The Wordie Creek Formation is an uppermost Permian and Lower Triassic geologic formation in Greenland, outcrops of which are located in Northeast Greenland National Park (until 2008 Tunu County, Danish: Østgrønland, English: East Greenland). In 2017, it was suggested to be raised to group status, as the Wordie Creek Group.
The Lower Triassic sediments in the region were discovered in 1926 independently by James Wordie and Lauge Koch, and the latter named the formation. The rock layers preserve fossils of invertebrates (e.g., ammonoids, gastropods), fishes (coelacanths, ray-finned fish, cartilaginous fish) and temnospondyl amphibians,. dating back to the Induan age.
Geology Following Surlyk et al., the Wordie Creek Group is subdivided into two formations, the Kap Stosch Formation and the overlying Godthåb Golf Formation. The Kap Stosch Formation was deposited in relatively deep, partly isolated turbiditic basin, and the Godthåb Golf Formation under relatively shallow marine conditions.
In 1935, Eigil Nielsen recognized five fossil-bearing horizons ("fish zones 1–5") corresponding to three ammonoid zones (in ascending order): Otoceras zone ("fish zones 1 and 2") Vishnuites zone ("fish zones 3 and 4") Proptychites zone ("fish zone 5")
The first two ammonoid zones are Griesbachian in age and the last one is Dienerian in age (Induan). The Kap Stosch Formation corresponds to these three zones. A sixth fossiliferous layer, the "Stegocephalian horizon", is present above, which belongs to the Godthåb Golf Formation (Dienerian). The Hypophiceras triviale ammonoid zone below Nielsen's "fish zones" is dated late Changhsingian.
The Kap Stosch Formation is subdivided into the following eight members (in ascending order): Nebalopok Member (upper Changhsingian–lower Griesbachian) Immaqa Member (lower Griesbachian) Fiskeplateau Member (lower Griesbachian) Knolden Member (lower Griesbachian) Pyramiden Member (lower–upper Griesbachian) Naasut Member (upper Griesbachian) Falkeryg Member (lower Dienerian) Vestplateau Member (lower Dienerian)
The Godthåb Golf Formation is not subdivided into members.
Paleobiota A diverse vertebrate fauna composed of temnospondyl amphibians and fishes is known from the formation.. Fossil fishes are also known from the Permian Ravnefjeld Formation ("Posidonomya shale") of Greenland.
Amphibians
Temnospondyls of the Wordie Creek Formation Taxon / Genus Species Subunit Notes ImagesLuzocephalusL. johannsoni?A lydekkerinid stereospondyl, originally described as "Lyrocephalus"L. kochiKap Stosch Formation, Pyramiden Member ("Fish zone 2"), Falkeryg Member ("Fish zone 5")A lydekkerinid stereospondyl, originally described as "Lyrocephalus"L. rapaxKap Stosch Formation, Falkeryg Member ("Fish zone 5")A lydekkerinid stereospondyl, originally described as "Lyrocephalus"SelenocaraS. groenlandicaGodthåb Golf Formation ("Stegocephalian horizon")A mastodonsauroid, originally described as Wetlugasaurus groenlandicusStoschiosaurusS. nielseniGodthåb Golf Formation ("Stegocephalian horizon")A trematosauridTupilakosaurusT. heilmaniKap Stosch Formation, Falkeryg Member ("Fish zone 5")A tupilakosaurid dvinosaur
Fish Lobe-finned
Sarcopterygii of the Wordie Creek Formation Taxon / Genus Species Subunit Notes ImagesLaugiaL. groenlandicaKap Stosch Formation, Pyramiden Member ("Fish zones 2–3") A laugiid coelacanthLaugia sp.Kap Stosch Formation ("Fish zone 1")A laugiid coelacanthSasseniaS. groenlandica?A rhabdodermatid coelacanth that was originally referred to as Sassenia sp. The genus is also known from the Vikinghøgda Formation of SpitsbergenWhiteiaW. nielseni?A whiteiid coelacanth that was originally described as Whiteia sp. and "undetermined coelacanth". The genus Whiteia had a cosmopolitan distribution during the Triassic
Ray-finned
Actinopterygii of the Wordie Creek Formation Taxon / Genus Species Subunit Notes ImagesAustralosomusA. kochiKap Stosch Formation, Pyramiden Member ("Fish zones 2–4") and Falkeryg Member ("Fish zone 5")A pholidopleuriform neopterygian. The genus had a cosmopolitan distribution during the Early Triassic epochA. simplexKap Stosch Formation (Pyramiden Member, "Fish zone 2")A pholidopleuriform neupterygian. The genus had a cosmopolitan distribution during the Early Triassic epochA. aff. simplexKap Stosch Formation, Falkeryg Member ("Fish zone 5")A pholidopleuriform neupterygian. The genus had a cosmopolitan distribution during the Early Triassic epochA. pholidopleuroidesKap Stosch Formation (Pyramiden Member, "Fish zone 2")A pholidopleuriform neupterygian. The genus had a cosmopolitan distribution during the Early Triassic epochBirgeriaB. groenlandicaKap Stosch Formation, Pyramiden Member ("Fish zone 2"), Falkeryg Member ("Fish zone 5")A birgeriid. The genus had a cosmopolitan distribution during the TriassicBobasatraniaB. groenlandicaKap Stosch Formation, Pyramiden Member ("Fish zones 2–3")A bobasatraniform The genus had a cosmopolitan distribution during the TriassicBobasatrania sp.Nebalopok MemberA bobasatraniform. One of the few Permian occurrences of the genusBoreosomusB. piveteauiKap Stosch Formation, Pyramiden Member ("Fish zones 2–4"), Falkeryg Member ("Fish zone 5")A ptycholepid. The genus had a cosmopolitan distribution during the Early Triassic epochBroughiaB. perleididoidesKap Stosch Formation, Pyramiden Member ("Fish zone 3"), Falkeryg Member ("Fish zone 5")A parasemionotiform neopterygianHelmolepisH. gracilisKap Stosch Formation, Pyramiden Member ("Fish zones 2–4")A platysiagid neopterygian. The genus had a cosmopolitan distribution during the Early TriassicOspiaO. whiteiKap Stosch Formation, Pyramiden Member ("Fish zone 3"), Falkeryg Member ("Fish zone 5")A parasemionotiform neopterygianPteronisculusP. arcticusKap Stosch Formation, Pyramiden Member ("Fish zone 2")A rhadinichthyid or turseoid, It was originally described as Glaucolepis arctica, but later referred to the genus Pteronisculus because the genus name Glaucolepis is preoccupiedP. aldingeriKap Stosch Formation, Pyramiden Member ("Fish zones 2 and 4")A rhadinichthyid or turseoid, It was originally described as Glaucolepis aldingeri, but later referred to the genus Pteronisculus because the genus name Glaucolepis is preoccupiedP. gunnariKap Stosch Formation, Pyramiden Member ("Fish zones 2?–3")A rhadinichthyid or turseoid, It was originally described as Glaucolepis gunnari, but later referred to the genus Pteronisculus because the genus name Glaucolepis is preoccupiedP. magnusKap Stosch Formation, Falkeryg Member ("Fish zone 5")A rhadinichthyid or turseoid, It was originally described as Glaucolepis magna, but later referred to the genus Pteronisculus because the genus name Glaucolepis is preoccupiedP. stensioeiKap Stosch Formation, Falkeryg Member ("Fish zone 5")A rhadinichthyid or turseoid, It was originally described as Glaucolepis stensioei, but later referred to the genus Pteronisculus because the genus name Glaucolepis is preoccupiedPteronisculus sp.Kap Stosch Formation, Pyramiden Member ("Fish zones 2–4"), Godthåb Golf Formation ("Stegocephalian horizon")A rhadinichthyid or turseoid, It was originally referred to the genus Glaucolepis, a homonym of PteronisculusSaurichthysS. aff. dayiKap Stosch Formation, Pyramiden Member ("Fish zone 2"), Falkeryg Member ("Fish zone 5")A saurichthyiform with a dense squamationS. cf. ornatusKap Stosch Formation, Falkeryg Member ("Fish zone 5")A three-dimensionally preserved skull of a saurichthyiform, which was analyzed using μCT-aided tomographyTeffichthysT. stoschiensisKap Stosch Formation, Pyramiden Member ("Fish zones 2–4"), Falkeryg Member ("Fish zone 5")A perleidiform neopterygian. It was originally described as Perleidus stoschiensis. Early Triassic species of Perleidus were subsequently referred to the genus Teffichthys
Cartilaginous
Chondrichthyes of the Wordie Creek Formation Taxon / Genus Species Subunit Notes ImagesPolyacrodusP. claveringensisKap Stosch Formation, Pyramiden Member ("Fish zone 2")A polyacrodontid hybodontiform shark. Known from isolated teeth and partial skeletons with fin spinesNemacanthus?N.? sp."Fish zone 1"Fin spines of the Nemacanthus-typeEdestidaeGen. et sp. indetKap Stosch Formation, Pyramiden Member ("Fish zone 2")Symphyseal tooth whorl of a eugeneodontid holocephalianHybodontiformesGen. et sp. indet"Fish zone 1"Fin spines of the Hybodus/Acrodus-type
See also
List of fossiliferous stratigraphic units in Greenland
References