| 词条 | Litometopus |
| 释义 |
| fossil_range = {{Geological range|522|516|Botomian (Olenellus-zone)}} | image = Litometopus linedrawing.jpg | image_upright = 0.5 | image_caption = Litometopus longispinus | regnum = Animalia | phylum = Arthropoda | classis = Trilobita | ordo = Agnostida | familia = Weymouthiidae | genus = Litometopus | genus_authority = Rasetti, 1966 | subdivision_ranks = species | subdivision =
}}Litometopus is an extinct genus from a well-known class of fossil marine arthropods, the trilobites. It lived during the Botomian stage.[2] TaxonomyLitometopus may be a synonym of Cobboldites.[3]DistributionLitometopus is known from the upper Lower Cambrian of the United States (Acimetopus bilobatus faunule, Taconic, Griswold Farm, New York).[3]DescriptionLike all Agnostida, Litometopus is diminutive and the headshield (or cephalon) and tailshield (or pygidium) are of approximately the same size (or isopygous) and outline. Like all Weymouthiidae, it lacks eyes and rupture lines (or sutures). The cephalon is almost semicircular. The central raised area of the cephalon (or glabella) has a furrow along its outline, but no furrows are crossing it. It tapers forward and touches the border furrow. The border is convex, and it carries pair of small marginal spines at approximately ⅓ of the cephalic length from the front, and large genal spines, that are directed backwards and slightly outwards (±15°). Pygidium is the same shape as the cephalon. The pygidial axis is tapering backwards and touches the border furrow. It has a furrow along its outline, but crossing furrows are very faint or indiscernible. The border is flat and wide, and its doublure is sloping adaxially, and with serrated margin.[3] References1. ^{{cite journal|last= Rasetti|first= Franco|year= 1966|title= New Lower Cambrian trilobite faunule from the Taconic sequence of New York|journal= Smithsonian Miscellaneous Collections|volume= 148|issue=9|pages= 1–52|url= https://archive.org/stream/smithsonianmisce14839196566smit/smithsonianmisce14839196566smit_djvu.txt}} {{Taxonbar|from=Q6648654}}{{agnostida-stub}}2. ^{{cite journal|last=Sepkoski |first=Jack |authorlink= |coauthors= |title=A compendium of fossil marine animal genera (Trilobita entry) |journal=Bulletins of American Paleontology |volume=364 |issue= |page=560 |publisher= |location= |year=2002 |url=http://strata.ummp.lsa.umich.edu/jack/showgenera.php?taxon=307&rank=class |doi= |id= |accessdate=12 January 2008 |deadurl=yes |archiveurl=https://web.archive.org/web/20060905162524/http://strata.ummp.lsa.umich.edu/jack/showgenera.php?taxon=307&rank=class |archivedate=5 September 2006 |df= }} 3. ^1 2 Whittington, H. B. et al. Part O, Treatise on Invertebrate Paleontology. Revised, Volume 1 – Trilobita – Introduction, Order Agnostida, Order Redlichiida. 1997 4 : Weymouthiidae|Agnostida genera|Cambrian trilobites of North America|Animals described in 1966 |
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