Wikipedia

Malone Formation

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

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

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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