Sabinal Formation

{{Short description|Geological formation in Oaxaca, Mexico}} {{Infobox rockunit|name=Sabinal Formation|type=sedimentary|age={{fossil range|Kimmeridgian|Valanginian|Kimmeridgian to Valanginian}}|period=Kimmeridgian|country=Mexico|area=|region=Oaxaca|lithology=Shale|namedfor=|otherlithology=Mudstone, wackestone, marl|underlies=Tlaxiaco Formation|unitof=Tlaxiaco Basin|overlies=Consuelo Group, Tecocoyuncan Group|coordinates={{coord|17.3|N|97.7|W|display=inline,title}}|paleocoordinates={{coord|11.6|N|49.7|W}}|map={{Location map+ | Mexico | relief = 1 | width = 250 | float = center | places = {{Location map~ | Mexico | lat_deg = 17.3 | lon_deg = -97.7 | mark = Lightgreen pog.svg | marksize = 10 }} }}}} The '''Sabinal Formation''' is a Late Jurassic and Early Cretaceous-aged geological formation in Oaxaca, Mexico. It preserves a highly diverse marine fauna.<ref name=":0">{{Cite journal |last1=Alvarado-Ortega|first1=Jesús|last2=Barrientos-Lara|first2=Jair Israel|last3=Espinosa-Arrubarrena|first3=Luis|last4=Pilar Melgarejo-Damián|first4=María del|date=2014-07-09 |title=Late Jurassic marine vertebrates from Tlaxiaco, Oaxaca State, southern Mexico |url=https://palaeo-electronica.org/content/2014/773-tlaxiaco-jurassic-vertebrates |access-date=2025-01-27 |journal=Palaeontologia Electronica |doi=10.26879/454 |language=en|doi-access=free}}</ref><ref name=":1">{{Cite journal |last1=Zell |first1=Patrick |last2=Stinnesbeck |first2=Wolfgang |last3=Beckmann |first3=Seija |last4=Adatte |first4=Thierry |last5=Hering |first5=Fabio |date=2015-10-01 |title=The Berriasian–Valanginian (Early Cretaceous) boundary transition at Santa Catarina Ticuá, Oaxaca state, southern Mexico: Ammonites, bivalves, calpionellids and their paleobiogeographic significance |url=https://www.sciencedirect.com/science/article/abs/pii/S0895981115000681 |journal=Journal of South American Earth Sciences |volume=62 |pages=33–57 |doi=10.1016/j.jsames.2015.04.009 |bibcode=2015JSAES..62...33Z |issn=0895-9811|url-access=subscription }}</ref>

It was initially thought to only encompass the Late Jurassic (Kimmeridgian & Tithonian), but more recent studies have redefined it to cover the earliest Cretaceous (Berriasian & Valanginian) as well. It is part of the Tlaxiaco Basin, a prominent structural basin in southern Mexico that accumulated both continental and marine sediments between the Early Jurassic and the Paleogene.<ref name=":1" /> The most prolific site of the formation is the Kimmeridgian-aged Llano Yosobe site near Tlaxiaco.<ref name=":0" />

== Vertebrate paleobiota ==

=== Cartilaginous fish === {| class="wikitable" width="100%" align="center" ! colspan="8" align="center" |'''Cartilaginous fish of the Sabinal Formation''' |- !Genus !Species !Location !Stratigraphic position !Material !Notes !Images |- |''Planohybodus'' |''P.'' sp. |Yosobé |Kimmeridgian |Teeth |A hybodont.<ref name=":0" /> |frameless|131x131px |}

=== Ray-finned fish === {| class="wikitable" width="100%" align="center" ! colspan="8" align="center" |Ray-finned fish of the Sabinal Formation' |- !Genus !Species !Location !Stratigraphic position !Material !Notes !Images |- |''Belonostomus'' |''B. ornatus'' |Cerro de la Virgen |Berriasian | |An aspidorhynchid.<ref>{{Cite journal |last1=Van Vranken|first1=Nathan E.|last2=Fielitz|first2=Christopher|last3=Ebersole|first3=Jun A.|date=2019-09-13 |title=New occurrences of Belonostomus (Teleostomorpha: Aspidorhynchidae) from the Late Cretaceous of the North American Gulf Coastal Plain, USA |url=https://palaeo-electronica.org/content/2019/2725-new-belonostomus-record |access-date=2025-01-27 |journal=Palaeontologia Electronica |doi=10.26879/983 |language=en|doi-access=free}}</ref><ref name=":2">{{Cite journal |last1=GONZÁLEZ-RODRÍGUEZ |first1=KATIA A. |last2=FIELITZ |first2=CHRISTOPHER |last3=BRAVO-CUEVAS |first3=VICTOR M. |last4=BAÑOS-RODRÍGUEZ |first4=ROCÍO E. |date=2016 |title=CRETACEOUS OSTEICHTHYAN FISH ASSEMBLAGES FROM MEXICO |url=https://www.researchgate.net/publication/303119013 |journal=New Mexico Museum of Natural History and Science Bulletin |issue=71}}</ref> |frameless |- |''Gyrodus'' |''G.'' sp. |Yosobé |Kimmeridgian |Teeth, partial skeleton |A pycnodont. The most abundant vertebrate fossil in the formation.<ref name=":0" /> |frameless |- |''Nhanulepisosteus'' |''N. mexicanus'' |Yosobé |Kimmeridgian |Partial cranium |A gar, the earliest known from the fossil record.<ref>{{Cite journal |last1=Brito |first1=Paulo M. |last2=Alvarado-Ortega |first2=Jésus |last3=Meunier |first3=François J. |date=2017-12-19 |title=Earliest known lepisosteoid extends the range of anatomically modern gars to the Late Jurassic |journal=Scientific Reports |language=en |volume=7 |issue=1 |page=17830 |doi=10.1038/s41598-017-17984-w |pmid=29259200 |pmc=5736718 |bibcode=2017NatSR...717830B |issn=2045-2322}}</ref> |frameless |- | rowspan="2" |''Otomitla'' |''O. mexicana'' | rowspan="2" |Cerro de la Virgen | rowspan="2" |Berriasian | | rowspan="2" |An ichthyodectiform.<ref name=":2" /> | |- |''O. speciosa'' | | |- |Pleuropholidae indet. | |Yosobé |Kimmeridgian |Trunk with scales |A pleuropholid.<ref name=":0" /> | |- |''Pleuropholis'' |''P. cisnerosorum'' |Yosobé |Kimmeridgian |Partial skull |A pleuropholid.<ref>{{Cite journal |last1=Alvarado-Ortega |first1=Jesús |last2=Brito |first2=Paulo M. |date=2016-09-02 |title=A Jurassic pleuropholid fish (Teleostei, Pleuropholidae) in the Tethys Sea domain of North America |url=https://www.tandfonline.com/doi/abs/10.1080/02724634.2016.1201767 |journal=Journal of Vertebrate Paleontology |volume=36 |issue=5 |article-number=e1201767 |doi=10.1080/02724634.2016.1201767 |bibcode=2016JVPal..36E1767A |issn=0272-4634|url-access=subscription }}</ref> |frameless |- |?''Thrissops'' |''T.'' sp. |Cerro de la Virgen |Berriasian | |An ichthyodectiform.<ref name=":2" /> |frameless |- |''Vinctifer'' |''V. ferrusquiai'' |Yosobé |Kimmeridgian |Parts of head and trunk |An aspidorhynchid.<ref>{{Cite journal |last1=Cantalice |first1=Kleyton M. |last2=Alvarado-Ortega |first2=Jesús |last3=Brito |first3=Paulo M. |last4=Cantalice |first4=Kleyton M. |last5=Alvarado-Ortega |first5=Jesús |last6=Brito |first6=Paulo M. |date=2018 |title=On the occurrence of Vinctifer ferrusquiai sp. nov. (Actinopterygii, Aspidorhynchiformes) in the Kimmeridgian (Late Jurassic) deposits near Tlaxiaco, Oaxaca, southern Mexico |url=https://www.scielo.org.mx/scielo.php?pid=S1026-87742018000200179&script=sci_arttext&tlng=en |journal=Revista Mexicana de Ciencias Geológicas |language=en |volume=35 |issue=2 |pages=179–187 |doi=10.22201/cgeo.20072902e.2018.2.713 |bibcode=2018RMxCG..35..179C |issn=1026-8774|doi-access=free }}</ref> |frameless |}

=== Reptiles ===

==== Crocodylomorphs ==== {| class="wikitable" width="100%" align="center" ! colspan="8" align="center" |Crocodylomorphs of the Sabinal Formation |- !Genus !Species !Location !Stratigraphic position !Material !Notes !Images |- |''Maledictosuchus'' |''M. nuyivijanan'' |Yosobé |Kimmeridgian |Nearly complete cranium, jaws, and some vertebrae |A metriorhynchid thalattosuchian. First record of this genus outside Europe.<ref>{{Cite journal |last1=Barrientos-Lara |first1=Jair I. |last2=Alvarado-Ortega |first2=Jesús |last3=Fernández |first3=Marta S. |date=2018-07-04 |title=The marine crocodile Maledictosuchus (Thalattosuchia, Metriorhynchidae) from the Kimmeridgian deposits of Tlaxiaco, Oaxaca, southern Mexico |url=https://www.tandfonline.com/doi/abs/10.1080/02724634.2018.1478419 |journal=Journal of Vertebrate Paleontology |volume=38 |issue=4 |pages=(1)–(14) |doi=10.1080/02724634.2018.1478419 |hdl=11336/82460 |issn=0272-4634|url-access=subscription }}</ref> |frameless |- |''Torvoneustes'' |''T. mexicanus'' (=''Plesiosaurus mexicanus'', ''Cricosaurus mexicanus'') |Unknown, but most likely Yosobé |Kimmeridgian |Parts of cranium and jaws |A metriorhynchid thalattosuchian. First record of this genus outside Europe.<ref>{{Cite journal |last1=Barriento Lara |first1=Jair Israel |last2=Herrera |first2=Laura Yanina |last3=Fernández |first3=Marta Susana |last4=Alvarado Ortega |first4=Jesús |date=2016 |title=Occurrence of Torvoneustes (crocodylomorpha, metriorhynchidae) in marine jurassic deposits of Oaxaca, Mexico |url=https://ri.conicet.gov.ar/handle/11336/130337 |journal=Revista Brasileira de Paleontologia |volume=19 |issue=3 |pages=415–424 |doi=10.4072/rbp.2016.3.07 |issn=1519-7530|hdl=11336/130337 |hdl-access=free }}</ref> |frameless |}

==== Turtles ==== {| class="wikitable" width="100%" align="center" ! colspan="8" align="center" |Turtles of the Sabinal Formation |- !Genus !Species !Location !Stratigraphic position !Material !Notes !Images |- |''Notoemys'' |''N. tlaxiacoensis'' |Yosobé |Kimmeridgian |Nearly complete carapace with plastron |A stem-group sideneck turtle.<ref>{{Cite journal |last1=López-Conde |first1=Oliver A. |last2=Sterli |first2=Juliana |last3=Alvarado-Ortega |first3=Jesus |last4=Chavarría-Arellano |first4=María L. |date=2017 |title=A new platychelyid turtle (Pan-Pleurodira) from the Late Jurassic (Kimmeridgian) of Oaxaca, Mexico |url=https://onlinelibrary.wiley.com/doi/abs/10.1002/spp2.1069 |journal=Papers in Palaeontology |language=en |volume=3 |issue=2 |pages=161–174 |doi=10.1002/spp2.1069 |bibcode=2017PPal....3..161L |issn=2056-2802|url-access=subscription }}</ref><ref>{{Cite journal |last1=Conde |first1=Oliver A. López |last2=Ortega |first2=Jesús Alvarado |date=2021-12-01 |title=New remains of Notoemys tlaxiacoensis from the Llano Yosobé, Sabinal Formation (Upper Jurassic, Kimmeridgian), Oaxaca, Mexico |url=https://paleontologiamexicana.geologia.unam.mx/index.php/paleontologia/article/view/306 |journal=Revista Paleontología Mexicana |language=en |volume=10 |issue=2 |pages=123–128 |doi=10.22201/igl.05437652e.2021.10.2.306 |issn=2007-5189|url-access=subscription |doi-access=free }}</ref> | |}

==== Plesiosaurs ==== {| class="wikitable" width="100%" align="center" ! colspan="7" align="center" |Plesiosaurs of the Sabinal Formation |- !Genus !Species !Location !Stratigraphic position !Material !Notes !Images |- |''Liopleurodon'' |''L.'' sp. |Yosobé |Kimmeridgian |Partial jaw with teeth |A pliosaur. First record of this genus outside Europe.<ref name=":3">{{Cite journal |last1=Barrientos-Lara |first1=Jair Israel |last2=Fernández |first2=Marta S. |last3=Alvarado-Ortega |first3=Jesús |last4=Barrientos-Lara |first4=Jair Israel |last5=Fernández |first5=Marta S. |last6=Alvarado-Ortega |first6=Jesús |date=2015 |title=Kimmeridgian pliosaurids (Sauropterygia, Plesiosauria) from Tlaxiaco, Oaxaca, southern Mexic |url=https://www.scielo.org.mx/scielo.php?pid=S1026-87742015000200293&script=sci_arttext&tlng=en |journal=Revista Mexicana de Ciencias Geológicas |language=en |volume=32 |issue=2 |pages=293–304 |issn=1026-8774}}</ref> |frameless |- |Pliosauridae indet. | |Yosobé |Kimmeridgian |Vertebrae and ribs |An indeterminate pliosaur. Remains appear to have been scavenged by ''Planohybodus''.<ref name=":3" /> | |}

==== Ichthyosauria ==== {| class="wikitable" width="100%" align="center" ! colspan="8" align="center" |Ichthyosaurs of the Sabinal Formation |- !Genus !Species !Location !Stratigraphic position !Material !Notes !Images |- |Ophthalmosauridae indet. | |Yosobé |Kimmeridgian |Vertebrae |An ophthalmosaurid ichthyosaur. | |}

== References == {{Reflist}}

Category:Jurassic Mexico Category:Cretaceous Mexico Category:Late Jurassic North America Category:Lower Cretaceous Series of North America Category:Kimmeridgian Stage Category:Tithonian Stage Category:Berriasian Stage Category:Valanginian Stage Category:Shale formations Category:Shallow marine deposits Category:Paleontology in Mexico Category:Geologic formations of Mexico