Mesones Group

The Mesones Group is a Cambrian geologic group in Spain. It preserves numerous soft-bodied and hard-shelled taxa such as echinoderms and trilobites. It is often stated to contain the Mansilla, Murero and Valdemiedes Formations, however just as often the Murero Formation is used to refer to the entire group, with the main lagerstätte being placed interchangeably in Mansilla, the “broader” Murero or occasionally a broader Valdemiedes.^[1]

Mesones Group
Stratigraphic range: Wuliuan-Drumian
Type	Group
Lithology
Primary	Shale
Location
Region	Zaragoza
Country	Spain

Paleobiota

Color key Taxon Reclassified taxon Taxon falsely reported as present Dubious taxon or junior synonym Ichnotaxon Ootaxon Morphotaxon		Notes Uncertain or tentative taxa are in small text; crossed out taxa are discredited.

Paleobiota
Genus	Species	Higher taxon	Notes	Images
Ctenoimbricata	C. spinosa	Echinodermata	Most basal known echinoderm, completely bilateral unlike modern forms[2]	Reconstruction of Ctenoimbricata
Dibrachicystis	D. purujoensis	Rhombifera	Bears unusual appendages, suggesting blastozoan and crinoid “arms” come from the same source[3]
Vizcainoia	V. moncaiensis	Rhombifera	Formerly placed inside Eocystites[3]
Protorophus	P. hispanicus	Edrioasteroidea	Earliest known member of Isorophidae[4]	Fossil of Protorophus
Graciacystis	G. ambigua	Cincta	Basal cinctan, known from over a hundred specimens of different ages[5]
Aragocystites	A. belli	Edrioasteroidea	A relatively basal edrioasteroid, related to Cambraster[6]
Cambraster	C. tastudorum	Edrioasteroidea	First edrioasteroid found in Spain[7]
Protocinctus	P. mansillaensis	Cincta	Earliest known cinctan genus[1]	Protocinctus fossil
Gogia	G. parsleyi	Eocrinoidea	Oldest records of the genus from Gondwana[8]	Fossils of G. parsleyi
Rhopalocystis?	?R. mesonesensis	Eocrinoidea	Unclear whether it even belongs to the genus[9]
Gyrocystis	G. platessa, G. erecta, G. testudiformis, G. badulesiensis?[10]	Cincta	A relatively diverse cinctan	Gyrocystis fossil
Caryosyntrips	C. cf. camurus[11]	Panarthropoda	Frontal appendages (the only part known) formerly identified as the lobopodian “Mureropodia apae”[12]	Fossil frontal appendage of C. cf. camurus (=Mureropodia apae)
Tuzoiidae indet.	Unapplicable	Hymenocarina	Only known from carapaces, alongside an indeterminate euarthropod[13]
Wimanicharion	W. matthewi[14]	Bradoriida	Also known from Sweden and Canada
Naraoia	N. sp.	Naraoiidae	Some of the first evidence of Naraoia in Europe[15]	N. sp. fossil from Murero
Peronopsis	P. ferox, P. insignis,[16] P. longinqua[17]	Agnostida	An incredibly common agnostid from all over the world	P. bidens fossil from Utah
Condylopyge	C. cruzensis[17]	Condylopygidae		Cephalon of C. rex from the Czech Republic
Megagnostus	M. sp	Agnostida	Less common than Peronopsis, makes up fewer of the enrolled specimens in Murero[16]
Bailiaspis	B. tuberculata	Conocoryphidae	Unclear whether any Mesones specimens belong to the species[18]	B. dalmani from the Whitesands Bay Formation
Bailiella	B. tenucincta	Conocoryphidae	A blind trilobite[19]
Conocoryphe	C. heberti	Conocoryphidae	An eyeless trilobite.[20]	C. heberti fossil from Murero
Cornucoryphe	C. schirmi	Conocoryphidae	An unusual trilobite with a horn in the middle of its head[21]
Eccaparadoxides	E. pradoanus E. mediterraneus	Paradoxididae	Very abundant in Murero, had unique specialisations for enrolment[22] and shows unusual variability[23]	E. pradoanus fossil from Murero
Pardailhania	P. hispida, P. multispinosa, P. sdzuyi	Solenopleuridae	Used for stratigraphy in Murero[24]
Solenopleuropsis	S. marginata, S. thorali	Solenopleuridae	Exhibits circular enrolment alongside Pardailhania[25]
Dinesus	D. truyolsi[26]	Dinesidae
Alueva	A. undulata	Ellipsocephalidae	Exhibits paedomorphosis[27]
Wronascolex?	?W. sp	Palaeoscolecida	Formerly placed within Palaeoscolex[28]	Palaeoscolex fossil
Marocella	M. morenensis	Helcionelloidea	Found in other localities across the world[29]
Trematobolus	T. simplex	Obolidae	Synonymous with the purported “bivalve” Lamellodonta[30]
Brahimorthis	B. alvaroi	Brahimorthidae (Orthida)	Relatively underived member of the genus[31]
Nisusia	N. sp[31]	Kutorginata
Serpulidae indet.	Unapplicable	Sabellida	Encrusted on shells[32]
Leptomitus	L. lineatus, L. conicus[33]	Protomonaxonida	L. lineatus specimens may not belong to the species[34]	L. teretiusculus from the Maotianshan Shales
Crumillospongia	C. mureroensis	Protomonaxonida	Bears larger pores than other members of the genus[35]	C. frondosa from the Maotianshan Shales
Eiffelia?	?E. sp	Protomonaxonida	Only known from six-rayed spicules[36]	E. globosa fossil from the Burgess Shale
Chancelloria	C. sp	Chancelloriidae	Also only known from spicules[36]	C. pentacta fossil (from the US?)
Psammosphaera	P. sp	Astrorhizida (Foraminifera)	Mainly encrusted on shells[32]