# Molaria
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{{Short description|Extinct genus of arthropods}}
{{Automatic taxobox
| fossil_range = {{Fossil range|Cambrian Series 2|Burgess Shale}}
| image = USNM PAL 57688 Molaria spinifera.jpg
| image_caption = ''M. spinifera'' lectotype
| image2 = Molaria spinifera.png
| image2_caption = Life restoration of ''M. spinifera''
| taxon = Molaria
| authority = [Walcott](/source/Charles_Doolittle_Walcott), 1912 [{{cite journal|author=Walcott, C. D.|year= 1912|title= Middle Cambrian Branchiopoda, Malacostraca, Trilobita and Merostomata|journal= Smithsonian Miscellaneous Collections|volume= 57|pages= 145–228|url=https://books.google.com/books?id=KRwrAAAAYAAJ&dq=Molaria+spinifera&pg=PA200}}]
| type_species = '''''Molaria spinifera'''''
| type_species_authority = Walcott, 1912
| subdivision_ranks = Other species
| subdivision = '''''Molaria steini''''' Peel, 2017
}}
'''''Molaria''''' is a genus of [Cambrian](/source/Cambrian) [arthropod](/source/arthropod), the type species ''M. spinifera'' is known from the [Middle Cambrian](/source/Middle_Cambrian) [Burgess Shale](/source/Burgess_Shale). 144 specimens of ''Molaria'' are known from the Greater [Phyllopod bed](/source/Phyllopod_bed), where they comprise 0.27% of the community.[{{cite journal|last1=Caron |first1=Jean-Bernard|last2=Jackson |first2=Donald A.|title=Taphonomy of the Greater Phyllopod Bed community, Burgess Shale|journal=PALAIOS |volume=21 |issue=5 |pages=451–65|date=October 2006|doi=10.2110/palo.2003.P05-070R|jstor=20173022|bibcode=2006Palai..21..451C |s2cid=53646959 }}] A second species ''M. steini'' was described from the [Sirius Passet](/source/Sirius_Passet) in Greenland in 2017.[{{Cite journal|last=Peel|first=J.S.|date=2017-06-30|title=Molaria (Euarthropoda) from the Sirius Passet Lagerstätte (Cambrian Series 2, Stage 3) of North Greenland|journal=Bulletin of Geosciences|pages=133–142|doi=10.3140/bull.geosci.1658|issn=1802-8225|doi-access=free}}]
== Etymology ==
The genus name derives from “Molar”, the name of a mountain peak east of the [Valley of the Ten Peaks](/source/Valley_of_the_Ten_Peaks) in [Alberta, Canada](/source/Alberta%2C_Canada),[ which in turn was so named by James Hector in 1859 because the shape of the mountain resembles a molar tooth. The specific name of the type species, ''spinifera'', comes from Latin ''spinifer'' “spine-bearing.”][{{Cite web |title=Molaria spinifera |url=https://burgess-shale.rom.on.ca/fossils/molaria-spinifera/ |website=The Burgess Shale |language=en-US}}]
== Description ==
USNM_PAL_272105_Molaria_spinifera.jpg|Specimen of ''M. spinifera'' showing the long telson
Molaria size comparison.svg|Size comparison of the two species
The body of ''Molaria'' consisted of a head shield ([cephalon](/source/Cephalon_(arthropod_head))), a trunk consisting of eight sections ([tergites](/source/tergites)), and a [telson](/source/telson), which included a short ventral spine and a long posterior spine. Three pairs of legs were beneath the cephalon and another eight pairs were attached to the trunk. Eyes were lacking, but a pair of short [antennae](/source/Antenna_(biology)) was present on the cephalon. Specimens of ''Molaria'' ranged from 8 to 26 mm in length from cephalon to telson, with the posterior spine slightly longer than the body length.[{{cite journal|last=Whittington|first=H. B.|title=Rare Arthropods from the Burgess Shale, Middle Cambrian, British Columbia|journal=Philosophical Transactions of the Royal Society B: Biological Sciences|date=1981|volume=292|issue=1060|pages=329–357|doi=10.1098/rstb.1981.0033|bibcode=1981RSPTB.292..329W|doi-access=free}}]
== Affinity ==
''Molaria'' was superficially similar to ''[Habelia](/source/Habelia)'', another Burgess Shale arthropod with a long tail spine, but which possessed 12 trunk tergites.[ It is currently considered a member of [Artiopoda](/source/Artiopoda).]