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Dicranopeltis
protaspis
Amphilichas
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ORDER LICHIDA (sensu Fortey 1997)
last revised 07
September 2011 by S.
M. Gon III
Introduction: typically spiny with densely
granulate or tuberculate exoskeletons. This is a concept
of the order that includes the Odontopleuridae and
Damesellidae, more recently considered members of a
related, but distinct order Odontopleurida.
Examine an alternate handling of Order
Lichida that does not include the odontopleurids
or damsellids.
Cephalon: opisthoparian
sutures; glabella broad, large, extending to anterior
border, unusal
lobation distinguishing a longitudinal lobe and lateral
lobes; such
lobation relatively simple (Dameselloidea &
Odontopleuroidea) to
complex with fused lateral and glabellar lobes
(Lichoidea); eyes
typically present, holochroal, usually not large;
conterminant
hypostome; typically with genal spines, sometimes
greatly extended.
Thorax: variable, 8-13 segments, usually
spine-tipped, sometimes with distinctive spines (e.g.,
Odontopleuroidea).
Pygidium: typically isopygous to macropygous, but
sometimes
short (e.g., Odontopleuroidea), otherwise often
longer than wide, with
3 or more pairs of furrowed pleurae, typically ending in
spinose tips.
Other:
similarities in protaspides of Lichidae and
Odontopleuridae suggests
common ancestry, but this relationship controversial
(see
Classification Notes below).
Occurrence: Middle Cambrian to Devonian
(Frasnian)
Superfamilies: Lichoidea, Odontopleuroidea,
Dameselloidea.
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Arctinurus
Lichakephalus
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Superfamily
Lichoidea
Introduction: medium to large trilobites,
typically surface sculpturing involves two size classes
of granules or tubercles.
Cephalon: opisthoparian sutures, glabella broad,
extending
to anterior border, with unique complex structure
(lateral glabellar and
occipital lobes often fused with each other and with
cranidium), hypostome conterminant, large.
Thorax: Typically 11 segments, pleurae initially
horizontal, bend
retrograde at fulcrum, end in free points.
Pygidium: large, usually flattened, often with 3
pleural pairs of leaflike or spinose structures.
Other: wide
doublure bearing terraced ridges.
Occurrence: Middle Cambrian to Upper Devonian
Families: Lichakephalidae, Lichidae
Genera: Lichakephalidae: Acidaspidella?,
Acidaspides?, Acidaspidina, Archikainella, Belovia,
Bestjubella, Brutonia, Colossaspis, Eoacidaspis,
Lichakephalus,
Lichokephalina, Metaacidaspis, Paraacidaspis,
Usoviana.
Lichidae: Acanthopyge (=Euarges), Akantharges,
Allolichas, Amphilichas (/Paralichas; /Platymetopus; =
Acrolichas; = Kerakephalichas; = Tetralichas),
Apatolichas, Arctinurus (/Oncholichas; /Platynotus;
/Pterolichas), Autoloxolichas, Borealarges, Ceratarges
(/Arges), Ceratolichas, Conolichas (=Cypholichas),
Craspedarges, Dicranogmus, Dicranopeltis
(=Dicranopeltoides; =Nonix; =Raymondarges;
/Trachylichas; =Tsunyilichas), Echinolichas,
Eifliarges, Gaspelichas, Hemiarges (=Choneilobarges),
Homolichas, Hoplolichas (=Cyranolichas),
Hoplolichoides, Jasperia, Leiolichas, Lichas
(=Apolichas; =Autolichas),
Lobopyge (=Belenopyge), Lyralichas, Mephiarges,
Metaleiolichas, Metalichas,
Metopolichas (/Metopias; =Holoubkovia;
=Macroterolichas), Neolichas, Nipponarges,
Ohleum, Oinochoe, Otarozoum, Paraleiolichas,
Perunaspis (=Nitidulopyge),
Platylichas (=Lingucephalichas), Probolichas,
Pseudotupolichas (=Arctinuroides),
Radiolichas (=Diplolichas; =Septidenta), Richterarges,
Rontrippia, Terataspis,
Terranovia, Trimerolichas, Trochurus (=Corydocephalus;
=Plusiarges; =Makromuktis),
Uralichas (=Bohemolichas; =Platopolichas),
Uripes.
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Kettneraspis
protaspis
Diacanthaspis
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Superfamily
Odontopleuroidea
Introduction: typically very spinose and densely
sculptured trilobites.
Cephalon: convex; glabella tapering forward or
subparallel,
extending to anterior margin or nearly so, less complex
lobation than in
Lichoidea; eye ridges run from anterior end of glabella
to palpebral lobe;
opisthoparian sutures, often placed on sutural ridges;
distinct notch in
margin of free cheek adjacent to where anterior sutures
cut cephalic margin;
facial sutures secondarily lost in some genera; short
genal spines typically
present.
Thorax: 8 – 10 segments; tips of each bear 2 – 3
pairs of spines (anterior pair often difficult to see,
ventrally directed); often with symmetrical row
arrangements of pleural spines or tubercles.
Pygidium: micropygous, short, transverse, with 2
– 3 axial
rings (3rd often faint), one or more pairs of tubular
border spines, the
largest of which connected to first axial ring by
prominent ridge.
Other: doublure
not
wide nor bearing terraced ridges as in Lichoidea;
protaspides similar
to, but about half the size of those of Lichida.
Occurrence: Upper Cambrian to Upper Devonian
(Frasnian)
Families: Odontopleuridae
Genera: Odontopleuridae: Acanthalomina, Acidaspidella?,
Acidaspides?, Acidaspis, Anacaenaspis
(=Bruxaspis), Apianurus, Archaeopleura, Boedaspis,
Borkopleura, Brutonaspis, Calipernurus, Ceratocara,
Ceratocephala (=Bounyoungia; =Onchaspis;
/Trapelocera), Ceratocephalinus, Ceratonurus,
Chlustinia, Dalaspis, Diacanthaspis, Dicranurus,
Dudleyaspis, Edgecombeaspis, Eoleonaspis
(=Bojokoralaspis), Exallaspis,
Gaotania, Globulaspis, Hispaniaspis, Isoprusia
(=Mauraspis), Ivanopleura,
Kettneraspis (=Grossia), Koneprusia, Laethoprusia,
Leonaspis (=Acanthaloma),
Meadowtownella, Miraspis (=Elbaspis), Ningnanaspis,
Odontopleura, Orphanaspis,
Periallaspis, Primaspis, Proceratocephala
(=Drummuckaspis), Radiaspis (=Xanionurus;
=Charybdaspis), Rinconaspis, Selenopeltis
(=Languedopeltis; =Polyeres), Selenopeltoides,
Sinespinaspis, Stelckaspis, Taemasaspis
(=Gondwanaspis; =Snoderaspis), Uriarra, Whittingtonia.
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Damesella
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Superfamily
Dameselloidea
Introduction: similar to Odontopleuroids,
surface finely to
coarsely granulose.
Cephalon: opisthoparian sutures; glabella narrow
or broad based, tapering forward, less complex lobation
than in Lichoidea; genal spines
typically present.
Thorax: with up to 13 segments, less specialized
than in Odontopleuroidea, more as in Lichoidea.
Pygidium: longer pygidia than in
Odontopleuroidea, with more axial segments; tapering
axis, thicker-set marginal spines, 1-7 pairs of
pleural pygidial spines of varying length
Occurrence: Middle Cambrian to Upper Cambrian(?)
Other:
protaspides of Damesellidae and Odontopleuridae similar.
Family: Damesellidae
Genera: Damesellidae: ?Adelogonus, Ariaspis,
Bergeronites (=Spinopanura), Blackwelderia
(=Parablackwelderia), Blackwelderioides, Chiawangella,
Cyrtoprora, Damesella (=Hybowania; =Eodamesella),
Damesops (=Meringaspis; =Paradamesops), Dipentaspis,
Dipyrgotes, Drepanura, Duamsannella, Fengduia,
Guancenshania, ?Hercantyx, Histiomona, Jiawangaspis,
Liuheaspis, Metashantungia, Neodamesella, Palaeodotes,
(=Pseudobergeronites), Paradamesella (=Falkopingia),
Parashantungia, Pingquania (=Oxygonaspis), Pionaspis,
Protaitzehoia, Pseudoblackwelderia, Shantungia,
Stephanocare, Taihangshania, Taitzehoia, Teinistion
(=Dorypygella), Xintaia, Yanshanopyge.
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Selenopeltis
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ADDITIONAL CLASSIFICATION NOTES FOR
LICHIDA:
Fortey (1997) lists Lichoidea, Odontopleuroidea, and
Dameselloidea as
constituent superfamilies of Order Lichida. Some
treatments recognize
an Order
Odontopleurida separate from Order
Lichida, although protaspid similarities suggest the two
are ultimately
related; both lichid and odontopleurid protaspides possess
distinctive
paired spine or tubercle patterns on cephalon and
protopygidium, have
an anterior border, distinct axis, and marginal spines on
protopygidium
(Thomas & Holloway 1988). However, Whittington (1956)
points out
that the lichid protaspis is twice the size of those of
odontopleurids.
Odontopleurid protaspide hypostomes also lack slits on the
lateral
hypostomal border borne by those of lichids (and
styginids).
Despite both groups being
ornamented with tubercles and typically spiny, the
lobation of the
glabella, complex in both, show some
major differences in origin (lichid lobes arising
from the axial
furrow,
while odontopleurid lobes arise via standard glabella
development
(Tripp
& Evitt 1981). Whittington (2002) adds that the
Odontopleuridae
and
Lichidae differ in several other respects, including
ornamentation (primarily
granules
and tubercles in lichids, spines in odontopleurids),
extent of ventral
calcification
(extended doublure with terrace ridges in lichids, not
developed in
odontopleurids),
and hypostome size (larger in lichids). Even if both
lichids and odontopleurids are kept in one
order
(Lichida), it is acknowledged that despite their common
origin, they
have
diverged significantly in the course of their evolution.
The primitive
family Lichakephalidae includes genera that have
affinities
to Lichidae and others to Odontopleuridae, and some
workers (e.g.,
Shergold et al 2000) do not accept the synonymy of
Eoacidaspididae and
Lichakephalidae. Examination of Cambrian
lichakephalid/eoacidaspidid
genera Acidaspides
and Acidaspidella (Bruton
1983)
suggest they should be assigned to Odontopleuridae. This
suggests that the Lichakephalidae as listed above is
paraphyletic, and
not all members should be included in Lichoidea. If
Lichakephalidae is
monophyletic, then it serves as the uniting taxon for an
Order Lichida
that includes both lichoids and odontopleuroids; if not,
then some
genera should be assigned to Odontopleuridae and others
retained in
Lichakephalidae.
Fortey (1990) included
the M-U Cambrian Damselloidea as a sister group to
Odontopleuroidea, citing several characters: 1) narrow,
ledglike
anterior cranidial border, against which glabella abuts
sharply, 2)
deeply scribed, inflated eye ridges, 3) transverse
hypostome with wide
posterior border, 4) spinosity, especially on pygidium and
anterolateral margins of free cheeks, 5) occipital
tubercle without
thoracic homologs 6) 3rd glabellar lobe reduced or absent.
Presence of Acidaspides
praecurrens
and 'odontopleurid protaspides' in Upper Cambrian
Kazakhstan
attributable to dameselloids further strengthen this
relationship
(Fortey pers com 2007). Primitive Ordovician
lichakephalids (e.g., Lichakephalus) bear
pygidia that are unlike typical lichids,
some being arguably styginid-like, however Whittington
(2002) suggests that
a close relationship between lichids and styginids appears
unlikely. If so, then sister taxon to the primitive
Lichida might
be found in the paraphyletic Redlichiida.
In 2005, Pollit et al applied cladistic analysis to the
Superfamily
Lichoidea (Lichidae+Lichakephalidae) and proposed
subfamilial and
tribal subdivisions for the family Lichidae. Click here
for a cladogram
of Lichoid
relationships from the Pollit et al 2005 paper
(warning, large graphic file).
Expanded and complete genera listings for the families
above adapted from Jell & Adrain (2003).
For details on Lichida ontogeny, see Dr. Rudy
Lerosey-Aubril's page: Larvae
& Trilobite Orders: Lichida
Bruton, D. 1983. Cambrian origins of
the odontopleurid trilobites. Palaeontology
26(4):875-85.
Fortey, R.A. 1990. Ontogeny, hypostome attachment, and
trilobite classification. Palaeontology
33:529-76.
Fortey, R.A. 1997. Classification. In: Kaesler,
R. L., ed. Treatise on Invertebrate
Paleontology, Part O, Arthropoda
1, Trilobita, revised. Volume 1: Introduction,
Order Agnostida, Order Redlichiida.
xxiv + 530 pp., 309 figs. The Geological Society of
America, Inc. & The
University of Kansas. Boulder, Colorado &
Lawrence, Kansas.
Jell, P.A. & J.M. Adrain. 2003. Available generic
names for trilobites. Memoirs of the Queensland
Museum 48(2):331-553.
Pollit, J.R., R.A. Fortey & M.A
Wills.
2005. Systematics of the Trilobite families Lichidae
Hawle & Corda,
1847 and Lichakephalidae Tripp, 1957: The application
of Bayesian
inference to morphological data. J.
Syst. Pal. 3(3):225-41.
Shergold, J.H., R. Feist & D. Vizcaino. 2000.
Early Late Cambrian
trilobites of Australo-Sinian aspect from the Montagne
Noir, Southern
France. Palaeontology
43(4):599-632.
Thomas A.T. and D.J. Holloway. 1988. Classification
and phylogeny of the trilobite order Lichida. Phil.
Trans. Royal Soc. London
321:179-262.
Whittington, H.B. 1956. Beecher's lichid
protaspis and Acanthopyge
consanguinea (Trilobita). J.
Paleontol. 30:1200-04.
Whittington, H.B. 2002. Lichidae
(Trilobita): Morphology and classification. J.
Paleontology 76(2):306-20.
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