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Aptian

System/
Period
Series/
Epoch
Stage/
Age
Age (Ma)
Paleogene Paleocene Danian younger
Cretaceous Upper/
Late
Maastrichtian 66.0–72.1
Campanian 72.1–83.6
Santonian 83.6–86.3
Coniacian 86.3–89.8
Turonian 89.8–93.9
Cenomanian 93.9–100.5
Lower/
Early
Albian 100.5–~113.0
Aptian ~113.0–~125.0
Barremian ~125.0–~129.4
Hauterivian ~129.4–~132.9
Valanginian ~132.9–~139.8
Berriasian ~139.8–~145.0
Jurassic Upper/
Late
Tithonian older
Subdivision of the Cretaceous system
according to the IUGS, as of July 2012.

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.[1]

The Aptian partly overlaps the upper part of the regionally used (in western Europe) stage Urgonian.

Contents

  • Stratigraphic definitions 1
    • Subdivision 1.1
  • Lithostratigraphic units 2
  • Palaeontology 3
    • †Ammonitida 3.1
    • †Belemnitida 3.2
    • Nautilida 3.3
    • †Orthocerida 3.4
    • †Phylloceratida 3.5
    • Sepiida 3.6
    • †Ankylosaurs 3.7
    • Birds (avian theropods) 3.8
    • †Ceratopsians 3.9
    • †Choristoderans 3.10
    • Crocodylomorpha 3.11
    • Fish 3.12
    • Mammalia 3.13
    • †Ornithopods 3.14
    • †Plesiosaurs 3.15
    • †Pterosaurs 3.16
    • †Sauropods 3.17
    • †Stegosaurs 3.18
    • †Non-Avian Theropods 3.19
  • References 4
    • Notes 4.1
    • Literature 4.2
  • External links 5

Stratigraphic definitions

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.

Subdivision

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).

Lithostratigraphic units

Antlers Formation, Cedar Mountain Formation, Cloverly Formation, Elrhaz Formation, Jiufotang Formation, Little Atherfield, Mazong Shan, Potomac Formation, Santana Formation, Twin Mountains Formation, Xinminbao Group, Yixian Formation

Palaeontology

Ammonitida

Tropaeum imperator

Belemnitida

Nautilida

Orthocerida

Phylloceratida

Sepiida

Ankylosaurs

Ankylosauria of the Aptian
Taxa Presence Location Description Images
Cedar Mountain Formation, Utah, USA
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 meter long) primitive ankylosaur
Aptian to Albian Cloverly Formation, Wyoming, Montana, Utah, USA A medium-sized nodosaurid, measuring about 5 meters (16.5 ft) 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)

Ceratopsians

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 meter 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 meters long early ceratopsian

†Choristoderans

Choristoderans of the Aptian
Taxa Presence Description Images

Genus:

  1. Hyphalosaurus lingyuanensis
  2. Hyphalosaurus baitaigouensis
Yixian Formation, Liaoning Province, China

Genus:

  1. Monjurosuchus splendens
China and Japan

Crocodylomorpha

Fish

Mammalia

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 prensile 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.
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

Ornithopods

Ornithopoda of the Aptian
Taxa Presence Location Description Images
Aptian/Albian Eumeralla Formation, Victoria, Australia 2–3 meters 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 meters long (20 ft), estimated to weigh about 1 ton
Mazong Shan, Gansu, China Primitive hadrosaur or iguanodont
Europe Worldwide distributed, type genus of the Iguanodontia. 10 meters long
Niger 9 meters 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 meters long hadrosauroid, possibly with a sail on the back
Cedar Mountain Formation, Utah A genus of advanced iguanodont
Victoria, Australia 1.8 meter 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 meters 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

Plesiosaurs

Plesiosaurs of the Aptian
Taxa Presence Location Description Images
Kansas, USA; Colombia A pliosaur that grew to around 10 meters in length, it represents the last known occurrence of a pliosaur in North America.
Brachauchenius
Kronosaurus
Umoonasaurus
Paja Formation, Colombia 8 meters long elasmosaurid
Aptian to Albian Boyaca, Colombia Among the largest pliosaurs, body-length estimates put the total length of Kronosaurus at 9–10 meters
Australia Relatively small cryptocleidid, around 2.5 m long, identified by the three crest-ridges on its skull.

Pterosaurs

Sauropods

Sauropods of the Aptian
Taxa Presence Location Description Images
Itapecuru Formation, Maranhão, Brazil A genus of 12 meters long diplodocoid.
Arundel Formation, Maryland, USA A large titanosaur, adults are estimated to have been more than 9m high and 15m to 18m long.
Napai Formation, Guangxi, China Probably a basal titanosaur, known by fragmentary postcranial remains
  • Jobaria
    • Jobaria tiguidensis
Aptian or Albian Sahara Desert Seems to be a very primitive sauropod. Unlike other Cretaceous sauropods, Jobaria had spoon-shaped teeth.
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
Antlers Formation, Oklahoma, USA The last known giant brachiosaurid; extrapolations indicate that the head of Sauroposeidon could reach 17 m in height, making it the tallest known dinosaur. With an estimated length of 30 m and a mass of 36–40 MT 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

Stegosaurs

Stegosauria of the Aptian
Taxa Presence Location Description Images
  • Wuerhosaurus
    • Wuerhosaurus homheni
    • Wuerhosaurus ordosensis
Xinjiang, Inner Mongolia, China 7 meter long stegosaurid
Wuerhosaurus

Non-Avian Theropods

Non Avian Theropods of the Aptian
Taxa Presence Location Description Images
Texas, Oklahoma, ?Maryland, USA Likely an apex predator, up to 12 meters long. Classification disputed (Carcharodontosaurid or Allosaurid)
Jiufotang Formation, Liaoning, China Small (90 centimeters long feathered dromeaosaurid, possibly the same species as Microraptor
Cloverly Formation, Montana and Wyoming, Antlers Formation, Oklahoma, Potomac Formation, Maryland, USA 3–4 meters long carnivorous dromaeosaurid
Chubut Province, Argentina Possibly ceratosaurian
Yixian Formation, Liaoning, China Large (1.8 meter 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 centimeters 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 2-3 meters in length. This small dinosaur seems to have had long, slender legs.
Elrhaz Formation, Niger Earliest-known abelisaurid
Isle of Wight, England, UK 7.5 meters long allosaurid
Yixian Formation, Liaoning, China Primitive oviraptosaur, possibly synonymous with Incisivosaurus
Jiufotang Formation, Liaoning, China Caudipterid oviraptosaur
China 1 meter long troodontid
Liaoning, China 1.20 meter long compsognathid, fossilized with traces of color pigmentation in its feathers
Tenere, Niger 12 meters long spinosaurid
Chubut Province, Argentina 12 meter long carcharodontosaurid
North America The largest known dromaeosaurid
Aptian Yixian Formation, China A 10-meter tyrannosauroid and the largest feathered dinosaur

References

Notes

  1. ^ Gradstein et al. (2004)
  2. ^ Mortimer, Mickey. "List of Dromaeosaurids". Retrieved July 8, 2011. 

Literature

External links

  • GeoWhen Database - Aptian
  • Mid-Cretaceous timescale, at the website of the subcommission for stratigraphic information of the ICS
  • Stratigraphic charts of the Lower Cretaceous: [3] and [4], at the website of Norges Network of offshore records of geology and stratigraphy
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