The Talacasto Formation is a geological formation in Argentina, exposed primarily across San Juan Province, with an additional outcrop in La Rioja Province. It preserves fossils dating back to the Devonian period.
Description The Talacasto Formation is exposed in the Precordillera Basin of Argentina, with outcrops most widespread in San Juan Province, though an isolated exposure also exists at Sierra de las Minitas in La Rioja Province. Along with the Punta Negra Formation, it makes up the Gualilán Group, which represent Devonian-aged deposits in the Argentine Precordillera. The thickness of the Talacasto Formation varies across its extent; at the type locality of Quebrada de Talacasto in the south it is thick, while at the Loma de los Piojos section near the Jáchal River in the north it exceeds in thickness.
Fossil content
Bivalves Bivalves reported from the Talacasto Formation Genus Species Presence Material Notes ImagesActinopteriaA. eschwegeiLoma de los PiojosAbout 20 specimensA pterineidA. modestaLoma de los PiojosSeveral specimensA pterineidAnthracoledaA. (Pseudoleda) minutaCerro del Fuerte Loma de los PiojosSeveral specimensA nuculanidDeceptrixD. (Devonodeceptrix) jachalensisLoma de los PiojosSeveral specimensA cardiolariidGlossitesG. cf. G. depressusLoma de los Piojos2 specimensA modiomorphidGrammysioideaG. capricornusLoma de los Piojos5 specimensA grammysiidNuculitesN. argentinumCerro del Fuerte Loma de los PiojosNumerous specimensA cucullellidNuculoideaN.? sp.Cerro del Fuerte4 specimensA nuculidPalaeoneiloP. cf. P. forbesiLoma de los Piojos5 internal mouldsA malletiidPholadellaP. radiataLoma de los Piojos7 specimensA sanguinolitid
Brachiopods Brachiopods reported from the Talacasto Formation Genus Species Presence Material Notes ImagesAnopliaA. azucenaePortezuelo del TambolarOver 70 specimensAn anopliidA. sp. ARío Talacasto6 specimensAn anopliidA. sp.Los Algarrobos sectionAn anopliidAthyrisA. sp.Los Algarrobos sectionAn athyrididAustralostrophiaA. penoensisLoma de los Piojos Cerro del Fuerte Agua del PeñónNumerous specimensA strophochonetidBoucotiaB. argentinaLoma de los Piojos Portezuelo del Tambolar3 isolated valvesA notanopliidChonostrophiaC. elenaeLoma de los Piojos Several specimensA chonostrophiidC. reversa var. andinaQuebrada de TalacastoSeveral specimensTentatively reclassified as a species of SanjuanetesEoschucertellaE. delicataQuebrada ZerinaNumerous specimensAn areostrophiidIridistrophiaI. aliciaeCerro del FuerteNumerous specimensA chilidiopsidI. dominansLoma de los Piojos Numerous specimensA chilidiopsidI. magnaCordón de Agua de PeñónNumerous specimensA chilidiopsidI. primaQuebrada La CortaderaNumerous specimensA chilidiopsidKentronetesK. giolittiiQuebrada Las Loras6 valvesA strophochonetidK. ortegaeLoma de los Piojos Numerous specimensA strophochonetidK. vallensisLoma de los Piojos 31 specimensA strophochonetidK. variabilisPortezuelo del Tambolar Poblete Sur Quebrada del río Talacasto Quebrada del Chañar (Cerro La Chilca) Loma de los Piojos 32 valvesA strophochonetidLingulaL. sp.Los Algarrobos sectionA lingulidLomaellaL. primorisLoma de los Piojos 9 specimensAn eodevonariidL. sanjuaninaLoma de los Piojos Several specimensAn eodevonariidMeristellaM. sp.Los Algarrobos sectionA meristellidMetaplasiaM. baldisiLos Algarrobos sectionAn ambocoeliidPleurochonetes?P. sp.Loma de los Piojos 32 specimensA chonetidPlicanopliaP. sp.Loma de los Piojos 5 specimensAn anopliidSanjuanetes?S. andinaQuebrada de Talacasto Los Algarrobos sectionSeveral specimensA strophochonetid, originally reported as Chonostrophia reversa var. andina
Cephalopods Cephalopods reported from the Talacasto Formation Genus Species Presence Material Notes ImagesBactritesB. gracilisQuebrada de Talacasto Below Keidel's Bed18 specimensA bactritidB. sp.Quebrada de Talacasto Sierra de las Minitas5 specimensA bactritidDevonobactritesD.? sp.Loma de los Piojos section2 specimensA bactritid
Corals Corals reported from the Talacasto Formation Genus Species Presence Material Notes ImagesEnterolasmaE. sp.Cerro del Fuerte sectionFragments & complete specimensA horn coralFavositesF.? sp.Cerro del Fuerte section1 colonyA tabulate coralParastriatoporaP. cf. giganteaTambolar section6 small branch fragmentsA tabulate coralP. sanjuaninaLos Algarrobos sectionA tabulate coralP. sp.Los Algarrobos sectionA tabulate coral
Echinoderms Echinoderms reported from the Talacasto Formation Genus Species Presence Material Notes ImagesArgentinasterA. bodenbenderiJachalSeveral specimensAn ophiurinid brittle starCrinoidea indet.IndeterminateLos Algarrobos sectionA crinoidFurcasterF. separatusJachalMultiple specimensA protasterid brittle starMarginixM. yachalensisJachalSeveral specimensAn encrinasterid brittle starPromopalaeasterP.? quadriserialisJachalSeveral specimensA valvatid starfish
Hyoliths Hyoliths reported from the Talacasto Formation Genus Species Presence Material Notes ImagesHyolithida indet.IndeterminateLos Algarrobos sectionA hyolithid
Ostracods Ostracods reported from the Talacasto Formation Genus Species Presence Material Notes ImagesAechminaA. sp.Talacasto Creek6 specimensA member of PodocopaAmphizonaA.? argentinensisPortezuelo del Tambolar Talacasto Creek Poblete Sur Las Tunas23 specimensA member of PodocopaBolliaB. talacastensisTalacasto Creek Poblete Sur20 specimensA member of PodocopaKeslingiellaK. teresaeLos Algarrobos Talacasto Creek Poblete Sur La Chilcas Las TunasSeveral specimensA member of PodocopidaLapazitesL. aff. L. trinodisPortezuelo del Tambolar La Cortadera Poblete Sur La Chilca12 specimensA member of PodocopaPetrisigmoopsisP.? rotundumTalacasto Creek La ChilcaSeveral specimensA member of PodocopaPircawayraP. antiquaPortezuelo del Tambolar La Cortadera Creek La Chilca Las Aguaditas Creek5 specimensA member of PalaeocopidaP. peregrinaLoma de los PiojosSeveral specimensA member of PalaeocopidaSuinellaS. huarpesiPortezuelo del Tambolar Talacasto Creek Poblete SurSeveral specimensA member of PodocopaThlipsurellaT. aff. T. puteaLos Algarrobos Talacasto Creek Poblete Sur Las Tunas33 specimensA member of PodocopidaUlrichiaU. sp.Talacasto Creek Poblete Sur La Chilca7 specimensA member of Podocopa
Sponges Sponges reported from the Talacasto Formation Genus Species Presence Material Notes ImagesTalacastospongiaT. minimaTalacasto section Los Algarrobos Las Aguaditas13 specimensA glass sponge
Trilobites Trilobites reported from the Talacasto Formation Genus Species Presence Material Notes ImagesAguaditaspisA. mediaspinaQuebrada de las Aguaditas Sierra de las MinitasSeveral specimensA dalmanitidBainellaB. cooperiCerro La Chilca6 specimensA calmoniidB. sanjuaninaCerro La Chilca8 specimensA calmoniidCalmoniaC. nov. sp. ALoma de los PiojosAn internal mould (CORD PZ 8613)A calmoniidDalmanitoidesD. boehmiLoma de los PiojosSeveral specimensA dalmanitidD. drevermanniLoma de los Piojos Cerro La ChilcaSeveral specimensA dalmanitidDalmanitidae indet.Gen. et. sp. nov.Quebrada de las AguaditasOne specimen (CEGH-UNC 27422)An unnamed dalmanitidIndeterminateLos Algarrobos sectionA dalmanitidDalmanitinae gen. et. sp. indet.IndeterminateSierra de las MinitasFragmentary pygidium (PULR-132 A-B)A dalmanitidDeltacephalaspisD. sp.Cerro La Chilca2 specimensA calmoniidEchidnopsE. taphomimusQuebrada de Las Aguaditas Sierra de Los Blaquitos Sierra de las Minitas12 specimensA phacopid, originally reported as an unnamed species of PaciphacopsIvanitesI. leonoraeQuebrada de Las Aguaditas Quebrada de Talacasto Loma de los PiojosSeveral specimensA dalmanitidMaurotarionM. (Malvinotarion) gauchoLoma de los Piojos10 specimensAn aulacopleuridM. (Malvinotarion) haudeiLoma de los Piojos2 specimensAn aulacopleuridM. (Malvinotarion) talacastoenseLa Cantera point5 specimensAn aulacopleuridM. (Malvinotarion) sp.Portezuelo del TambolarOne specimen (CEGH-UNC 7.086)An aulacopleuridM. (Malvinotarion) sp. BCerro La ChilcaOne specimenAn aulacopleuridM. megacephalumLoma de los Piojos23 specimensAn aulacopleuridM. sp.Los Algarrobos sectionAn aulacopleuridPaciphacopsP. (Paciphacops) sp.Sierra de las MinitasSeveral specimensNow known as Echidnops taphomimusP. sp.Los Algarrobos sectionA phacopidP.? sp.Sierra de las MinitasOne specimen (PULR-127 A-B)A phacopidParabouleiaP. eldredgeiQuebrada de Talacasto9 specimensA calmoniidP. sp.Los Algarrobos sectionA calmoniidTalacastopsT. zarelaeQuebrada de Las Aguaditas Sierra de las MinitasMultiple specimensA calmoniidTarijactinoidesT. jarcasensisCerro La Chilca Loma de los Piojos13 specimensA calmoniidTormesiscusT. cf. hildaeSierra de las MinitasPartial specimen (PULR-130)A calmoniidUnguliproetusU.? sp.Sierra de las MinitasTwo associated fragmentsA proetid
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