ertebral column of the triassic fish si uà1ci1z{is iactino?terygii) and

Maggio1990
THE !'ERTEBRAL COLUMN OF THE TRIASSICFISH SI UÀ1CI1Z{IS
IACTINO?TERYGII) AND ITS STRATIGRA"HICAL SIGNIFICANCE
ANDRXA TINTORI
Ket@i|
Trissi., ,Àúl')E
(^dinopErysii), vdtcbnl column, S@tigràphy
À':zrub, Escmpllriappdcncntialgenqcs.,'crúrtsonorclativadertcconuri in rúm il TriNicoe
ìn tutisli imbienti bmin2lico. fordxli anosicidcl NÒrìcoddh reddeocciden'
sirinvcnsonofrcqucnlcmente
hh- ^l;cio qua;ro spcic po$ono venirctacilmenrcindivìduatcsopúrtutto in bdc alle criàÙsislichedclh
più sviluPPalc
chc ùellesPccicprcnoriche-Li lùnsbcza
coloonavdEbrule:ruùc do$rano infaitiprczigapolìsi
reldivr di quc$o procGo ò ndsimt nellcduc sPcic dclNorico suPcriorc'.iggiunecndounti!nghczzr Pari
Talc sienifidtivr vriuione viere msa tóntadvanentcin rchzionccón un
elilmÒno seiscgnenrivÒdebmli.
deiPbalidalror,la"dúnntc ilNo'ico Porta
inpoúne cànbimcnto nclh faun! ! pesci.La cónprrsr in rs
dl; sclituzionc dì gian pre dci pìccolip6ci chc ccliúivino il cibo Principalcdci &,t.'l'l'rr' I !ólidofori,
úino infùiìn sndodi nuotaremcsliodciSubholoseicdci Chondrorei chePoPoÌùlno ì nri.idsici prima
del No.ko stso. Esendo h nololosh di sa,t.r!rr' sìà ben dbra ilh Prcdazioic'ì'unìcocrnbildento
uú magsior
possìbilepor4aconsisicrcin ùn irrobustinenrodelh colo.navrÈbnlc dlo sopo di svìluPPare
J foscro $$úzì'lmste
potenzialitàdiscatto.tr infaÌti phlsibilc chc le modalid di Pr€dazio.cdi&d.,,t
;imili a guelledcgli "luali lùcci c búmcudr. Lhurcre evidcnziah pdsibìlnà di ùn ùtiìizzosfatisrafico,sir
di .!,zt úrr, pù lo mcnonel No.ico
p!re informrlc,ddh lu nshezarehtiv. delleprezisàpofisi
belónging
,-lLtzd The Norhn bedsofthc Soulhdn CalúÈous ^lPs havevieldsdt ledt folr species
wlich, in Òichofthdd nominalsPcci6,4
ro S.,'.:/dr', Thet veftcbril .oluù. h6lrrgc p.úzygapoPhyscs,
Bin adiffer;nt dativelenelh. Thclúer is invÒ^clyProPoilioial!o ase in fi(, the vo!n86! two coevdspe'
.t lcdt six lines s long 6 a vrebùl semcni Sucha mtrPjcuous
ci6 haverhe lo.ec$ praezygrpophyss,
changein an otrer*iri conscnativcecnus,is hùe relncd to a najor ichthyófrunalbruk thr! sawthc flórish'
'rhe
rchtivc lensrh of the PneygapoPhyss can bc i vcry ùsefùl$'rtiSraphicrl
i4 ol r\e Iholidaph.ide.
mans, *ledr ìn theNorian (UPprTri6sic).
lntroduction.
The chondrosteangems Saaichdry is one of the bescLnown Triassicfishes.
Detailcdpapershavebeenpublishedby Stensiò(1925),Lehnan (19s2),Griffith (19s9,
fron all over
1962,1977)and Rieppel(19ss);severalauúors havc describedspecimens
-DipailineÙodi 5cÈ.4 dclh Tùd dell'Unive*itàdcsliStudidi Milano,via Mangi4alli34' 20133Mi
94
A. Tintai
the world (Beltan 8. Tinrori, 1980).Unfortunately,most of rhe nominal speciesare
often a singletooth. As a consequcnce,
bascdon vcry scantyor fragmentaryspecimens,
the talonomy is vcry conplicatedand will certainlyneeda revision,which is beyond
rhe aim of this paper.For rhis reasonI referto my new materìalas9ancDróy sp. A and
hunchtbls sp.R (kon thc BergamoPreaìps):rndSaaúchtlr)rsp.C (fróm the PreoneVaf
leyi seeTinúri er aL.,198s).The specimenfrom the Garza Vallcy is ascribedto S
seefeldsnsis
Strard, 1928on the bxseo{ a comparisonwith topotypical specìmens.
In the BergamoPreaLps
severalspecimens
o{ &arlclr}1r hrvc beencollected;they
arc more or lesscomplete,and one of them is, as far as I know, thc longestknown
Saurihirls specincn,its standardlength reaching165 cm. Thc disrinctionol two spccies amongthcm is duc to diffcrencesin squamationand in the skull post-orbital
length-orbitaldiameterratio. Furthermore,Srrdcl:r{p sp.B shorvsa rnoredenderbody
than Saurícbthysp.A, eventhough the elementsof the vertebralcolumn are srouter.
BehanandTinrori (1980)haverlreadybriefly describeda specirnenof Sazrlcll4s sp. A,
poìntingour the dermocranialcharrcters.
cspcciaLly
Up to thc prcscntday only a body fragnent oi a small saurichthydis available
from the Prcone Vallcy localities,ìts vertebralelementsbeing clcarly different from
Again, only body fragmen$of ! seflderur Strand
rhoseof borh the Bcrgamospccìcsare taken into account,both frorn thc Seefeldbedsand the GarzaValley locality- S.
rdeÉllerrúis the only Norian species
thxt hîs b€enrcliably dated,beingfound with conodonts which jndicate a lowerrnostAlaunian age (rr'rp?rt6 ammonitc zonc, sensu
Krysq,n, 1983;Donofrio ct al., in prcss).
A closcinvesigatìonof the vertebraÌcolumn leadsto new interestinganatomical
as rvcll as to a key to Norian kzacútfor spccies,alsousefulin stratigraconsiderations
phv.
A detaileddescriptionof the vertebralcolumn has been given onLy for a fcw
Saurichtb)cspecics(Srensió, 1925;Lehman,1952tGriffirh, 1959,1962).According to
thcseauthors,the Saurichthywrtebral elementsshow a sìmilar morphology in mosr
spccies.Paircd ncural rrches,which are presentall rlong the body, are couplcdwith
haemalarchesare
ossifiedhaemalrrchesonly behindthe pelvicfins. Pairsof subsequent
alwaysfused,so that then numberis only half of that of corresponding
neuralelenents.
However Rieppcl (1985),giving a dcrailedrcstorationof thc axjal skeletonof rhree
Ladinirn (Middle Triassic)species,
describedfor S.rrio&ii (B€llotti)à co,npleteserìesof
haemalelementsthat neverfusedin couples.The other two Ladinianspccicshad a simi'
lrr pattern, confirmcd by personalobscrvationson undcscribedspecimens.
Thìs con
figurationseemsto be resrrictedto thesethreespecjes,
eventhough it nay alsobe pfc'
sentin BreaisauichtbyoxerrBcltîn(Bcltin, 1972,pl. 1a,fig. B).
Though either the genc.alshapeof thc dcrrml skulLcovcringof rll the Norian
specnnens
closeìyresemblethoseol most of the Sauncbt$'sspccìes,
a detailedobsera
rr^sn ft, sMnkbs
95
tion o{ my materìalpoints ouc a peculiarcharacterwhich is unknown in all thc pre
vìouslydescribedspecies.
This is the prcsenceof very well dcvelopedpraezygapophyses
(sensuRieppel,1985;anteriorprocessor zygapophyses
of Stensió,1925),comparablein
sizc to thc neural spines.Praezygapophyses
are known only ìn few specicslS. ozara-r
Stensìófrom the Lower Triassic (Stensió,1925) ar'd S. cuionii, S. maoocepbahs
(Deecke), and especiallyS. costaqaanwar Rieppel from the Ladinian (Rieppel, 198s)1,
but rheyneverreachthe ertensionseenin the Norian specimens.
Abbreviatìons:MCSNB = Museo Civico di StoriaNaturale,Bergmo; PT and
=
GT
Dipartimcnto Scienze dellaTerra, Milano, field cataloguqMFSNU = Museo
FriLrlanodi StorìaNaturale,Udine; IGPUI = Institut fùr ceologie und Palàonrologie
der Universitàt Innsbruck; na : neural arches;ns = neural spines;p = praezygapophyses;
s = scales.
P a l eo n t o l o g i c aI d e sc r l p t l o n s
saurlchlhyssp.A (Fig.14,ll).
Sauicbtlry sp.A (two specimens,
PT2 and MCSNB 6170,from uppermosrCalcaredi Zorzino, upperNorian) hasvery stoutvertebralelementswìth neuralarchesand
spineslike those af S. kr.LnberyeîiSchlosser(Griffith, 1962),exceptÍor the praezygapophyses.
The neuralspinesare distallytruncated,wide and very closeto eachother,
so that, vithour suitableprepìration, rhe praezygapophyses
are seldomvisible.These
laner also arc blunt and laterallyflattened,with no possibiliryof relativelongitudinai
shift in eachpair. They are moreor lcssaslong astheir reLativeneuralspines.The angle
formed by the praezygapophyses
with the body axis is about lo", wider úan in
9r nir'tf,ssp.B. Neur.rl.piner"how; romcwhrrw,dcrrnsle.,round3s".
Saurlchthys
sp.B (Fig.18,2,lH).
In one specimenoÍ hari.hir.f sp.B (MCSNB 1906from uppermostCalcaredi
Zorzino, upperNorìan) nore than 1s7neuralarchesareprcscnt,smalland subqua&ate;
their sizeincreases
ratherquickly backto the middle of the abdorninalregion,then only
very slightly. Thc neuralspinesfollow the sameparrern,being 8.1 mm long near rhe
30th vertebralsegment,12 mm at the Sothand 13 mm in rhe caudalpeduncle.Neural
spinesare very slender;they slopebackwardsfrorn rhe posrelo-dorsal
corner of each
neuralarch at a 35+5' anglewith rhc body axis.Neural archeslie closeto eacholherj
spinesarewell spaced,so that praezygapophyses
arelargelyvisible.
The praeTjlSapophyses
occur aLl along the vertebral column. Since they are
directedforwards,I presumerhey rnighteitherbe missingor be reducedin ùe foremosr
vertebralsegments.
Unfortunately,becar:se
of the dermalbonecovering,it hasbeenim
possiblcto observerhis regionin any ofthe preparedspecimens.
The praezygapophyses,
like the ncural spines,increasein lengrh backwardsfrom the anterior region, from
96
Fig. I
Conpúiro' ol 'dúbml colùmn elenen6 in: A) s""'.rú)t sp ^, sPccimc^P12, s.l. 90o mm,
ddril of rhc po$dor abdodinalesion; anerior to thc lcftr x 1.q B) 9/r./rrlr sp. B, spccnnen
MCSNB19o6,
s.l, + 5oomm, ddÀil of rle anerio. abdomin.lr€ion; anerio. ro rhc rlght; x 2 7; C)
&,r.rrrrr sp. C, speinc. MISNU G!1300,s.l.unknovni r.R.ior 10ihc righr;x 11.2.
Tìi^'n fth Sdrfihthy'
97
about 12 mm to 16.5mrn nearthe 8othvertebralsegment.They aresplintlike, tapering
very gently from their base,slopingforwardsat an angleof about 15' in the anlerior
lies very
abdominalregion and 12'in the pelvic fins region.Each praezygapophvsis
from
one side
only
elements
proximal
region,
so
that
in
its
ones,
to
the
adjacent
close
gently
v'avv:
this
have
been
transversally
must
region
thcy
are visiblc. In the sime
eLe
paired
Distallv
both
elements.
the
might have causeda mcdian contact between
partìal
of
a
probably
to
shifring
duc
mentsof the pairs are cornpletelyvisible.This is
neuralarchrow duringfossilization(Fig.2).
EE
Fig. 2
s,/'.,órr sp. D. Schcn*ic .stón!ìon ofr Èasnent oflhc vokbúl colum. in thc abdominalrc_
gion, bÀcd hainly on spcinen MCSNB 1906;MtÚior rÒ the risht A_B)Ìn life re$onlion (A'
l.Errlvicwi B, dosd view in which thclcft sìdeshowsonly nelrtl arch6and 5Pin6 and lhe risht
full blackis for r conPletevrebml segrenr' C_D)Afto Ío$il
sidcshowsonlypraezysapophys6ì
iadon (C, heraì view in which no right neuftl sPins hNeben shownrD, do6al vièwi fuìl blrck
is for rish! vùebmÌ eleders).
A. Tiî1tori
98
apIn the posterior caudal region, borh neural archesand praezygapophyses
parenrlyform a lower angiewith the body axis,but no detailedobscrvxtionscould be
However,this is consistentwith dxtaconcerning.tconayyamo'
doneon my specimens.
a2).
Jl'(Rieppel, 198s!fig.
Saurichthyssp.C (Fig. 1C, 3D.
This spcciesis so far known only by onc specimcn (MFSNU GP1800)
from ?reoneVallcy (LowerNorian).
It has subquadrateneural archeswith slighdy concavcanterior and posterior
at the basc
edges.The neuralspinesarc short and eachone lies in a shallowdepressÌon
Thesel:tter look very massivc,bcing rnediallywell
of the following praezygapophysis.
and the ncural spinesslopeat a very lov
expanded.Sinceboth the praezygpophyses
anglefrom the neuralarch,the vertebralcolumnresultsto be a compact,lo\{ structure,
' arecloselyuedro eachoth,r.
whereelemenr
1928(Fig.3G).
SaurichthysseefeldensisStrand,
This specìes
(specimens
GTl and IGPU1P902a)hasneuralarchesand spincsvery
are shorter,meîsuring
similar ro those of Sa îichthfs sp.A, but its pr:ezygapophyses
neuralspines.Thc anglebetq,eentheselatter and the body
abourhalf the corresponding
sLopeat l0' in thc kalian specimentnd at 45' in
axis is 3s'-37'; thc praezygapophyses
the Seefeldone. Suchdifferenceis clearlyrelatedto thc fact rhar the two studiedfrignents belongto differentpartsof rhe fish body.
Conclusions.
Sauicbthy is a long ranginggenus,spanningat lexst30 M.Y. in the Triassic(Belanatomicalpartern changes
tan 8r Tintori, 1980).During this long period the generaL
in rhe light of the results
only in detailsof squamrtionrnd dermalbones.Nevertheless,
:rt leasrduring
of the presentsrudy,the vertebralcolumn is involvedin najor changes,
the Norian.
havconly doublehaemalarchesposterìor
As alreadypointedour, severalspecìes
praezygapophyscs.
All the Lower Triassic
pelvic
with
very
small
fins,
absentor
ro rhe
speciesshov this pattern (Stensió,1925;Lehmîn, 1952).Another group of specieshas
and single haemal archesall along the body, with well
srnall praezygapophyscs
have
developedhaernalspinesposteriorto the pelvicfins (Rieppel,198s).Nofirn species
becamelonger
no haernalarchesin {ront of thc pelvìcfins and their praezygapophyses
.",1l^naÉr
/1,,.;. o rhlr sloè
may be consideredas a very im
The abnormalgrowth of the praczygapophyses
portant derivedcharacrcr,probablyconnectedto a major changein ihe svimming.
rÍi8nfuh sú*htbs
99
o
9
o
o
9
.
ó
J
..2
o
9
2
o
9
i
FG.3
?,are
- ThedóBalvcilcbraldcmonBin someof lhebs! known&,rcrry speci6;aneriorto thcleft.
Lr 9ní&ùr's onat"'SteÉ;6, Àftù SEnsiò,1925;
B)'4siùtbs nzddsgeffi'ùlivclerú, aft( Lèhnrn, 1952;
C, 9qtúttry' útúqun6,'
Rieppel,dtcr Rieppel,1985;
D) gli.ttttr
eàù;ílBellótrù, afir Rieppel,1985;
E) e'îichtt ,\ sùìotzd' (Brcnn),rftr Grimth, 1e5e;
r) brnúbyf
sp. t,
G)esncbbRn.f.uds;ssÎl^rdl
tt g,i.tùr\ sp.Bl
1)g'à.lrt
16sp. tr.
îhe SanichthF morphology suggestsan &orlike attack parterni with a well
devclopedforward lunge.Iqpisosreas
showsa similar body shape,but its predation is
characterized
by sidewaystriking. Its ability to bend suddenLyìs probably due to the
presence
vertebrae,a unjquecharacterof Lepisotteas
of opistocoelus
itselÍ.
So,why did thìs changeoccuronly in the Norìan, rhusnearthe end of the history
genuslActually,ìt is coevalwith a major ichthyofaunalchange.The
ofthis conservative
Pbolidophoridae,ìn fact, were increasingin variety and numbcr so much that they outnumbered,by the end of this stage,all the other small fishesot slhich kurbhthy
100
A. Tintori
preyed;durìngthe precedingTrìassictime they were mainly "subholosteans"
(Rieppel,
198s),vorse swimmers than the Phalidolúorídae.hîúcbtlr)t hxd, by th^t tnne, acquired
a highly specìalized
shape;it is possiblethat, to be still competjtivein rhe predrtion, its
inner structureshad to bccomcstronger,
A first appearance
of this processis scenin S.castquanosasfron Lower Laóinian
(Rieppel,1e8s).Nevertheless
it secmsto fail: specicssuchas S. caionii aîd S. ru ao.
cEhalas,knawn from most of the Ladiniatr(pers.obs.),show lessdevelopedpraezy
gapophyses(Rieppel,198s) and Carnian specieshave no praezygapophyses
at all
(wonn);
1e5e
pers.
'trioLat
ts
Griffith,
and
obs.,
and
S.
calcautus
Griffith;
Grìffìth,
Í5.
19771.
The definite increasein the praezygapophyses
sizestartsonly with the Norian
Sauríchtlrysp. C and reachesits maxirnumin the rwo Bergamospecies.
In Sauibtllts
sp. C praezygapophyses
are as long as only one vertebralsegment,in S.reeflleNr they
are three ro four tirnesand in Satricbthy sp.A and B up to six*even times.The hypothesizcdlink betwccnthe sizeof praezygpophyses
and the growìng of the pholidophorid populationcannotbe dcfìnitclyproved,but i appcarsa phusiblc solutionto thc
whatever the causeof the process,rh9 continuousincreaseof the relativeLength
ln Norian Saurícbiry praezTgapophyses
can representa usefulstratigraphicaimeansin
rhis stage.Body fragmentsof Sauichtlrlsare comnonly found in Norìan basinalblack
sedimentsand lenglh of the praezygapophyses
canbe easilymeasuredafter a short preparation.The facrthat biostratigraphical
rneansin sirnilarenvironmen*arev€ry scarce,
increases
the irnportanceof praezygapophyses
evolutionin Norian Sazri,rÀrfor.
I am s! clul to G. Mu$io, Udinc, rod R. Brandncr,Innsb.uck,lor thc lorn olspccimcnsin then c1.c.
C- PdGnon (London),R. Nunall (Edmonton),H.P. Schuhze(Lrwreo@)sivc n.$imuhting idc6 ibout this
p+c.. Pho.osrrphicrcproduclions!ú by G. Chiodi rdd drrwing by D. C.str MÙerirl frotu Lónblrdy hs
bccn collcctcdb), thè rulho. dlring neld vork súppoiredby 1 40% MPI gftnt (TriNico ^lpi Meridiomli e
Mednrraneolto C. RosiRoncbetiì.Milano-
LITEIìATUlìE
CITED
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Aftes Rdlcelona,v. 41, pp. 179-325.22pl., n fig., Rarcelona.
Beltm L. 3. Tintori A. (1980) ' The genùs Sd'tùcbtlrs (Pil6, ActìnopterysiD durjns the
Gondwanz.Perìod.Plac. rifrh Int. Ganduan t $rnp., pp.53's9, 2 fig., lìotterdamDonofrjo D.A., Poleschi$ki lf. & Brandncr R. (in pres) - Conodontcn ru dcn Seefcl<lcr
Schìchten(Hîuptdolonjt, Obernor) und ihre stridsraphischenlùllikatione!. CeolPaàont. M;t r.. In \sbtuck.
Trisícftù hw;cbthy
101
criffirh J. (1959)- on rhe anatomy o{ two saurìchthyid îjsles, Sd!Íicbtl\'s stríalatw (Brom) and s
cftknii (Belloni). Proc, zool, Soc,Landor, v,r32, pp, 587-606,London.
Griffith J. (1962)- The Triassic fish k$ichtlry kranberyn;SchloseL Paleontolog), !.5, n 2, pp.
344-354,
3 fig., LoDdon.
Giffith J. (1977)' The Upper TrìNic fjlhs from Polzbe€ bei Lll z, AÌ$tria. Zool.l. Linnedn
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Ostn. Ak. lYís. kbàf [email protected]., v. 5, pp. 7 -16, Wrcn
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Patterson C. (1968)- The caudalokeleronin the Lowcr Lia$ic Pholidophorid fishet. Btil. ar. Mn.
5 pl., 12fi9., Londorl
N. H. (Geolost,v.16, pp.203-239,
tuelpel O. (1985)' Die TÌirfauna der Tssiner Kalkalpell- XXV. Die Gattung Sdhicrtbs (Pjlcs,
Actioopt€rysii) au dcr mnderen Triar des Monte San Giorgio, Kanton Tsin. .t @.
Pdkont.Abb.,v. Lo9,pp. L-103,9 pl.,51fig., Barel.
tr. llatgl. So. VeEi. Hdnd..v.2, pp.1-267,34
SteruióE. (1925)' Triî$ic Fìshesfroo Spitzbergen.
pl., s8 fis., Stocklolm.
Tinrori A., Múcio G. & Nardon S. (1985) - The Triassic fossl filhc! localitiet in ltaly. Ri?,. h
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