Holmiidae

{{Short description|Family of trilobites}} {{Automatic taxobox | fossil_range = {{fossil range|Atdabanian}} | image = 特力斯多寒武智慧蟲化石.jpg | image_caption = ''Cambropallas telesto'',from Morocco | display_parents = 2 | taxon = Holmiidae | authority = Hupé, 1953 }}

'''Holmiidae''' is a family of trilobites, that lived during the Lower Cambrian (Atdabanian). The Holmiidae is a diverse family of eight genera containing at least 17 species. It includes some of the earliest trilobites of Baltica. Holmiidae occur throughout Baltica (Scandinavia and the eastern seaboard of the Baltic Sea) and Western Laurentia (in the Great Basin of the US and northwestern Canada), and also in Morocco.<ref name='Lieberman 1999'>{{cite journal |last1=Lieberman |first1=B.S. |year=1999 |title=Systematic Revision of the Olenelloidea (Trilobita, Cambrian) |journal=Bulletin of the Peabody Museum of Natural History |volume=45 |url=http://peabody.yale.edu/sites/default/files/documents/scientific-publications/ypmB45_1999.pdf |access-date=2019-05-09 |archive-date=2016-06-24 |archive-url=https://web.archive.org/web/20160624111229/http://peabody.yale.edu/sites/default/files/documents/scientific-publications/ypmB45_1999.pdf |url-status=dead }}</ref>

== Taxonomy == Hupé (1953) defined the Holmiidae as a subfamily (Holmiinae) within the Olenellidae containing ''Holmia'', ''Kjerulfia'' and ''Bondonella''. Harrington et al. (1959) excluded ''Kjerulfia'', while assigning ''Schmidtiellus'' to it. Bergström (1973) included ''Holmia'', ''Elliptocephala'', ''Esmeraldina'', ''Schmidtiellus'' and ''Wanneria''. Repina (1979) assigned ''Holmia'', ''Schmidtiellus'', ''Kjerulfia'', ''Elliptocephala'', ''Bondonella'', ''Andalusiana'' and ''Holmiella'' to the Holmiinae, that together with the monotypic Callaviinae comprised the Holmiidae. Palmer and Repina (1993) added ''Holmiella'' but excluded ''Kjerulfia'', they assigned to the Callaviinae. Lieberman, who made cladistic analyses of the Olenellina and the included superfamilies, regards ''Andalusiana'' an advanced "Nevadioidea", ''Callavia'' and ''Bondonella'' as Judomioidea, and ''Elliptocephala'' and ''Wanneria'' stemgroup genera closely related to the common ancestor of the Holmiidae and the Biceratopsidae.<ref name='Lieberman 1999'/>

==Genera== * ''Andalusiana'' Lotze 1958<ref>{{cite web |url=https://paleobiodb.org/classic/checkTaxonInfo?taxon_no=19110 |title=Andalusiana Lotze 1958 (trilobite) |website=The Paleobiology Database}}</ref> * ''Callavia'' Matthew 1897<ref>{{cite web |url=https://paleobiodb.org/classic/checkTaxonInfo?taxon_no=19120 |website=The Paleobiology Database |title=Callavia Matthew 1897 (trilobite) }}</ref> * ''Cambropallas'' Geyer 1993<ref>{{cite web |url=https://paleobiodb.org/classic/checkTaxonInfo?taxon_no=154091 |website=The Paleobiology Database |title=Cambropallas Geyer 1993 (trilobite)}}</ref> * ''Elliptocephala''<ref>{{cite web |url=https://paleobiodb.org/classic/checkTaxonInfo?taxon_no=366989 |website=The Paleobiology Database |title=Elliptocephala Emmons 1844}}</ref> * ''Esmeraldina'' Resser and Howell, 1938<ref name='Lieberman 1999'/> * ''Grandinasus'' Hollingsworth, 2006<ref name="Hollingsworth">{{cite journal|last= Hollingsworth|first= J.S.|year= 2006|title= Holmiidae (Trilobita: Olenellina) of the Montezuman Stage (Early Cambrian) in Western Nevada|journal= Journal of Paleontology|volume= 80|issue= 2|pages= 309–332|jstor=4095128|doi=10.1666/0022-3360(2006)080[0309:htootm]2.0.co;2|s2cid= 131683623}}</ref> * ''Holmia'' Matthew, 1890<ref name='Lieberman 1999'/><ref name="Ebbestad et al.">{{cite journal|last1= Ebbestad|first1=J.O.R.|last2=Ahlberg|first2= P.|last3= Høyberget|first3= M.|year= 2003|title= Redescription of ''Holmia inusitata'' (Trilobita) from the Lower Cambrian of Scandinavia|journal= Palaeontology|volume= 46|issue= 5|pages=1039–1054|doi=10.1111/1475-4983.00332|bibcode=2003Palgy..46.1039E |doi-access= }}</ref> synonym ''Baltobergstroemia'' * ''Holmiella'' Fritz, 1972<ref name='Lieberman 1999'/> * ''Iyouella'' Geyer and Palmer 1995<ref>{{cite web |url=https://paleobiodb.org/classic/checkTaxonInfo?taxon_no=19135 |website=The Paleobiology Database |title=Iyouella Geyer and Palmer 1995 (trilobite)}}</ref> * ''Kjerulfia'' Kiaer, 1917<ref name='Lieberman 1999'/> * ''Montezumaspis'' Hollingsworth, 2006<ref name="Hollingsworth"/> * ''Palmettaspis'' Fritz, 1995<ref name='Lieberman 1999'/> * alt=Holmia kjerulfi trilobite fossil|thumb|''Holmia kjerulfi''''Schmidtiellus'' Moberg ''in'' Moberg and Segerberg, 1906<ref name='Lieberman 1999'/>

=== Relationships within the Holmiidae === The eye ridges in Baltic and Moroccan Holmiidae (''Holmia'', ''Schmidtiellus'') are wide, have a furrow atop the ridges, and the resulting inner band merges with the frontal lobe (L4) of the glabella without an axial furrow. This is interpreted as advanced compared with the arrangement of the simple ocular lobes of Laurentian holmiids, which are separated from the L4 by a prominent axial furrow around the glabellar outline.<ref name="Hollingsworth"/>

== Description == As with most early trilobites, Holmiidae have an almost flat exoskeleton, that is only thinly calcified, and has crescent-shaped eye ridges. As part of the Olenellina suborder, the Holmiidae lack dorsal sutures in the cephalon. Like all other members of the Olenelloidea superfamily, the eye-ridges spring from the back of the frontal lobe (L4) of the central area of the cephalon (or glabella).<ref name='Lieberman 1999'/> Specifically for the Holmiidae are the following diagnostic characters. The glabella is straight-sided to somewhat constricted and mostly expands forward. The frontal lobe (or L4) is usually broad and rounded. The furrows that separate the lobes are usually curved, moderately incised, and rarely completely cross the midline. The eye ridges of Baltic holmiids are often wide with an ocular furrow, inner band merging with L4 without axial furrow. Laurentian holmiids (''Montezumaspis'', ''Palmetaspis'', ''Grandasinus'', ''Esmeraldina'' and ''Holmiella'') have unfurrowed ocular lobes separated from L4 by axial furrow. The cephalon carries so called genal spines at the corner between the half circle front/side margin and the back margin that is roughly perpendicular to the midline. These spines extend back to at least the fourth thorax segment (T4), counted front to back. The back margin of the cephalon normally carries a node or spine (or intergenal spine), straight behind the point the eye ridge is furthest from the midline or even somewhat further out. Back margin of cephalon inside the intergenal angle transverse or directed posteriorly. The third thorax segment (T3) is not larger than the neighboring segments and does not carry larger spines. Anterior thoracic pleural spines weakly to strongly thornlike except in ''Kjerulfia'' and ''Grandinasus''.<ref name="Hollingsworth"/>

== References == {{Reflist}}

Category:Olenelloidea Category:Trilobite families Category:Cambrian trilobites Category:Cambrian first appearances Category:Terreneuvian extinctions Category:Fossils of Canada