Bajocian

Bajocian
	170.3 ± 1.4 – 168.3 ± 1.3 Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓
Chronology
	Key events in the Jurassic -200 — – -195 — – -190 — – -185 — – -180 — – -175 — – -170 — – -165 — – -160 — – -155 — – -150 — – -145 — – M; e; s; o; z; o; i; c T J; u; r; a; s; s; i; c K L; T E; a; r; l; y M; i; d; d; l; e L; a; t; e E; K Rhaetian Hettangian Sinemurian Pliensbachian Toarcian Aalenian Bajocian Bathonian Callovian Oxfordian Kimmeridgian Tithonian Berriasian how to approximate the timescale of key Jurassic events.; Vertical axis: millions of years ago.;
Etymology
Name formality	Formal
Usage Information
Celestial body	Earth
Regional Usage	Global (ICS)
Time scale(s) used	ICS Time Scale
Definition
Chronological unit	Age
Stratigraphic unit	Stage
Time span formality	Formal
Lower boundary definition	FAD of the Ammonites Hyperlioceras mundum, Hyperlioceras furcatum, Braunsina aspera, and Braunsina elegantula
Lower boundary GSSP	Cabo Mondego, Portugal; 40.1992°N 8.9042°W
GSSP ratified	1996[1]
Upper boundary definition	FAD of the Ammonite Gonolkites convergen
Upper boundary GSSP	Ravin du Bès, Bas-Auran, Alpes de Haute, France; 43.9606°N 6.3153°E
GSSP ratified	July 2008[2]

In the geologic timescale, the Bajocian is an age and stage in the Middle Jurassic. It lasted from approximately 170.3 Ma to around 168.3 Ma (million years ago). The Bajocian age succeeds the Aalenian age and precedes the Bathonian age.[3]

Stratigraphic definitions

The Bajocian stage takes its name from the Latin name (Bajocae) of the town of Bayeux, in the region of Normandy in France. The stage was named and introduced in scientific literature by French palaeontologist Alcide d'Orbigny in 1842.

The base of the Bajocian stage is defined as the place in the stratigraphic column where fossils of the ammonite genus Hyperlioceras first appear. A global reference profile (a GSSP) for the base is located at Murtinheira, close to Cabo Mondego in Portugal.[4] The top of the Bajocian (the base of the Bathonian) is at the first appearance of ammonite species Parkinsonia convergens.

Subdivision

The Bajocian is often divided into Lower/Early and Upper/Late subages or substages.

In the Tethys domain, the Bajocian contains seven ammonite biozones:

zone of Parkinsonia parkinsoni
zone of Garantiana garantiana
zone of Strenoceras niortense
zone of Stephanoceras humphriesianum
zone of Sonninia propinquans
zone of Witchellia laeviuscula
zone of Hyperlioceras discites

Palaeontology

†Thalattosuchians

Thalattosuchians of the Bajocian
Taxa	Presence	Location	Description	Images
Eoneustes	Bajocian-Bathonian	France	A basal metriorhynchoid.

†Ornithischians

Ornithischians of the Bajocian
Taxa	Presence	Location	Description	Images
Xiaosaurus	Bajocian-Callovian	Xiashaximiao Formation

†Sauropodomorphs (except Sauropods)

Sauropods of the Bajocian
Taxa	Presence	Location	Description	Images
Yunnanosaurus Yunnanosaurus youngi		Zhanghe Formation, China	a late surviving prosauropod

†Sauropods

Sauropods of the Bajocian
Taxa	Presence	Location	Description	Images
' Rhoetosaurus		Queensland, Australia	Rhoetosaurus is the first sauropod discovered in Australia

Theropods

Sauropods of the Bajocian
Taxa	Presence	Location	Description	Images
Asfaltovenator	Toarcian-Bajocian	Cañadón Asfalto Basin, Patagonia, Argentina	A large basal carnosaur. The unique combination of characteristics seen in Asfaltovenator may indicate megalosauroids and allosauroids shared a common ancestor not shared with Coelurosauria.
Condorraptor	Aalenian-Bajocian	Cañadón Asfalto Basin, Patagonia, Argentina	It was among the earliest large South American theropods.
Duriavenator	Bajocian	Dorset, England	An earlier close relative of Megalosaurus, formerly known as Megalosaurus hesperis, estimated to be 7 meters long.
Magnosaurus	Aalenian-Bajocian	Dorset, England	Magnosaurus was one of the first Megalosauroidea to evolve.
Ozraptor	Middle Bajocian	Colalura Sandstone, Australia	A theropod of uncertain affinities, around 2 meters long. Possibly an abelisauroid, the oldest one known if that is the case.

†Plesiosauria

Plesiosaurs of the Bajocian
Taxa	Presence	Location	Description	Images
Maresaurus coccai		Los Molles Formation, Argentina.	A rhomaleosaurid.
Simolestes keileni		France	A large pliosaurid.

†Ammonitida

Ammonitids of the Bajocian
Taxa	Presence[5]	Location	Description	Images
Alfeldites	Confirmed.		The only known species in this Alaskan genus. Abbasites is believed to be ancestral to the ammonite family Otoitidae.	Life restorations of two different ammonite genera.
Apsorroceras	Confirmed.
Asphinctites	Confirmed.
Asthenoceras	Confirmed.
Bigotites	Confirmed.
Bradfordia	Confirmed.
Cadomites	Confirmed.
Cadomoceras	Confirmed.
Caumontisphinctes	Confirmed.
Chondroceras	Confirmed.
Cleistosphinctes	Confirmed.
Cranocephalites	Confirmed.
Darellia	Confirmed.
Dimorphinites	Confirmed.
Diplesioceras	Confirmed.
Docidoceras	Confirmed.
Dorsetensia	Confirmed.
Durotrigensia	Confirmed.
Duashnoceras	Confirmed.
Emileia	Confirmed.
Eocephalites	Confirmed.
Epistrenoceras	Confirmed.
Ermoceras	Confirmed.
Euaptetoceras	Confirmed.
Eudmetoceras	Confirmed.
Euhoploceras	Confirmed.
Fissilobiceras	Confirmed.
Fontannesia	Confirmed.
Frogdenites	Confirmed.
Garantiana	Confirmed.
Guhsania	Confirmed.
Graphoceras	Confirmed.
Haplopleuroceras	Confirmed.
Hebetoxyites	Confirmed.
Hlawiceras	Confirmed.
Hyperlioceras	Confirmed.
Kosmermoceras	Confirmed.
Kumatostephanus	Confirmed.
Labyrinthoceras	Confirmed.
Leptosphinctes	Confirmed.
Lissoceras	Confirmed.
Lupherites	Confirmed.
Magharina	Confirmed.
Megasphaeroceras	Confirmed.
Metrolytoceras	Confirmed.
Nannolytoceras	Confirmed.
Newmarracarroceras	Confirmed.
Normannites	Confirmed.
Oecoptychius	Confirmed.
Oecotraustes	Confirmed.
Okribites	Confirmed.
Oppelia	Confirmed.
Orthogarantiana	Confirmed.
Otoites	Confirmed.
Oxycerites	Confirmed.
Padragosiceras	Confirmed.
Parastrenoceras	Confirmed.
Parkinsonia	Confirmed.
Phaulostephanus	Confirmed.
Poecilomorphus	Confirmed.
Praebigotites	Confirmed.
Praeparkinsonia	Confirmed.
Praestrigites	Confirmed.
Procerites	Confirmed.
Prorsisphinctes	Confirmed.
Protoecotrausites	Confirmed.
Pseudogarantiana	Confirmed.
Pseudotoites	Confirmed.
Reynesella	Confirmed.
Shirbuirnia	Confirmed.
Siemiradzkia	Confirmed.
Skirroceras	Confirmed.
Skolekostephanus	Confirmed.
Sohlites	Confirmed.
Sonninia	Confirmed.
Sphaeroceras	Confirmed.
Spinammatoceras	Confirmed.
Spiroceras	Confirmed.
Stegoxyites	Confirmed.
Stemmatoceras	Confirmed.
Strenoceras	Confirmed.
Strigoceras	Confirmed.
Subcollina	Confirmed.
Telermoceras	Confirmed.
Teloceras	Confirmed.
Thamboceras	Confirmed.
Toxamblyites	Confirmed.
Toxolioceras	Confirmed.
Trilobiticeras	Confirmed.
Trimarginia	Confirmed.
Tugurites	Confirmed.
Vermisphinctes	Confirmed.
Witchellia	Confirmed.
Zemistephanus	Confirmed.
Zurcheria	Confirmed.

†Belemnites

Belemnites of the Bajocian
Taxa	Presence[5]	Location	Description	Images
Belemnitina	Confirmed.			Belemnites
Hibolites	Confirmed.
Holcobelus	Confirmed.
Produvalia	Confirmed.
Sachsibelus	Confirmed.

Nautiloids

Nautiloids of the Bajocian
Taxa	Presence[5]	Location	Description	Images
Ophionautilus	Confirmed.			An illustration of a variety of fossil nautiloids.
Somalinautilus	Confirmed.			An illustration of a variety of fossil nautiloids.

References

Notes

Pavia, G.; Enay, R. (March 1997). "Definition of the Aalenian-Bajocian Stage boundary". Episodes. 20 (1): 16–22. doi:10.18814/epiiugs/1997/v20i1/004. Retrieved 23 December 2020.
Fernández-López, Sixto Rafael; Pavia, Giulio; Erba, Elisabetta; Guiomar, Myette; Maria Helena Henriques; Lanza, Roberto; Mangold, Charles; Morton, Nicol; Olivero, Davide; Daniele Tiraboschi (2009). "The Global Boundary Stratotype Section and Point (GSSP) for base of the Bathonian Stage (Middle Jurassic), Ravin du Bès Section, SE France" (PDF). Episodes. 32 (4): 222–248. doi:10.18814/epiiugs/2009/v32i4/001.
See for a detailed geologic timescale Gradstein et al. (2004)
The GSSP is described by Pavia & Enay (1997)
Sepkoski (2002)

Literature

Gradstein, F.M.; Ogg, J.G. & Smith, A.G.; 2004: A Geologic Time Scale 2004, Cambridge University Press.
Alcide d´Orbigny; 1842: Paléontologie française. 1. Terrains oolitiques ou jurassiques, 642 pp., Bertrand, Paris.
Pavia, G. & Enay, R.; 1997: Definition of the Aalenian-Bajocian Stage boundary, Episodes, 20(1): pp 16–22.
Sepkoski, J.; 2002: A compendium of fossil marine animal genera (entry on cephalopoda), Bulletins of American Paleontology 364, p 560.
Rodríguez-de la Rosa, Rubén A.; Velasco-de León, María Patricia; Lozano-Carmona, Diego-Enrique; Arellano-Gil, Javier (2018). "Middle Jurassic ankylosaur tracks from Mexico" (PDF). Boletín de la Sociedad Geológica Mexicana. 70 (2): 379–395.

External links

GeoWhen Database - Bajocian
Jurassic-Cretaceous and Lower Jurassic timescales, at the website of the subcommission for stratigraphic information of the ICS
Stratigraphic chart of the Upper Jurassic, at the website of Norges Network of offshore records of geology and stratigraphy

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[1] Pavia, G.; Enay, R. (March 1997). "Definition of the Aalenian-Bajocian Stage boundary". Episodes. 20 (1): 16–22. doi:10.18814/epiiugs/1997/v20i1/004. Retrieved 23 December 2020.

[2] Fernández-López, Sixto Rafael; Pavia, Giulio; Erba, Elisabetta; Guiomar, Myette; Maria Helena Henriques; Lanza, Roberto; Mangold, Charles; Morton, Nicol; Olivero, Davide; Daniele Tiraboschi (2009). "The Global Boundary Stratotype Section and Point (GSSP) for base of the Bathonian Stage (Middle Jurassic), Ravin du Bès Section, SE France" (PDF). Episodes. 32 (4): 222–248. doi:10.18814/epiiugs/2009/v32i4/001.

[3] See for a detailed geologic timescale Gradstein et al. (2004)

[4] The GSSP is described by Pavia & Enay (1997)

[Sepkoski_Ceph-5] Sepkoski (2002)