Malone Formation

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Malone Formation
Stratigraphic range:
Kimmeridgian-Tithonian
~153–149 Ma
↓
[1]
TypeGeological formation
Sub-units
  • Upper member
  • Lower member
UnderliesTorcer Formation
OverliesBriggs Formation[2]
Thickness
  • 45 meters (east side)
  • 325 meters (northwest part of Malone Mountains)
Lithology
PrimarySiliclastic strata & limestone[1]
Location
Region Texas
Country United States
Type section
Named forMalone Mountains

The Malone Formation is a geologic formation in Texas. It preserves fossils dating back to the Jurassic period.

Description[edit]

One of the few geological formations in Texas dating to the Jurassic period, the Malone Formation unconformably overlies the Permian 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 suggesting a Kimmeridgian age, and an upper member containing Kossmatia indicating a Tithonian age.[2] Geochronological analysis of detrital zircon suggests an age of 151±2 Ma for the formation, supporting its dating to the late Jurassic.[1]

Depositional environment[edit]

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

Fossil content[edit]

Color key
Taxon Reclassified taxon Taxon falsely reported as present Dubious taxon or junior synonym Ichnotaxon Ootaxon Morphotaxon
Notes
Uncertain or tentative taxa are in small text; crossed out taxa are discredited.

Vertebrates[edit]

Remains of vertebrates in this formation are rare and mostly poorly-preserved. Two cycloid fish scales, a pycnodont tooth and bone fragments of '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[edit]

Annelids[edit]

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[edit]

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[edit]

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[edit]

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[edit]

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[edit]

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[edit]

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[edit]

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

See also[edit]

References[edit]

  1. ^ a b c d e f g h i j 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". Rocky Mountain Geology. 58 (1): 19–37. doi:10.24872/rmgjournal.58.1.19. ISSN 1555-7340.
  2. ^ a b c Albritton, C. C. (1938-12-01). "Stratigraphy and structure of the Malone Mountains, Texas". Geological Society of America Bulletin. 49 (12_1): 1747–1806. doi:10.1130/GSAB-49-1747. ISSN 0016-7606.
  3. ^ a b c d e f g h i j k l m n o p q r s t u v w x y z aa ab ac ad ae af ag ah ai aj ak al am an ao ap aq ar as at au av aw ax ay az ba bb bc bd be bf bg bh bi bj bk bl bm bn bo bp bq br bs bt bu bv bw bx by bz ca cb cc cd ce cf cg ch ci cj ck cl cm cn co cp cq cr cs ct cu cv cw cx cy cz da db dc dd de df dg dh di dj dk dl dm dn do dp dq dr ds dt du dv dw dx dy dz ea eb ec ed ee ef eg eh ei ej ek el em en eo ep eq er es et eu ev ew ex ey ez fa fb fc fd fe ff fg fh fi fj fk fl fm fn fo fp fq fr fs ft fu fv fw fx fy fz ga gb gc Cragin, Francis Whittemore (1905). Paleontology of the Malone Jurassic Formation of Texas. Johns Hopkins university.
  4. ^ a b Cooper, Michael; Leanza, Héctor (2019-02-10). "On the Middle Jurassic – Early Cretaceous Megatrigoniinae (Bivalvia, Trigoniida): their biogeography, evolution and classification". Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen. 291 (1): 19–40. doi:10.1127/njgpa/2019/0787. ISSN 0077-7749. S2CID 134666790.


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