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 Ma to the start of the Silurian Period 443.8 Ma.
A trace fossil, also known as an ichnofossil, is a fossil record of biological activity by lifeforms but not the preserved remains of the organism itself. Trace fossils contrast with body fossils, which are the fossilized remains of parts of organisms' bodies, usually altered by later chemical activity or mineralization. The study of such trace fossils is ichnology and is the work of ichnologists.
Parrotfish are a group of fish species traditionally regarded as a family (Scaridae), but now often treated as a subfamily (Scarinae) or tribe (Scarini) of the wrasses (Labridae). With roughly 95 species, this group's largest species richness is in the Indo-Pacific. They are found in coral reefs, rocky coasts, and seagrass beds, and can play a significant role in bioerosion.
The Carmel Formation is a geologic formation in the San Rafael Group that is spread across the U.S. states of Wyoming, Utah, Colorado, north east Arizona and New Mexico. Part of the Colorado Plateau, this formation was laid down in the Middle Jurassic during the late Bajocian, through the Bathonian and into the early Callovian stages.
A calcite sea is a sea in which low-magnesium calcite is the primary inorganic marine calcium carbonate precipitate. An aragonite sea is the alternate seawater chemistry in which aragonite and high-magnesium calcite are the primary inorganic carbonate precipitates. The Early Paleozoic and the Middle to Late Mesozoic oceans were predominantly calcite seas, whereas the Middle Paleozoic through the Early Mesozoic and the Cenozoic are characterized by aragonite seas.
Carbonate hardgrounds are surfaces of synsedimentarily cemented carbonate layers that have been exposed on the seafloor. A hardground is essentially, then, a lithified seafloor. Ancient hardgrounds are found in limestone sequences and distinguished from later-lithified sediments by evidence of exposure to normal marine waters. This evidence can consist of encrusting marine organisms, borings of organisms produced through bioerosion, early marine calcite cements, or extensive surfaces mineralized by iron oxides or calcium phosphates. Modern hardgrounds are usually detected by sounding in shallow water or through remote sensing techniques like side-scan sonar.
Trypanites is a narrow, cylindrical, unbranched boring which is one of the most common trace fossils in hard substrates such as rocks, carbonate hardgrounds and shells. It appears first in the Lower Cambrian, was very prominent in the Ordovician Bioerosion Revolution, and is still commonly formed today. Trypanites is almost always found in calcareous substrates, most likely because the excavating organism used an acid or other chemical agent to dissolve the calcium carbonate. Trypanites is common in the Ordovician and Silurian hardgrounds of Baltica.
The Matmor Formation is a geologic formation of up to 100 metres (330 ft) thick, that is exposed in Hamakhtesh Hagadol in southern Israel. The Matmor Formation contains fossils from a Jurassic equatorial shallow marine environment. Bivalves, gastropods, sponges, corals, echinoderms, and sclerobionts are present in the Matmor Formation to various degrees. The stratigraphy of the Matmor Formation consists of alternating layers of limestone and marl.
Teredolites is an ichnogenus of trace fossil, characterized by borings in substrates such as wood or amber.
Gastrochaenolites is a trace fossil formed as a clavate (club-shaped) boring in a hard substrate such as a shell, rock or carbonate hardground. The aperture of the boring is narrower than the main chamber and may be circular, oval, or dumb-bell shaped. Gastrochaenolites is most commonly attributed to bioeroding bivalves such as Lithophaga and Gastrochaena. The fossil ranges from the Ordovician to the Recent. The first Lower Jurassic Gastrochaenolites ichnospecies is Gastrochaenolites messisbugi Bassi, Posenato, Nebelsick, 2017. This is the first record of boreholes and their producers in one of the larger bivalves of the globally occurring Lithiotis fauna which is a unique facies in the Lower Jurassic Tethys and Panthalassa.
The queen parrotfish is a species of marine ray-finned fish, a parrotfish, in the family Scaridae. It is found on reefs in the tropical West Atlantic Ocean and the Caribbean Sea. Other common names include blownose, blue chub, blue parrotfish, blueman, joblin crow parrot, moontail, okra peji and slimy head. The young males and adult female queen parrotfish are a reddish-brown color, and quite different in appearance from the bluish-green color of the final phase male. This is a common species throughout its range and the International Union for Conservation of Nature has rated its conservation status as "least concern".
Petroxestes is a shallow, elongate boring originally found excavated in carbonate skeletons and hardgrounds of the Upper Ordovician of North America. These Ordovician borings were likely made by the mytilacean bivalve Corallidomus as it ground a shallow groove in the substrate to maintain its feeding position. They are thus the earliest known bivalve borings. Petroxestes was later described from the Lower Silurian of Anticosti Island (Canada). and the Miocene of the Caribbean.
Rogerella is a small pouch-shaped boring with a slit-like aperture currently produced by acrothoracican barnacles. These crustaceans extrude their legs upwards through the opening for filter-feeding. They are known in the fossil record as borings in carbonate substrates from the Devonian to the Recent.
Entobia is a trace fossil in a hard substrate formed by sponges as a branching network of galleries, often with regular enlargements termed chambers. Apertural canals connect the outer surface of the substrate to the chambers and galleries so the sponge can channel water through its tissues for filter feeding. The fossil ranges from the Devonian to the Recent.
Sclerobionts are collectively known as organisms living in or on any kind of hard substrate. A few examples of sclerobionts include Entobia borings, Gastrochaenolites borings, Talpina borings, serpulids, encrusting oysters, encrusting foraminiferans, Stomatopora bryozoans, and “Berenicea” bryozoans.
Osprioneides is an ichnogenus of unbranched, elongate borings in lithic substrate with oval cross−section, single−entrance and straight, curved or irregular course. Osprioneides kampto Beuck and Wisshak, 2008 is the largest known Palaeozoic boring trace. It occurs in the Ordovician and Silurian (Wenlock) of Baltica. The borings are up to 120 mm long measuring 5–17 mm in diameter. The distribution of Osprioneides is more environmentally limited than that of Trypanites in the Silurian of Saaremaa, Estonia (Baltica). Osprioneides probably occurred only in large hard substrates of relatively deepwater muddy bottom open shelf environments. Osprioneides were relatively rare, as compared to Trypanites-Palaeosabella borings in the Wenlock of Saaremaa.
Pholad borings are tubular burrows in firm clay and soft rock that have been created by bivalve molluscs in the family Pholadidae. The common names of clams in this family are "pholads", "piddocks", and "angel wings"; the latter because their shells are white, elongated and tend to be shaped like a wing and have sculpture somewhat reminiscent of a wing.
Anoigmaichnus is an ichnogenus of bioclaustrations. Anoigmaichnus includes shafts perpendicular to their hosts' growth surfaces or tilted (up to 45°); conical to cylindrical; circular to oval cross-sections; lacking separate wall. Their apertures are elevated above their hosts' growth surfaces, forming short chimney-like structures. Anoigmaichnus is the world's earliest known macroscopic endobiotic symbiont and it may have been a parasite. It occurs in the Middle Ordovician bryozoans of Osmussaar Island, Estonia.
Olev Vinn is an Estonian paleobiologist and paleontologist.
Liostrea is a genus of extinct oysters, marine bivalve mollusks in the family Gryphaeidae.
