The Ballagan Formation is a

geologic formation A geological formation, or simply formation, is a body of rock having a consistent set of physical characteristics ( lithology) that distinguishes it from adjacent bodies of rock, and which occupies a particular position in the layers of rock exp ...

Scotland Scotland is a Countries of the United Kingdom, country that is part of the United Kingdom. It contains nearly one-third of the United Kingdom's land area, consisting of the northern part of the island of Great Britain and more than 790 adjac ...

and

England England is a Countries of the United Kingdom, country that is part of the United Kingdom. It is located on the island of Great Britain, of which it covers about 62%, and List of islands of England, more than 100 smaller adjacent islands. It ...

. It preserves

fossils A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...

dating back to the early part of the

Carboniferous The Carboniferous ( ) is a Geologic time scale, geologic period and System (stratigraphy), system of the Paleozoic era (geology), era that spans 60 million years, from the end of the Devonian Period Ma (million years ago) to the beginning of the ...

period Period may refer to: Common uses * Period (punctuation) * Era, a length or span of time *Menstruation, commonly referred to as a "period" Arts, entertainment, and media * Period (music), a concept in musical composition * Periodic sentence (o ...

(

Tournaisian The Tournaisian is in the ICS geologic timescale the lowest stage or oldest age of the Mississippian, the oldest subsystem of the Carboniferous. The Tournaisian age lasted from Ma to Ma. It is preceded by the Famennian (the uppermost st ...

– early Visean). Its name comes from the "Ballagan Beds" of Ballagan Glen, near

Strathblane Strathblane (, ) is a village and List of civil parishes in Scotland, parish in the registration county of Stirling, situated in the southwestern part of the Stirling (council area), Stirling council area, in central Scotland. It lies at the foo ...

, which has a good example of this geological formation. The Ballagan Formation was historically known as the Cementstone Group, but more recently it has been placed as the middle formation of the

Inverclyde Group The Inverclyde Group is a Carboniferous lithostratigraphic group (a sequence of rock strata) in southern Scotland and northernmost England. The name is derived from Inverclyde. The rocks of the Inverclyde Group have also previously been referred ...

. This change was motivated by the recognition that the youngest parts of the Devonian Upper Old Red Sandstone (now known as the

Kinnesswood Formation The Kinnesswood Formation is a geological formation in the Central Lowlands of Scotland Scotland is a Countries of the United Kingdom, country that is part of the United Kingdom. It contains nearly one-third of the United Kingdom's land ...

) were geologically continuous with the lowest parts of the Lower Carboniferous

Calciferous Sandstone Measures Calciferous sandstone is an obsolete geological term relating to strata at the base of the Carboniferous formation, below the coal measures. The rocks of this formation are now considered part of the Inverclyde Group and Strathclyde Group. Typ ...

(now known as the Ballagan and Clyde Sandstone formations). This interval of Devonian-Carboniferous overlap was named the Inverclyde Group, and the cementstone-rich "drab beds" in the middle of the group were renamed to the Ballagan Formation. In

Lothian Lothian (; ; ) is a region of the Scottish Lowlands, lying between the southern shore of the Firth of Forth and the Lammermuir Hills and the Moorfoot Hills. The principal settlement is the Scottish capital, Edinburgh, while other signific ...

, the Ballagan and Clyde Sandstone formations are sometimes known as the Tyninghame Formation.

Fossil sites

Many localities of the Ballagan Formation preserve exceptional fossils. The majority of fossiliferous sites are in the Midland Valley (particularly the

Scottish Borders The Scottish Borders is one of 32 council areas of Scotland. It is bordered by West Lothian, Edinburgh, Midlothian, and East Lothian to the north, the North Sea to the east, Dumfries and Galloway to the south-west, South Lanarkshire to the we ...

and

East Lothian East Lothian (; ; ) is one of the 32 council areas of Scotland, as well as a Counties of Scotland, historic county, registration county and Lieutenancy areas of Scotland, lieutenancy area. The county was called Haddingtonshire until 1921. In ...

), in the southeast corner of Scotland. One of the earliest sites to be studied was the fish bed at Foulden, which hosts many well-preserved fish fossils, notably including endemic

actinopterygians Actinopterygii (; ), members of which are known as ray-finned fish or actinopterygians, is a class of bony fish that comprise over 50% of living vertebrate species. They are so called because of their lightly built fins made of webbings of skin ...

(ray-finned fish) and the first complete skeleton of a

rhizodont Rhizodontida is an extinct group of predatory tetrapodomorphs known from many areas of the world from the Givetian through to the Pennsylvanian - the earliest known species is about 377 million years ago (Mya), the latest around 310 Mya. Rhizod ...

. Plants and arthropods also form a significant portion of Foulden fossils. This site and its fish fossils were publicized by E.I. White in 1927, and further excavations were performed by Stan Wood in 1980-1981. The Foulden fish bed was the primary theme for volume 76 of the '' Transactions of the Royal Society of Edinburgh: Earth Sciences'' journal, published in 1985. Willie's Hole, near

Chirnside Chirnside is a hillside village in Berwickshire, Scotland, west of Berwick-upon-Tweed, and east of Duns, Scottish Borders, Duns. Church The parish church at Chirnside dates from the 12th century. It was substantially rebuilt in 1878 and ...

, is another site known for its high quality of preservation. It was initially recognized for its

crustacean Crustaceans (from Latin meaning: "those with shells" or "crusted ones") are invertebrate animals that constitute one group of arthropods that are traditionally a part of the subphylum Crustacea (), a large, diverse group of mainly aquatic arthrop ...

fossils, forming "shrimp beds" akin to those observed throughout the later Scottish Carboniferous. Willie's Hole has continued to produce well-preserved fossils of

arthropods Arthropods ( ) are invertebrates in the phylum Arthropoda. They possess an arthropod exoskeleton, exoskeleton with a cuticle made of chitin, often Mineralization (biology), mineralised with calcium carbonate, a body with differentiated (Metam ...

, fish, and partial tetrapod skeletons.'''' The Spouts Burn - geograph-2396335-by-Lairich-Rig

By far the largest exposures of the Ballagan Formation occur along the coastal end cliffs of

Burnmouth Burnmouth is a small fishing village located adjacent to the A1 road on the east coast of Scotland. It is the first village in Scotland on the A1, after crossing the border with England. Burnmouth is located in the Parish of Ayton, in the ...

. Tetrapod, fish, and arthropod fragments are common in several layers at Burnmouth, not just in fine-grained

overbank An overbank is an alluvial geological deposit consisting of sediment that has been deposited on the floodplain of a river or stream by flood waters that have broken through or overtopped the banks. The sediment is carried in suspension, and becau ...

deposits but also coarse

river channel In physical geography and hydrology, a channel is a landform on which a relatively narrow body of water is situated, such as a river, river delta or strait. While ''channel'' typically refers to a natural formation, the cognate term ''canal'' de ...

conglomerates, an unusual mode of preservation. Tetrapod fossils have been found in the vicinity of

Tantallon Castle Tantallon Castle is a ruined mid-14th-century fortress, located east of North Berwick, in East Lothian, Scotland. It sits atop a promontory opposite the Bass Rock, looking out onto the Firth of Forth. The last medieval curtain wall castle to b ...

. Additional Midland Valley sites include Crumble Edge (along

Whiteadder Water Whiteadder Water is a river in East Lothian and Berwickshire, Scotland. It also flows for a very short distance through Northumberland before joining the River Tweed. In common with the headwaters of the Biel Water it rises on the low hillside ...

Coldstream Coldstream () is a town and civil parishes in Scotland, civil parish in the Scottish Borders area of Scotland. A former burgh, Coldstream was where the Coldstream Guards, a regiment in the British Army, originated. Description Coldstream li ...

Cockburnspath Cockburnspath ( ) is a village in Berwickshire in the Scottish Borders. It lies near the North Sea coast between Berwick-upon-Tweed and Dunbar. Cockburnspath is the eastern terminus of the Southern Upland Way as well as the northern terminus of ...

, Cove (in

Berwickshire Berwickshire (; ) is a historic county, registration county and lieutenancy area in south-eastern Scotland, on the English border. The county takes its name from Berwick-upon-Tweed, its original county town, which was part of Scotland at the ...

), and Whitrope Burn (near

Hawick Hawick ( ; ; ) is a town in the Scottish Borders council areas of Scotland, council area and counties of Scotland, historic county of Roxburghshire in the east Southern Uplands of Scotland. It is south-west of Jedburgh and south-south-east o ...

). A few locales in nearby

Northumberland Northumberland ( ) is a ceremonial counties of England, ceremonial county in North East England, on the Anglo-Scottish border, border with Scotland. It is bordered by the North Sea to the east, Tyne and Wear and County Durham to the south, Cumb ...

encompass fossil-bearing outcrops of the Ballagan Formation, such as

Berwick-upon-Tweed Berwick-upon-Tweed (), sometimes known as Berwick-on-Tweed or simply Berwick, is a town and civil parish in Northumberland, England, south of the Anglo-Scottish border, and the northernmost town in England. The 2011 United Kingdom census recor ...

Barrow Scar (near

Alwinton Alwinton (previously named "Allenton" and sometimes still referred to as this) is a village and former parish in Northumberland, England. Alwinton is named after the nearby River Alwin, and means farm on the River Alwin. Alwinton lies at the ...

), and a borehole core at

Norham Norham ( ) is a village and civil parish in Northumberland, England, south-west of Berwick on the south side of the River Tweed where it is the border with Scotland. History Its ancient name was Ubbanford. Ecgred of Lindisfarne (d.845) replac ...

. Some sites are also found along the west coast of Scotland. Auchenreoch Glen, near

Dumbarton Dumbarton (; , or ; or , meaning 'fort of the Britons (historical), Britons') is a town in West Dunbartonshire, Scotland, on the north bank of the River Clyde where the River Leven, Dunbartonshire, River Leven flows into the Clyde estuary. ...

, was the collection site for the nearly complete type fossil of '' Pederpes finneyae'', which was the oldest named tetrapod of the Carboniferous upon its discovery. Diverse assemblages of fish teeth and other

microfossils A microfossil is a fossil that is generally between 0.001 mm and 1 mm in size, the visual study of which requires the use of light or electron microscopy. A fossil which can be studied with the naked eye or low-powered magnification, ...

have been found at

Ayrshire Ayrshire (, ) is a Counties of Scotland, historic county and registration county, in south-west Scotland, located on the shores of the Firth of Clyde. The lieutenancy areas of Scotland, lieutenancy area of Ayrshire and Arran covers the entirety ...

and at Hawk's Nib and Mill Hole, on the

Isle of Bute The Isle of Bute (; or '), known as Bute (), is an island in the Firth of Clyde in Scotland, United Kingdom. It is divided into highland and lowland areas by the Highland Boundary Fault. Formerly a constituent island of the larger County of ...

Paleobiota

The Ballagan Formation preserves a plethora of

tetrapod A tetrapod (; from Ancient Greek :wiktionary:τετρα-#Ancient Greek, τετρα- ''(tetra-)'' 'four' and :wiktionary:πούς#Ancient Greek, πούς ''(poús)'' 'foot') is any four-Limb (anatomy), limbed vertebrate animal of the clade Tetr ...

, fish, and

invertebrate Invertebrates are animals that neither develop nor retain a vertebral column (commonly known as a ''spine'' or ''backbone''), which evolved from the notochord. It is a paraphyletic grouping including all animals excluding the chordata, chordate s ...

fossils, reconstructing one of the most diverse continental ecosystems known from the Tournaisian stage. A variety of plant megafossils and spores are known from the Ballagan Formation.

Tetrapods

* '' Aytonerpeton microps'' * '' Diploradus austiumensis'' * '' Koilops herma'' * '' Mesanerpeton woodi'' * '' Ossirarus kierani'' * '' Pederpes finneyae'' (

Whatcheeriidae Whatcheeriidae is an extinct family of stem-tetrapods which lived in the Mississippian sub-period, a subdivision of the Carboniferous period. It contains the genera '' Pederpes'', '' Whatcheeria'', and possibly '' Ossinodus''. Fossils of a pos ...

) * '' Perittodus apsconditus'' * '' Tantallognathus woodi'' * UMZC 2011.7.2: A small unnamed five-fingered tetrapod similar to ''

Gephyrostegus ''Gephyrostegus'' is a genus of extinct gephyrostegid reptiliomorph amphibian. It was a small animal at 22 cm snout-vent length, of generally lizard-like build and presumably habit. It had large eyes and a large number of small, pointed te ...

'' and ''

Silvanerpeton ''Silvanerpeton'' is an extinct genus of early reptiliomorph found by Stan Wood in the East Kirkton Quarry of West Lothian, Scotland, in a sequence from the Brigantian substage of the Viséan ( Lower Carboniferous). The find is important, as th ...

'' * SPW 4165 ("Ribbo"): A large unnamed tetrapod with robust ribs and limbs * ''

Crassigyrinus ''Crassigyrinus'' (from , 'thick' and , 'tadpole') is an extinct genus of carnivorous stem tetrapod from the Early Carboniferous Clackmannan Group of Scotland and possibly Greer, West Virginia. Discovery The type specimen was originally descri ...

''-like bone fragments * An ''

Eogyrinus ''Pholiderpeton'' (from , 'horny scale' and , 'creeping thing') is an extinct genus of embolomere amphibian which lived in the Late Carboniferous period (Bashkirian) of England. The genus was first named by Thomas Henry Huxley in 1869 to incl ...

''-like tetrapod scute * Indeterminate Tetrapoda and Whatcheeriidae fragments.

Fish

Acanthodii Acanthodii or acanthodians is an extinct class of gnathostomes (jawed fishes). They are currently considered to represent a paraphyletic grade of various fish lineages basal to extant Chondrichthyes, which includes living sharks, rays, and ...

("spiny sharks"): '' Acanthodes ovensi'' (

Acanthodidae Acanthodiformes (alternatively spelled Acanthodida) is an Order (biology), order of "Acanthodii, acanthodians" which lived from the Early Devonian to the Early Permian. Members of the order have been found Cosmopolitan distribution, worldwide in ...

), '' Gyracanthus'' sp. (

Gyracanthidae Gyracanthidae is a family of extinct fish belonging to the class Acanthodii, known from early Devonian to late Carboniferous. Members are characterized by large, broad-based, paired fin spines with the pectoral fin spines having a distinct longit ...

), and rare indeterminate

Climatiiformes The Climatiiformes is a paraphyletic order of extinct fish belonging to the class Acanthodii. Like most other "spiny sharks", the Climatiiformes had sharp spines. These animals were often fairly small in size and lived from the Late Silurian to t ...

. * Actinisitia (

coelacanths Coelacanths ( ) are an ancient group of lobe-finned fish (Sarcopterygii) in the class Actinistia. As sarcopterygians, they are more closely related to lungfish and tetrapods (the terrestrial vertebrates including living amphibians, reptiles, bi ...

): cf. ''

Rhabdoderma ''Rhabdoderma'' is an extinct genus of coelacanth fish in the class Sarcopterygii. Fossils of ''Rhabdoderma'' have been found in Europe, Madagascar and North America, in Carboniferous and Early Triassic (Induan) aged rocks, with a hiatus in betwe ...

'' *

Actinopterygii Actinopterygii (; ), members of which are known as ray-finned fish or actinopterygians, is a class (biology), class of Osteichthyes, bony fish that comprise over 50% of living vertebrate species. They are so called because of their lightly built ...

(ray-finned fish): '' Aetheretmon valentiacum'' ( Strepheoschemidae), '' Cosmoptychius striatus'' ( Cosmoptychiidae), '' Phanerosteon ovensi'' ( Carbovelidae), '' Strepheoschema fouldenensis'' (Strepheoschemidae), '' Styracopterus fulcratus'' ( Styracopteridae) *

Chondrichthyes Chondrichthyes (; ) is a class of jawed fish that contains the cartilaginous fish or chondrichthyans, which all have skeletons primarily composed of cartilage. They can be contrasted with the Osteichthyes or ''bony fish'', which have skeleto ...

(cartilaginous fish): '' Ageleodus pectinatus'', ''

Cladodus ''Cladodus'' is an extinct genus of cartilaginous fishes in the family Ctenacanthidae. As the name implies, they are a type of cladodont, primitive sharks with teeth designed to snag fish and swallow them whole, instead of sawing off chunks to s ...

'' sp. (

Ctenacanthiformes Ctenacanthiformes is an extinct order of cartilaginous fish. They possessed ornamented fin spines at the front of their dorsal fins and cladodont-type dentition, that is typically of a grasping morphology, though some taxa developed cutting and g ...

?), '' Cooleyella'' sp. ( Anachronistidae), '' Deihim'' sp. ( Protacrodontidae), '' Deltodus tubineus'' ( Cochliodontidae), ''

Harpagofututor ''Harpagofututor'' is an extinct genus of eel-like cartilaginous fish from the Early Carboniferous ( Mississippian). It is primarily known from complete specimens discovered in the Bear Gulch Limestone of Montana, as well as an isolated tooth fr ...

'' sp. (

Chondrenchelyidae Chondrenchelyiformes is an extinct order of holocephalan cartilaginous fish, known from the Early Carboniferous of Europe and North America. There are currently two recognised genera known from largely complete remains, '' Chondrenchelys'' from t ...

), '' Helodus ?simplex'' ( Helodontiformes), '' Onychoselache'' (shark fin spines), '' Platyxystrodus'' sps. (Chondrenchelyidae), '' Protacrodus'' sp. (Protacrodontidae), '' Whitropus longicalcus'' ( Cochliodontiformes) *

Dipnoans Lungfish are freshwater vertebrates belonging to the class Dipnoi. Lungfish are best known for retaining ancestral characteristics within the Osteichthyes, including the ability to breathe air, and ancestral structures within Sarcopterygii, inc ...

(

lungfish Lungfish are freshwater vertebrates belonging to the class Dipnoi. Lungfish are best known for retaining ancestral characteristics within the Osteichthyes, including the ability to breathe air, and ancestral structures within Sarcopterygii, inc ...

): '' Ballagadus caustrimi'', '' Ballagadus rossi'', '' Coccovedus cellatus'', '' Ctenodus roberti'', '' Ctenodus whitropei,'' '' Ctenodus williei,'' '' Limanichthys fraseri'', '' Occludus romeri,'' '' Uronemus splendens,'' '' Xylognathus macrustenus'' *

Megalichthyidae Megalichthyidae is an extinct family (biology), family of tetrapodomorphs which lived from the Middle Devonian, Middle–Late Devonian to the Early Permian. They are known primarily from freshwater deposits, mostly in the Northern Hemisphere (Eur ...

: ?''

Megalichthys ''Megalichthys'' is a genus of prehistoric lobe-finned fish which lived during the Devonian and Carboniferous periods. It is the type genus of the family Megalichthyidae. The type species is ''M. hibberti''. The species ''M. mullisoni,'' named f ...

'' sp. *

Rhizodonts Rhizodontida is an extinct group of predatory tetrapodomorphs known from many areas of the world from the Givetian through to the Pennsylvanian (geology), Pennsylvanian - the earliest known species is about 377 million years ago (Mya), the latest ...

: cf. ''Archichthys portlocki'', '' Strepsodus? anculomanensis'', cf. '' Strepsodus sauroides'' * Indeterminate

. * Indeterminate

, including Helodontidae, Psephodontidae, Cochliodontiformes, Protacrodontidae,

Holocephali Holocephali (Sometimes spelled Holocephala; Romanization of Greek, Greek for "complete head" in reference to the fusion of Palatoquadrate, upper jaw with the rest of the skull) is a Subclass (biology), subclass of Chondrichthyes, cartilaginous fi ...

, Xenacanthiformes,

Hybodontiformes Hybodontiformes, commonly called hybodonts, are an extinct group of shark-like cartilaginous fish (chondrichthyans) which existed from the late Devonian to the Late Cretaceous. Hybodonts share a close common ancestry with modern sharks and rays ( ...

, ctenacanths, and

Menaspiformes Menaspiformes are an extinct order of holocephalans known from the Carboniferous and Permian periods, with a possible member, ''Listracanthus'', known from the Early Triassic. Members of the order are believed to be durophagous Durophagy is th ...

. * Indeterminate fragments of lungfish and rhizodonts, some estimated up to 3 meters or 10 feet in length

Invertebrates

* Eumalacostracan

crustaceans Crustaceans (from Latin meaning: "those with shells" or "crusted ones") are invertebrate animals that constitute one group of Arthropod, arthropods that are traditionally a part of the subphylum Crustacea (), a large, diverse group of mainly aquat ...

shrimps A shrimp (: shrimp ( US) or shrimps ( UK)) is a crustacean with an elongated body and a primarily swimming mode of locomotion – typically Decapods belonging to the Caridea or Dendrobranchiata, although some crustaceans outside of this orde ...

"): '' Bairdops elegans'' ( Permimecturidae)'','' '' Belotelson traquairi'' ( Belotelsonidae)'','''' Dithyocaris, Pseudogalathea, Pseudotealliocaris etheridgei,''''

Tealliocaris ''Tealliocaris'' is an extinct genus of pygocephalomorphans that lived from the Late Devonian to Early Carboniferous periods in Europe and North America. The genus was established in 1908 by Ben Peach, and many species have been assigned to it s ...

'' *

Millipedes Millipedes (originating from the Latin , "thousand", and , "foot") are a group of arthropods that are characterised by having two pairs of jointed legs on most body segments; they are known scientifically as the class Diplopoda, the name derive ...

'': Woodesmus sheari'' and at least five other millipede taxa, including members of

Archipolypoda Archipolypoda is an extinct group of millipedes known from fossils in Europe and North America and containing the earliest known land animals. The Archipolypoda was erected by Scudder (1882) but redefined in 2005 with the description of sever ...

Juliformia Juliformia is a taxonomic superorder of millipedes containing three living orders: Julida, Spirobolida, and Spirostreptida, and the extinct group Xyloiuloidea known only from fossils. Morphology The species possess long cylindrical bodies with ...

, and

Euphoberiidae Euphoberiidae is an extinct family of archipolypodan millipedes known from the Upper Pennsylvanian of Europe and North America. The family includes relatively large millipedes measuring up to long bearing distinctive spines and were the dominan ...

* Xiphosurans (

horseshoe crabs Horseshoe crabs are arthropods of the family Limulidae and the only surviving xiphosurans. Despite their name, they are not true crabs or even crustaceans; they are chelicerates, more closely related to arachnids like spiders, ticks, and scorpi ...

): '' Albalimulus bottoni'' (

Limulidae Horseshoe crabs are arthropods of the family Limulidae and the only surviving xiphosurans. Despite their name, they are not true crabs or even crustaceans; they are chelicerates, more closely related to arachnids like spiders, ticks, and scorpi ...

), '' Rolfeia fouldenensis'' ( Paleolimulidae) *

Scorpions Scorpions are predatory arachnids of the Order (biology), order Scorpiones. They have eight legs and are easily recognized by a pair of Chela (organ), grasping pincers and a narrow, segmented tail, often carried in a characteristic forward cur ...

: '' Gigantoscorpio'' cf. ''willsi'' ( Gigantoscorpionidae),'''' '' Trachyscorpio squarrosus'' ( Eoscorpiidae) *

Eurypterids Eurypterids, often informally called sea scorpions, are a group of extinct marine arthropods that form the order Eurypterida. The earliest known eurypterids date to the Darriwilian stage of the Ordovician period, 467.3 million years ago. The ...

: '' "Cyrtoctenus" (Hibbertopterus) peachi'' (

Hibbertopteridae Hibbertopteridae (the name deriving from the type genus ''Hibbertopterus'', meaning "Hibbert's wing") is a family of eurypterids, an extinct group of aquatic arthropods. They were members of the superfamily Mycteropoidea. Hibbertopterids were lar ...

) * '' Polyurida aenigmatica'', an enigmatic worm-like animal initially mistaken for a

myriapod Myriapods () are the members of subphylum Myriapoda, containing arthropods such as millipedes and centipedes. The group contains about 13,000 species, all of them terrestrial. Although molecular evidence and similar fossils suggests a diversifi ...

* "Spirorbiform" microconchids, initially mistaken for ''

Spirorbis ''Spirorbis'' is a genus of very small () polychaete worms, usually with a white coiled shell. Members of the genus live in the littoral, lower littoral and Sublittoral zone, sublittoral zones of rocky shores. ''Spirorbis'' worms usually live att ...

polychaete Polychaeta () is a paraphyletic class of generally marine Annelid, annelid worms, common name, commonly called bristle worms or polychaetes (). Each body segment has a pair of fleshy protrusions called parapodia that bear many bristles, called c ...

worm tubes *

Ostracod Ostracods, or ostracodes, are a Class (biology), class of the crustacean, Crustacea (class Ostracoda), sometimes known as seed shrimp. Some 33,000 species (only 13,000 of which are extant taxon, extant) have been identified,Brandão, S.N.; Antoni ...

s *

Bivalves Bivalvia () or bivalves, in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class of aquatic molluscs (marine and freshwater) that have laterally compressed soft bodies enclosed by a calcified exoskeleton consis ...

: '' Modiolus latus'' (

Mytilidae The Mytilidae are a family (biology), family of small to large Marine life, marine and Brackish water, brackish-water bivalve molluscs in the order (biology), order Mytilida. One of the genera, ''Limnoperna fortunei, Limnoperna'', even inhabits f ...

), '' Naiadites, Schizodus'' *

Gastropods Gastropods (), commonly known as slugs and snails, belong to a large taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, freshwater, and from the land. Ther ...

Brachiopods Brachiopods (), phylum Brachiopoda, are a phylum of animals that have hard "valves" (shells) on the upper and lower surfaces, unlike the left and right arrangement in bivalve molluscs. Brachiopod valves are hinged at the rear end, while the fron ...

References