''Westergaardodina'' is a species-rich

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

of spine, U or W-shaped paraconodont known from

Middle Cambrian Middle or The Middle may refer to: * Centre (geometry), the point equally distant from the outer limits. Places * Middle (sheading), a subdivision of the Isle of Man * Middle Bay (disambiguation) * Middle Brook (disambiguation) * Middle Creek ...

Lower Ordovician The Ordovician ( ) is a geologic period and system, the second of six periods of the Paleozoic Era. The Ordovician spans 41.6 million years from the end of the Cambrian Period million years ago (Mya) to the start of the Silurian Period Mya. Th ...

strata.

Use in stratigraphy

Paibi Paibi (), a village in Paibi Township (), Huayuan County, Xiangxi Tujia and Miao Autonomous Prefecture Hunan, China, is the location of the Global Boundary Stratotype Section and Point (GSSP) which marks the boundary between the third and Furongia ...

, a village in Hunan, China, is the location of the

Global Boundary Stratotype Section and Point A Global Boundary Stratotype Section and Point (GSSP) is an internationally agreed upon reference point on a stratigraphic section which defines the lower boundary of a stage on the geologic time scale. The effort to define GSSPs is conducted b ...

(GSSP) which marks the boundary between the

Miaolingian The Miaolingian is the third Series of the Cambrian Period, and was formally named in 2018. It lasted from about to million years ago and is divided in ascending order into 3 stages: the Wuliuan, Drumian, and Guzhangian. The Miaolingian is pr ...

and

Furongian The Furongian is the fourth and final epoch and series of the Cambrian. It lasted from to million years ago. It succeeds the Miaolingian series of the Cambrian and precedes the Lower Ordovician Tremadocian Stage. It is subdivided into three ...

epochs of the Cambrian Period on the

geologic time scale The geologic time scale, or geological time scale, (GTS) is a representation of time based on the rock record of Earth. It is a system of chronological dating that uses chronostratigraphy (the process of relating strata to time) and geochr ...

. The GSSP was ratified by the International Union of Geological Sciences in late 2003. It established the first formally agreed upon subdivision of the Cambrian. Markers which occur near the boundary include the first appearance of ''Westergaardodina proligula'' and the

Steptoean positive carbon isotope excursion The Steptoean Positive Carbon Isotope Excursion (SPICE) was a geological event which occurred about 494.6 million years ago near the beginning of the International Furongian Epoch of the Cambrian Period. The SPICE event was a positive shift in car ...

, a large positive shift in

carbon-13 Carbon-13 (13C) is a natural, stable isotope of carbon with a nucleus containing six protons and seven neutrons. As one of the environmental isotopes, it makes up about 1.1% of all natural carbon on Earth. Detection by mass spectrometry A mas ...

isotope Isotopes are two or more types of atoms that have the same atomic number (number of protons in their nuclei) and position in the periodic table (and hence belong to the same chemical element), and that differ in nucleon numbers (mass numb ...

References

External links

* Paraconodontida Conodont genera Cambrian conodonts Ordovician conodonts Fossils of Denmark Fossils of China Fossils of Canada Cambrian first appearances Ordovician extinctions Paleozoic life of Newfoundland and Labrador {{conodont-stub