# Malone Formation

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The **Malone Formation** is a [geologic formation](/source/Formation_(geology)) in [Texas](/source/Texas). It preserves [fossils](/source/Fossils) dating back to the [Jurassic](/source/Jurassic) [period](/source/Period_(geology)).

## Description

One of the few geological formations in Texas dating to the Jurassic period, the Malone Formation unconformably overlies the [Permian](/source/Permian) [Briggs Formation](/source/Briggs_Formation),[2] and laterally changes thickness dramatically from 45 meters on the east side to 325 meters in the northwest part of the Malone Mountains.[1] It has been split into two subdivisions: a lower member containing *[Idoceras](/source/Idoceras)* suggesting a [Kimmeridgian](/source/Kimmeridgian) age, and an upper member containing *[Kossmatia](/source/Kossmatia)* indicating a [Tithonian](/source/Tithonian) age.[2] [Geochronological](/source/Geochronology) analysis of detrital [zircon](/source/Zircon) suggests an age of 151±2 Ma for the formation, supporting its dating to the [late Jurassic](/source/Late_Jurassic).[1]

### Depositional environment

The Malone Formation represents a fan-delta system in a shallow [marine](/source/Marine_life) to marginal marine environment, deposited along the northern edge of the Chihuahua trough (a sedimentary basin mostly located in northeast [Mexico](/source/Mexico)).[1] Many fossils found in the formation represent marine invertebrates.[3]

## Fossil content

### Vertebrates

Remains of vertebrates in this formation are rare and mostly poorly-preserved. Two [cycloid fish scales](/source/Cycloid_scale), a [pycnodont](/source/Pycnodontiformes) tooth and bone fragments of '[enaliosaurs](/source/Enaliosaurs)' (a classification now obsolete) have been reported from the Malone Formation, but are not well-described.[3]

Vertebrates reported from the Malone Formation Genus Species Presence Material Notes Images cf. Plesiosauria Northwest Malone Mountains (Jackson Ranch area).[1] Propodial (TMM 47259–1).[1] A small, possibly juvenile plesiosaur. cf. Pliosauridae Northwest Malone Mountains (Jackson Ranch area).[1] Vertebra (TMM 44038–1).[1] A pliosaur.

### Invertebrates

#### Annelids

Annelids reported from the Malone Formation Genus Species Presence Material Notes Images Serpula S. gordialis 1.5 miles east of Malone station.[3] Numerous specimens.[3] A tube worm. S. sp. 1.5 miles east of Malone station.[3] Multiple specimens.[3] Larger than S. gordialis. S. sp. 1.5 miles east of Malone station.[3] 1 specimen now lost.[3] Distinct from the other Serpula of the formation.

#### Bivalves

Bivalves reported from the Malone Formation Genus Species Presence Material Notes Images Anatina A. obliquiplicata 1.5 miles east of Malone station.[3] 8 specimens.[3] A duck clam. A.? pliculifera 1.5 miles east of Malone station.[3] 1 specimen.[3] A duck clam. Arca A.? dumbli 1.5 miles east of Malone station.[3] 5 specimens.[3] An ark clam. A. taffii 1.5 miles east of Malone station.[3] 1 specimen.[3] An ark clam. Astarte A. breviacola 1.5 miles east of Malone station.[3] Numerous specimens.[3] An astartid. A.? craticula 1.5 miles east of Malone station.[3] 1 specimen.[3] An astartid. A.? isodontoides 1.5 miles east of Malone station.[3] 1 specimen.[3] An astartid. A. malonensis Various localities in & around Malone Mountain.[3] Numerous specimens.[3] An astartid. A. posticalva 1.5 miles east of Malone station.[3] 21 specimens.[3] An astartid. Corbula C.? maloniana West base of Malone Mountain.[3] Cast of a right valve.[3] A corbulid. Cucullaea C. castilloi Northwest end of Malone Mountain.[3] 2 specimens.[3] A false ark shell. C. catorcensis East of Malone Mountain.[3] 4 casts.[3] A false ark shell. C.? texticostata 1.5 miles east of Malone station.[3] 1 specimen & a fragment.[3] A false ark shell. C. transpecosensis 1 mile northeast of Malone, El Paso County, Texas.[3] 1 specimen.[3] A false ark shell. Craginella C. goodellii 2.4 km east for Malone station.[4] 18 specimens.[3] A megatrigoniid, originally reported as Trigonia goodelli.[4] Cyprina C. coteroi 1.5 miles east of Malone station.[3] 4 (& 2 doubtful) specimens.[3] C.? streeruvitzii 1.5 miles east of Malone station.[3] 11 incomplete specimens.[3] Exogyra E. potosina West of Malone Mountain.[3] 6 specimens.[3] A gryphaeid. E. subplicifera 1.5 miles east of Malone station.[3] 19 specimens.[3] A gryphaeid. Gervillia G. cinderella West base of Malone Mountain.[3] 1 specimen.[3] A bakevelliid. G. corrugata 1.5 miles east of Malone station.[3] 23 imperfect specimens & fragments.[3] A bakevelliid. G.? riograndensis West base of Malone Mountain.[3] 1 specimen.[3] A bakevelliid. Gryphaea G. mexicana Various localities in & around Malone Mountain.[3] Numerous specimens.[3] A gryphaeid. Leda L.? navicula East slope of Malone Mountain.[3] Cast of a left valve.[3] Lima L. interlineata 1.5 miles east of Malone station.[3] Valves & fragments.[3] A file shell. L. (Ctenostreon) riograndensis 1.5 miles east of Malone station.[3] 1 specimen.[3] A file shell. Lucina L.? emarginata 1.5 miles east of Malone station.[3] 3 specimens.[3] A lucinid. L. planiuscula Northwest end of Malone Mountain.[3] 4 shells & about a dozen casts.[3] A lucinid. L. potosina 1.5 miles east of Malone station.[3] 5 specimens.[3] A lucinid. L. potosina var. metrica Various localities in & around Malone Mountain.[3] Over 200 specimens.[3] A lucinid. Martesia M. maloniana Various localities in & around Malone Mountain.[3] Casts.[3] A piddock. Modiola M. geniculata 1 mile east of Finlay station.[3] A left valve.[3] A mussel. M. maloniana Various localities in & around Malone Mountain.[3] 4 specimens.[3] A mussel. Mytilus M. nuntius 1.5 miles east of Malone station.[3] A well-preserved cast.[3] A mussel. Ostrea O. sp. 1.5 miles east of Malone station.[3] 3 imperfect valves.[3] A true oyster. Pecten P. (Camptonectes) insutus Various localities in & around Malone Mountain.[3] About 50 specimens.[3] A scallop. Pholadomya P. marcoui 1.5 miles east of Malone station.[3] 10 specimens.[3] A pholadomyid. P. paucicosta 1.5 miles east of Malone station, & 2 miles east-southeast from Finlay station.[3] 27 specimens.[3] A pholadomyid. P. praeposita 1.5 miles east of Malone station.[3] 4 specimens.[3] A pholadomyid. P. tosta 1.5 miles east of Malone station.[3] 25 specimens.[3] A pholadomyid. Pinna P. quadrifrons Various localities in & around Malone Mountain.[3] Numerous specimens.[3] A pen shell. Pleuromya P. inconstans Various localities in & around Malone Mountain.[3] Numerous specimens.[3] P. inconstans var. curta Southern part of Malone Mountain & 1.5 miles east of Malone station.[3] Multiple specimens.[3] Plicatula P. sportella 1.5 miles east of Malone station.[3] 1 specimen.[3] A plicatulid. Ptychomya P. stantoni 1.5 miles east of Malone station.[3] 23 specimens.[3] A crassatellid. Tapes T.? cuneovatus 1.5 miles east of Malone station.[3] A right valve.[3] A venus clam. Thracia T.? maloniana 1.5 miles east of Malone station.[3] 6 specimens.[3] A thraciid. Trigonia T. calderoni 1.5 miles east of Malone station, & a mile east of Finlay station.[3] 11 specimens.[3] A trigoniid. T. conferticostata 1.5 miles east of Malone station.[3] A shell, 2 valves & fragments.[3] A trigoniid. T. goodellii 1.5 miles east of Malone station.[3] 18 specimens.[3] Reassigned to Craginella. T. munita West & east of Malone station.[3] 3 imperfect specimens & several fragments.[3] A trigoniid. T. praestriata East slope of Malone Mountain.[3] A mold.[3] A trigoniid. T. proscabra 1.5 miles east of Malone station.[3] About 35 specimens.[3] A trigoniid. T. rudicostata 1.5 miles east of Malone station.[3] 2 specimens.[3] A trigoniid. T. vyschetzkii 1.5 miles east of Malone station.[3] Numerous specimens.[3] A trigoniid. Unicardium U.? semirotundum Various localities in & around Malone Mountain.[3] 12 specimens.[3] A lucinid. U.? transversum Various localities in & around Malone Mountain.[3] 16 specimens.[3] A lucinid.

#### Bryozoans

Bryozoans reported from the Malone Formation Genus Species Presence Material Notes Images Berenicea B. maloniana 1.5 miles east of Malone station.[3] Colonies.[3] A bereniceid.

#### Cephalopods

Cephalopods reported from the Malone Formation Genus Species Presence Material Notes Images Aspidoceras A. alamitocensis 1.5 miles east of Malone station.[3] Portion of a shell.[3] An ammonite. Nautilus N. burkarti West side of the mountain southwest of Malone station.[3] An imperfect specimen.[3] A nautiloid. N. naufragus Northwest end of Malone Mountain.[3] 2 imperfect specimens.[3] A nautiloid. Olcostephanus O. malonianus 1.5 miles east of Malone station.[3] A few parts of the whorls.[3] An ammonite. Oppelia O.? fallax 1.5 miles east of Malone station.[3] Fragmentary specimens.[3] An ammonite. Perisphinctes P. aguilerai Foothills west of Malone Mountain.[3] 7 fragments.[3] An ammonite. P. clarki Various localities in & around Malone Mountain.[3] Multiple specimens.[3] An ammonite. P. felixi 1.5 miles east of Malone station.[3] 2 specimens.[3] An ammonite. P. potosinus 1.5 miles east of Malone station.[3] Fragment.[3] An ammonite. P. schucherti Various localities in & around Malone Mountain.[3] Multiple specimens.[3] An ammonite.

#### Corals

Corals reported from the Malone Formation Genus Species Presence Material Notes Images Astrocoenia A. maloniana 1.5 miles east of Malone, Texas.[3] 9 specimens.[3] An astrocoeniid.

#### Echinoderms

Echinoderms reported from the Malone Formation Genus Species Presence Material Notes Images Holectypus H.? sp. East slope of Malone Mountain.[3] A fragment.[3] A sea urchin. Pygurus P. sp. West side of Malone Mountain.[3] A fragment.[3] A sea urchin.

#### Gastropods

Gastropods reported from the Malone Formation Genus Species Presence Material Notes Images Acteonina A.? maloniana 1.5 miles east of Malone station.[3] Cast bearing 2 fragments.[3] An acteonid. Cerithium C. arcuiferum 1.5 miles east of Malone station.[3] 1 specimen.[3] A cerith. Delphinula D. stantoni 1.5 miles east of Malone station.[3] 5 specimens.[3] Natica N. bilabiata 1.5 miles east of Malone station.[3] 1 specimen.[3] A moon snail. N. finlayensis Northwest end of Malone Mountain.[3] 1 specimen.[3] A moon snail. N. inflecta 1.5 miles east of Malone station.[3] 3 shells.[3] A moon snail. N. williamsi 1.5 miles east of Malone station.[3] Nearly 100 specimens.[3] A moon snail. Nerinea N. circumvoluta 1.5 miles east of Malone station.[3] Several specimens.[3] A nerineid. N. goodellii 1.5 miles east of Malone station, & southern end of Malone Mountain.[3] Multiple specimens.[3] A nerineid. Nerinella N. stantoni Various localities in & around Malone Mountain.[3] Several specimens.[3] A nerinellid. Nerita N. finlayensis Northwest end of Malone Mountain.[3] 1 specimen.[3] A nerite. N. nodilirata Lower strata.[3] 54 specimens.[3] A nerite. N. peroblata 1.5 miles east of Malone station.[3] 1 specimen.[3] A nerite. Pleurotomaria P. circumtrunca 1.5 miles east of Malone station.[3] 11 specimens.[3] A pleurotomariid. Pseudomelania P. goodellii Various localities in & around Malone Mountain.[3] Multiple specimens.[3] A pseudomelaniid. Turbo T.? beneclathratus 1.5 miles east of Malone station.[3] 1 specimen.[3] A turban snail. Turritella T. burkarti East slope of Malone Mountain.[3] 1 specimen.[3] A turritellid. Vermetus V. cornejoi 1.5 miles east of Malone station.[3] 8 specimens.[3] A worm shell.

### Plants

Fossil remains of plants, including driftwood, are abundant in the Malone Formation, but not well preserved.[1]

## See also

- [List of fossiliferous stratigraphic units in Texas](/source/List_of_fossiliferous_stratigraphic_units_in_Texas)
- [Paleontology in Texas](/source/Paleontology_in_Texas)

## References

1. May, Steven R.; Bader, Kenneth S.; Boucher, Lisa D.; Jacobs, Louis L.; Lively, Joshua R.; Myers, Timothy S.; Polcyn, Michael J. (2023-06-01). ["A record of Late Jurassic vertebrates from Texas"](https://pubs.geoscienceworld.org/rmg/article/58/1/19/624204/A-record-of-Late-Jurassic-vertebrates-from-Texas). *Rocky Mountain Geology*. **58** (1): 19–37. [doi:10.24872/rmgjournal.58.1.19](https://doi.org/10.24872/rmgjournal.58.1.19). [ISSN 1555-7340](https://www.worldcat.org/issn/1555-7340)

1. Albritton, C. C. (1938-12-01). ["Stratigraphy and structure of the Malone Mountains, Texas"](https://pubs.geoscienceworld.org/gsabulletin/article/49/12_1/1747-1806/3602). *Geological Society of America Bulletin*. **49** (12_1): 1747–1806. [doi:10.1130/GSAB-49-1747](https://doi.org/10.1130/GSAB-49-1747). [ISSN 0016-7606](https://www.worldcat.org/issn/0016-7606)

1. Cragin, Francis Whittemore (1905). [*Paleontology of the Malone Jurassic Formation of Texas*](https://books.google.com/books?id=9nwrAAAAYAAJ). Johns Hopkins university.

1. Cooper, Michael & Leanza, Héctor (2019-02-10). ["On the Middle Jurassic – Early Cretaceous Megatrigoniinae (Bivalvia, Trigoniida): their biogeography, evolution and classification"](https://www.researchgate.net/publication/330639165). *Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen*. **291** (1): 19–40. [doi:10.1127/njgpa/2019/0787](https://doi.org/10.1127/njgpa/2019/0787). [ISSN 0077-7749](https://www.worldcat.org/issn/0077-7749). [S2CID 134666790](https://api.semanticscholar.org/CorpusID:134666790)

## Further reading

- ((Various Contributors to the Paleobiology Database)). ["Fossilworks: Gateway to the Paleobiology Database"](https://web.archive.org/web/20220325060448/http://www.fossilworks.org/cgi-bin/bridge.pl?action=home). Archived from [the original](https://www.fossilworks.org/) on 25 March 2022. Retrieved 17 December 2021.

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Adapted from the Wikipedia article [Malone Formation](https://en.wikipedia.org/wiki/Malone_Formation) by Wikipedia contributors ([contributor history](https://en.wikipedia.org/wiki/Malone_Formation?action=history)). Available under [Creative Commons Attribution-ShareAlike 4.0 International](https://creativecommons.org/licenses/by-sa/4.0/). Changes may have been made.