Otlaltepec Formation

{{short description|Geologic formation in Mexico}}

{{Infobox Rockunit|name=Otlaltepec Formation|namedby=|extent=Otlaltepec Basin|caption=|type=Geological formation|age=Middle Jurassic,
{{fossilrange|Bathonian|Callovian}}|period=Bathonian|prilithology=Sandstone|otherlithology=|namedfor=Otlaltepec Basin|image=|country=Mexico|region=|paleocoordinates=|unitof=|subunits=|overlies=Piedra Hueca Formation|underlies=|thickness=Typically at least {{convert|50|m|abbr=on}}| coordinates ={{coord|18.4019|N|97.9086|W|display=inline,title}}}}

The Otlaltepec Formation is a Middle Jurassic (Bathonian Callovian) geologic formation located in Mexico. The unit is derived from rocks of Late Carboniferous or Early Permian age due to the presence of microscopic zircon crystals dating to around 312-280 Ma found in sandstone deposited within the formation, although the fossil content preserved in the formation dates it to the Middle Jurassic (Bathonian-Callovian).{{Cite journal|last=Martini|first=Michelangelo|last2=Ramírez-Calderón|first2=Monica|last3=Solari|first3=Luigi|last4=Villanueva-Amadoz|first4=Uxue|last5=Zepeda-Martínez|first5=Mildred|last6=Ortega-Gutiérrez|first6=Fernando|last7=Elías-Herrera|first7=Mariano|date=2016|title=Provenance analysis of Jurassic sandstones from the Otlaltepec Basin, southern Mexico: Implications for the reconstruction of Pangea breakup|url=https://pubs.geoscienceworld.org/geosphere/article/12/6/1842-1864/208014|journal=Geosphere|language=en|volume=12|issue=6|pages=1842–1864|doi=10.1130/GES01366.1|issn=1553-040X|doi-access=free}} It overlies the Piedra Hueca Formation, which dates to no later than the Sinemurian (Early Jurassic).

Dinosaur remains pertaining to an indeterminate member of the Flagellicaudata, representing the first conclusive evidence of the occurrence of Flagellicaudata in this part of North America, are known from this formation.{{cite journal|author1=Héctor E. Rivera-Sylva|author2=Luis Espinosa-Arrubarrena|year=2020|title=Remains of a diplodocid (Sauropoda: Flagellicaudata) from the Otlaltepec Formation Middle Jurassic (Bathonian-Callovian) from Puebla, Mexico|url=http://www.ojs-igl.unam.mx/index.php/Paleontologia/article/view/640|journal=Paleontología Mexicana|volume=9|issue=2|pages=145–150}} Brachyphyllum, Platycladium, Podocarpites, and Masculostrobus are identified from the formation.{{Cite journal |last=Morales-Toledo |first=J. |last2=Cevallos-Ferriz |first2=S.R.S. |date=21 July 2023 |title=Is biodiversity promoted in rift-associated basins? Evidence from Middle Jurassic conifers from the Otlaltepec Formation in Puebla, Mexico |url=https://linkinghub.elsevier.com/retrieve/pii/S0034666723001215 |journal=Review of Palaeobotany and Palynology |language=en |pages=104952 |doi=10.1016/j.revpalbo.2023.104952|url-access=subscription }}