GCR block - Silurian - Devonian Chordata (SIL-DEV-CH)

Silurian - Devonian Chordata

Block Description

UK map showing distribution of GCR sites of GCR block SIL-DEV-CH
Distribution of GCR sites of GCR block Silurian - Devonian Chordata

In contrast to the manner in which most invertebrate fossils are represented in the GCR, fossils of vertebrates, arthropods (except trilobites) and terrestrial plants do have their own dedicated GCR Blocks, because of the relative rarity of the fossil material. The GCR sites selected for the Silurian-Devonian Chordata GCR Block represent the British fossil record of fishes of two periods in the middle of the Palaeozoic Era from about 438 to 355 million years ago (Ma); i.e. from the emergence of the fishes. At the end of the Devonian Period there was significant, global, mass extinction, enabling this ‘unit’ of the fossil record to have a characteristic faunal distinctiveness from later assemblages.

Palaeontological characteristics

The term ‘fishes’, unlike ‘mammals’ or ‘birds’ includes a range for aquatic vertebrates across several taxonomic classes. It refers to the living bony fishes (the teleosts) and cartilaginous sharks, rays and skates (the chondrichthyans), as well as a number of surviving representatives of older groups that were much more common in the past, such as the coelacanths, dipnoans (lungfishes), myxinoids (hagfishes) and petromyzontids (lampreys). The hagfishes and lampreys are jawless (agnathan) fishes. There are also two other groups of ‘fish-like’ aquatic chordates, which are not strictly ‘fishes’. These are the living lancelets (cephalochordates) and the extinct conodonts, which are both important for understanding fish evolution and are considered within this GCR Block.

Following the appearance of fishes in Ordovician-Silurian times, when the group were entirely marine, non-marine environments are represented in British Devonian rocks. The Devonian Period had been unmistakably an ‘Age of Fishes’ with its proliferation of species in the marine realm and the entry into fresh waters on all continents.

The end-Devonian mass-extinction event involved the total demise of all the older groups of agnathans. Only the myxinoids (hagfishes), lampreys and most of the gnathostomes survived.

As well as displaying the evolution of fossil fishes during Silurian-Devonian times, Britain continues to yield invaluable material that helps eluidicate the origins and early evolution of tetrapods; the localities yielding important ‘Amphibia’ material are few in number, but are also globally rare. The first tetrapods entered the stratigraphical record in Late Devonian times; there are bones and teeth and their footprints from well before that period was ended.

Palaeogeography

The different depositional environments that developed in Britain during mid Palaeozoic times are summarised on the following pages:

See LDY; LUD; MAR-DEV; NMAR-DEV; PRIDOL; WEN.

GCR site selection

For the purposes of site evaluation and selection, the GCR sites can be grouped into three principal themes or ‘networks’:

• Silurian fossil fishes of Scotland

• Late Silurian fossil fishes of the Welsh Borders

• Early Devonian fossil fishes of the Welsh Borders

• Early Devonian fossil fishes of Scotland

• Mid Devonian fossil fishes of Scotland

• Mid and Late Devonian fossil fishes of England and Wales

• Late Devonian fossil fishes of Scotland

Within the overall rationale of the GCR, sites were assesed with the following weightings in mind:

• sites of international significance because they have yielded fossils that are the ‘type’ material.

• sites yielding an assemblage (number and variety) of species that are signficant to the understanding of early vertebrates

• sites where the fossils are exceptionally well preserved, showing features not seen elsewhere

• best-available sites for major fish/early tetrapod–amphibia assemblages necessary to represent evolutionary succession

• sites with particular significance to science and history of palaeontology in the development of studies of early vertebrates

• sites enabling the interpretation of the environments in which the animals lived.


Volume Introduction

Silurian - Devonian Chordata


Site List

Your selection found 55 GCR sites. Sites are sorted alphabetically by country, local authority and then by site name -
CodeNameCountryLocal AuthorityGrid RefGCR Site Account
2246Bedruthan StepsEnglandCornwall and Isles of ScillySW848696Site Account
2244Mill RockEnglandDevon CCSS455432Site Account
2166LydneyEnglandGloucestershireSO652016Site Account
1617Tite's Point, (Purton Passage)EnglandGloucestershireSO686045Site Account
1615Bradnor Hill QuarryEnglandHerefordshire, County ofSO291577Site Account
1616Church Hill QuarryEnglandHerefordshire, County ofSO412738Site Account
2054Downton Castle area (Castle Bridge Mill Quarry)EnglandHerefordshire, County ofSO443743Not available
2055Downton Castle area (Downton Castle Bridge)EnglandHerefordshire, County ofSO445742Not available
2058Downton Castle area (Forge Rough Weir)EnglandHerefordshire, County ofSO456752Not available
2812Ledbury CuttingEnglandHerefordshire, County ofSO712385Site Account
1727Wayne Herbert QuarryEnglandHerefordshire, County ofSO335320Site Account
2056PortisheadEnglandNorth and North East Somerset, South GloucestershireST461770Site Account
1618Besom Farm QuarryEnglandShropshire CCSO607819Site Account
1728Devil's HoleEnglandShropshire CCSO672929Site Account
2059Downton Castle area (Tin Mill Race)EnglandShropshire CCSO460754Not available
1642Ludford Lane and Ludford CornerEnglandShropshire CCSO512741Site Account
2057Oak Dingle, TugfordEnglandShropshire CCSO565871Site Account
1695Prescott CornerEnglandShropshire CCSO663811Site Account
1641Temeside, LudlowEnglandShropshire CCSO519743Site Account
391Den of Findon, GamrieScotlandAberdeen City and AberdeenshireNJ796635Site Account
356The TouttiesScotlandAberdeen City and AberdeenshireNO881866Site Account
947Aberlemno QuarryScotlandAngus and Dundee CityNO527550Site Account
946Tillywhandland QuarryScotlandAngus and Dundee CityNO530536Site Account
945Whitehouse DenScotlandAngus and Dundee CityNO426396Site Account
351Achanarras QuarryScotlandCaithness and Sutherland and Ross and CromartyND149546Site Account
364Banniskirk QuarryScotlandCaithness and Sutherland and Ross and CromartyND167578Site Account
361Blackpark, EddertonScotlandCaithness and Sutherland and Ross and CromartyNH677833Not available
647Holborn Head QuarryScotlandCaithness and Sutherland and Ross and CromartyND079710Site Account
353John o' GroatsScotlandCaithness and Sutherland and Ross and CromartyND380735Site Account
648PennylandScotlandCaithness and Sutherland and Ross and CromartyND114687Site Account
352Spittal QuarryScotlandCaithness and Sutherland and Ross and CromartyND172541Site Account
354Westerdale QuarryScotlandCaithness and Sutherland and Ross and CromartyND120516Site Account
355Weydale QuarryScotlandCaithness and Sutherland and Ross and CromartyND145653Site Account
3139Dippal BurnScotlandEast Ayrshire and North Ayrshire MainlandNS693318Not available
392Slot BurnScotlandEast Ayrshire and North Ayrshire MainlandNS678320Site Account
1078Boghole, Muckle BurnScotlandInverness and Nairn and Moray, Badenoch and StrathspeyNH972540Site Account
720Dipple BraeScotlandInverness and Nairn and Moray, Badenoch and StrathspeyNJ330588Site Account
1106Scaat CraigScotlandInverness and Nairn and Moray, Badenoch and StrathspeyNJ236565Site Account
951Tynet Burn, ElginScotlandInverness and Nairn and Moray, Badenoch and StrathspeyNJ383621Site Account
1168Ardmore - GallanachScotlandLochaber, Skye and Lochalsh and Argyll and the IslandsNM788266Site Account
358Cruaday QuarryScotlandOrkney IslandsHY247216Site Account
357Wolf`s Hole QuarryScotlandPerth and Kinross and StirlingNS790981Site Account
943MelbyScotlandShetland IslandsHU165560Site Account
2349Papa StourScotlandShetland IslandsHU186605Site Account
929Sumburgh HeadScotlandShetland IslandsHU407078Site Account
944The Cletts, ExnaboeScotlandShetland IslandsHU407127Site Account
359Birk KnowesScotlandSouth LanarkshireNS737346Site Account
394Birkenhead BurnScotlandSouth LanarkshireNS762359Site Account
3140DunsideScotlandSouth LanarkshireNS746362Site Account
393Shiel BurnScotlandSouth LanarkshireNS777290Site Account
931Hawk's HeughScotlandThe Scottish BordersNT790714Site Account
930Oxendean BurnScotlandThe Scottish BordersNT771561Site Account
1981Cwm MillWalesMONMOUTHSHIRE AND NEWPORTSO311156Site Account
1980Hoel Senni QuarryWalesPOWYSSN915222Site Account
2263Cwar Glas QuarryWalesSOUTH WEST WALESSN727247Site Account
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