Bajocian

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.[2]

System/
Period		 Series/
Epoch		 Stage/
Age		 Age (Ma)
Cretaceous Lower/
Early		 Berriasian younger
Jurassic Upper/
Late		 Tithonian ~145.0 152.1
Kimmeridgian 152.1 157.3
Oxfordian 157.3 163.5
Middle Callovian 163.5 166.1
Bathonian 166.1 168.3
Bajocian 168.3 170.3
Aalenian 170.3 174.1
Lower/
Early		 Toarcian 174.1 182.7
Pliensbachian 182.7 190.8
Sinemurian 190.8 199.3
Hettangian 199.3 201.3
Triassic Upper/
Late		 Rhaetian older
Subdivision of the Jurassic system
according to the ICS, as of 2020.[1]

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.[3] 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:

Palaeontology

†Thalattosuchians
Thalattosuchians of the Bajocian
Taxa Presence Location Description Images
Metriorhynchus An opportunistic carnivore that fed on fish, belemnites and other marine animals and possible carrion. Metriorhynchus grew to an average adult length of 3 meters (9.6 feet), although some individuals may have reached lengths rivaling those of large nile crocodiles.
A life restoration of a Metriorhynchus species.
Teleidosaurus
Steneosaurus
Teleidosaurus Normandie, France The most plesiomorphic known metriorhynchid.
Teleosaurus

†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

  1. 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
Los Molles Formation, Argentina. A rhomaleosaurid.
France A large pliosaurid.

†Ammonitida
Ammonitids of the Bajocian
Taxa Presence[4] 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[4] Location Description Images
Belemnitina Confirmed.
Belemnites
Hibolites Confirmed.
Holcobelus Confirmed.
Produvalia Confirmed.
Sachsibelus Confirmed.

Nautiloids
Nautiloids of the Bajocian
Taxa Presence[4] Location Description Images
Confirmed.
An illustration of a variety of fossil nautiloids.
Confirmed.
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References

Notes
  1. http://www.stratigraphy.org/index.php/ics-chart-timescale
  2. See for a detailed geologic timescale Gradstein et al. (2004)
  3. The GSSP is described by Pavia & Enay (1997)
  4. 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.
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