Hyoliths are animals with small conical shells, known as fossils from the Palaeozoic era. They are at least considered as lophotrochozoan, and possibly being lophophorates, a group which includes the brachiopods, while others consider them as being basal lophotrochozoans, or even molluscs.
Tabulata, commonly known as tabulate corals, are an order of extinct forms of coral. They are almost always colonial, forming colonies of individual hexagonal cells known as corallites defined by a skeleton of calcite, similar in appearance to a honeycomb. Adjacent cells are joined by small pores. Their distinguishing feature is their well-developed horizontal internal partitions (tabulae) within each cell, but reduced or absent vertical internal partitions. They are usually smaller than rugose corals, but vary considerably in shape, from flat to conical to spherical.
Namacalathus is a problematic metazoan fossil occurring in the latest Ediacaran. The first, and only described species, N. hermanastes, was first described in 2000 from the Nama Group of central and southern Namibia.
Hederellids are extinct colonial animals with calcitic tubular branching exoskeletons. They range from the Silurian to the Permian and were most common in the Devonian period. They are more properly known as "hederelloids" because they were originally defined as a suborder by Bassler, who described about 130 species. Although they have traditionally been considered bryozoans, they are clearly not because of their branching patterns, lack of an astogenetic gradient, skeletal microstructure, and wide range in tube diameters. Work continues on assessing the true affinities of hederelloids, but they appear to be most closely related to phoronids and other lophophorates.
Namapoikia rietoogensis is among the earliest known animals to produce a calcareous skeleton. Known from the Ediacaran period, before the Cambrian explosion of calcifying animals, the long-lived organism grew up to a metre in diameter and resembles a colonial sponge. It was an encruster, filling vertical fissures in the reefs in which it originally grew.
Haplophrentis is a genus of tiny shelled hyolithid which lived in the Cambrian Period. Its shell was long and conical, with the open end protected by an operculum, from which two fleshy arms called helens protruded at the sides. These arms served to elevate the opening of the shells above the sea floor, acting like stilts.
Conulariida are an extinct group of medusozoan cnidarians known from fossils spanning from the latest Ediacaran up until the Late Triassic. They are almost exclusively known from their hard external structures, which were pyramidal in shape and made up of numerous lamellae.
Tentaculites oswegoensis is a small animal of unresolved phylogenetic affinities that has often been classified with molluscs or even with marine worms and has recently been interpreted as a lophophorate based on shell microstructure. The genus Tentaculites was named in 1820 by von Schlotheim. Tentaculites oswegoensis was named by 1877 and is known from the Upper Ordovician rocks of the Maquoketa Group. It ranged from Oswego, IL to possibly Kankakee River State Park (KRSP) in Will County, Illinois. At KRSP it appears in the basal Silurian of the Kankakee Formation but has not been found in the underlying Ordovician rocks.
The small shelly fauna, small shelly fossils (SSF), or early skeletal fossils (ESF) are mineralized fossils, many only a few millimetres long, with a nearly continuous record from the latest stages of the Ediacaran to the end of the Early Cambrian Period. They are very diverse, and there is no formal definition of "small shelly fauna" or "small shelly fossils". Almost all are from earlier rocks than more familiar fossils such as trilobites. Since most SSFs were preserved by being covered quickly with phosphate and this method of preservation is mainly limited to the late Ediacaran and early Cambrian periods, the animals that made them may actually have arisen earlier and persisted after this time span.
Phoronids are a small phylum of marine animals that filter-feed with a lophophore, and build upright tubes of chitin to support and protect their soft bodies. They live in most of the oceans and seas, including the Arctic Ocean but excluding the Antarctic Ocean, and between the intertidal zone and about 400 meters down. Most adult phoronids are 2 cm long and about 1.5 mm wide, although the largest are 50 cm long.
Cornulitida is an extinct order of encrusting animals from class Tentaculita, which were common around the globe in the Ordovician to Devonian oceans, and survived until the Carboniferous. Organisms that may be the oldest cornulitids have been found in Cambrian sediments of Jordan.
Tommotiids are an extinct group of Cambrian invertebrates thought to be early lophophorates.
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 order Microconchida is a group of small, spirally-coiled, encrusting fossil "worm" tubes from the class Tentaculita found from the Upper Ordovician to the Middle Jurassic (Bathonian) around the world. They have lamellar calcitic shells, usually with pseudopunctae or punctae and a bulb-like origin. Many were long misidentified as the polychaete annelid Spirorbis until studies of shell microstructure and formation showed significant differences. All pre-Cretaceous "Spirorbis" fossils are now known to be microconchids. Their classification at the phylum level is still debated. Most likely they are some form of lophophorate, a group which includes phoronids, bryozoans and brachiopods. Microconchids may be closely related to the other encrusting tentaculitoid tubeworms, such as Anticalyptraea, trypanoporids and cornulitids.
Tentaculita is an extinct class of uncertain placement ranging from the Early Ordovician to the Middle Jurassic. They were suspension feeders with a near worldwide distribution. For a more thorough discussion, see Tentaculites.
Trypanoporida is an extinct order of encrusting animals within Class Tentaculita, which were common in Devonian oceans. Their affinity is unknown; they have been placed among worms and corals. They appear to be closely related to other taxa of uncertain affinity, including the microconchids, cornulitids, and tentaculitids. Spirally coiled trypanoporids (Devonian) were most likely derived from the geologically older microconchids.
Anticalyptraea is a fossil genus of encrusting tentaculitoid tubeworms from the Silurian to Devonian of Europe and North America . Anticalyptraea commonly encrust various invertebrate fossils such as stromatoporoids, rugose corals, bryozoans, brachiopods and crinoids, but they can also be common on the hardgrounds.
Cornulites is a genus of cornulitid tubeworms. Their shells have vesicular wall structure, and are both externally and internally annulated. They usually occur as encrusters on various shelly fossils. Their fossils are known from the Middle Ordovician to the Carboniferous.
Burrinjuckia is an ichnogenus of bioclaustrations. Burrinjuckia includes outgrowths of the brachiopod's secondary shell with a hollow interior in the mantle cavity of a brachiopod. Burrinjuckia was probably a parasite. They have a stratigraphic range from the Late Ordovician to the Devonian. The earliest Burrinjuckia species B. clitambonitofilia Vinn, Wilson and Toom, 2014 occurs in brachiopod Clitambonites squamatus from the Late Ordovician oilshale of Estonia.
Olev Vinn is Estonian paleobiologist and paleontologist.
