Wood Bay Formation

The Wood Bay Formation is a geologic formation found on the island of Spitsbergen, Svalbard in Norway. It preserves fossils dating back to the Pragian and Emsian stages of the Devonian period.

Stratigraphy The Wood Bay Formation is divided into two main areas: the Woodfjorden area in the north and the Dicksonfjorden–Austfjorden area in the south. In the Woodfjorden area, the formation is further split into the Sigurdfjellet, Kapp Kjeldsen, Keltiefjellet, and Stjørdalen divisions, which are distinguished by the types of fish fossils found there. The Dicksonfjorden–Austfjorden area is divided into the Austfjorden, Dicksonfjorden, and Verdalen members based on differences in sedimentary features. These differing methods of classifying the formation's sub-units have led to difficulty in determining how one area corresponds to the other.

Paleoenvironment The Wood Bay Formation was likely coastal and may represent an estuarine or fjord-like environment. The presence of a Lingula fossil recovered from the formation might suggest some degree of marine influence.

Fossil content

Acanthodians Acanthodians are a group of stem–chondrichthyans found in Paleozoic deposits around the world. They are commonly represented in the fossil record by their spines and scales. The Acanthodian fauna of the Wood Bay Formation is not as well understood as the other animal groups present, but Xylacanthus grandis, the largest known acanthodian, is exclusively found here. AcanthodiansGenusSpeciesDivisionNotesImages"Gomphonchus""G." sp. Sigurdfjellet DivisionAn ischnacanthid."Nostolepis""N." sp.A climatiid.StriacanthusS. overathensis Sigurdfjellet Division Kapp Kjeldsen DivisionA diplacanthiform of uncertain placement. Originally described as the form genus "Onchus" overathensis.Acanthodes?A.? sp. Kapp Kjeldsen DivisionAn acanthodid. Only known within the Wood Bay Formation from scale fossils.Cheiracanthus?C.? sp.A cheiracanthid. Only known within the Wood Bay Formation from scale fossils.Ptychodictyon?P.? sp.A diplacanthiform. Only known within the Wood Bay Formation from scale fossils.XylacanthusX. grandisAn ischnacanthid.X. minutus Keltiefjellet DivisionMesacanthusM. grandisA mesacanthid.

Agnathans Agnathans are by far the most species–rich and well–known animal group present in the Wood Bay Formation. Osteostracans alone account for over one third of the total genera present in the formation. All Agnathans known from the formation are considered "Ostracoderms", an informal grouping of armored jawless fish from the Paleozoic.

Heterostracans HeterostracansGenusSpeciesDivisionNotesImagesWoodfjordaspisW. felixi Sigurdfjellet DivisionA pteraspidid.XylaspisX. primaA protopteraspidid. Previously named Spitsbergaspis prima.DoryaspisD. arctica Sigurdfjellet Division Kapp Kjeldsen DivisionA doryaspidid. D. lyktensis and D. minor were previously assigned to Grummantaspis lyktensis and Ennosveaspis minor respectively.D. groenhorgensis Kapp Kjeldsen DivisionD. lyktensisD. nathorsti Kapp Kjeldsen Division Keltiefjellet DivisionD. minor Stjørdalen DivisionGigantaspisG. minima Sigurdfjellet DivisionA pteraspidid. G. laticephala was previously assigned to Zascinaspis laticephala.G. isachseni Kapp Kjeldsen DivisionG. laticephalaG. bocki

Osteostracans OsteostracansGenusSpeciesDivisionNotesImagesBenneviaspisB. grandis Sigurdfjellet DivisionA benneviaspidid. B. loevgreeni was changed from B. lövgreeni, as diacritics are not allowed in scientific names according to the International Code of Zoological Nomenclature. B. loevgreeniB. maximaNorselaspisN. glacialisA kiaeraspidid.BelonaspisB. puellaA boreaspidid.MachairaspisM. isachseniA zenaspidid.M. battaili Kapp Kjeldsen DivisionCephalaspis"C." curta Sigurdfjellet DivisionA cephalaspid. Previously considered a wastebasket taxon. Many species assigned to Cephalaspis have been reassigned to different genera or are considered dubious."C." sp. Sigurdfjellet Division Kapp Kjeldsen DivisionBoreaspis"B." ceratops Sigurdfjellet DivisionA boreaspidid."B." ginsburgi"B." batoides Kapp Kjeldsen DivisionB. puellaB. triangularis"B." intermedia Sigurdfjellet Division Kapp Kjeldsen DivisionB. macrorhynchusB. rostrataB. spinicornis Kapp Kjeldsen Division Keltiefjellet DivisionSpatulaspisS. robustaA boreaspidid. Previously assigned to Boreaspis.S. costataAxinaspisA. whitei Kapp Kjeldsen DivisionA kiaeraspidid.AcrotomaspisA. instabilisDicranaspisD. circinusA boreaspidid.D. curtirostris Kapp Kjeldsen Division Keltiefjellet DivisionD. gracilisHildenaspisH. digitalis Keltiefjellet DivisionA cephalaspidid.GustavaspisG. trinodus Keltiefjellet Division Stjørdalen DivisionPreviously assigned to Acrotomaspis trinodus.DiademaspisD. poplinae Sigurdfjellet Division Kapp Kjeldsen Division Keltiefjellet Division Stjørdalen DivisionA zenaspidid.ParameteoraspisP. oblonga Sigurdfjellet Division Kapp Kjeldsen DivisionA parameteoraspidid. previously assigned to Cephalaspis and previously named Meteoraspis. P. hoegi and P. borealis are considered nomina dubia. There are an additional four undescribed species, at least three of which belong to the Kapp Kjeldsen Division.P. caroli Kapp Kjeldsen DivisionP. oberonP. lataP. laticornisP. gigas Keltiefjellet DivisionP. hoegiP. lanternariaP. menoidesP. moythomasia Stjørdalen DivisionP. semicircularisP. borealis UnknownNectaspisN. peltata Kapp Kjeldsen DivisionA cephalaspidid.N. areolata Kapp Kjeldsen Division Keltiefjellet Division Stjørdalen DivisionN. dellei Stjørdalen Division

Thelodonts ThelodontsGenusSpeciesDivisionNotesImagesTuriniaT. pagei Sigurdfjellet DivisionA coelolepid.SigurdiaS. lataAmaltheolepisA. sp. Sigurdfjellet Division Keltiefjellet DivisionA turiniid.A. winsnesi Stjørdalen Division

Osteichthyans Osteichthyans, or bony fish, are primarily represented by sarcopterygians in the Wood Bay Formation. Osteichthyans in general are poorly represented at the formation compared to other animal groups. OsteichthyansGenusSpeciesDivisionNotesImagesPowichthysP. spitsbergensis Sigurdfjellet DivisionA powichthyid.PorolepisP. sp.A porolepidid. P. elongata and P. brevis may be junior synonyms of P. spitsbergensis.P. elongata Kapp Kjeldsen DivisionP. brevis Keltiefjellet DivisionP. spitsbergensis UnknownJanvierpaucidentesJ. tuulingi Dicksonfjorden Member (= Keltiefjellet Division)A dipnoan.HeimeniaH. ensis Stjørdalen DivisionA porolepidid.OrvikuinaO. sp.A palaeoniscoid.

Placoderms Placoderms are a group of armored fish that lived during the Late Silurian and Devonian periods of the Paleozoic. They represent the second most well–known group of animals from the Wood Bay Forrmation. PlacodermsGenusSpeciesDivisionNotesImagesSigaspisS. lepidophora Sigurdfjellet DivisionAn actinolepid or actinolepidoid arthrodire placoderm.ArctaspisA. sp. indet.A phlyctaeniid.A. holtedahli Kapp Kjeldsen DivisionA. kiaeriA. maxima Keltiefjellet DivisionDicksonosteusD. arcticus Kapp Kjeldsen DivisionA phlyctaeniid.HeintzosteusH. brevisAn arctolepid. Previously assigned to Jaekelaspis brevis.LehmanosteusL. hyperboreusA basal arthrodire.ElegantaspisE. reticornis Unknown, potentially the Kapp Kjeldsen DivisionA phlyctaeniid.LataspisL. brevicornis Unspecified, at least one species found in the Kapp Kjeldsen DivisionPreviously named Plataspis.L. rotundicornisArctolepisA. decipens Keltiefjellet DivisionA phlyctaeniid.ActinolepisA. sp. Stjørdalen DivisionAn actinolepid.HerasmiusH. granulatusA heterosteid.HeterogaspisH. giganteaA phlyctaeniid.HomosteusH. arcticusA homostiid. Also referred to as Homostius.

Invertebrates Invertebrate fossils from the Wood Bay Formation are scarce and are mostly represented by microfossils. InvertebratesGenusSpeciesDivisionNotesImages"Spirorbis""S." sp. Kapp Kjeldsen DivisionAn extant genus of tube-forming annelid worm that was once assigned to many fossil specimens. A 2009 study determined that all instances of the genus from before the Jurassic period likely represent microconchid molluscs instead. This would include the specimens from the Wood Bay Formation.Pterygotus?P.? sp.Fragments of a large eurypterid that are assigned to Pterygotus. Occurs alongside Gigantaspis laticephala.LingulaL. sp "Uppermost Wood Bay Formation"A modern brachiopod with a fossil record potentially extending to the Cambrian period. Only represented in the Wood Bay Formation by one specimen.IsochilinaI. isochilinoides UnspecifiedAn ostracod crustacean.HoltedahliaH. teresAn ostracod crustacean.

Plants PlantsGenusSpeciesDivisionNotesImagesTrochiliscus?T.? sp. Kapp Kjeldsen DivisionA charophyte algae."Hostinella""H." sp.A form genus that represents the branching stems of a plant. Previously named Hostimella.

Ichnotaxa

IchnotaxaGenusSpeciesDivisionNotesCruzianaC. polaris Kapp Kjeldsen Division Keltiefjellet DivisionTraces of a trilobite or trilobite-like arthropod.PIanolitesP. isp. Keltiefjellet DivisionMerostomichnitesM. isp.The trackways of an arthropod, potentially a eurypterid.RusophycusR. isp.Arthropod resting traces.LockeiaL. isp.IsopodichnusI. isp. Keltiefjellet Division Stjørdalen DivisionThe resting or feeding traces of an arthropod. Similar in appearance to Cruziana.TaenidiumT. isp.SkolithosS. helicoidalis Verdalen Member (= Stjørdalen Division)A vertical, helical tube interpreted as the trace of a plant rhizolith or animal burrow.UndichnaU. septemsulcata "Middle Wood Bay Formation"A swimming trace of an acanthodian, possibly Diplacanthus. One of the oldest vertebrate trace fossils known.SvalbardichnusS. trilobus "Upper Wood Bay Formation"Feeding traces of a supposedly Nahecaris-like phyllocardid crustacean.BeaconitesB. baretti UnspecifiedFound predominantly in sandstone beds with wave marks.SiskemiaS. cf. elegans UnspecifiedInterpreted as the trackways of an arthropod pushing itself through the sediment.

Wood Bay Formation

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