BumastusBarriensis-NaturalHistoryMuseum-August23-08

''Bumastus'' is an

extinct Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

of corynexochid

trilobite Trilobites (; meaning "three lobes") are extinct marine arthropods that form the class Trilobita. Trilobites form one of the earliest-known groups of arthropods. The first appearance of trilobites in the fossil record defines the base of the At ...

s which existed from the Early

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

period Period may refer to: Common uses * Era, a length or span of time * Full stop (or period), a punctuation mark Arts, entertainment, and media * Period (music), a concept in musical composition * Periodic sentence (or rhetorical period), a concept ...

to the Late

Silurian The Silurian ( ) is a geologic period and system spanning 24.6 million years from the end of the Ordovician Period, at million years ago ( Mya), to the beginning of the Devonian Period, Mya. The Silurian is the shortest period of the Paleozo ...

period. They were relatively large trilobites, reaching a length of . They were distinctive for their highly globular, smooth-surfaced

exoskeleton An exoskeleton (from Greek ''éxō'' "outer" and ''skeletós'' "skeleton") is an external skeleton that supports and protects an animal's body, in contrast to an internal skeleton (endoskeleton) in for example, a human. In usage, some of the ...

. They possessed well-developed, large compound eyes and were believed to have dwelled in shallow-water sediments in life. ''Bumastus'' fossils have been found in

North North is one of the four compass points or cardinal directions. It is the opposite of south and is perpendicular to east and west. ''North'' is a noun, adjective, or adverb indicating Direction (geometry), direction or geography. Etymology T ...

and

South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the southe ...

Europe Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a Continent#Subcontinents, subcontinent of Eurasia ...

Asia Asia (, ) is one of the world's most notable geographical regions, which is either considered a continent in its own right or a subcontinent of Eurasia, which shares the continental landmass of Afro-Eurasia with Africa. Asia covers an area ...

, and

Australia Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...

. They are classified under the

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

Styginidae in the

order Order, ORDER or Orders may refer to: * Categorization, the process in which ideas and objects are recognized, differentiated, and understood * Heterarchy, a system of organization wherein the elements have the potential to be ranked a number of d ...

Corynexochida Corynexochida is an order of trilobite that lived from the Lower Cambrian to the Late Devonian. Like many of the other trilobite orders, Corynexochida contains many species with widespread characteristics. The middle region of the cephalon (the ...

Description

''Bumastus'' is a large trilobite, reaching a length of . The body is oblong-oval, about twice as long as it is wide, It had a strongly convex profile, giving it its distinctive globular appearance. Like all trilobites, the body is divided into three functional segments known as tagmata (singular: tagma), which in turn are divided into three lobes - the central lobe (axial) and two lateral lobes (pleural). Aside from faint depressions in the

thorax The thorax or chest is a part of the anatomy of humans, mammals, and other tetrapod animals located between the neck and the abdomen. In insects, crustaceans, and the extinct trilobites, the thorax is one of the three main divisions of the cre ...

, ''Bumastus'' is unusual in that the three lobes are barely discernible from each other. The axial lobe of ''Bumastus'' is also very broad in comparison to the pleural lobes. The

cephalon Cephalon, Inc. was an American biopharmaceutical company co-founded in 1987 by pharmacologist Frank Baldino, Jr., neuroscientist Michael Lewis, and organic chemist James C. Kauer—all three former scientists with the DuPont Company. Baldino s ...

(head segment) is very large and strongly convex. The

facial sutures Trilobites (; meaning "three lobes") are extinct marine arthropods that form the class Trilobita. Trilobites form one of the earliest-known groups of arthropods. The first appearance of trilobites in the fossil record defines the base of the A ...

(the divisions by which the cephalon splits when the trilobite molts) is opisthoparian, with the suture ending along the hind cephalic margin. The

gena Gena (Amharic: ገና) or qarsa (ቃርሳ) is a traditional field hockey game popular in the Ethiopian highlands. It is a game played in the space between villages but with no defined boundaries. It is played among two teams who attempt to throw ...

angles The Angles ( ang, Ængle, ; la, Angli) were one of the main Germanic peoples who settled in Great Britain in the post-Roman period. They founded several kingdoms of the Heptarchy in Anglo-Saxon England. Their name is the root of the name ' ...

of the cephalon - the edges where the lateral and rear margins of the cephalon meet - are rounded. The cephalon is effaced (smooth and mostly featureless), an evolutionary trend also seen in ''

Illaenus ''Illaenus'' is a genus of trilobites from Russia and Morocco, from the middle 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 ...

'' and ''

Trimerus ''Trimerus'' is an extinct genus of trilobite in the family Homalonotidae Homalonotidae is a family of trilobites that lived from the Ordovician to the Devonian. They are characterised by a shovel-like cephalon (head), and are closely relat ...

'', though not as pronounced as that of ''Bumastus''. The

glabella The glabella, in humans, is the area of skin between the eyebrows and above the nose. The term also refers to the underlying bone that is slightly depressed, and joins the two brow ridges. It is a cephalometric landmark that is just superior to ...

(the central lobe of the head) is almost fused to the fixigena. The thorax has ten narrow segments while the

pygidium The pygidium (plural pygidia) is the posterior body part or shield of crustaceans and some other arthropods, such as insects and the extinct trilobites. In groups other than insects, it contains the anus and, in females, the ovipositor. It is compo ...

(the tail) is smooth and very rounded. It is isopygous - that is, the pygidium is about the same size as the cephalon. The pygidium completely lacks any visible trilobation. It is usually semicircular in shape but can be pointed in some species like '' B. niagarensis''. The smooth

compound eye A compound eye is a visual organ found in arthropods such as insects and crustaceans. It may consist of thousands of ommatidia, which are tiny independent photoreception units that consist of a cornea, lens, and photoreceptor cells which disti ...

s are large and peculiarly well-developed. This, along with the rounded contours of their body, suggests that ''Bumastus'' may have spent most of its time buried in sediment with its eyes protruding. The surface of the exoskeleton of most species is studded with minute punctures. Bumastus morphology

Paleoecology

The rounded smooth shape of ''Bumastus'', as well as the almost complete effacement of its cephalon, is believed to have been an adaptation for burrowing. The presence of well-developed eyes also suggest that it may have kept them above the substrate by burrowing into

sediments Sediment is a naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of wind, water, or ice or by the force of gravity acting on the particles. For example, sand a ...

backward. They are situated in such a way that they provide the trilobite with a semicircular

field of vision The visual field is the "spatial array of visual sensations available to observation in introspectionist psychological experiments". Or simply, visual field can be defined as the entire area that can be seen when an eye is fixed straight at a point ...

on each side, keeping them aware of movements near them. Trilobite - Bumastus reconstruction 3d scene

''Bumastus'' could also curl up (known as enrollment) into a ball-like shape. This is believed to indicate that its habitat might have been the shallow waters of the

Littoral zone The littoral zone or nearshore is the part of a sea, lake, or river that is close to the shore. In coastal ecology, the littoral zone includes the intertidal zone extending from the high water mark (which is rarely inundated), to coastal areas ...

. When

waves Waves most often refers to: *Waves, oscillations accompanied by a transfer of energy that travel through space or mass. * Wind waves, surface waves that occur on the free surface of bodies of water. Waves may also refer to: Music * Waves (ban ...

wash them out from the sediments it could simply roll up and be carried along. Enrollment protects the softer body parts below the exoskeleton, while the spherical shape offers the least resistance to wave action. ''Bumastus'' is a bottom-dwelling ( nektobenthic) trilobite. It was probably either

detritivorous Detritivores (also known as detrivores, detritophages, detritus feeders, or detritus eaters) are heterotrophs that obtain nutrients by consuming detritus (decomposing plant and animal parts as well as feces). There are many kinds of invertebrat ...

, feeding on decomposing organic material drifting down in the currents, or

carnivorous A carnivore , or meat-eater (Latin, ''caro'', genitive ''carnis'', meaning meat or "flesh" and ''vorare'' meaning "to devour"), is an animal or plant whose food and energy requirements derive from animal tissues (mainly muscle, fat and other sof ...

Occurrence

''Bumastus'' existed during the

Paleozoic era The Paleozoic (or Palaeozoic) Era is the earliest of three geologic eras of the Phanerozoic Eon. The name ''Paleozoic'' ( ;) was coined by the British geologist Adam Sedgwick in 1838 by combining the Greek words ''palaiós'' (, "old") and ' ...

, from the Arenigian

epoch In chronology and periodization, an epoch or reference epoch is an instant in time chosen as the origin of a particular calendar era. The "epoch" serves as a reference point from which time is measured. The moment of epoch is usually decided by ...

of the Early Ordovician period to the

Ludlow epoch In the geological timescale, the Ludlow Epoch (from 427.4 ± 0.5 million years ago to 423.0 ± 2.3 million years ago) occurred during the Silurian Period, after the end of the Homerian Age. It is named for the town of Ludlow in Shropshire, England ...

of the Late Silurian period (approximately 478.6 ± 1.7 to 418.7 ± 2.8

million years ago The abbreviation Myr, "million years", is a unit of a quantity of (i.e. ) years, or 31.556926 teraseconds. Usage Myr (million years) is in common use in fields such as Earth science and cosmology. Myr is also used with Mya (million years ago). ...

). Their

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...

s can be found worldwide. Specimens have been recorded from the Silurian of

Argentina Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the second-largest country in South America after Brazil, th ...

Canada Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by tot ...

, the

Czech Republic The Czech Republic, or simply Czechia, is a landlocked country in Central Europe. Historically known as Bohemia, it is bordered by Austria to the south, Germany to the west, Poland to the northeast, and Slovakia to the southeast. The ...

Estonia Estonia, formally the Republic of Estonia, is a country by the Baltic Sea in Northern Europe. It is bordered to the north by the Gulf of Finland across from Finland, to the west by the sea across from Sweden, to the south by Latvia, a ...

Greenland Greenland ( kl, Kalaallit Nunaat, ; da, Grønland, ) is an island country in North America that is part of the Kingdom of Denmark. It is located between the Arctic and Atlantic oceans, east of the Canadian Arctic Archipelago. Greenland is t ...

Kazakhstan Kazakhstan, officially the Republic of Kazakhstan, is a transcontinental country located mainly in Central Asia and partly in Eastern Europe. It borders Russia to the north and west, China to the east, Kyrgyzstan to the southeast, Uzbeki ...

Norway Norway, officially the Kingdom of Norway, is a Nordic country in Northern Europe, the mainland territory of which comprises the western and northernmost portion of the Scandinavian Peninsula. The remote Arctic island of Jan Mayen and t ...

, the

Russian Federation Russia (, , ), or the Russian Federation, is a List of transcontinental countries, transcontinental country spanning Eastern Europe and North Asia, Northern Asia. It is the List of countries and dependencies by area, largest country in the ...

Sweden Sweden, formally the Kingdom of Sweden,The United Nations Group of Experts on Geographical Names states that the country's formal name is the Kingdom of SwedenUNGEGN World Geographical Names, Sweden./ref> is a Nordic country located on ...

Ukraine Ukraine ( uk, Україна, Ukraïna, ) is a country in Eastern Europe. It is the second-largest European country after Russia, which it borders to the east and northeast. Ukraine covers approximately . Prior to the ongoing Russian inv ...

, the

United Kingdom The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Europe, off the north-western coast of the continental mainland. It comprises England, Scotland, Wales and North ...

, and the

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...

. They can also be found in the Ordovician formations of

China China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's most populous country, with a population exceeding 1.4 billion, slightly ahead of India. China spans the equivalent of five time zones and ...

, the Czech Republic, the Russian Federation,

Spain , image_flag = Bandera de España.svg , image_coat = Escudo de España (mazonado).svg , national_motto = ''Plus ultra'' (Latin)(English: "Further Beyond") , national_anthem = (English: "Royal March") , i ...

, the

; with specific occurrences from the Dobrotivian

age Age or AGE may refer to: Time and its effects * Age, the amount of time someone or something has been alive or has existed ** East Asian age reckoning, an Asian system of marking age starting at 1 * Ageing or aging, the process of becoming older ...

stage Stage or stages may refer to: Acting * Stage (theatre), a space for the performance of theatrical productions * Theatre, a branch of the performing arts, often referred to as "the stage" * ''The Stage'', a weekly British theatre newspaper * Sta ...

(

Llandeilo Llandeilo () is a town and community in Carmarthenshire, Wales, situated at the crossing of the River Towy by the A483 on a 19th-century stone bridge. Its population was 1,795 at the 2011 Census. It is adjacent to the westernmost point of the B ...

age) of China and

France France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of Overseas France, overseas regions and territories in the Americas and the Atlantic Ocean, Atlantic, Pacific Ocean, Pac ...

, and the

Whiterockian The Whiterockian, often referred to simply as the Whiterock, is an earliest or lowermost stage of the Middle Ordovician. Although the Whiterockian or Whiterock Stage refers mainly to the early Middle Ordovician in North America, it is often used in ...

stage of the United States. They are typically found in reef limestone, though they are sometimes found in

crinoid Crinoids are marine animals that make up the class Crinoidea. Crinoids that are attached to the sea bottom by a stalk in their adult form are commonly called sea lilies, while the unstalked forms are called feather stars or comatulids, which are ...

al limestone.

Discovery

''Bumastus'' was first described by the Scottish

geologist A geologist is a scientist who studies the solid, liquid, and gaseous matter that constitutes Earth and other terrestrial planets, as well as the processes that shape them. Geologists usually study geology, earth science, or geophysics, althou ...

, Sir Roderick Impey Murchison in 1839. The

type species In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specimen ...

, '' Bumastus barriensis'' was recovered from the

Coalbrookdale Coalbrookdale is a village in the Ironbridge Gorge in Shropshire, England, containing a settlement of great significance in the history of iron ore smelting. It lies within the civil parish called the Gorge. This is where iron ore was first s ...

Formation Formation may refer to: Linguistics * Back-formation, the process of creating a new lexeme by removing or affixes * Word formation, the creation of a new word by adding affixes Mathematics and science * Cave formation or speleothem, a secondar ...

of the

Wenlock Group The Wenlock Group (Wenlockian), in geology, is the middle series of strata in the Silurian (Upper Silurian) of Great Britain. This group in the typical area in the Welsh border counties contains the following formations: Much Wenlock Limestone Form ...

England England is a country that is part of the United Kingdom. It shares land borders with Wales to its west and Scotland to its north. The Irish Sea lies northwest and the Celtic Sea to the southwest. It is separated from continental Europe b ...

. Murchison first believed that the specimens he discovered (including a large by specimen) belonged to the genus ''

Isotelus ''Isotelus'' is a genus of asaphid trilobites from the middle and upper Ordovician period, fairly common in the Northeastern United States, northwest Manitoba, southwestern Quebec and southeastern Ontario. One species, ''Isotelus rex,'' is curre ...

'' because of the size, shape, and almost featureless cephalon. But he noted the almost absent trilobation of body and the difference in the number of segments in the thorax (10 in ''B. barriensis'' and 8 in ''Isotelus''). He also recognized its close relationship with the genus ''

'', but ultimately classified it as a new genus based on the extremely advanced state of effacement in the cephalon of ''Bumastus''. The genus is so named because of its curious resemblance to a large round

grape A grape is a fruit, botanically a berry, of the deciduous woody vines of the flowering plant genus ''Vitis''. Grapes are a non- climacteric type of fruit, generally occurring in clusters. The cultivation of grapes began perhaps 8,000 years ago, ...

. It comes from

Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...

''būmastus'' (large grapes that resemble the

udder An udder is an organ formed of two or four mammary glands on the females of dairy animals and ruminants such as cattle, goats, and sheep. An udder is equivalent to the breast in primates and elephantine pachyderms. The udder is a single mass han ...

s of a cow), which in turn came from

Greek Greek may refer to: Greece Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group. *Greek language, a branch of the Indo-European language family. **Proto-Greek language, the assumed last common ancestor ...

βοῦς (''bous'' - cow) and μαστός (''mastós'' - breasts). The word was familiar in the

English language English is a West Germanic language of the Indo-European language family, with its earliest forms spoken by the inhabitants of early medieval England. It is named after the Angles, one of the ancient Germanic peoples that migrated to the is ...

during Murchison's time, being a word encountered in book two of

Virgil Publius Vergilius Maro (; traditional dates 15 October 7021 September 19 BC), usually called Virgil or Vergil ( ) in English, was an ancient Roman poet of the Augustan period. He composed three of the most famous poems in Latin literature: t ...

Georgics The ''Georgics'' ( ; ) is a poem by Latin poet Virgil, likely published in 29 BCE. As the name suggests (from the Greek word , ''geōrgika'', i.e. "agricultural (things)") the subject of the poem is agriculture; but far from being an example ...

. The specific name of the type species, ''barriensis'', roughly meaning "of Barr", comes from its common name among collectors. It was then known as the "Barr trilobite" referring to the plentiful occurrence of ''B. barriensis'' in the limestone formations of

Great Barr Great Barr is now a large and loosely defined area to the north-west of Birmingham, England. The area was historically in Staffordshire, and the parts now in Birmingham were once known as Perry Barr, which is still the name of an adjacent Birmi ...

Staffordshire Staffordshire (; postal abbreviation Staffs.) is a landlocked county in the West Midlands region of England. It borders Cheshire to the northwest, Derbyshire and Leicestershire to the east, Warwickshire to the southeast, the West Midlands Cou ...

Taxonomy

''Bumastus'' is classified under the

Styginidae by P.A. Jell and J.M. Adrain in 2003, and under the

of trilobites by

Jack Sepkoski Joseph John Sepkoski Jr. (July 26, 1948 – May 1, 1999) was a University of Chicago paleontologist. Sepkoski studied the fossil record and the diversity of life on Earth. Sepkoski and David Raup contributed to the knowledge of extinction events. ...

in 2002.

Species

Listed below are the

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

classified under ''Bumastus'' and the countries of their recorded type localities. The list is incomplete and may be inaccurate. *''Bumastus armatus'' - United States *''Bumastus barriensis'' - Estonia, Kazakhstan, Ukraine, United Kingdom, United States *''Bumastus beckeri'' - United States *''Bumastus bellmanni'' - Argentina *''Bumastus bouchardi'' - Czech Republic, Ukraine *''Bumastus chicagoensis'' - United States *''Bumastus cuniculus'' - United States **''Bumastus cuniculus, Bumastus cuniculus vieillensis'' - Canada *''Bumastus dayi'' - United States *''Bumastus erastusi'' - Canada *''Bumastus globosus'' - Canada, United States (Synonym (biology), synonym?:''Illaenus globosus'') *''Bumastus graftonensis'' - United States *''Bumastus hornyi'' - Czech Republic *''Bumastus indeterminatus'' - Canada *''Bumastus insignis'' - United Kingdom, United States *''Bumastus ioxus'' - United States *''Bumastus lenzi'' - Canada *''Bumastus limbatus'' - United States *''Bumastus milleri'' - United States *''Bumastus niagarensis'' - United States *''Bumastus orbicaudatus'' - Canada, United States *''Bumastus phrix'' - Estonia, Ukraine, United Kingdom *''Bumastus springfieldensis'' - United States *''Bumastus sulcatus'' - Sweden *''Bumastus tenuirugosus'' - Canada *''Bumastus tenuis'' - United States *''Bumastus transversalis'' - United States *''Bumastus trentonensis'' - United States

References

External links

*
Order Corynexochida
fro
A Guide to the Orders of Trilobites
{{Taxonbar, from=Q44049 Styginidae Corynexochida genera Silurian trilobites of South America Ordovician trilobites Wenlock series fossils Early Ordovician first appearances Silurian extinctions Silurian trilobites of Europe Silurian trilobites of North America Silurian trilobites of Asia Bromide Formation Paleozoic life of Ontario Paleozoic life of Nunavut Paleozoic life of Quebec Taxa named by Roderick Murchison

Description

Paleoecology

Occurrence

Discovery

Taxonomy

Species

See also

References

External links