| Askepasma Temporal range: | |
|---|---|
Scientific classification  | |
| Kingdom: | Animalia |
| Phylum: | Brachiopoda |
| Class: | † Paterinata |
| Order: | † Paterinida |
| Family: | † Cryptotretidae |
| Genus: | † Askepasma Laurie, 1986 |
| Species | |
| |
Askepasma is an extinct genus of brachiopods which existed in what is now Australia and southern China during the Lower Cambrian.
The type species is A. toddense. A. transversalis occurs in Guizhou, and A. saproconcha is the oldest known southern Australian brachiopod from the lower Cambrian. [1]
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 485.4 million years ago (Mya) to the start of the Silurian Period 443.8 Mya.
Lingulata is a class of brachiopods, among the oldest of all brachiopods having existed since the Cambrian period. They are also among the most morphologically conservative of the brachiopods, having lasted from their earliest appearance to the present with very little change in shape. Shells of living specimens found today in the waters around Japan are almost identical to ancient Cambrian fossils.
The Emu Bay Shale is a geological formation in Emu Bay, South Australia, containing a major Konservat-Lagerstätte. It is one of two in the world containing Redlichiidan trilobites. The Emu Bay Shale is dated as Cambrian Series 2, Stage 4, correlated with the upper Botomian Stage of the Lower Cambrian.
The halkieriids are a group of fossil organisms from the Lower to Middle Cambrian. Their eponymous genus is Halkieria, which has been found on almost every continent in Lower to Mid Cambrian deposits, forming a large component of the small shelly fossil assemblages. The best known species is Halkieria evangelista, from the North Greenland Sirius Passet Lagerstätte, in which complete specimens were collected on an expedition in 1989. The fossils were described by Simon Conway Morris and John Peel in a short paper in 1990 in the journal Nature. Later a more thorough description was undertaken in 1995 in the journal Philosophical Transactions of the Royal Society of London and wider evolutionary implications were posed.
The Obolellata are a class of Rhynchonelliform brachiopods with two orders, Obolellida and Naukatida. They are essentially restricted to the lower-middle Cambrian.
Brachiopods, phylum Brachiopoda, are a phylum of trochozoan animals that have hard "valves" (shells) on the upper and lower surfaces, unlike the left and right arrangement in bivalve molluscs. Brachiopod valves are hinged at the rear end, while the front can be opened for feeding or closed for protection. Two major categories are traditionally recognized, articulate and inarticulate brachiopods. The word "articulate" is used to describe the tooth-and-groove structures of the valve-hinge which is present in the articulate group, and absent from the inarticulate group. This is the leading diagnostic skeletal feature, by which the two main groups can be readily distinguished as fossils. Articulate brachiopods have toothed hinges and simple, vertically-oriented opening and closing muscles. Conversely, inarticulate brachiopods have weak, untoothed hinges and a more complex system of vertical and oblique (diagonal) muscles used to keep the two valves aligned. In many brachiopods, a stalk-like pedicle projects from an opening near the hinge of one of the valves, known as the pedicle or ventral valve. The pedicle, when present, keeps the animal anchored to the seabed but clear of sediment which would obstruct the opening.
Tommotiids are Cambrian (Terreneuvian) shelly fossils thought to belong to the Brachiopod + Phoronid lineage (Brachiozoa).
The origin of the brachiopods is uncertain; they either arose from reduction of a multi-plated tubular organism, or from the folding of a slug-like organism with a protective shell on either end. Since their Cambrian origin, the phylum rose to a Palaeozoic dominance, but dwindled during the Mesozoic.
The Kirengellids are a group of problematic Cambrian fossil shells of marine organisms. The shells bear a number of paired muscle scars on the inner surface of the valve.
Longtancunella is a genus of problematic brachiopod from the Lower Cambrian Chengjiang Lagerstätte. Its pedicle, which resembles the modern Chileates', is often preserved; the organisms often live in clusters of around a dozen attached to the same basal object.
Mickwitziids are a Cambrian group of shelly fossils with originally phosphatic valves, belonging to the Brachiopod stem group, and exemplified by the genus Mickwitzia – the other genera are Heliomedusa and Setatella. The family Mickwitziidae is conceivably paraphyletic with respect to certain crown-group brachiopods.
Stage 10 of the Cambrian is the still unnamed third and final stage of the Furongian series. It follows the Jiangshanian and precedes the Ordovician Tremadocian Stage. The proposed lower boundary is the first appearance of the trilobite Lotagnostus americanus around 489.5 million years ago, but other fossils are also being discussed. The upper boundary is defined as the appearance of the conodont Iapetognathus fluctivagus which marks the beginning of the Tremadocian and is radiometrically dated as 485.4 million years ago.
Armin Aleksander Öpik was an Estonian paleontologist who spent the second half of his career at the Bureau of Mineral Resources in Australia.
Paterinata is an extinct class of linguliform brachiopods which lived from the Lower Cambrian (Tommotian) to Upper Ordovician (Ashgill). It contains the single order Paterinida and the subfamily Paterinoidea. Despite being some of the earliest brachiopods to appear in the fossil record, paterinides stayed as a relatively subdued and low-diversity group even as other brachiopods diversified later in the Cambrian and Ordovician.
The Forteau Formation is a geologic formation in Newfoundland and Labrador. It preserves fossils dating back to the Cambrian period.
Marcusodictyon is a genus of problematic fossils. It has been considered the oldest bryozoan in several publications. Taylor (1984) revised the systematics of the genus and removed it from Bryozoa. The fossil constitutes a phosphatic network of low ridges that enclose polygons about 0.3–1.2 mm wide that are generally 6-sided but can be 4-, 5- or 7-sided. The internal microstructure of Marcusodictyon is composed of laminae parallel to external surfaces of ridges. Marcusodictyon occurs on late Cambrian and Tremadocian lingulate brachiopods of Baltica.
Acrotheloidea is a superfamily of Discinid brachiopods, alternatively ascribed to the lingulids—for a discussion of discinid taxonomy, see Discinida.
Micrina is an extinct genus of tommotiids with affinities to brachiopods.
Siphonotretida is an extinct order of linguliform brachiopods in the class Lingulata. The order is equivalent to the sole superfamily Siphonotretoidea, itself containing the sole family Siphonotretidae. They were most abundant in the Late Cambrian and Early Ordovician, and were traditionally considered to have gone extinct in the Upper Ordovician (Ashgill). However, they may have been present as early as Cambrian Stage 4, and as late as the Silurian (Ludlow). Siphonotretoids were originally placed as a superfamily of Acrotretida, before being raised to their own order.
Lingulellotretidae is an extinct family of brachiopods, with an extended pseudointerarea, including some soft-shelled representatives.