Marjum Formation
Geological formation in Utah, United States
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The Marjum Formation is a Cambrian geological formation that overlies the Wheeler Shale in the House Range, Utah.[1][3] It is named after its type locality, Marjum Pass, and was defined in 1908.[2] The formation is known for its occasional preservation of soft-bodied tissue, and is slightly younger than the Burgess Shale,[4] falling in the Ptychagnostus praecurrens trilobite zone.[5]
| Marjum Formation | |
|---|---|
| Stratigraphic range: Middle Cambrian, | |
Notch Peak Sill intruding into the layers of white marble and grey argillite of the Marjum Formation | |
| Type | Geological formation |
| Overlies | Wheeler Shale |
| Thickness | Up to 430 meters[1] |
| Lithology | |
| Primary | limestone |
| Other | shale, metasedimentary rocks |
| Location | |
| Region | Utah |
| Country | United States |
| Extent | House Range |
| Type section | |
| Named for | Marjum Pass[2] |
| Named by | Charles D. Walcott |
| Year defined | 1908[2] |
Fossil content
Color key
|
Notes Uncertain or tentative taxa are in small text; |
Ambulacrarians
| Ambulacrarians reported from the Marjum Formation | |||||
|---|---|---|---|---|---|
| Genus | Species | Presence | Material | Notes | Images |
| Castericystis | C. vali | Numerous specimens.[6] | A solutan. | .jpg) | |
| Eldonia | E. ludwigi | Marjum Pass (Ptychagnostus punctuosus Zone).[7] | SM X.50204.1 (part) & SM X.50204.2 (counterpart).[7] | A cambroernid. |  |
| Marjumicystis | M. mettae | 7 specimens.[6] | An eocrinoid. | ||
| Mastigograptus | M. sp. | A single specimen.[8] | A mastigograptid graptolite. | _3.jpg) | |
| Totiglobus | T.? lloydi | Locality 811.[9] | 1 specimen (USNM 172047).[9] | An edrioasteroid. | |
Arthropods
| Arthropods reported from the Marjum Formation | |||||
|---|---|---|---|---|---|
| Genus | Species | Presence | Material | Notes | Images |
| Anomalocaris | A. nathorsti | Sponge Gully.[10] | Partial body (USNM 374593).[10] | Species moved to the genus Peytoia. | |
| Asaphiscus | A. wheeleri | Bathyuriscus fimbriatus Subzone.[11] | A ptychopariid trilobite. |  | |
| Baltagnostus | B. eurypyx | All subzones of the Bolaspidella Zone.[11] | Multiple specimens.[11] | A diplagnostid trilobite. | |
| Bathyuriscidella | B. aff. B. amplicauda | Bolaspidella contracta Subzone.[11] | 3 pygidia.[11] | A dolichometopid trilobite. | |
| Bathyuriscus | B. elegans | Bolaspidella contracta Subzone.[11] | Numerous specimens.[11] | A dolichometopid trilobite. | |
| B. fimbriatus | Bathyuriscus fimbriatus & lower Bolaspidella contracta Subzone.[11] | Numerous specimens.[11] | A dolichometopid trilobite. | .jpg) | |
| Bolaspidella | B. contracta | Bolaspidella contracta & lower Lepojyge calva Subzones.[11] | A menomoniid trilobite. | ||
| B. housensis | Bathyuriscus fimbriatus Subzone.[11] | A menomoniid trilobite. | |||
| B. jarrardi | Localities 347, 391, and 716 (mid-Bolaspidella Zone).[12] | Multiple specimens.[12] | A menomoniid trilobite. | ||
| Branchiocaris | B. pretiosa | Sponge Gully.[10][13] | 3 specimens.[10] | A hymenocarine. |  |
| Buccaspinea | B. cooperi | Kells Knolls locality.[14] | An almost complete specimen (BPM 1108).[14] | A hurdiid, originally reported as Hurdia sp. | .png) |
| Burlingia | B. halgedahlae | Localities 347 and 716 (mid-Bolaspidella Zone).[12] | Multiple specimens.[12] | A burlingiid trilobite. | |
| Caryosyntrips | C. camurus | 'Red Wash' locality.[14] | 2 isolated frontal appendages.[14] | A panarthropod of uncertain classification. |  |
| Cotalagnostus | C. laevus | Bolaspidella contracta Subzone.[11] | Over 50 specimens.[11] | A diplagnostid trilobite. | |
| C. sp. | Bolaspidella contracta Subzone.[11] | A pygidium. | A diplagnostid trilobite. | ||
| Dicranocaris | D. guntherorum | Red Wash, Modocia Flats & Sponge Gully.[13] | 4 specimens.[13] | An arthropod of uncertain classification. | |
| Dytikosicula | D. desmatae | West of Delta, House Range.[7] | 1 specimen (SM X.50203).[7] | A putative megacheiran. | |
| Elrathia | E. alapyge | Bolaspidella contracta & Lejopyge calva Subzones.[11] | Numerous specimens.[11] | A ptychopariid trilobite. | |
| E. marjumi | Bathyuriscus fimbriatus & Bolaspidella contracta Subzones.[11] | Numerous specimens.[11] | A ptychopariid trilobite. | ||
| Emeraldella | E.? sp. | Red Wash.[10] | Part & counterpart (KUMIP 204791).[10] | An artiopod. |  |
| Hemirhodon | H. amplipyge | Bolaspidella contracta Subzone.[11] | 14 incomplete specimens.[11] | A dolichometopid trilobite. |  |
| Holteria | H. problematica | Marjum Pass (Lejopyge calva Subzone).[11] | A pygidium.[11] | A corynexochid trilobite. | |
| Homagnostus | H. incertus | Bolaspidella contracta Subzone.[11] | Multiple specimens.[11] | An agnostid trilobite. | |
| Hypagnostus | H. parvifrons | All subzones of the Bolaspidella Assemblage Zone.[11] | Numerous specimens.[11] | A diplagnostid trilobite. | _-_6,8_mm.jpg) |
| Itagnostus | I. interstrictus | House Range.[15] | A peronopsid trilobite originally reported as Peronopsis interstricta. | _-_8_mm_2_(cropped).jpg) | |
| Leanchoilia | L.? cf. protogonia | Sponge Gully.[13] | Part & counterpart of a complete specimen (UU 06011.01).[13] | A megacheiran. |  |
| Lejopyge | L. calva | Marjum Pass (Lejopyge calva Subzone).[11] | Numerous specimens.[11] | A ptychagnostid trilobite. | |
| Linguagnostus | L. perplexus | Bolaspidella contracta Subzone.[11] | Over 20 specimens.[11] | A diplagnostid trilobite. | |
| Marjumia | M. callas | Bolaspidella contracta Subzone.[11] | A marjumiid trilobite. | ||
| M. typa | Bolaspidella contracta Subzone.[11] | A marjumiid trilobite. | |||
| Modocia | M. laevinucha | Bathyuriscus fimbriatus & Bolaspidella contracta Subzones.[11] | Many specimens.[11] | A marjumiid trilobite. | |
| M. nuchaspina | Bolaspidella contracta Subzone.[11] | A marjumiid trilobite. | |||
| M. typicalis | 50 or more specimens.[11] | A marjumiid trilobite. | |||
| Naraoia | N. compacta | Sponge Gully.[16] | 4 specimens.[16] | A naraoiid. |  |
| Neolenus | N. inflatus | East of Antelope Springs.[17] | Multiple specimens & fragments.[17] | A trilobite. | |
| N. intermedius | East of Antelope Springs.[17] | A trilobite. | |||
| N. intermedius pugio | East of Antelope Springs.[17] | 4 specimens of a pygidium.[17] | A trilobite. | ||
| N. superbus | East of Antelope Springs.[17] | Multiple specimens & fragments.[17] | A trilobite. | ||
| Nettapezoura | N. basilika | Sponge Gully.[13] | An arachnomorph. | ||
| Olenoides | O. decorus | Bolaspidella contracta Subzone.[11] | 7 specimens.[11] | A dorypygid trilobite. | |
| O. inflatus | Bolaspidella contracta Subzone.[11] | A dorypygid trilobite. |  | ||
| O. marjumensis | Bolaspidella contracta Subzone.[11] | A dorypygid trilobite. | |||
| O. pugio | Bolaspidella contracta Subzone.[11] | Numerous specimens.[11] | A dorypygid trilobite. | ||
| O. superbus | Bolaspidella contracta Subzone.[11] | 7 specimens.[11] | A dorypygid trilobite. |  | |
| Pahvantia | P. hastata | Precise localities unknown.[14] | 3 specimens.[14] | A hurdiid. |  |
| Peronopsis | P. interstricta | House Range.[15] | Numerous specimens.[11] | Reassigned to the genus Itagnostus. | |
| P. segmenta | House Range.[15] | Multiple specimens.[11] | A peronopsid trilobite. | ||
| Perspicaris | P.? ellipsopelta | Ptychagnostus punctuosus Zone.[18] | Valves & carapaces.[18] | A bivalved arthropod. | |
| Peytoia | P. nathorsti | Sponge Gully.[10] | Partial body (USNM 374593) & partial mouthpart (KUMIP 314095).[19] | A hurdiid, formerly named Anomalocaris nathorsti. |  |
| Ptychagnostus | P. akanthodes | Bolaspidella contracta Subzone.[11] | Numerous specimens.[11] | A ptychagnostid trilobite. | |
| P. atavus | House Range.[15] | A ptychagnostid trilobite. |  | ||
| P. hybridus | Bolaspidella contracta Subzone.[11] | About 10 specimens.[11] | A ptychagnostid trilobite. | ||
| P. richmondensis | Bathyuriscus fimbriatus Subzone.[11] | Numerous specimens.[11] | A ptychagnostid trilobite. | ||
| P. sp. | Bolaspidella contracta Subzone.[11] | At least 5 pygidia. | A ptychagnostid trilobite. | ||
| Trymataspis | T. depressa | Bolaspidella contracta Subzone.[11] | Over 30 specimens.[11] | A lonchocephalid trilobite. | |
| T. lomaleie | Bolaspidella contracta Subzone.[11] | 10 cranidia.[11] | A lonchocephalid trilobite. | ||
| T. pristina | Bolaspidella contracta Subzone.[11] | Over 20 cranidia.[11] | A lonchocephalid trilobite. | ||
| Tuzoia | T. guntheri | Ptychagnostus punctuosus Zone.[18] | Multiple valves & carapaces.[18][20] | A hymenocarine. |  |
| Utagnostus | U. trispinulus | Bolaspidella contracta & Lejopyge calva Subzones.[11] | Multiple specimens.[11] | An agnostid trilobite. | |
| Utaspis | U. marjumensis | House Range & Wheeler Amphitheater.[11] | A ptychopariid trilobite. |  | |
| Zacanthoides | Z. sp. | Wheeler Amphitheater (Bolaspidella contracta Subzone).[11] | A cranidium.[11] | A zacanthoidid trilobite. |  |
Chancelloriids
| Chancelloriids reported from the Marjum Formation | |||||
|---|---|---|---|---|---|
| Genus | Species | Presence | Material | Notes | Images |
| Chancelloria | C. sp. | Bathyuriscus fimbriatus & Bolaspidella contracta Subzones.[11] | About 20 spicules.[11] | A chancelloriid. | .jpg) |
Chordates
| Chordates reported from the Marjum Formation | |||||
|---|---|---|---|---|---|
| Genus | Species | Presence | Material | Notes | Images |
| Megasiphon | M. thylakos | House Range.[21] | One specimen (UMNH.IP.6079).[21] | A tunicate. |  |
| Nuucichthys | N. rhynchocephalus | House range.[22] | One specimen (UMNH.IP.6084)[22] | A basal chordate related to Metaspriggina. |  |
| Skeemella | S. clavula | North of Red Wash (Ptychagnostus punctuosus Biozone).[23] | 2 specimens (KUMIP 314102 & KUMIP 314103).[23] | A vetulicolian. |  |
Cnidarians
Moon, Caron & Moysiuk (2023) considered these fossils would be ctenophores instead.[24]
| Cnidarians reported from the Marjum Formation | |||||
|---|---|---|---|---|---|
| Genus | Species | Presence | Material | Notes | Images |
| Coronatae? | Indeterminate | Sponge Gully.[25] | 1 specimen (UU07021.05).[25] | Originally considered as a scyphozoan jellyfish, may be referrable to the crown jellyfish family, later reclassified to stem-ctenophore Calathites macrocalyx.[26] |  |
| Cubozoa? | Indeterminate | Sponge Gully.[25] | 2 specimens (UU07021.01 & UU07021.02).[25] | Specimens possibly referrable to box jellyfish. Later reclassified to stem-ctenophore Calathites macrocalyx and Theiokylinxia cartwrightae.[26] |  |
| Narcomedusae? | Indeterminate | Sponge Gully.[25] | 5 specimens (UU07021.03, UU07021.04, UU07021.06, UU07021.07 & UU07021.08).[25] | Originally considered as a hydrozoan tentatively assigned to this family. Later reclassified to stem-ctenophore Theiokylinxia cartwrightae and indeterminate dinomischid for figured specimens.[26] |  |
| Semaeostomeae? | Indeterminate | Sponge Gully.[25] | 2 specimens (UU07021.09 & UU07021.10).[25] | Originally considered as a scyphozoan jellyfish tentatively assigned to this family. Later reclassified to indeterminate stem-ctenophore dinomischid.[26] |  |
Ctenophores
| Ctenophores reported from the Marjum Formation | |||||
|---|---|---|---|---|---|
| Genus | Species | Presence | Material | Notes | Images |
| Calathites | C. macrocalyx | House Range | A stem-group ctenophore within the family Dinomischidae.[26] | | |
| Ctenorhabdotus | C. campanelliformis | House Range (likely from the lower Ptychagnostus punctuosus Zone).[27] | 1 specimen (UMNH.IP.6125).[27] | A ctenophore. |  |
| Dinomischidae | Indeterminate | House Range | |||
| Dinomischus | D. nudus | House Range | A stem-group ctenophore within the family Dinomischidae.[26] | ||
| D. sp. A | House Range | ||||
| Thalassostaphylos | T. elegans | House Range (lower Ptychagnostus punctuosus Zone).[27] | 1 specimen (UMNH.IP.6086).[27] | A ctenophore. | |
| Theiokylixia | T. cartwrightae | House Range | A stem-group ctenophore within the family Dinomischidae.[26] |  | |
Lophotrochozoans
| Lophotrochozoans reported from the Marjum Formation | |||||
|---|---|---|---|---|---|
| Genus | Species | Presence | Material | Notes | Images |
| Acrothele | A. subsidua | Bathyuriscus-Elrathina & Bolaspidella Zones.[11] | A brachiopod. |  | |
| Helcionella | "H." arguta | Bathyuriscus fimbriatus & Bolaspidella contracta Subzones.[11] | More than 100 specimens.[11] | A helcionellid. | |
| Hyolithes | H. sp. | All subzones of the Bolaspidella Zone.[11] | More than 100 specimens.[11] | A hyolith. | .jpg) |
| Lingulella | L. sp. | Bathyuriscus fimbriatus & Bolaspidella contracta Subzones.[11] | An obolid brachiopod. |  | |
| Micromitra | M. modesta | Multiple specimens.[11] | A paterinide brachiopod. |  | |
| Nisusia | N. sulcata | 18 specimens.[28] | A kutorginate brachiopod. |  | |
| Pegmatreta | P. bellatula | Bathyuriscus fimbriatus & Bolaspidella contracta Subzones.[11] | Numerous specimens.[11] | A brachiopod. | |
| P. ophirensis | All subzones of the Bolaspidella Zone.[11] | A brachiopod. | |||
| Pelagiella | P. sp. | Bolaspidella contracta Subzone.[11] | More than 50 internal molds.[11] | A pelagiellid. |  |
| Prototreta | P. attenuata | Bathyuriscus-Elrathina Zone & Bolaspidella Zone.[11] | A brachiopod. | ||
| P. mimica | Bolaspidella contracta Subzone.[11] | A brachiopod. | |||
| Stenothecoides | S. elongata | Bathyuriscus fimbriatus Subzone.[11] | Over 30 valves.[11] | A stenothecoid. | |
Scalidophorans
| Scalidophorans reported from the Marjum Formation | |||||
|---|---|---|---|---|---|
| Genus | Species | Presence | Material | Notes | Images |
| Arrakiscolex | A. aasei | Grey Marjum locality (Ptychagnostus punctuosus Zone).[29] | Cuticle fragments.[29] | A palaeoscolecid also known from the Upper Weeks Formation. | |
| Ottoia | O. prolifica | Sponge Gully.[5] | A complete individual (KUMIP 204770).[5] | Referral of the specimen to this species is insecure, better classified as O.? sp.[29][30] | |
| O.? sp. | Sponge Gully.[29] | A complete individual (KUMIP 204770).[29] | A stem-priapulid, specimen formerly referred to Ottoia prolifica or Scathascolex minor.[29] |  | |
| Scathascolex | S. minor | Sponge Gully.[5] | A complete individual (KUMIP 204770).[5][31] | Specimen reassigned to Ottoia? sp.[29] | |
| Selkirkia | S. willoughbyi | Sponge Gully.[5] | Tube with associated soft parts (KUMIP 204788).[5] | A stem-priapulid. |  |
Sponges
| Sponges reported from the Marjum Formation | |||||
|---|---|---|---|---|---|
| Genus | Species | Presence | Material | Notes | Images |
| Choia | C. carteri | Sponge Gulch.[32] | A demosponge. |  | |
| C. hindei | Red Cliffs Wash.[32] | 2 specimens & 3 other fragments.[32] | A demosponge. | ||
| C. utahensis | Sponge Gulch.[32] | Several specimens.[32] | A demosponge. | ||
| Diagoniella | D. cyathiformis | Red Cliffs Wash & Kells Knolls Gulch.[32] | Numerous specimens.[32] | A reticulosan. | |
| D. hindei | Sponge Gulch.[32] | Approximately 40 specimens.[32] | A reticulosan. |  | |
| D. magna | Kells Knolls Gulch (Bathyuriscus fimbriatus zone).[33] | A fragment (USNM 535922).[33] | A reticulosan. | ||
| D. sp. | Sponge Gulch.[32] | 2 large fragments.[32] | A reticulosan. | ||
| Hamptonia | H. bowerbanki | Red Cliffs Wash & Sponge Gulch.[32] | Multiple specimens.[32] | A demosponge. | |
| Hazelia | H. palmata | Near Marjum Pass.[34] | One specimen.[34] | A demosponge. |  |
| Hintzespongia | H. bilamina | Kells Knolls Gulch (Bathyuriscus fimbriatus zone).[32][33] | Multiple specimens.[32][33] | A reticulosan. | |
| Hexactinellida | Indeterminate | Miscellaneous spicules.[11] | Indeterminate glass sponges, originally reported as Hyalospongiae (now a junior synonym). | ||
| Kiwetinokia | Drum Mountains.[32] | 4 large slabs.[32] | A reticulosan. | ||
| Leptomitus | L. metta | Red Cliffs Wash locality.[32] | 22 specimens.[32] | A demosponge. | |
| Polygoniella | P. turrelli | House Range[35] | Around 200 specimens[35] | A glass sponge |  |
| Protospongia | P.? elongata | Sponge Gulch.[32] | 1 specimen.[32] | A reticulosan. | |
| Testiispongia | T. venula | Sponge Gulch.[32] | Several specimens.[32] | A glass sponge. | |
| Valospongia | V. gigantis | Sponge Gulch.[32] | A reticulosan. | ||
| V.? gigantus | Kells Knolls Gulch (Bathyuriscus fimbriatus zone).[33] | A fragment (USNM 535917).[33] | A reticulosan. | ||
