{{Short description|Extinct genus of trilobites}} {{Automatic taxobox | fossil_range = {{fossil range|478.6|418.7|Early Ordovician to Late Silurian}} | image = Trilobite - Bumastus reconstruction 3d.jpg | image_caption = An artist's reconstruction of ''Bumastus'' | taxon = Bumastus | authority = Murchison, 1839 | subdivision_ranks = Species | subdivision = See text | type_species = ''Bumastus barriensis'' | type_species_authority = Murchison, 1839 }} [[File:BumastusBarriensis-NaturalHistoryMuseum-August23-08.jpg|thumb|upright|''Bumastus barriensis'', from the Silurian Wenlock series, found at Dudley, Worcestershire.]]
'''''Bumastus''''' is an extinct genus of corynexochid trilobites which existed from the Early Ordovician period to the Late Silurian period.<ref name="brit">{{cite web|url=http://www.britannica.com/EBchecked/topic/84570/Bumastus|title=''Bumastus''|publisher=Encyclopædia Britannica|access-date=April 11, 2011}}</ref> They were relatively large trilobites, reaching a length of {{convert|6|in|cm|abbr=on}}. They were distinctive for their highly globular, smooth-surfaced exoskeleton. 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 and South America, Europe, Asia, and Australia. They are classified under the family Styginidae in the order Corynexochida.<ref name="sepkoski"/>
==Description== ''Bumastus'' is a large trilobite, reaching a length of {{convert|6|in|cm|abbr=on}}.<ref name="morris">{{cite book|author=Christopher G. Morris|isbn=978-0-12-200400-1|title =Academic Press dictionary of science and technology|publisher =Gulf Professional Publishing|year =1992|url=https://books.google.com/books?id=nauWlPTBcjIC|page=325}}</ref><ref name="ohio">{{cite journal|author=Douglas L. Shrake|year=2005|title=Ohio Trilobites|journal=Geofacts|volume=5|publisher=Ohio Department of Natural Resources, Division of Geological Survey|url=http://www.dnr.state.oh.us/Portals/10/pdf/GeoFacts/geof05.pdf|access-date=April 12, 2011|archive-url=https://web.archive.org/web/20110628095843/http://www.dnr.state.oh.us/Portals/10/pdf/GeoFacts/geof05.pdf|archive-date=2011-06-28}}</ref> The body is oblong-oval, about twice as long as it is wide,<ref name="taylor"/> It had a strongly convex profile, giving it its distinctive globular appearance.<ref name="tesmer">{{cite book|author1=Irving H. Tesmer |author2=Jerold C. Bastedo |title =Colossal cataract: the geologic history of Niagara Falls|publisher =SUNY Press|year =1981|isbn =978-0-87395-522-5|url=https://books.google.com/books?id=_IFDxu0oGQMC}}</ref>
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, ''Bumastus'' is unusual in that the three lobes are barely discernible from each other.<ref name="murch"/><ref name="rich">{{cite book |author=Pat Vickers Rich |author2=Mildred Adams Fenton |author3=Carroll Lane Fenton |author4=Thomas Hewitt Rich|title =The fossil book: a record of prehistoric life|series=Dover books on animals|publisher =Courier Dover Publications|year =1989|url=https://books.google.com/books?id=_ntSspji0LYC&q=Bumastus|pages=198, 201, 210|isbn=978-0-486-29371-4}}</ref> The axial lobe of ''Bumastus'' is also very broad in comparison to the pleural lobes.<ref name="tesmer"/>
The cephalon (head segment) is very large and strongly convex. The facial sutures (the divisions by which the cephalon splits when the trilobite molts) is opisthoparian,<ref name="black"/> with the suture ending along the hind cephalic margin.<ref name="suture">{{cite web|url=http://www.trilobites.info/sutures.htm|title=Trilobite Facial Sutures |author=Samuel M. Gon III|date= November 12, 2009|publisher=A Guide to the Orders of Trilobites|access-date=April 12, 2011}}</ref> The genal angles of the cephalon - the edges where the lateral and rear margins of the cephalon meet - are rounded.<ref name="paleoz">{{cite book|page=119|url=https://books.google.com/books?id=QX0RB-XI6doC&q=Bumastus|author=Britannica Educational Publishing|title=The Paleozoic Era: Diversification of Plant and Animal Life|publisher=The Rosen Publishing Group|isbn=978-1-61530-196-6|year=2010}}</ref> The cephalon is effaced (smooth and mostly featureless), an evolutionary trend also seen in ''Illaenus'' and ''Trimerus'', though not as pronounced as that of ''Bumastus''. The glabella (the central lobe of the head) is almost fused to the fixigena.<ref name="black"/>
The thorax has ten narrow segments<ref name="taylor"/> while the pygidium (the tail) is smooth and very rounded.<ref name="taylor"/> It is isopygous - that is, the pygidium is about the same size as the cephalon.<ref name="pyg">{{cite web|url=http://www.trilobites.info/pygyterms.htm|title=The Pygidium |author=Samuel M. Gon III|date= November 12, 2009|publisher=A Guide to the Orders of Trilobites|access-date=April 12, 2011}}</ref> 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 eyes 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.<ref name="black">{{cite book|author=Rhona M. Black|title =The elements of palaeontology|publisher =Cambridge University Press|edition=2|year =1988|pages= 151–152|isbn =978-0-521-34836-2|url=https://books.google.com/books?id=cEh5Yn0neiUC}}</ref>
The surface of the exoskeleton of most species is studded with minute punctures.<ref name="page"/> center|500px
==Paleoecology== [[File:Bumastus beckeri.png|thumb|left|170px|Side and ventral views of an enrolled specimen of ''Bumastus beckeri'' from Iowa.<ref name="walter">{{cite journal|author= Otto Theodore Walter|title=Trilobites of Iowa and some Related Paleozoic Forms|journal=Iowa Geological Survey Annual Report|volume=31|year=1924|publisher=Iowa Geiological Survey|url=http://ir.uiowa.edu/cgi/viewcontent.cgi?article=1260&context=igsar|archive-url=https://web.archive.org/web/20111006143803/http://ir.uiowa.edu/cgi/viewcontent.cgi?article=1260&context=igsar|url-status=dead|archive-date=October 6, 2011|access-date=April 12, 2011 }}</ref>]] 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.<ref name="rich"/> The presence of well-developed eyes also suggest that it may have kept them above the substrate by burrowing into sediments backward. They are situated in such a way that they provide the trilobite with a semicircular field of vision on each side, keeping them aware of movements near them.<ref name="black"/> [[File:Trilobite - Bumastus reconstruction 3d scene.jpg|thumb|right|An artist's reconstruction of several individuals of ''Bumastus'' in shallow water. ''Bumastus'' were believed to have burrowed backwards into the sediment, leaving only their well-developed compound eyes exposed.<ref name="black"/>]] ''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. When waves 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.<ref name="black"/>
''Bumastus'' is a bottom-dwelling (nektobenthic) trilobite.<ref name="paleoz"/> It was probably either detritivorous, feeding on decomposing organic material drifting down in the currents,<ref name="tesmer"/> or carnivorous.<ref name="paleodb"/>
==Occurrence== ''Bumastus'' existed during the Paleozoic era, from the Arenigian epoch of the Early Ordovician period to the Ludlow epoch of the Late Silurian period (approximately 478.6 ± 1.7 to 418.7 ± 2.8 million years ago).<ref name="sepkoski"/><ref name="chrono">{{cite web|url=http://nicolas.tormo.free.fr/mirror/trilobites_distribution.pdf|title=Systematic Relationships and Chronological Extent of the nine Trilobite Orders|author1=Samuel M. Gon III|author2=Enrico Bonino|name-list-style=amp|publisher=A Guide to the Orders of Trilobites|access-date=April 12, 2011|archive-url=https://web.archive.org/web/20110823071202/http://nicolas.tormo.free.fr/mirror/trilobites_distribution.pdf|archive-date=August 23, 2011}}</ref><ref name="manten">{{cite book|author=A. A. Manten|title =Silurian reefs of Gotland|publisher =Elsevier|year =1971|isbn =978-0-444-40706-1|url=https://books.google.com/books?id=InkJkJNKAsgC}}</ref> Their fossils can be found worldwide.<ref name="bishop">{{cite book |author=Arthur Clive Bishop |author2=Alan Robert Woolley |author3=William Roger Hamilton |title =Guide to minerals, rocks and fossils|publisher =Cambridge University Press|year =1999|url=https://archive.org/details/cambridgeguideto00bish|url-access=registration|page=[https://archive.org/details/cambridgeguideto00bish/page/276 276]|isbn=978-0-521-77881-7}}</ref>
Specimens have been recorded from the Silurian of Argentina, Canada, the Czech Republic, Estonia, Greenland, Kazakhstan, Norway, the Russian Federation, Sweden, Ukraine, the United Kingdom, and the United States.<ref name="taylor">{{cite book|url=https://books.google.com/books?id=7kPwZ2LeSAoC&q=Bumastus|author1=Paul D. Taylor |author2=David N. Lewis |title=Fossil Invertebrates|publisher=Harvard University Press|isbn=978-0-674-02574-5|year=2007|page=143}}</ref><ref name="paleodb"/>
They can also be found in the Ordovician formations of Australia, Canada, China,<ref name="china">{{cite book|pages=198, 221|url=https://books.google.com/books?id=MmdeiVgTSAIC&q=Bumastus|author1=Wen-tang Zhang |author2=Pei-ji Chen |author3=A. R. Palmer |title=Biostratigraphy of China|publisher=Elsevier|isbn=978-7-03-011314-6|year=2003}}</ref> the Czech Republic, the Russian Federation, Spain, the United States; with specific occurrences from the Dobrotivian age/stage (Llandeilo age) of China and France, and the Whiterockian stage of the United States.<ref name="paleodb">{{cite web|url=http://flatpebble.nceas.ucsb.edu/cgi-bin/bridge.pl?a=checkTaxonInfo&taxon_no=19516&is_real_user=1|title=†''Bumastus Murchison'' 1839 (trilobite)|publisher=Paleobiology Database|access-date=April 12, 2011}}{{dead link|date=July 2017 |bot=InternetArchiveBot |fix-attempted=yes }}</ref>
They are typically found in reef limestone, though they are sometimes found in crinoidal limestone.<ref name="black"/><ref name="manten"/>
==Discovery== ''Bumastus'' was first described by the Scottish geologist, Sir Roderick Impey Murchison in 1839. The type species, ''Bumastus barriensis'' was recovered from the Coalbrookdale Formation of the Wenlock Group in England.<ref name="jell">{{cite journal|author1=P.A. Jell |author2=J.M. Adrain |name-list-style=amp |year=2002|title=Available generic names for trilobites|journal=Memoirs of the Queensland Museum|volume=48|issue=2|issn=0079-8835 |publisher=Queensland Museum|url=http://www.trilobites.info/generic_names_Jell%26Adrain2003.pdf|access-date=April 12, 2011 }}</ref>
Murchison first believed that the specimens he discovered (including a large {{convert|5|in|cm|abbr=on}} by {{convert|3.5|in|cm|abbr=on}} specimen) belonged to the genus ''Isotelus'' 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 ''Illaenus'', but ultimately classified it as a new genus based on the extremely advanced state of effacement in the cephalon of ''Bumastus''.<ref name="murch">{{cite book|author= Roderick Impey Murchison|year=1839|title=The Silurian System|volume= Part II|publisher=J. Murray|url=https://books.google.com/books?id=A7sQAAAAIAAJ|access-date=April 12, 2011 }}</ref>
The genus is so named because of its curious resemblance to a large round grape.<ref name="mantell">{{cite book|author=Gideon A. Mantell|title =The Medals of Creation: Or, First Lessons in Geology and the Study of Organic Remains|publisher =H. G. Bohn|year =1854|url=https://books.google.com/books?id=-9_baqgEWEgC&pg=PA537|page=537|isbn =978-0-405-12718-2}}</ref> It comes from Latin ''būmastus'' (large grapes that resemble the udders of a cow), which in turn came from Greek βοῦς (''bous'' - cow) and μαστός (''mastós'' - breasts). The word was familiar in the English language during Murchison's time, being a word encountered in book two of Virgil's Georgics.<ref name="rollin">{{cite book|author=Charles Rollin|title =The history of the arts and sciences of the ancients|publisher =Blackie, Fullarton|year =1829|url=https://archive.org/details/bub_gb_8w8MAQAAIAAJ}}</ref><ref name="cooper">{{cite book|author=Joab Goldsmith Cooper|title =Opera, or, The works of Virgil: with copious notes, mythological |publisher =Sheldon & co.|year =1866|url=https://books.google.com/books?id=wkgQAAAAIAAJ}}</ref>
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, Staffordshire.<ref name="page">{{cite book|author=David Page|author-link=David Page (geologist)|title =Handbook of geological terms, geology and physical geography|publisher =W. Blackwood and sons|year =1865|page=121|url=https://books.google.com/books?id=cBw5AAAAMAAJ}}</ref>
==Taxonomy== [[File:Bumastus niagarensis.jpg|thumb|right|upright|''Bumastus niagarensis'' from Wauwatosa, Wisconsin, has a more pointed pygidium.<ref name="kentucky">{{cite web|url=https://louisvillefossils.blogspot.com/2010/06/bumastus-niagarensis-trilobite.html|title=''Bumastus niagarensis'' Trilobite|date=2 June 2010 |publisher=Louisville Fossils|access-date=April 12, 2011}}</ref>]] [[File:Bumastus ioxus.jpg|thumb|right|upright|''Bumastus ioxus'' from Middleport, New York in the Field Museum of Natural History.]] ''Bumastus'' is classified under the family Styginidae by P.A. Jell and J.M. Adrain in 2003,<ref name="jell"/> and under the order Corynexochida of trilobites by Jack Sepkoski in 2002.<ref name="sepkoski">{{cite journal |author=J. J. Sepkoski |title=A compendium of fossil marine animal genera (Trilobita entry) |journal=Bulletins of American Paleontology |volume=364 |page=560 |publisher=Paleontological Research Institution |year=2002 |url=http://strata.ummp.lsa.umich.edu/jack/showgenera.php?taxon=307&rank=class |isbn=978-0-87710-450-6 |access-date=April 13, 2011 |archive-url=https://web.archive.org/web/20060905162524/http://strata.ummp.lsa.umich.edu/jack/showgenera.php?taxon=307&rank=class |archive-date=September 5, 2006 }}</ref>
==Species== Listed below are the species classified under ''Bumastus'' and the countries of their recorded type localities.<ref name="gbif">{{cite web|url=http://secretariat.mirror.gbif.org/species/browse/taxon/16278452/|title=Classification of Genus: ''Bumastus''|publisher=Global Biodiversity Information Facility|access-date=April 12, 2011}}{{dead link|date=July 2017 |bot=InternetArchiveBot |fix-attempted=yes }}</ref><ref name="wales">{{cite book|author=Robert Maurice Owens|title =Catalogue of type, figured and cited fossils in the National Museum of Wales: Supplement 1971-1994|publisher =National Museum Wales|year =1995|pages= 44–45|isbn =978-0-7200-0422-9|url=https://books.google.com/books?id=dRRs8d2W74gC}}</ref> The list is incomplete and may be inaccurate. {{Div col}} *''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 *''Burmatus Harrisi'' - 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 {{Div col end}}
==See also== {{Portal-inline|Paleontology}} {{Portal-inline|Arthropods}}
==References== {{Reflist|32em}}
==External links== *{{Commons category-inline|Bumastus|''Bumastus''}} *[http://www.trilobites.info/ordcorynexochida.htm Order Corynexochida] from [http://www.trilobites.info/ A Guide to the Orders of Trilobites]
{{Trilobites}} {{Taxonbar|from=Q44049}}
Category:Styginidae Category:Corynexochida genera Category:Silurian trilobites of South America Category:Ordovician trilobites Category:Wenlock series fossils Category:Early Ordovician first appearances Category:Silurian extinctions Category:Silurian trilobites of Europe Category:Silurian trilobites of North America Category:Silurian trilobites of Asia Category:Bromide Formation Category:Paleozoic life of Ontario Category:Paleozoic life of Nunavut Category:Paleozoic life of Quebec Category:Taxa named by Roderick Murchison