Talacasto Formation
{{Infobox rockunit
| name = Talacasto Formation
| image =
| caption =
| type = Geological formation
| period = Devonian
| age = Devonian
| prilithology =
| otherlithology =
| namedfor =
| namedby = Padula et al
| year_ts = 1967
| region = *San Juan Province
| country = Argentina
| coordinates =
| unitof = Gualilán Group
| subunits =
| underlies =
| overlies =
| thickness = {{convert|300|-|1000|m|ft|abbr=on}}
| extent = Precordillera Basin
| area =
| map =
| map_caption =
}}
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.{{Cite journal |last1=Cichowolski |first1=Marcela |last2=Rustán |first2=Juan J. |date=April 2017 |title=First report of Devonian bactritids (Cephalopoda) from South America: paleobiogeographic and biostratigraphic implications |url=https://www.researchgate.net/publication/316490185 |journal=Journal of Paleontology |language=en |volume=91 |issue=3 |pages=417–433 |doi=10.1017/jpa.2017.17 |bibcode=2017JPal...91..417C |issn=0022-3360|hdl=11336/183599 |hdl-access=free }}{{Cite journal |last1=Rustán |first1=Juan J. |last2=Vaccari |first2=N. Emilio |last3=Astini |first3=Ricardo A. |date=June 2011 |title=Early Devonian Trilobites from the Sierra De Las Minitas, Northernmost Precordillera (La Rioja Province), Argentina |url=https://www.researchgate.net/publication/259196992 |journal=Ameghiniana |language=en |volume=48 |issue=2 |pages=226–241 |doi=10.5710/AMGH.v48i1(335) |issn=0002-7014|hdl=11336/53580 |hdl-access=free }} Along with the Punta Negra Formation, it makes up the Gualilán Group, which represent Devonian-aged deposits in the Argentine Precordillera.{{Cite journal |last1=García Muro |first1=Victoria J. |last2=Rubinstein |first2=Claudia V. |last3=Rustán |first3=Juan J. |last4=Steemans |first4=Philippe |date=2018-10-01 |title=Palynomorphs from the Devonian Talacasto and Punta Negra Formations, Argentinean Precordillera: New biostratigraphic approach |url=https://linkinghub.elsevier.com/retrieve/pii/S0895981118301512 |journal=Journal of South American Earth Sciences |volume=86 |pages=110–126 |doi=10.1016/j.jsames.2018.06.009 |bibcode=2018JSAES..86..110G |issn=0895-9811|hdl=11336/87283 |hdl-access=free }} The thickness of the Talacasto Formation varies across its extent; at the type locality of Quebrada de Talacasto in the south it is {{convert|300|m|ft|abbr=on}} thick, while at the Loma de los Piojos section near the Jáchal River in the north it exceeds {{convert|1000|m|ft|abbr=on}} in thickness.
Fossil content
{{Paleobiota-key-compact}}
=Bivalves=
| class="wikitable" align="center" | ||||
| colspan="6" align="center" | Bivalves reported from the Talacasto Formation | ||||
|---|---|---|---|---|
| Genus | Species | Presence
!Material | Notes | Images |
| rowspan="2" |Actinopteria{{Cite journal |last1=Sanchez |first1=Teresa M. |last2=Waisfeld |first2=Beatriz G. |last3=Toro |first3=Blanca A. |date=1995 |title=Silurian and Devonian Molluscan Bivalves from Precordillera Region, Western Argentina |url=https://www.jstor.org/stable/1306352 |journal=Journal of Paleontology |volume=69 |issue=5 |pages=869–886 |doi=10.1017/S002233600003554X |jstor=1306352 |bibcode=1995JPal...69..869S |issn=0022-3360|url-access=subscription }}
|A. eschwegei |Loma de los Piojos |About 20 specimens |A pterineid | | ||||
| A. modesta
|Loma de los Piojos |Several specimens |A pterineid | | ||||
| Anthracoleda
|A. (Pseudoleda) minuta |
|Several specimens |A nuculanid | | ||||
| Deceptrix
|D. (Devonodeceptrix) jachalensis |Loma de los Piojos |Several specimens |A cardiolariid | | ||||
| Glossites
|G. cf. G. depressus |Loma de los Piojos |2 specimens |A modiomorphid | | ||||
| Grammysioidea
|G. capricornus |Loma de los Piojos |5 specimens |A grammysiid | | ||||
| Nuculites
|N. argentinum |
|Numerous specimens |A cucullellid | | ||||
| Nuculoidea
|N.? sp. |Cerro del Fuerte |4 specimens |A nuculid | | ||||
| Palaeoneilo
|P. cf. P. forbesi |Loma de los Piojos |5 internal moulds |A malletiid | | ||||
| Pholadella
|P. radiata |Loma de los Piojos |7 specimens | |
=Brachiopods=
=Cephalopods=
| class="wikitable" align="center" | ||||
| colspan="6" align="center" | Cephalopods reported from the Talacasto Formation | ||||
|---|---|---|---|---|
| Genus | Species | Presence
!Material | Notes | Images |
| rowspan="2" |Bactrites
|B. gracilis |
|18 specimens |A bactritid | | ||||
| B. sp.
|
|5 specimens |A bactritid | | ||||
| Devonobactrites
|D.? sp. |Loma de los Piojos section |2 specimens |A bactritid | |
=Corals=
| class="wikitable" align="center" | ||||
| colspan="6" align="center" | Corals reported from the Talacasto Formation | ||||
|---|---|---|---|---|
| Genus | Species | Presence
!Material | Notes | Images |
| Enterolasma
|E. sp. |Cerro del Fuerte section |Fragments & complete specimens |A horn coral | | ||||
| Favosites
|F.? sp. |Cerro del Fuerte section |1 colony | | ||||
| rowspan="3" |Parastriatopora{{Cite journal |last1=García-López |first1=Susana |last2=Fernández Martínez |first2=Esperanza |date=1995-01-01 |title=The genus Parastriatopora Sokolov, 1949 (Tabulata) in the Lower Devonian of Argentina: Palaeobiogeographic implications |url=https://linkinghub.elsevier.com/retrieve/pii/S0016699595802231 |journal=Geobios |volume=28 |issue=2 |pages=175–183 |doi=10.1016/S0016-6995(95)80223-1 |bibcode=1995Geobi..28..175G |issn=0016-6995|url-access=subscription }}
|P. cf. gigantea |Tambolar section |6 small branch fragments | | ||||
| P. sanjuanina
|Los Algarrobos section | | | ||||
| P. sp.
|Los Algarrobos section | | |
=Echinoderms=
| class="wikitable" align="center" | ||||
| colspan="6" align="center" | Echinoderms reported from the Talacasto Formation | ||||
|---|---|---|---|---|
| Genus | Species | Presence
!Material | Notes | Images |
| Argentinaster{{Cite journal |last1=Martínez |first1=Sergio |last2=Río |first2=Claudia del |date=2015 |title=Fossil Asterozoa (Echinodermata) of Argentina |url=https://www.redalyc.org/journal/449/44943929001/html/ |journal=Revista de Biología Tropical |language=en |volume=63 |issue=2 |pages=1–6 |doi=10.15517/rbt.v63i2.23123|doi-broken-date=2024-11-17 }}
|A. bodenbenderi |Jachal |Several specimens |An ophiurinid brittle star | | ||||
| Crinoidea indet.
|Indeterminate |Los Algarrobos section | |A crinoid | | ||||
| Furcaster
|F. separatus |Jachal |Multiple specimens |A protasterid brittle star | | ||||
| Marginix
|M. yachalensis |Jachal |Several specimens |An encrinasterid brittle star | | ||||
| Promopalaeaster
|P.? quadriserialis |Jachal |Several specimens |A valvatid starfish | |
=Hyoliths=
| class="wikitable" align="center" | ||||
| colspan="6" align="center" | Hyoliths reported from the Talacasto Formation | ||||
|---|---|---|---|---|
| Genus | Species | Presence
!Material | Notes | Images |
| Hyolithida indet.
|Indeterminate |Los Algarrobos section | |A hyolithid | |
=Ostracods=
| class="wikitable" align="center" | ||||
| colspan="6" align="center" | Ostracods reported from the Talacasto Formation | ||||
|---|---|---|---|---|
| Genus | Species | Presence
!Material | Notes | Images |
| Aechmina{{Cite journal |last=Salas |first=María José |date=October 2016 |title=New Insights on Earliest Devonian (Lochkovian) Ostracods from the Argentine Precordillera |url=https://www.researchgate.net/publication/304813347 |journal=Ameghiniana |language=en |volume=53 |issue=5 |pages=565–585 |doi=10.5710/AMGH.04.07.2016.2967 |issn=0002-7014}}
|A. sp. |Talacasto Creek |6 specimens |A member of Podocopa | | ||||
| Amphizona
|A.? argentinensis |
|23 specimens |A member of Podocopa | | ||||
| Bollia
|B. talacastensis |
|20 specimens |A member of Podocopa | | ||||
| Keslingiella
|K. teresae |
|Several specimens |A member of Podocopida | | ||||
| Lapazites
|L. aff. L. trinodis |
|12 specimens |A member of Podocopa | | ||||
| Petrisigmoopsis
|P.? rotundum |
|Several specimens |A member of Podocopa | | ||||
| rowspan="2" |Pircawayra{{Cite journal |last1=Salas |first1=María J. |last2=Rustán |first2=Juan J. |last3=Sterren |first3=Andrea F. |date=2013-08-01 |title=Lower and Middle Devonian Malvinokaffric ostracods from the Precordillera Basin of San Juan, Argentina |url=https://linkinghub.elsevier.com/retrieve/pii/S0895981113000266 |journal=Journal of South American Earth Sciences |volume=45 |pages=56–68 |doi=10.1016/j.jsames.2013.02.002 |bibcode=2013JSAES..45...56S |issn=0895-9811|hdl=11336/24991 |hdl-access=free }}
|P. antiqua |
|5 specimens |A member of Palaeocopida | | ||||
| P. peregrina
|Loma de los Piojos |Several specimens |A member of Palaeocopida | | ||||
| Suinella
|S. huarpesi |
|Several specimens |A member of Podocopa | | ||||
| Thlipsurella
|T. aff. T. putea |
|33 specimens |A member of Podocopida | | ||||
| Ulrichia
|U. sp. |
|7 specimens |A member of Podocopa | |
=Sponges=
| class="wikitable" align="center" | ||||
| colspan="6" align="center" | Sponges reported from the Talacasto Formation | ||||
|---|---|---|---|---|
| Genus | Species | Presence
!Material | Notes | Images |
| Talacastospongia{{Cite journal |last1=Carrera |first1=Marcelo G. |last2=Rustán |first2=Juan José |date=November 2015 |title=The new genus Talacastospongia: insights on the first record of a Devonian sponge from South America |url=https://www.researchgate.net/publication/298204878 |journal=Journal of Paleontology |language=en |volume=89 |issue=6 |pages=912–919 |doi=10.1017/jpa.2016.9 |bibcode=2015JPal...89..912C |issn=0022-3360|hdl=11336/43851 |hdl-access=free }}
|T. minima |
|13 specimens |A glass sponge | |