax | P. acuminatus | Monyash. | A rhynchonellid. |
| Pugnax | P.cordiformis | Monyash. | A rhynchonellid. |
| Pugnax | P. pseudopugnus | Monyash. | A rhynchonellid. |
| Pugnax | P. cf. pugnoides | Monyash. | A rhynchonellid. |
| Pugnax | P. sp. | Monyash. | A rhynchonellid. |
| Pustula | P. sp. | Monyash. | A productid. |
| Rugosochonetes | R. sp. | Monyash. | A productid. |
| Schizophoria | S. resupinata | Monyash. | An orthid. |
| Schizophoria | S. sp. | Monyash. | An orthid. |
| Sinuatella | S. cf. sinuata | Monyash. | A productid. |
| Sinuatella | S. sp. | Monyash. | A productid. |
| Spirifer | S. bisulcatus | Monyash. | A spiriferid. |
| Spirifer | S. cf. bisulcatus | Monyash. | A spiriferid. |
| Spirifer | S. planicostus | Monyash. | A spiriferid. |
| Spirifer | S. triangularis | Monyash. | A spiriferid. |
| Spiriferoidea indet. | Indeterminate | Monyash. | A spiriferid. |

#### Bryozoans

Bryozoans reported from the Eyam Limestone :
| Genus | Species | Presence | Material | Notes | Images |
| Fenestelloidea | Indeterminate | Monyash. | | | |

#### Cnidarians

Cnidarians reported from the Eyam Limestone :
| Genus | Species | Presence | Material | Notes | Images |
| Diphyphyllum | D. sp. | Monyash. | | A horn coral. | |

#### Echinoderms

Echinoderms reported from the Eyam Limestone :
| Genus | Species | Presence | Material | Notes | Images |
| Crinoidea indet. | Indeterminate | Monyash. | | | |

#### Molluscs

Molluscs reported from the Eyam Limestone :
| Genus | Species | Presence | Notes |
| Aviculopecten | A. interstitialis | Monyash. | A bivalve. |
| Aviculopinna | A. mutica | Monyash. | A pinnid bivalve. |
| Bivalvia indet. | Indeterminate | Monyash. | A bivalve. |
| Conocardium | C. sp. | Monyash. | A rostroconch. |
| Girtypecten | G. stellaris | Monyash. | A bivalve. |
| Leiopteria | L. sp. | Monyash. | A bivalve. |
| Parallelodon | P. sp. | Monyash. | A parallelodontid bivalve. |
| Pinna | P. flabelliformis | Monyash. | A pinnid bivalve. |