Kaili Formation
Encyclopedia
The Kaili Formation named for nearby city of Kaili in the Guizhou province of southwest China, the Kaili formation is more than 200 meters thick with boundaries dated from the Lower–Middle Cambrian
boundary to the early Middle Cambrian (~513 to 506 million years ago). The Kaili Formation subdivided into three trilobite zones: Bathynotus holopygous–Ovatoryctocara granulate Zone, Oryctocephalus indicus Zone, and Olenoides jialaoensis Zone. Ocryctocephalus indicus and Ovatoryctocara granulata, which were suggested to be index species for the GSSP of the Lower–Middle Cambrian boundary, occur at the similar stratigraphic horizon in Siberia
and China
. FAD
of the trilobites Oryctocephalus indicus and Ovatoryctocara granulate are suggested as a two alternative standards of the Lower–Middle Cambrian boundary. Kaili Formation correlated with Amgian Stage in Siberia.
The biggest middle part of the Kaili Formation, Oryctocephalus indicus Zone, contains a Burgess Shale-type Lagerstätte with many well-preserved fossils known collectively as the Kaili Biota. This biota is located between the two most important and famous Cambrian Lagerstätten: the middle Lower Cambrian Maotianshan Shale (containing the Chengjiang Biota) and the Middle Cambrian Burgess Shale
.
among 11 phyla
; of these, some 40 genera are also found in the Burgess Shale, and some 30 are also found in the Maotianshan Shale. Trilobite
s and eocrinoids with hard parts that are easily preserved are the most common fossils, but many animals with only soft tissues are also preserved. For example, an arthropod
similar to the Ediacaran biota Parvancorina
of the Neoproterozoic
age Ediacara Hills
of South Australia has been found at the Kaili site. Some other notable fossils discovered at Kaili are putative invertebrate eggs and embryos, trace fossils of the genus Gordia
, naraoiids, chancellorids, Microdictyon
, Wiwaxia
, and Marrella.
Cambrian
The Cambrian is the first geological period of the Paleozoic Era, lasting from Mya ; it is succeeded by the Ordovician. Its subdivisions, and indeed its base, are somewhat in flux. The period was established by Adam Sedgwick, who named it after Cambria, the Latin name for Wales, where Britain's...
boundary to the early Middle Cambrian (~513 to 506 million years ago). The Kaili Formation subdivided into three trilobite zones: Bathynotus holopygous–Ovatoryctocara granulate Zone, Oryctocephalus indicus Zone, and Olenoides jialaoensis Zone. Ocryctocephalus indicus and Ovatoryctocara granulata, which were suggested to be index species for the GSSP of the Lower–Middle Cambrian boundary, occur at the similar stratigraphic horizon in Siberia
Siberia
Siberia is an extensive region constituting almost all of Northern Asia. Comprising the central and eastern portion of the Russian Federation, it was part of the Soviet Union from its beginning, as its predecessor states, the Tsardom of Russia and the Russian Empire, conquered it during the 16th...
and China
China
Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...
. FAD
First appearance datum
First appearance datum is a term used by geologists and paleontologists to designate the first appearance of a species in the geologic record. In other words, FADs represent the geologically oldest fossil of a particular species that has yet been discovered.FADs are frequently used to designate...
of the trilobites Oryctocephalus indicus and Ovatoryctocara granulate are suggested as a two alternative standards of the Lower–Middle Cambrian boundary. Kaili Formation correlated with Amgian Stage in Siberia.
The biggest middle part of the Kaili Formation, Oryctocephalus indicus Zone, contains a Burgess Shale-type Lagerstätte with many well-preserved fossils known collectively as the Kaili Biota. This biota is located between the two most important and famous Cambrian Lagerstätten: the middle Lower Cambrian Maotianshan Shale (containing the Chengjiang Biota) and the Middle Cambrian Burgess Shale
Burgess Shale
The Burgess Shale Formation, located in the Canadian Rockies of British Columbia, is one of the world's most celebrated fossil fields, and the best of its kind. It is famous for the exceptional preservation of the soft parts of its fossils...
.
Fossils
The faunal assemblage is highly diverse, comprising some 110 generaGenera
Genera is a commercial operating system and development environment for Lisp machines developed by Symbolics. It is essentially a fork of an earlier operating system originating on the MIT AI Lab's Lisp machines which Symbolics had used in common with LMI and Texas Instruments...
among 11 phyla
Phylum
In biology, a phylum The term was coined by Georges Cuvier from Greek φῦλον phylon, "race, stock," related to φυλή phyle, "tribe, clan." is a taxonomic rank below kingdom and above class. "Phylum" is equivalent to the botanical term division....
; of these, some 40 genera are also found in the Burgess Shale, and some 30 are also found in the Maotianshan Shale. Trilobite
Trilobite
Trilobites are a well-known fossil group of extinct marine arthropods that form the class Trilobita. The first appearance of trilobites in the fossil record defines the base of the Atdabanian stage of the Early Cambrian period , and they flourished throughout the lower Paleozoic era before...
s and eocrinoids with hard parts that are easily preserved are the most common fossils, but many animals with only soft tissues are also preserved. For example, an arthropod
Arthropod
An arthropod is an invertebrate animal having an exoskeleton , a segmented body, and jointed appendages. Arthropods are members of the phylum Arthropoda , and include the insects, arachnids, crustaceans, and others...
similar to the Ediacaran biota Parvancorina
Parvancorina
Parvancorina is a genus of shield-shaped Ediacaran fossils. It has a raised ridge down the central axis of symmetry. This ridge can be high in unflattened fossils. At the 'head' end of the ridge there are two quarter circle shaped raised arcs attached. In front of this are two nested...
of the Neoproterozoic
Neoproterozoic
The Neoproterozoic Era is the unit of geologic time from 1,000 to 542.0 ± 1.0 million years ago. The terminal Era of the formal Proterozoic Eon , it is further subdivided into the Tonian, Cryogenian, and Ediacaran Periods...
age Ediacara Hills
Ediacara Hills
Ediacara Hills are a range of low hills in the northern part of the Flinders Ranges of South Australia, around 650 km north of Adelaide. The area has many old copper and silver mines from mining activity in the late 19th century...
of South Australia has been found at the Kaili site. Some other notable fossils discovered at Kaili are putative invertebrate eggs and embryos, trace fossils of the genus Gordia
Gordia
Gordia marina is a lower Cambrian ichnofossil, and is the most common trace fossil in the Kaili biota. It is often associated with the remains of a variety of dead organisms , suggesting that it was made my a scavenging worm-like creature...
, naraoiids, chancellorids, Microdictyon
Microdictyon
Microdictyon is an extinct "armored worm" coated with dot-likescleritic scales, known from the Early CambrianMaotianshan shale of Yunnan China. Microdictyon is sometimes included...
, Wiwaxia
Wiwaxia
Wiwaxia is a genus of soft-bodied, scale-covered animals known from Burgess shale type Lagerstätte dating from the upper Lower Cambrian to Middle Cambrian. The organisms are mainly known from dispersed sclerites; articulated specimens, where found, range from to a little over 50.8 millimeters in...
, and Marrella.