The Aptian is an age in the geologic timescale or a stage in the stratigraphic column. It is a subdivision of the Early or Lower Cretaceous epoch or series and encompasses the time from 125.0 ± 1.0 Ma to 113.0 ± 1.0 Ma (million years ago), approximately. The Aptian succeeds the Barremian and precedes the Albian, all part of the Lower/Early Cretaceous.[3]

Aptian
~125.0 – ~113.0 Ma
Chronology
Etymology
Name formalityFormal
Usage information
Celestial bodyEarth
Regional usageGlobal (ICS)
Time scale(s) usedICS Time Scale
Definition
Chronological unitAge
Stratigraphic unitStage
Time span formalityFormal
Lower boundary definitionNot formally defined
Lower boundary definition candidates
Lower boundary GSSP candidate section(s)Gorgo a Cerbara, Piobbico, Central Apennines, Italy
Upper boundary definitionFAD of the Planktonic Foraminifer Microhedbergella renilaevis
Upper boundary GSSPCol de Pré-Guittard section, Arnayon, Drôme, France
44°29′47″N 5°18′41″E / 44.4964°N 5.3114°E / 44.4964; 5.3114
GSSP ratifiedApril 2016[2]
Palaeogeography of the Earth in Aptian.

The Aptian partly overlaps the upper part of the Western European) Urgonian stage.

The Selli Event, also known as OAE1a, was one of two oceanic anoxic events in the Cretaceous period, which occurred around 120 Ma and lasted approximately 1 to 1.3 million years.[4][5] The Aptian extinction was a minor extinction event hypothesized to have occurred around 116 to 117 Ma.[6]

Stratigraphic definitionsEdit

The Aptian was named after the small city of Apt in the Provence region of France, which is also known for its crystallized fruits. The original type locality is in the vicinity of Apt. The Aptian was introduced in scientific literature by French palaeontologist Alcide d'Orbigny in 1840.

The base of the Aptian stage is laid at magnetic anomaly M0r. A global reference profile for the base (a GSSP) had in 2009 not yet been appointed. The top of the Aptian (the base of the Albian) is at the first appearance of coccolithophore species Praediscosphaera columnata in the stratigraphic record.

SubdivisionEdit

In the Tethys domain, the Aptian contains eight ammonite biozones:

Sometimes the Aptian is subdivided in three substages or subages: Bedoulian (early or lower), Gargasian (middle) and Clansayesian (late or upper). In modern formal chronostratigraphy the Aptian is divided into Lower and Upper sub-stages. The Lower Aptian is equivalent to the Bedoulian, and it includes the oglanensis to furcata Tethyan ammonite zones. The Upper Aptian is equivalent to the Gargasian and Clansayesian, it includes the subnodosocostatum to jacobi Tethyan ammonite zones (Gradstein et al. 2004).

Lithostratigraphic unitsEdit

Examples of rock units formed during the Aptian are: Antlers Formation, Cedar Mountain Formation, Cloverly Formation, Elrhaz Formation, Jiufotang Formation, Little Atherfield, Mazong Shan, Potomac Formation, Santana Formation, Twin Mountains Formation, Xinminbao Group and Yixian Formation.

PalaeontologyEdit

AmmonitidaEdit

 
Tropaeum imperator

BelemnitidaEdit

NautilidaEdit

OrthoceridaEdit

PhylloceratidaEdit

SepiidaEdit

AmphibiaEdit

Amphibians of the Aptian
Taxa Presence Location Description Images
Wonthaggi Formation, Victoria, Australia A large brachyopoid stereospondyl and the youngest known temnospondyl.
 
Koolasuchus
 
Liaobatrachus
  • Liaobatrachus
    • Liaobatrachus zhaoi
    • Liaobatrachus beipiaoensis
Yixian Formation, Liaoning Province, China. Α genus of prehistoric spadefoot toads and the oldest modern frog known to date. Later discoveries were named Callobatrachus sanyanensis and Mesophryne beipiaoensis until both were classified as synonymous with Liaobatrachus.

AnkylosaursEdit

Ankylosauria of the Aptian
Taxa Presence Location Description Images
Cedar Mountain Formation, Utah, USA
 
Gobisaurus
 
Minmi
 
Sauropelta
Ulansuhai Formation, Inner Mongolia, China
Yixian Formation, Liaoning, China Nodosaurid with ventral armor plating
  • Minmi
    • Minmi paravertebra
Bungil Formation, Queensland, Australia Small (1 metre (3 feet)) primitive ankylosaur
Aptian to Albian Cloverly Formation, Wyoming, Montana, Utah, USA A medium-sized nodosaurid, measuring about 5 metres (16 feet) long, Sauropelta had a distinctively long tail which made up about half of its body length. Its neck and back were protected by an extensive bony body armor including characteristically large spines
Mongolia Ankylosaurid

Birds (avian theropods)Edit

CeratopsiansEdit

Ceratopsia of the Aptian
Taxa Presence Location Description Images
Mazong Shan, Gansu, China A basal neoceratopsian, appears to have been bipedal and quite small (about 1 metre (3 feet) long) with a comparatively large head. Unlike many later ceratopsians it doesn't have any horns and has only a small bony frill projecting from the back of its head.
Xinminbao Group, Gansu, China, South Korea Basal neoceratopsian
  • Psittacosaurus
    • Psittacosaurus meileyingensis
    • Psittacosaurus mongoliensis
China, Mongolia, Russia Psittacosaurid Ceratopsian
Victoria, Australia 2-metre (7-foot) long early ceratopsian

†ChoristoderansEdit

Choristoderans of the Aptian
Taxa Presence Description Images
  1. Hyphalosaurus lingyuanensis
  2. Hyphalosaurus baitaigouensis
Yixian Formation, Liaoning Province, China
  1. Khurendukhosaurus orlovi
  2. Khurendukhosaurus bajkalensis
Mongolia and Russia
China and Japan
Jiufotang Formation, China
  1. Tchoiria namsari
  2. Tchoiria klauseni
Hühteeg Formation, Hüren Dukh, central Mongolia

CrocodylomorphaEdit

Crocodylomorphs of the Albian
Taxa Presence Location Description Images
Aptian - Albian Tegama Group, Niger A small notosuchian under 1 metre (3.3 ft) long with a duck-like snout.
Aptian - Albian Wulong Formation, China The first notosuchian found with heterodont teeth, thought to be a herbivore
Niger Initially described as related to Peirosauridae, more recent works usually find Stolokrosuchus to be one of the basalmost neosuchians.

FishEdit

MammaliaEdit

Mammals of the Hauterivian
Taxa Presence Location Description Images
several species from Hauterivian to Albian Spain, Mongolia
Yixian Formation, Liaoning, China A long-tailed, nocturnal tetrapod (with prehensile fingers and toes) which hunted insects, its food, during the night
Yixian Formation, Liaoning, China The largest mammal known from the Cretaceous period of the Mesozoic, and the one for which there is the best evidence that it fed on dinosaurs.
Yixian Formation, Liaoning, China
Flat Rocks, Victoria, Australia The earliest known monotreme.
Yixian Formation, Hebei, China A small mammal, barely 13 centimetres (5 inches) long. It was lightly built and fed on insects, worms and other invertebrates, probably hunting at night. Like most early mammals, Yanoconodon had short, sprawling legs and claws that were most likely used for burrowing underground or digging

Zhangheotherium

Yixian Formation, Liaoning, China

OrnithopodsEdit

Ornithopoda of the Aptian
Taxa Presence Location Description Images

Aptian-Albian

Khukhtek Formation, Mongolia
Aptian/Albian Eumeralla Formation, Victoria, Australia 2-to-3-metre (7-to-10-foot) long hypsilophodont
Quantou Formation, Jilin, China As a small basal ornithopod, Changchunsaurus would have been a swift bipedal herbivore, feeding close to the ground.
Barremian-?Aptian Bernissart, Belgium; ?England; ?Germany A lightly constructed iguanodont, about 6 metres (20 feet) long, estimated to weigh about 1 tonne (1 long ton; 1 short ton)
Mazong Shan, Gansu, China Primitive hadrosaur or iguanodont
Europe Worldwide distributed, type genus of the Iguanodontia. 10 metres (33 feet) long
Niger 9-metre (30-foot) long heavily built Iguanodont
Atherfield, England, UK formerly known as Iguanodon atherfieldensis
Lakota Formation, South Dakota, USA A genus intermediate between Camptosaurus and more derived iguanodonts.
Echkar Formation, Niger 7-metre (23-foot) long hadrosauroid, possibly with a sail on the back
Cedar Mountain Formation, Utah A genus of advanced iguanodont
Victoria, Australia 1.8-metre (6-foot) long hypsilophodontid
Xinminbao Group, Gansu, China A hypsilophodontid or other basal ornithopod, Siluosaurus would have been a bipedal herbivore.
  • Tenontosaurus
    • Tenontosaurus tilletti
    • Tenontosaurus dossi
Cloverly Formation, Wyoming and Montana, Antlers Formation, Oklahoma, Twin Mountains Formation, Texas, USA 8-metre (26-foot) long early iguanodont
Aptian to Albian Purgatoire Formation, Colorado, USA An iguanodont described as intermediate in derivation between Camptosaurus and Iguanodon
Cloverly Formation, Montana, USA Hypsilophodont

PlesiosaursEdit

Plesiosaurs of the Aptian
Taxa Presence Location Description Images
Paja Formation, Colombia 8-metre (26-foot) long elasmosaurid
 
Kronosaurus
 
Umoonasaurus
Aptian to Albian Boyaca, Colombia Among the largest pliosaurs, body-length estimates put the total length of Kronosaurus at 9 to 10 metres (30 to 33 feet)
Aptian to Albian China Possibly a pliosauroid.
Australia Relatively small cryptocleidid, around 2.5 metres (8 feet) long, identified by the three crest-ridges on its skull.

PterosaursEdit

SauropodsEdit

Sauropods of the Aptian
Taxa Presence Location Description Images
Itapecuru Formation, Maranhão, Brazil A genus of 12 metres (39 feet) long diplodocoid.
Cedar Mountain Formation, Utah; Paluxy Formation, Texas A brachiosaurid
Napai Formation, Guangxi, China Probably a basal titanosaur, known by fragmentary postcranial remains
Malawi Titanosaurid which fossils consist solely of parts of a lower mandible and a few teeth
Argentina A basal titanosaurid
Malawi One of the few titanosaurs for which skull material has been found
Elrhaz Formation, Niger Diplodocoid dinosaur, one of the most common genera found in the rich fossil vertebrate fauna of the Elrhaz Formation
Twin Mountains Formation, Texas, USA A basal titanosauriform
Sao Khua Formation, Thailand
Antlers Formation, Oklahoma, USA The last known giant brachiosaurid; extrapolations indicate that the head of Sauroposeidon could reach 17 metres (56 feet) in height, making it the tallest known dinosaur. With an estimated length of 30 metres (98 feet) and a mass of 36 to 40 tonnes (35 to 39 long tons; 40 to 44 short tons) it also ranks among the longest and heaviest.
Grès Supérior Formation, Laos A basal titanosaur, known from the remains of two or three individuals.
Cedar Mountain Formation, Utah, USA A titanosaur, known from an incomplete skeleton of an adult and a juvenile

StegosaursEdit

Stegosauria of the Aptian
Taxa Presence Location Description Images
  • Wuerhosaurus
    • Wuerhosaurus homheni
    • Wuerhosaurus ordosensis
Xinjiang, Inner Mongolia, China 7-metre (23-foot) long stegosaurid
 
Wuerhosaurus

Non-Avian TheropodsEdit

Non Avian Theropods of the Aptian
Taxa Presence Location Description Images
Texas, Oklahoma, ?Maryland, USA Likely an apex predator, up to 12 metres (39 feet) long. Classification disputed (Carcharodontosaurid or Allosaurid)
Yixian Formation A therizinosaur.
Cloverly Formation, Montana and Wyoming, Antlers Formation, Oklahoma, Potomac Formation, Maryland, USA 3-to-4-metre (10-to-13-foot) long carnivorous dromaeosaurid.
Chubut Province, Argentina Possibly ceratosaurian.
Yixian Formation, Liaoning, China Large (1.8 metres (6 feet) long) compsognathid.
Marree Formation, South Australia, Australia A little-known maniraptoran known primarily from a single fossilized tibia, which had been fossilized through a rare process in which the bone through hydration turned to opal. Apart from the tibia, the first find included some small probable fibula fragments. Later a foot digit was referred that might have come from the same species, but the assignment is dubious. The tibia is broken into about ten larger pieces and roughly 33 centimetres (13 inches) long. It is very slender in build and shows the impression of the ascending process of the astragalus, an ankle bone itself lost. The process seems to have been very long and narrow. Kakuru is believed to have been carnivorous, was bipedal and about 2 to 3 metres (7 to 10 feet) in length. This small dinosaur seems to have had long, slender legs.
Elrhaz Formation, Niger Earliest-known abelisaurid.
Jiufotang Formation, Liaoning, China Small (90 centimetres (35 inches) long) feathered dromaeosaurid, possibly the same species as Microraptor zhaoianus.

"†Nanshiungosaurus" bohlini

Barremian-Aptian Upper Xinminbao Group A species of relatively large therizinosaur dinosaur measuring around 6 meters long and 1.3 tonnes heavy. Due to the lack of shared unique traits and the large age difference with the slightly smaller Nanshiungosaurus brevispinus, it is generally considered that "Nanshiungosaurus" bohlini is unrelated to the previous and might warrant its own genus.
Isle of Wight, England, UK 7.5-metre (25-foot) long allosauroid
Yixian Formation, Liaoning, China Primitive oviraptorosaur, possibly synonymous with Incisivosaurus
Jiufotang Formation, Liaoning, China Caudipterid oviraptorosaur
China 1-metre (3-foot) long troodontid.
Liaoning, China 1.2-metre (4-foot) long compsognathid, fossilized with traces of color pigmentation in its feathers
Jiufotang Formation, Liaoning, China A species of large basal proceratosaurid tyrannosaur, reaching a total estimated length of 7.5–10 m and a maximum weight of 1.2-2.5 tonnes.
Tenere, Niger 12-metre (39-foot) long spinosaurid.
Chubut Province, Argentina 12-metre (39-foot) long carcharodontosaurid.
North America The largest known dromaeosaurid.
Aptian Yixian Formation, China A medium sized tyrannosauroid and a close relative of the later Alectrosaurus and eutyrannosaurian tyrannosaurs.
Aptian Yixian Formation, China A 9-metre (30-foot) tyrannosauroid and the largest dinosaur with feathers preserved.

See alsoEdit

ReferencesEdit

NotesEdit

  1. ^ Super User. "ICS - Chart/Time Scale". www.stratigraphy.org.
  2. ^ Kennedy, J.W.; Gale, A.S.; Huber, B.T.; Petrizzo, M.R.; Bown, P.; Jenkyns, H.C. (2017). "The Global Boundary Stratotype Section and Point (GSSP) for the base of the Albian Stage, of the Cretaceous, the Col de Pré-Guittard section, Arnayon, Drôme, France" (PDF). Episodes. 40 (3): 177–188. doi:10.18814/epiiugs/2017/v40i3/017021.
  3. ^ Gradstein et al. (2004)
  4. ^ Li, Yong-Xiang; Bralower, Timothy J.; Montañez, Isabel P.; Osleger, David A.; Arthur, Michael A.; Bice, David M.; Herbert, Timothy D.; Erba, Elisabetta; Premoli Silva, Isabella (2008-07-15). "Toward an orbital chronology for the early Aptian Oceanic Anoxic Event (OAE1a, ~ 120 Ma)". Earth and Planetary Science Letters. 271 (1–4): 88–100. Bibcode:2008E&PSL.271...88L. doi:10.1016/j.epsl.2008.03.055.
  5. ^ Leckie, R.; Bralower, T.; Cashman, R. (2002). "Oceanic anoxic events and plankton evolution: Biotic response to tectonic forcing during the mid-Cretaceous" (PDF). Paleoceanography. 17 (3): 1–29. Bibcode:2002PalOc..17.1041L. doi:10.1029/2001pa000623.
  6. ^ Archangelsky, Sergio. "The Ticó Flora (Patagonia) and the Aptian Extinction Event." Acta Paleobotanica 41(2), 2001, pp. 115-22.
  7. ^ Mortimer, Mickey. "List of Dromaeosaurids". Archived from the original on October 3, 2011. Retrieved July 8, 2011.

LiteratureEdit

  • Gradstein, F.M.; Ogg, J.G. & Smith, A.G.; 2004: A Geologic Time Scale 2004, Cambridge University Press.
  • d'Orbigny, A.C.V.M.; 1842: Paléontologie française: Terrains crétacés, vol. ii. (in French)

External linksEdit